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vehicle demonstration of 2 stroke engine brake in a heavy duty truck.

by:Trust&Deal Breeding Equipment     2020-03-07
Abstract: With the combination of engine braking technology and vehicle braking technology, heavy vehicle trains have been developed in the past 20 years.
The Jacobs Vehicle system has developed high power density (HPD)
Engine brakes that increase the deceleration force, especially at low engine speed.
The system works by converting the engine from 4 stroke to 2 stroke during positive power to slow down the power.
This has more than doubled the energy at the cruise engine speed, reduced the speed reduction of the control vehicle, compensated for the reduction of natural vehicle deceleration due to increased aerodynamics and friction, as engine redundancy becomes common, the same vehicle deceleration power is achieved with a smaller alternative engine.
This paper describes lessons learned from a vehicle demonstration project recently undertaken by Jacobs, including performance, durability, integration with engine power systems, control development, calibration, air system management and transient
Quote: Howell, T. , Swanbon, B. , Baltrucki, J. , Steines, A. etal.
, \"Vehicle demonstration of 2 stroke engine brake for heavy truck\", SAE Int. J. Commer. Veh. 9(2):2016,doi:10. 4271/2016-01-8061.
Introduction compression-
Release engine brake or \"Jack brake\" for slow down heavy machinery such as heavy trucks and construction/agricultural equipment [1].
In many markets around the world, engine brakes have become standard equipment, as it is able to provide a faded free parking capability while reducing the wear of wheel brakes.
The compression release engine brake works together with the positive power valve train of the engine. through the selective control of various engine valves, the diesel engine is effectively converted from the power generator to the power consumption air compressor.
Several fuel efficiency trends drive performance improvements, especially when engine rpm is low: * reduce aerodynamic resistance and rolling resistance reduce natural deceleration of trucks * compared to large displacement engines, engine reduction reduces total deceleration power * deceleration acceleration promotes operation at low engine rpm to reduce if no downshift * quality reduction due to its quality and cooling assembly, loss associated with the transmission system increases the requirement * to promote legislation that allows higher truck GVW in many areas * the reduced freight time required to remain fast and competitive increases the desire for higher downhill speeds * in keeping in the process of NOx conversion, the result of the post-processing system is efficiency, it is necessary to improve the deceleration performance of the engine, especially in the case of low engine speed.
The market and vehicle selection European fleet often specify the drive system slow speed device, which shows that people have an understanding of the value of the high vehicle slow speed device.
The kinetic energy of the vehicle is converted to heat by a hydraulic turbine connected to the transmission system, and the transmission system slowing acts.
The heat generated in the hydraulic fluid dissipated in the engine cooling system.
While the drive system slacks offer a higher speed performance than the standard compression release brakes, they are an expensive option that adds considerable quality to the vehicle and in the long2].
Compared to the standard CR brake, the 2-stroke engine brake provides a higher deceleration power within the engine speed range with little loss and no increase in the heat input of the cooling system, exceeding the standard CR brakes, and greatly reducing the cost and system complexity of the andriveline speedometer.
JVS selected Mercedes Actros of 1845 LSN, 4x2 specifications as the basic vehicle (
Figure 1, table 1)
Demonstrate 2 brake technologies.
This makes a comparison with the production hardware on the truck that the jvs has already provided on the integrated platform with the CR brake and drive system slowing option.
This was done without Daimler\'s help, with the aim of having the joint venture publish the test data and get the voice of customer feedback from multiple shares --holders.
Compression release engine brake or Jack Brake [R]
It is a common equipment in vehicles with more than 30 tons.
The engine brake provides additional braking force for heavy vehicles, thus reducing the heat distribution on the vehicle service brake.
Typical diesel compression release engine brakes work by starting one or more exhaust valves near the dead center at the top of the piston (TDC)
In the compression stroke.
When the piston is close to the HKTDC of the compression stroke, the exhaust valve is opened and the high pressure air in the combustion chamber is discharged (Figure 2).
