KR20180088518A - Method and apparatus for determining exhaust brake failure - Google Patents

Abstract

The controller of the internal combustion engine receives the request to activate the exhaust brake subsystem and, in response, activates the exhaust brake subsystem. The controller then determines that at least one parameter of the exhaust system and the inspiratory subsystem, or both, is adversely compared to at least one threshold. When at least one parameter compares favorably with the at least one threshold, the controller determines that the exhaust braking subsystem has failed. In embodiments, the determination that the at least one parameter compares adversely to at least one threshold may include determining that the back pressure in the exhaust system is lower than the back pressure threshold and / or the boost pressure in the intake subsystem is higher than the threshold Determination.

Description

Method and apparatus for determining exhaust brake failure

This application is a continuation-in-part of prior US Patent Application Serial No. 15 / 253,708 entitled "Method and Apparatus for Combined Exhaust and Compression Release Engine Braking," filed on August 31, 2016, This claims the benefit of U.S. Provisional Application Serial No. 62 / 213,002 entitled " System and Method for Controlling Backpressure and System Loading " filed September 1, 2015, the teachings of which are incorporated herein by reference / RTI > This application claims the benefit of U.S. Provisional Patent Application No. 62 / 271,272 entitled " System and Method for Determining Potential Brake Failure " filed on December 27, 2015, the teachings of which are incorporated herein by reference. Are hereby incorporated by reference in their entirety.

[0002] The present invention relates generally to engine braking and, more particularly, to methods and apparatus for combined exhaust and decompression engine braking.

[0003] Engine braking systems have been known and used for decades in connection with internal combustion engines, particularly diesel engines. Such systems include decompression brakes and exhaust brakes. These braking systems may be used alone or in combination with others.

[0004] Briefly, a decompression brake removes a load from a standard service brake by replacing the internal combustion engine with a power-absorbing air compressor using a decompression mechanism. When the decompression type brake is activated, the exhaust valves of one or more unfueled cylinders are opened near the top of the compression stroke. This releases the highly compressed air through the exhaust system with some energy returning to the piston. As the cycle repeats, the energy of the vehicle's forward motion (which is the same as that delivered to the engine through the drive train of the vehicle) is diverted, causing the vehicle to slow down.

[0005] On the other hand, exhaust brakes use exhaust backpressure in the engine to significantly increase braking force by limiting the flow of exhaust gases and increasing the back pressure inside the engine. As used herein, the engine exhaust backpressure is the pressure generated by the engine to overcome the hydraulic resistance of the exhaust system of the engine to release the gases into the atmosphere. Increased backpressure in the engine creates resistance to the pistons, slowing the rotation of the crankshafts and helping to control the vehicle speed.

[0006] As known in the art, decompression and exhaust engine brakes can be used together to achieve a significant level of braking force. Unfortunately, one of the disadvantages of the combination of decompression and exhaust braking is that overhead or valve trains, i.e., engine valves, during transient events, Such as those that vertically transmit valve actuation motions to cams, rocker arms, cam followers (rollers or flats) Is a high system load exhibited by the components of the system. One example of this is illustrated in FIG.

In particular, Figure 1 shows a control signal 104, which is used to control the operation of the exhaust engine brake subsystem, measured in seconds, another control signal used to control the operation of the decompression engine brake subsystem And a trace 102 illustrating the force applied to the valve train components resulting from the cylinder pressure in accordance with time. As is known in the art, each peak illustrated in trace 102 represents the peak forces applied to the valve train through each piston cycle of a given engine cylinder. When control signals 104 and 106, in this example, convert both the decompression and exhaust engine brake subsystems from a low state to a high state for approximately simultaneous activation, ) Results in a peak 108 after a typical decompression followed by a persistent period of abnormally high peaks 110. As a result of periods of excessively high loads 110, damage may be imposed on the valve train or overhead.

[0008] Techniques to overcome these problems will represent a welcome advance in the art.