Releasing the compressed gas into the exhaust device prevents the energy stored in the compressed gas from returning to the piston in the subsequent expansion stroke.
This net energy loss is called \"engine deceleration\" and slows down the vehicle.
The valve movement of the 4-stroke engine brake is shown in figure 3. the compression release exhaust valve lift is 0 ℃, and the brake gas recycling valve event is located at the center of the bottom dead angle, so that the charge in the cylinder increases the exhaust manifold when the intake valve is closed.
Fuchs et al describe the engine braking thermodynamics of standard 4-stroke and 2-stroke braking2].
A standard compression release brake, as many in today\'s production, follows a 4-stroke engine cycle with a compression release event occurring after the compression stroke, resulting in the crankshaft turning every 2 times (see Figure 3).
2 stroke compression release brake has a compression release event in each HKTDC event.
This is achieved by disabling the main intake and exhaust valve events and starting the valve in order to achieve the engine brake event in each rotation of the crankshaft (see Figure 4).
Therefore, the valve event that occurs in the 2 stroke brake is twice that of the 4 stroke brake.
This leads to an increase in deceleration power, especially at the low engine speed at which the engine works during the vehicle cruise.
A key aspect of developing effective deceleration performance is the interaction between the engine valve movement and the engine starting system.
The level of lift that can be achieved has a very large impact on the available deceleration power, as the increased traction mass in the cylinder is compressed, resulting in an increase in pressure during compression events.
The turbochargers are usually optimized around positive energy cruise conditions, which results in the turbine requiring more enthalpy than when the engine is braking because there is no heat generated by combustion during the deceleration process.
This causes the turbocharger to work in an area of the turbocharger map during engine operation, resulting in a low level of supercharging at low engine speed.
2 stroke engine brake engine running, mass flow is much higher than standard compression release operation, resulting in compressor running at low engine speed to increase boost and mass flow compared to 4 stroke CR brake, thereby significantly improving the engine speed at low engine (Figure 5).
With the increase of low speed deceleration power of the engine, in order to achieve the desired deceleration performance, the requirements for deceleration are reduced, which reduces the fuel usage used in the deceleration process to accelerate the engine to match the shaft speed, due to the low running of the engine, the driver\'s comfort is improved and the possibility of overspeed of the engine is reduced by selecting an inappropriate proportion.
Control strategy benchmark in order to understand the requirements of HPD engine brakes, JVS conducted a benchmark study on US freighters Cascadia and UK Actros.
Freighters are easier to provide early information on how vehicles use engine brakes.
For example, Figure 6 shows the use of the engine brake during the upgrade of the AMT request.
By applying the engine brake after the transmission is turned off, the engine speed will be reduced to the target engagement speed in a shorter period of time, thus achieving a faster shift event.
The engine brake solenoid signal was used before the last refueling event, but before the engine brake valve was moved, due to the delay in the hydraulic system associated with the engine brake drive.
The front engine brake solenoid activates the first 3 cylinders for the AMT upshift event.
This requires a quick application of the engine brake, when the truck completes the shift event, there is no risk of refueling due to the cylinder shutdown.
For high and medium braking operations, start the engine braking on 6 cylinders (
Front and rear solenoid).
The difference between high and medium braking is based on the lifting level of the valve position.
Since the location of the exhaust gas recycling valve is controlled by Daimler\'s proprietary CAN protocol, an alternative supercharged control method is required.
For low braking, it was found that the engine brake activation was different between the purchased freighter and HPD vehicle.
The freighter applies the front engine brake to achieve low braking, while the Actros provides low engine braking for the rear 3 cylinders through the rear solenoid.
Therefore, the control strategy requires the ability to independently control the front and rear solenoid during braking.
Considering the key operating modes observed in the vehicle, the hydraulic system needs to have the following operating modes: 1.
6 cylinder 2 stroke engine brake mode.
Brake mode of the first 3-cylinder 2-stroke engine 3.
2 stroke engine brake mode on rear 3 Cylinder 4.
Engine braking without valve stop on the first 3 cylinders (for upshift)
Starting from the benchmarking vehicle, the following requirements are put forward for the braking control strategy: 1.
Start the engine brake in 6 cylinder operation and control the boostpressure to achieve high, medium braking.
This was later modified to provide unlimited control between high and medium braking levels using the potentiometer 2 installed by adash.
Start the engine brake in 3 cylinder operation (front or rear)
And control to level 3 of the target.
Only the first 3 engine brakes for the upper 4 start.
Do not activate the engine brake under any other operating conditions. Additional use of the engine brake identified in the vehicle, for example during parking, DPF regeneration is not included in the initial development of the demo vehicle
HPD hardware design and packaging 2 stroke engine brake hardware as shown in Figure 7, including 2 additional Rokers, deactivated Bridge, bias spring rod and additional solenoid compared to standard CR braking.
Other standard engine components such as Cam, rocker shaft, main active rocker arm machine and engine wiring harness have been modified.
The two-stroke hardware is designed to encapsulate into the existing om471 overhead with minimal modifications.
Some modifications need to be made, such as shortening the length of the engine valve, modifying the additional machining of the valve cover and the Cam carrier.
Brake pads for engine (Figure 8)
Traditional engine braking techniques include an executive mechanism piston to engage the brake cam, which is extended using engine oil pressure when the solenoid valve connects the brake circuit to the engine oil Road.
The hydraulic lock behind the actuator piston is implemented using a control valve that acts as a check valve when braking, however, when the solenoid takes the oil pressure out of the brake circuit, open a drain channel, this channel allows a quick oil drain from the actuator piston.
When the actuator piston is extended, the brake rocker drives an engine valve through the bridge pin.
Deactivated Bridge (Figure 9)
When in an external position, the wedge mechanically locks the positive power, thus preventing the external piston from collapsing in the hole of the body during the valve drive.
When the oil pressure is delivered to the bridge through the drilling hole in the main active rocker of the Elephant Foot, the inner piston is pushed down, which allows the wedge to be forced into the groove on the inner piston, when the rocker transfers motion from the cam profile, the outer piston is able to collapse inside the bridge body, thus deactivating the valve.
By eliminating the oil pressure, the internal piston is tilted upwards, making the wedge re-
When the cam is located on the base circle, engage with the shell, causing the valve movement to be reactivated.
Use performance simulation to optimize valveprofiles to maximize engine deceleration power while keeping the engine at an acceptable limit.
The model of the baseline engine is related to the measured dyno performance data (Figure 10)
It is also used to design the new valve profile to achieve the target performance.
The valve profile is converted into a cam profile to ensure that the required valve lift is achieved without endangering the piston\'s contact with the valve.
The interaction between the valve lift and the turbine is essential to hinder performance, and changes in the valve lift can cause the valve train to overload.
The initial way to control the booster level is to turn off the exhaust gas recycling path (
Daimler for lifting control)
The butterfly valve is used after the exhaust gas recycling cooler and the booster is controlled by adjusting the waste door.
Based on this control method, the first iteration of the valve profile was developed.
The valve configuration file in this iteration and the related control strategy, that is, through the lifting control of the waste gate, are only installed on the truck for testing.
The second iteration of the valve profile studies the control of supercharging through exhaust gas recycling and exhaust gas gating, however, this is a higher risk approach because of the modeling complexity of asymmetric turbines, therefore, the exhaust manifold of the first 3 cylinders is maintained at higher pressure to drive the challenge of exhaust gas recycling for wastegate and control EGRpath without access to the Daimler CAN protocol.
The second iterative cam profile and the associated exhaust gas recycling control strategy are not installed on the truck for testing in this paper, but the dyno results for this setting are included in this paper.
The load value in the worst case is used for durability analysis of valvetrain components such as fatigue and contact stress assessment.
These designs are optimized to withstand high load conditions associated with engine braking operations.
The hydraulic layout hydraulic system designs 5 solenoid as shown in Figure 11 in order to be able to realize the operating mode described in detail in the system requirements section.