[0009] The present disclosure describes methods and apparatuses for determining an exhaust brake failure. In one embodiment, the controller of the internal combustion engine receives a request to activate the exhaust brake subsystem, and in response activates the exhaust brake subsystem. The controller then determines that the parameters of at least one of the exhaust system and the intake subsystem, or both, adversely compare with at least one threshold. When at least one parameter compares favorably with the at least one threshold, the controller determines that the exhaust braking subsystem has failed. The determination that at least one parameter compares adversely to at least one threshold may be based on a determination that the back pressure in the exhaust system is lower than the back pressure threshold and / or a determination that the boost pressure in the intake subsystem is higher than the threshold have.

[0010] The features described in this disclosure are particularly pointed out in the appended claims. These features and attendant advantages will become apparent from consideration of the following detailed description, taken in conjunction with the accompanying drawings. One or more embodiments are now described for illustrative purposes only, with reference to the accompanying drawings, wherein like numerals represent like elements.
[0011] Figure 1 is a time plot of control signals and forces applied to valve train components in systems including exhaust and decompression engine braking assist systems and in accordance with prior art techniques.
[0012] FIG. 2 is a schematic, cross-sectional view of engine cylinder and valve actuation systems in accordance with the present disclosure.
[0013] FIG. 3 is a schematic illustration of an internal combustion engine according to the present disclosure.
[0014] FIG. 4 is a flow chart illustrating processing according to the present disclosure.
[0015] FIG. 5 is a time plot of control signals and forces applied to systems including exhaust and decompression engine braking assist systems and to valve train components in accordance with the present disclosure.

[0016] FIG. 2 is a schematic, cross-sectional view of engine cylinder and valve actuation systems in accordance with the present disclosure; As shown, the engine cylinder 202 is configured to generate positive power (i.e., combustion of fuel to drive the piston 204) and engine braking operation (i.e., use of a piston to achieve air compression) The piston 204 is repeatedly reciprocated upward and downward. At the top of the cylinder 202, there may be at least one intake valve 206 and at least one exhaust valve 208. The intake valve 206 and the exhaust valve 208 may be opened and closed to provide communication with the intake gas passage 210 and the exhaust gas passage 212, respectively. The intake valve 206 and the exhaust valve 208 may be actuated by the valve actuating subsystems 214 such as, for example, the intake valve actuating subsystem 216, the positive power exhaust valve actuating subsystem 218, And may be opened and closed by the exhaust valve actuation subsystem 220. The positive power exhaust valve activation subsystem 218 and the engine braking exhaust valve activation subsystem 220 may be integrated into a single system or may be separate from other systems in some embodiments.

[0017] The valve actuation subsystems 214 may include any number of mechanical, hydraulic, hydraulic mechanical, electromagnetic, or other types of valve train elements. For example, as is known in the art, the exhaust valve actuation subsystems 218 and / or 220 may include one or more cams, such as the one or more cams used to deliver valve actuation motion to the exhaust valves 208, Cam followers, rocker arms, valve bridges, push tubes, and the like. In addition, one or more lost motion components may be included in any of the valve actuation subsystems 214, thereby providing a valve actuation (not shown) that is typically carried by the valve actuation subsystems 214 Some or all of the motions are prevented from reaching the valves 206 and 208, i.e., the valve motion is " lost ".

[0018] The valve actuation subsystems 214 may be configured to generate engine valve conditions, such as, but not limited to, main inspiration, major exhaust, decompression braking, and other assistive valve movements The intake valve 206 and the exhaust valve 208 can be actuated. The valve actuation subsystems 214 may be controlled by the controller 222 to selectively control the amount and timing of, for example, engine valve operations. The controller 222 may include any electronic, mechanical, hydraulic, electrohydraulic, or other type of control device for communicating with the valve actuation subsystems 214, and may include some of the possible intake and exhaust valve operations Or both, to be delivered to the intake valve 206 and the exhaust valve 208. The controller 222 may control the engine speed, vehicle speed, oil temperature, coolant temperature, manifold (or port) temperature, manifold (or port) pressure, cylinder temperature, cylinder pressure, particulate information, Based on inputs such as engine speeds, driver inputs (e.g., requests to start engine braking), transmission inputs, vehicle controller inputs, engine crank angle, and various other engine and vehicle parameters And may include mechanisms that are linked to the microprocessor and other engine components to determine and select operation. In particular, and in accordance with embodiments described in greater detail below, the controller may activate the engine braking exhaust valve lift subsystem 220 in response to a request for engine braking.