As shown in Table 2, these devices need to be applied in different operating modes.
In order to achieve a reliable system, the order of disabling the main events of intake and exhaust and enabling the events of exhaust and braking is carefully selected, and vice versa.
GT-optimized design
The kit simulation model that ensures the design of the valve movement sequence.
Activate the brake event before disabling the main event during the brake turn-
Turn on and enable the main event activation before the brake event is deactivated during braking-
In order to avoid exceeding the cylinder pressure limit, it is necessary to close to ensure that the valve is opened during the transient period.
As shown in Figure 12, this order is achieved by hydraulic and mechanical delays.
When braking turns
Open, first power the solenoid valve, so that the pressure oil into the engine brake hydraulic circuit.
The oil then engages the control valve in each brake rocker and rolls out the actuator piston.
The delay associated with the engagement control valve and the extended actuator piston results in a delay in the pressure rise of the main event rocker, so that the internal piston movement is delayed, resulting in a delay in the major event deactivation after the brake movement begins.
When braking turns
Off, solenoid valve off
Power on, so that the pressurized oil is discharged from the brake hydraulic circuit, and reduce the pressure in the hydraulic circuit.
When the pressure is lower than the design level, the spring pushes the inner piston back to its original position to re-
Lock the external piston on the bridge that reactivate the main event.
This process is faster than removing the control valve, so the brake valve movement is disabled after restarting than the main event.
If the system fails, causing the exhaust main event to remain disabled when the brake valve movement is not activated, the exhaust brake valve will always open a small amount due to the failure
Safe cam profile to protect the engine by preventing excessive cylinder pressure. The fail-
The safety cam profile is obtained by the brake gas recycling event during the forward power exhaust stroke, where the lift is higher than the valve gap in the exhaust system (
So higher lift than the other 3 brake cam events)
When the executive mechanism piston retracts.
Therefore, if the main exhaust event has not been opened, the brake rocker will open the valve, I . E. e.
, If the exhaust main event is still disabled.
Perform fatigue strength and wear tests on physical components before mounting to the engine.
Engineering tests were carried out to evaluate the deceleration performance and to obtain data related to the performance simulation, verify the control operation, and calibrate the operation of the engine brake.
After successful calibration, the engine performed a short endurance test and component inspection to confirm reliable operation before installation to the vehicle.
Several problems were found during the test, requiring implementation of solutions, such as increasing the strength and the profile in The Bridge pin, to prevent fatigue failure due to edge loads during the tilt of the bridge, during the tilt of the bridge, analyze the inner hole of the bridge pin to avoid contact, resulting in scratches on the top of the stem, due to the manufacturing tolerance change of the cam timing, resulting in insufficient occlusion of the intake brake movement, the actuator piston stroke increases.
Control Development custom HPD control unit (HCU)
Developed to provide driving signals to five brake solenoid in HPD (see Figure11)
And the butterfly valve in the exhaust gas recycling path.
HCU uses a commercial Haltech ECU to provide closed-loop control of boost by modulation of waste.
Different target promotion tables for different deceleration levels (
3 cylinder operation or 6 cylinder operation)
Selected by HCU, the voltage input is provided to haltech through the gear selection input.
The target lifting value changes with the engine speed (
Built from crank position sensor)
Based on calibration defined through engine dynamic testing to ensure compliance with engine limits. In six-
Cylinder deceleration operation, by selecting the highest \"gear\" and the selected adash position, the boost level can be changed between the fully opened wastewater gate to achieve the lowest possible deceleration, 6 cylinders
Potentiometer installed.
At the same time, the exhaust gas recycling path is closed by an additional butterfly valve, which is in series with the production exhaust gas recycling valve ordered by Haltech ECU, in order to achieve supercharging control by only treating waste.
A key requirement of the HCU control strategy is to be transparent to the production truck control strategy to avoid the error code affecting the deceleration or positive power operation.
To achieve this, theHCU intercepted the front lineand rear-
Solenoid signal from production MotorControl Module (MCM)
This usually turns on the production engine brake, provides electrical load to simulate the standard solenoid, and controls the two-stroke engine brake based on the state of these signals.
The Haltech ECU controls the waste gate of the engine through the variable voltage of the HCU.
Figure 13 is a schematic diagram of the HPD system that illustrates the connection of MCM and other engine components to the HCU.
The level required for HPD braking is determined by the presence or absence of the frontand rear-
Solenoid signal, plus the settings of the dashboard-
Potentiometer installed.
A short summary
Period on the front line-
Solenoid signal causes very low braking of up-
Shift activity in frontor rear-
A separate solenoid signal causes a low level brake and, depending on the setting of the potentiometer, the detection of these two signals results in a low level brake to a high level.
During the deceleration operation, the potentiometer can be adjusted to adjust the braking level in order to maintain the target speed under driving conditions.
Due to the delay of boost rise, once any signal from the front or rear solenoid is detected, the butterfly valve is turned off to be able to boost rise when braking is needed.
Butterflyvalve starts fast enough, and when braking, it runs fast enough (i. e.
During the promotion activities)
There is no problem with MCM control strategy.
When the front solenoid signal is detected separately, hcu immediately activates solenoid 5 (see Figure 11)
, Engage the front of the exhaust brake, turn off the exhaust brake butterfly valve.
HCU waits for the specified up-
The shift duration before activating solenoids1 and 2 is a 3 cylinder deceleration.
If the vehicle moves up, the front solenoid signal turns off while moving up
Shift duration causes the HCU to turn off the engine brake by turning the signal off to solenoid valve 5 and turn on the butterfly valve in the exhaust gas recycling system.
If after up
Shift duration, front-
The solenoid signal is still there, but not behind-
Solenoid signal, HCU command low braking using the front set of valves: solenoid 1 is activated (
Front group with valve)
After solenoid 2 (
Front group of exhaust valve)isactivated.
There is a short delay between activating solenoid 1 and solenoid 2 to ensure that the exhaust valve never brakes before the air inlet, in order to avoid excessive load on the intake valve defined in the hydraulic simulation and confirmed in the engine dynamic test. If the rear-
Without the front, the solenoid signal will open and hcucommand will brake low with a set of valves at the back: solenoid 3 (
Rear group that controls the intake valve)
Then solenoid 4 (
Control the rear group of exhaust valve)
The intake and exhaust valves are enabled to provide a 2-stroke brake action. If both rear-and front-
The solenoid signal appears at a similar time, as shown in Figure 14, the solenoid 5 is activated, the secondary exhaust gas recycling valve is closed, the solenoid 3 is activated immediately, followed by the solenoid 4, 1 and 2 are separated by calibration delay.
Finally, the voltage request lift control sent to the Haltech ECU, as per the 6 cylinder operation, in the 6 cylinder operation, the level of lift pressure can be changed through the dashboard --
Potentiometer installed.
Once the system brake is high, it will remain in a high braking state until the front-and rear-
The solenoid valve signal disappeared.
It was observed in the test that when the system provided a high level of deceleration power, MCM seemed to find that the performance was much higher than expected.
So, to reduce performance, theMCM removes one of the solenoid signals.
This is not an ideal effect, as it causes the engine to overspeed on steep hills as slow speed performance drops.
Therefore, MCM is covered and maintained at a high braking level before the brake request is completely removed.
The consequence of this is that the driver is unable to move directly from high deceleration to low deceleration.
The software in HCU implements the above logic in astate machine with the following states: * HCU is running but does not require braking-
No brake solenoid * Up-shift wait-
Drive solenoid 5 and exhaust gas recycling butterfly valve * open solenoid during calibration duration-
Open the appropriate brake solenoid * high brake according to the order and timing in the calibration-
Using six cylinders, the exhaust gas butterfly valve and the Haltech-
Control boost pressure * low braking-
Use the first and last three cylinders and exhaust gas recycling butterfly valves to slow down the operation.