[0019] As noted above, the pressure set in the cylinder 202 through the reciprocation of the piston 204 places the loads on the valve actuation subsystems 214 during the opening of the engine valves 206, 208 . For example, when the piston 204 is at or near its bottom dead center position, the pressure in the cylinder 202 may be relatively low, and when opening the valves 206, 208 , The load placed on the valve actuation subsystems 214 will also be relatively low. On the other hand, when the piston 204 is at or close to its top dead center position, the pressure in the cylinder 202 may be relatively high and when opening the valves 206 and 208 , The load placed on the movable subsystems 214 will also be relatively high. This latter scenario is particularly true when the exhaust valve 208 is initially opened when the piston 204 is very close to its top dead point, as opposed to a positive power generation operation .

[0020] Figure 2 additionally illustrates the concept of back pressure 213, in which the resistance of the hydraulic fluid flow of the exhaust system is controlled by the exhaust valve 208, in contrast to the pressure induced in the cylinder 202, As shown in Fig. As is known in the art, the activation of an exhaust braking system results in increased backpressure in the exhaust system. However, this increased back pressure can take a predetermined period of time to set. With this in mind, referring again to FIG. 1, the duration of excessively high loads 110, referred to herein as mass flow inertia pulses (MFIP), is increased backpressure, (Which would be a load applied to the first and second cylinders 218, 220), the sudden application of the cylinder pressure set by the decompression braking subsystem.

[0021] Referring now to FIG. 3, an internal combustion engine 300 is shown operatively connected to an exhaust system 330. The internal combustion engine 300 includes a plurality of cylinders 302, an intake manifold 304, and an exhaust manifold 306. As will be appreciated by those skilled in the art, the number and configuration of the cylinders 302 as well as the configuration of the intake and exhaust manifolds 304, 306 may be different from the example illustrated as a matter of design choice. Figure 3 also schematically illustrates a decompression braking subsystem 220 for activating one or more exhaust valves, as is known in the art. As a result, the exhaust system 330 includes exhaust braking subsystem 332 and, in the exemplary embodiment, a turbocharger 334, as well as general piping. As is known in the art, the turbocharger 334 is configured such that the exhaust gases (exemplified by black arrows) output by the exhaust manifold 306 are directed to the turbine 336 And a turbine 336 operatively connected to a compressor 338 that rotates the turbine 336 to operate. Exhaust braking subsystem 332 may include any of a number of commercially available exhaust brakes.

[0022] As further shown in FIG. 3, various components can form an intake system that provides air to intake manifold 304. In the illustrated example, the inlet pipe 308 is connected to a compressor 338 that provides pressurized air to a charge air cooler 312 that ultimately cools the pressurized air through the compressor outlet pipe 310 Provide ambient air. The output of the charge air cooler 312 routes the cooled and compressed air to the intake manifold inlet 314. As is known in the art, the level of compression (or boost pressure) provided by the compressor 338 depends on the pressure of the exhaust gases exiting through the exhaust system 330.

3, a controller 222 is provided and operatively connected to the decompression braking subsystem 220 and the exhaust braking subsystem 332. As shown in FIG. In this manner, the controller 222 controls the operation of both the decompression braking subsystem 220 and the exhaust braking subsystem 332. In the illustrated embodiment, the controller 222 includes a processor or processing device 342 that is coupled to the storage component or memory 344. The memory 204, in turn, includes stored executable instructions and data. In one embodiment, processor 342 may include a microprocessor, microcontroller, digital signal processor, co-processor, etc., or any combination thereof, that executes stored instructions and may operate on stored data . Similarly, memory 204 may include one or more devices, such as volatile or nonvolatile memory, including, but not limited to, random access memory (RAM) or read only memory (ROM). Processor and storage arrangements of the types illustrated in FIG. 2 are well known to those skilled in the art. In one embodiment, the processing techniques described herein are implemented as a combination of executable instructions and data in memory 344 that is executed / operated by processor 342. [