In addition, several states reflect various fault situations: * failure during system initialization * failure during construction-
In the test, run in half
The second interval * improvement of the health status of the continuous inspection system
Output of pressure * A value-of-
From analog input * A to software failure-
Undefined state achieved during execution * other faults that assist in debugging during integration of HCU with other parts of the system, when HCU is run by a specified signal of an rgb led on one card in HCU, each of these states is indicated.
The software includes calibration values such as the order and time of opening each brake solenoid, the coefficient of the conversion equation for reading the boost pressure, the boost pressure limit for different brake levels, and the limit of the simulation value-to-
The digital input of each analog signal received by HCU.
The electronic hardware of HCU includes an off-the-
Custom PCB for signal regulation and power conversion and LED for communication of HCU status, for example, what went wrong in the event of a failure, or which solenoid is currently powered.
The micro-controller has input for the front-and rear-
To determine the required operation of the engine brake, check the output status and various analog signals monitoring the booster pressure, as well as a series of discrete inputs used to check the HCU output status.
Mux manually operates multiple analog signals with multiple channel interfaces through a single analog port on the micro-controller.
The output includes braking-
Analog output of solenoid driver and Haltech.
Figure 13 shows the I/O of the HCU in and out of the rest of the HPD system.
Thesolenoid drivers are \"smart\" because they are up to date-limited,fault-
Tolerate and provide fault status to the micro controller.
HCU can run on 12 [V. sub. DC]or 24 [V. sub. DC].
Also developed a test set to provide the front endandrear-
Solenoid Valve signal and booster pressure.
This unit also includes the leds connected directly to the signal, so it is possible to verify what is on or off and confirm the software-
Controlled LEDs on HCUitself.
The test set is used for bench testing, and the HCU software and hardware can be fully tested before being integrated into the truck.
DYNO test and results the engine was tested on the 900 hp automotive dyno including HPDhardware and control systems.
The engine uses a dvrt meter to capture the entire valve lift and a prox probe, by modifying the spring retainer to incorporate the target to capture 1 air inlet for each cylinder and the air outlet temperature for each cylinder on one exhaust valve, the cylinder pressure in cylinder 1 and the standard dyno instrument (e. g.
Pressure and temperature along the air system, oil pressure and temperature, coolant temperature, etc).
Data is recorded at a high speed of 0.
25 degree increment and low speed data at 10 hz.
The control device is calibrated to provide maximum delay within acceptable engine limits, to generate calibration for moderate and low-level deceleration, and to verify transient events in the hydraulic on and off of engine brakes, thus calibrate the delay in the control to ensure proper sequence start/stop and brake valve lift of the positive power valve movement.
As mentioned earlier, two Cam iterations are developed that require different boost control methods, and the results are shown in Figure 15, as well as the baseline deceleration performance.
First time (
Calibration of trucks, purple diamonds)
Initial camshaftand boost control was installed in the vehicle by closing the exhaust gas recycling valve and adjusting the exhaust gas discharge position.
The second iteration (
New calibration, blue X)
Completed in dyno and Cam correction and improvement in the boost control strategy by using exhaust gas recycling to adjust the boost only at high deceleration level, the exhaust gas terminal used at low deceleration level delays the power supply.
This level of hardware and software was not installed in the vehicle prior to vehicle testing, but after the topic of this article, the vehicle will be upgraded.
Both the truck and the new calibration provide more than double the performance of the baseline compression release brake up to 16 rpm.
The second iteration (New calibration)
With a minimum moreretarding power of 50%, up to 2200 rpm, the 1300 can be obtained at 611 KW rpm with a moderator of more than 2500 rpm.
Calibration has also been developed to provide control of the deceleration power level of the vehicle, as shown in Figure 16.
Through the potentiometer installed in the instrument panel, the non-variable operation of the 3 cylinders and the boost operation of the 6 cylinders are controlled.
The installation and integration of vehicle integration and calibration hardware and control requires additional consideration in addition to dyno integration.
One of the main questions is whether the truck will mark a fault because of an unexpected situation.
Therefore, starting with the control installation, the system is installed in a gradual manner, but the engine valve column is not changed to verify the electrical connection, and the replacement of the load in the circuit is acceptable.
The additional controls are located in the cab for easy debugging and protection of the environment.
Valvetrain hardware is installed on the truck and additional butterfly valves are installed after exhaust gas recycling cooler and additional exhaust gas gate pneumatic control valve.
No problem packing extra items around the engine.
With the vehicle operating in positive power mode, the research on braking performance has begun.
Several unexpected behavior of the vehicle requires subsequent modifications to the control device, including: * If the truck is in a 6-cylinder deceleration state and the base brake is pressed, the truck will become a 3-cylinder deceleration.
This is very disturbing when going down the mountain, as the deceleration performance decreases with the light application of the base brake.
* Trucks occasionally switch from 6 cylinders to 3-cylinder braking (
Reduce the number of solenoid according to MCM requirements).
Again, this is not advisable when going down the mountain.
It is believed that this may be due to the fact that truck sensing exceeds the protection capacity and the reduction of deceleration by default.
In order to overcome these situations, if the input signal from MCM operates from a request of 6 to 3 cylinders without a period of time for the insect retina request, the software is modified in 6 cylinder operations.
While this does address both issues, it also allows the driver to change from high latency to low latency without fully turning off the brakes first.
The boost control interface for 6 cylinder operation is located on the dashboard and the driver can easily reach the same side of the standard vehicle deceleration control (
Stem on steering wheel column).
The potentiometer is a 270 degree range with a good resolution that enables easy identification of current settings and quick change of set points.
Due to the high deceleration power, it is easy to let the truck drop to a very low rpm when it drops in a less aggressive grade at low speed (such as 6. 7%)
At this time, the brakes will be turned off in order to prevent the engine from turning off.
Once the engine brake is turned off, the vehicle will start to accelerate, which will increase the engine speed and cause the engine brake to turn back on.
As a result, vehicles tend to move from deceleration to taxiing every few seconds.
To reduce this, the calibration is adjusted to provide low deceleration performance below 1000 rpm for a smoother transition.
In some cases, it is not possible to improve the driving ability due to the failure of the Jacobs Vehicle system to enter the vehicle or engine calibration.
For example, a prompt
If the power from deceleration to positive power suddenly changes from high deceleration power to positive power due to the rapid shutdown of the engine brake;
It is necessary to prevent refueling and braking.
Can improve driving ability by adding a slight deceleration performance before refueling.
This is simulated by manually reducing the boost to reduce the magnitude of the transmission and resulting in a great improvement in the tipin feel.
Downshift events during deceleration need to be significantly improved, as these events include a rapid transition from high deceleration power to zero deceleration, followed by high deceleration power.
Transmission calibration is set to reduce delay performance, which can cause excessive deceleration when not needed due to additional delay power.
In general, this can be overcome by using AMT to drive a truck in manual mode, thus selecting inappropriate gears for each level under given driving conditions.
One challenge is that in the long deceleration event, the truck shift strategy is not optimized and the manual transmission is not allowed to shift more than one ratio at a time to make full use of the high engine speed range 2 strokeengine brake to provide the deceleration torque, at the same time minimize shift events.
The HPD results for truck preparation and testing were carried out in Milbrook ProvingGrounds, UK, and the site includes a range of grades, including 6. 7%, 11.
6%, 14%, 17% and 21%.
HPD trucks are compared to the same production trucks with high brake option compression release brakes.
The two trucks were loaded to 40,000 kg GVW on the 6 th.
Class 7%, the production vehicle will remain at 35kph in gears 7, while the truck will not escape, although in gears 8 the vehicle cannot be controlled.
HPD vehicles slow down vehicles at 8 thgear above 50kph.
Due to the corners on the track, it is not possible to test higher speeds in 9 thgear.
At level 11%, production vehicles maintain 30 kph of gears 6 at an engine speed of 1700 rpm.