[0024] Although the controller 222 is described as one form for implementing the techniques described herein, those skilled in the art will appreciate that other, functionally equivalent techniques may be employed. As is known in the art, for example, some or all of the functions that are implemented functionally through the executable instructions may also be implemented in a computer-readable medium, such as application specific integrated circuits (ASICs), programmable logic arrays, Firmware and / or hardware devices. In addition, other implementations of the controller 222 may include a greater or lesser number of components than those illustrated. Once again, those skilled in the art will appreciate the various modifications that can be made in this manner. Additionally, it is understood that although a single controller 222 is illustrated in FIG. 3, a combination of such processing devices may be configured to operate in conjunction with, or independent from, one another to implement the teachings of the present disclosure.

[0025] Referring now to FIG. 4, processing according to the present disclosure is illustrated. In particular, the processing illustrated in FIG. 4 may be implemented by the controller 222 as described above. At the start of block 402, the controller receives a request for engine braking. As noted above, such a request may be provided in the form of user input, for example via activation of a switch or other user-selectable mechanism, as is known in the art. Nevertheless, in response to a received request, processing continues at block 404, where the controller 404 activates the exhaust brake subsystem. As is known in the art, activation of the braking subsystem (whether exhaust, decompression or other type) results in a flow of hydraulic fluid to the lost motion system or actuator that initiates, for example, engine braking operation Lt; RTI ID = 0.0 > solenoid < / RTI > One example of the signal 504 used for this purpose is illustrated in Figure 5, wherein the transition of the signal 504 from low to high voltage corresponds to activation of the exhaust braking system. Those skilled in the art will appreciate that the particular forms of control signals illustrated herein are not intended to be limiting, and indeed other forms (e.g., transition from high state to low state) may equally be employed.

[0026] Thereafter, at block 408, it is determined whether a predetermined period of time has been completed after activation of the exhaust braking system. That is, concurrently with the activation of the exhaust braking subsystem substantially, the controller initiates a timer that measures a period of time in accordance with known techniques, and then in this example, successively, the timer expires (Step 408). In one embodiment, the predetermined period of time is long enough to allow activation of the exhaust brake to set an increased back pressure in the exhaust system so that the loads placed on the exhaust valve train can be cylinder pressure, Thereby minimizing or eliminating any period of high loads 110, as described above. Indeed, the desired period of time can be a function of engine speed, exhaust flow and volume of the exhaust system, and therefore will necessarily vary with the particular implementation and operation of the engine and exhaust system. For example, in some commonly available engine and exhaust systems, it has been revealed in the test that the period of the predetermined period of time should be at least one second.

[0027] Regardless of the particular period of time employed, once the period of time has elapsed, processing continues to block 410, where the decompression braking subsystem is activated. This is once again shown in FIG. 5 where the decompression brake subsystem converts the control signal 506 from a low voltage to a high voltage after the completion of the predetermined time period 510. As a result, as further illustrated in FIG. 5, the forces applied to the valve train are increased starting with a typical decompression transient 508. However, unlike the system illustrated in FIG. 1, the MFIP-induced period of the excessively high loads 110 is very short or absent. Once again, the backpressure (during which the exhaust braking subsystem is active only) set during a period of time 510 significantly offsets otherwise high loads 110 that would result.

[0028] As is known in the art, failure of the exhaust brake subsystem can have significant adverse effects on the engine. If the exhaust braking subsystem fails in such a way that even after the exhaust braking subsystem is deactivated, the limit in the exhaust system is maintained, there will be a significant increase in back pressure during positive power generation, , And in turbocharger-equipped systems, it is possible to reduce the boost pressure. On the other hand, if the exhaust braking subsystem fails when the exhaust braking subsystem is activated and the restrictions in the exhaust system are not provided, then the engine, which, as described above, can lead to damage to the valve train components There will be a significant reduction in back pressure during braking.