The HPD controls the speed of the 7-gear 40kph at a similar engine speed of 1700 rpm, providing a 30% downhill speed increase.
The difference at level 21% was very significant, and HPDvehicle controlled the downhill speed at 16 kph in the fourth gear.
In order to prevent the engine from speeding during the descent process, the production vehicle needs to apply the basic braking multiple times.
While this situation is likely to be rare during driving, the controls provided by HPD provide important confidence in engine braking.
For the driver, the margin provided by the engine speed when controlling the vehicle is critical to the vehicle\'s driving ability and sense of control.
Under normal circumstances, in order to achieve the engine speed of the rpm on 1800, Downshift-
2000 rpm is required to control the speed drop.
However, if the selected ratio does not provide sufficient deceleration performance, the base brake is used to control the speed of the vehicle to prevent the engine from speeding. With only 300-
The 500 rpm range is very important before speeding occurs, because it is not possible to downshift when you are on the mountain.
In a two-stroke brake that provides high power at low engine speed, the engine speed is usually around 1500 rpm, providing about 800 rpm before speeding occurs.
This extra profit allows the driver to choose a higher ratio and avoid speeding while maintaining a higher downhill speed.
Upward movement is usually similar to a baseline vehicle driven only through a solenoid 5 using a treatment with a 3-cylinder brake.
The duration of these events is controlled by MCM.
Conclusion The integration of the two-stroke engine brake into the production vehicle has successfully demonstrated the benefits of increasing the deceleration power.
The high level of continuous deceleration torque within the engine speed range makes downhill descent faster and avoids the use of base brakes to prevent the engine from speeding, even in extreme deceleration conditions.
The challenge of integration involves calibration of transmission shift points and tips
Due to the increase in deceleration power, in school.
Enhancements in this area require vehicle calibration that is not feasible in this project.
The current first iteration of future work 2 stroke hardware and calibration gets 440 KW reduction power at 2300 rpm, and the hardware and control of the second iteration will be installed on the truck, the card car will produce a deceleration power of 564 KW at 2300 rpm, and the calibration will remain at a constant torque level above 1300 rpm.
Continuous high torque levels and variable controls are expected to enhance downhill control over the current collector.
The tip will continue to be calibrated-
If trying to enhance this feeling as much as possible, though it is unlikely that significant improvements will be made without a base engine calibration.
To evaluate which one has the best user interface, a different method of driver interaction with variable boostcontrol will be tested.
The demonstration trucks will be tested in several locations near ardeurope to increase feedback from the fleet and dealers to assess interest in technology and enhancement areas.
Finally, drive-
Through the NVH test, the truck will be continuously slowed down at high speed and in urban conditions compared to the currently produced engine brakes. REFERENCES [1. ]Cummins C. L.
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Cycle engine brake for medium and heavy duty diesel engines, \"SAE Int. J. Commer. Veh. 6(1):34-
46,2013, doi: 10. 4271/2013-01-0586.
Thomas Howell, Bruce Swansea, Justin baruki, Alan Stines, Nancy Neve, and Biao Road Jacobs Vehicle Systems
Contact information for Tom Howell Thomas.
@ JakeBrake.
Bruce swanben Bruce
Swanbon @ JakeBrake.
Baltrucki @ JakeBrake.
Alan Stines Allen
Steines @ JakeBrake.
Nancy Neff NancyNeff@JakeBrake.
Com standard Land standard. Lu@JakeBrake.
The authors of Com ackknowledge want to thank Jacob\'s vehicle systems management for their support in this project, specifically SergioSgarbi and Steve Ernest, as well as the help of the marketing department in the demo campaign, in particular, Hickory Schmidt, Paul Parry, and Lauren Lily.
Finally, the author thanked the late Neil forth for his contribution.
Definition/abbreviation AMT-
Automatic manual transmission CR-
Exhaust gas recycling-
Exhaust gas recycling ECU-
HCU-electronic control unit-
HPD control unit HPD-
High power density MCM-
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