[0029] To avoid the potentially damaging effects of failure of the exhaust braking subsystem during engine braking in a combined exhaust / decompression engine braking system, other optional processing (illustrated by dashed lines) shown in FIG. 5 Can also be performed. It should be noted that the optional processing of FIG. 5 is illustrated in conjunction with the described method for minimizing or eliminating the high valve train loads 110 described above, but this is not a requirement of this disclosure. That is, other optional processing (particularly blocks 406 and 414) of FIG. 5 in conjunction with the processing of blocks 402 and 404 may be implemented separately in the system where only the exhaust brake subsystem is provided have. Thus, for example, the determination of whether or not the exhaust brakes have failed can be made only by activating the exhaust brakes, i.e., responding to requests received by the controller, in order to cause the exhaust brakes to limit the flow of exhaust outside the exhaust system . ≪ / RTI >

[0030] Nevertheless, in this additional embodiment, after activation of the exhaust braking subsystem, it is determined at block 406 whether a failure of the exhaust braking subsystem exists. In practice, this can be achieved in several ways. In particular, if the exhaust braking subsystem fails to provide an essential restriction on the exhaust system, such a failure can be detected when it is determined that the back pressure in the exhaust system is below the threshold. For example, and with reference to FIG. 3, this can be determined through measurement of pressure within a portion of the exhaust system between the exhaust manifold or turbocharger 334 and the exhaust braking subsystem 332. In yet another embodiment, the presence of limitations in the exhaust system during normal operation of the exhaust braking subsystem occurs at the outlet of the compressor 338 (or, as measured, for example, before or after the charge air cooler 312, (At the manifold 304) to reduce the boost pressure. As a result, the measurement of the boost level, which is retained or even increased after activation of the exhaust braking subsystem, represents a failure of the exhaust braking subsystem, which provides an essential limitation. In one embodiment, the determination of the measured parameters (i.e., exhaust backpressure and / or boost pressure) is performed based on a number of data samples taken over a period of time and subsequently averaged. In this case, the determined average is compared with an associated threshold when determining whether a failure of the exhaust brake has occurred.

[0031] Regardless of the manner in which it is determined, at block 406, if it is determined that there is no failure of the exhaust brake subsystem, processing continues to block 408, as described above. However, if a failure is detected at block 406, processing continues at block 414, where instead of activating the decompression braking subsystem in a general manner at block 410, Braking force mode. As used herein, the reduced braking force mode is characterized by being lower than the total braking force that can otherwise be provided by the decompression braking subsystem, and not including any braking force. For example, to achieve a reduced braking force mode, the controller may operate the decompression braking subsystem in such a manner that only a portion of the decompression braking subsystem operates. Thus, in one embodiment, not all cylinders are operated in accordance with decompression engine braking techniques. In another embodiment, during decompression braking, the timing of opening of the exhaust valves, if possible, may be modified such that the exhaust valves are not open when in or near periods of cylinder peak pressure, Thereby reducing loads to be otherwise placed on the trains.

[0032] In another embodiment, if possible, the controller may also configure one or more components of the exhaust system (other than the exhaust brake subcomponent) to increase backpressure in the exhaust system. For example, and referring to Figure 3, if the turbocharger 334 is a so-called variable geometry turbocharger (VGT) as is known in the art, the configuration of the turbocharger (e.g., turbine 336, (Aspect ratio) may be adjusted to increase the back pressure of the exhaust system 330. [

Additionally, even when a failure is not detected at block 406 and the decompression braking is activated as indicated at block 410, the failure of the exhaust braking subsystem, as illustrated at block 412, It may be desirable to continue to check for failures. If such a fault is even detected after activation of the decompression braking subsystem, processing may continue to block 414 where a reduced braking force mode of operation is employed as described above.

[0034] While particularly preferred embodiments have been shown and described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the teachings herein. It is, therefore, contemplated that any and all modifications, variations, or equivalents of the above described teachings fall within the scope of the basic underlying principles set forth herein and contemplated herein.

Claims (10)

CLAIMS What is claimed is: 1. A method for determining a failure of an exhaust brake subsystem,
A controller for use with an internal combustion engine operatively connected to an exhaust system, the exhaust system including an exhaust braking subsystem and the controller communicating with the exhaust braking subsystem In addition,
The method comprising:
Receiving, by the controller, a request to activate the exhaust brake subsystem;
Activating the exhaust brake subsystem by the controller in response to the request to activate the exhaust brake subsystem;
Determining, by the controller, that at least one parameter of the exhaust system and the intake subsystem of the internal combustion engine, or both, adversely compares with at least one threshold; And
Determining, by the controller, that the exhaust braking subsystem has failed, when the at least one parameter compares favorably with the at least one threshold.
A method for determining failure of an exhaust brake subsystem. The method according to claim 1,
Wherein determining that the at least one parameter adversely compares with at least one threshold comprises:
Further comprising, by the controller, determining that the back pressure in the exhaust system is lower than the back pressure threshold,
A method for determining failure of an exhaust brake subsystem. 3. The method of claim 2,
Wherein determining that the back pressure is lower than the back pressure threshold comprises:
Determining, by the controller, an average of a plurality of samples of the back pressure to provide an average back pressure; And
Further comprising comparing the back pressure threshold and the average back pressure by the controller,
A method for determining failure of an exhaust brake subsystem. The method according to claim 1,
Wherein determining that the at least one parameter adversely compares with at least one threshold comprises:
Further comprising determining, by the controller, that the boost pressure in the intake subsystem is higher than a threshold,
A method for determining failure of an exhaust brake subsystem. 5. The method of claim 4,
Wherein determining that the boost pressure is greater than the threshold comprises:
Determining, by the controller, an average of a plurality of samples of the boost pressure to provide an average boost pressure; And
Further comprising comparing, by the controller, the average boost pressure and the threshold value,
A method for determining failure of an exhaust brake subsystem. A controller for use with an internal combustion engine operatively connected to an exhaust system,
Wherein the exhaust system includes an exhaust brake subsystem and the controller is in communication with the exhaust brake subsystem,
The controller comprising:
At least one processing device; And
When executed by the at least one processing device, comprises at least one processing device;
Receiving a request to activate the exhaust brake subsystem;
Responsive to the request to activate the exhaust brake subsystem, activating the exhaust brake subsystem;
Determining that at least one parameter of the exhaust system and the intake subsystem of the internal combustion engine, or both, is adversely compared with at least one threshold; And
A memory in which executable instructions are stored that cause the exhaust braking subsystem to determine that the exhaust braking subsystem has failed when the at least one parameter is compared against the at least one threshold value.
A controller for use with an internal combustion engine operatively connected to an exhaust system. The method according to claim 6,
Executable instructions for the at least one processor to determine that the at least one parameter compares favorably with the at least one threshold comprises causing the at least one processor to:
Further operable to cause the back pressure in the exhaust system to be determined to be lower than the back pressure threshold,
A controller for use with an internal combustion engine operatively connected to an exhaust system. 8. The method of claim 7,
These executable instructions that cause the at least one process to determine that the back pressure is less than the back pressure threshold may cause the at least one processor to:
Determining an average of a plurality of samples of the back pressure to provide an average back pressure; And
Further operable to cause the comparison of the back pressure threshold and the average back pressure,
A controller for use with an internal combustion engine operatively connected to an exhaust system. The method according to claim 6,
Executable instructions that cause the at least one processor to determine that the at least one parameter compares favorably with the at least one threshold comprises causing the at least one processor to:
To cause the boosting pressure in the intake subsystem to be determined to be higher than the threshold,
A controller for use with an internal combustion engine operatively connected to an exhaust system. 10. The method of claim 9,
These executable instructions that cause the at least one process to determine that the back pressure is less than a back pressure threshold,
Determining an average of a plurality of samples of the boost pressure to provide an average boost pressure; And
Further operable to cause the comparison of the average boost pressure and the threshold,
A controller for use with an internal combustion engine operatively connected to an exhaust system.

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