JP4214395B2 - Exhaust brake device - Google Patents

Description

  The present invention relates to an exhaust brake device, and more particularly to an exhaust brake device that reduces exhaust pressure acting on an exhaust brake valve when the exhaust brake is released.

  Some internal combustion engines are equipped with an exhaust brake device that exerts powerful engine braking performance when the vehicle is decelerated. In this exhaust brake device, an exhaust brake valve disposed in an exhaust passage of the internal combustion engine, an actuator that supplies air to close the exhaust brake valve, and air received from the actuator is exhausted. 2. Description of the Related Art Generally, a configuration including a rod that transmits to a brake valve side and a cylinder having a spring that opens the valve against the pressure of air is known.

In general, a butterfly valve is used as the exhaust brake valve, and is applied to an exhaust gas aftertreatment device for increasing the exhaust temperature in addition to an auxiliary brake device for a vehicle.
When the vehicle is requested to decelerate in the auxiliary brake device of the vehicle, the butterfly valve closes the exhaust passage by the pressurizing force of air from the actuator, and negative work is generated by the increase of the exhaust pressure and the engine brake is exerted. On the other hand, when the vehicle is requested to be accelerated, the supply of air is stopped and the air is extracted from the cylinder, and the butterfly valve opens the exhaust passage by the reaction force of the spring to release the engine brake.

  Here, the exhaust pressure upstream of the position where the exhaust brake valve is disposed becomes high during braking by the exhaust brake as described above, and acts over the entire surface of the butterfly valve. After that, even when the driver gives an intention to accelerate, that is, at the time when the brake release signal by the exhaust brake is output, the exhaust pressure on the upstream side still remains high. Since the pressure is still operating over the entire surface of the butterfly valve, the reaction force of the spring in the cylinder cannot overcome the exhaust pressure in the exhaust passage, and the release responsiveness of the exhaust brake valve is reduced. . In other words, there is a problem that the actual operation for fully opening the exhaust passage by the exhaust brake valve is greatly delayed from the driver's intention to accelerate.

In addition, the fact that this exhaust brake valve requires a long time until the exhaust passage is fully opened hinders the intake of fresh air into the cylinder, and there is a problem that black smoke is generated due to a shortage of intake air. Will occur.
Thus, various technologies for exhaust brake devices that take this situation into account have been proposed (see, for example, Patent Documents 1 to 3).

Japanese Patent Laid-Open No. 6-213013 (paragraph numbers 0007 to 0011, FIG. 3 etc.) JP 2002-371828 A (paragraph number 0004, FIG. 4 etc.) Japanese Patent No. 3114787 (paragraph numbers 0017 to 0019, FIG. 1, etc.)

  By the way, in the conventional technique described in Patent Document 1, the configuration on the actuator side is improved. In other words, it is possible to improve the release responsiveness of the exhaust brake valve, but if the exhaust pressure in the exhaust passage becomes even higher, there is a limit to just adjusting the air pressure from the actuator. There is a problem that it may be difficult to open the exhaust passage.

  Here, as described in Patent Document 2, it is conceivable to apply a technique of temporarily opening the EGR valve when releasing the brake by the exhaust brake to improve the release responsiveness of the exhaust brake valve. However, if the EGR valve is uniformly opened as described in Patent Document 2, a large amount of EGR gas is recirculated into the cylinder even when the exhaust pressure is low. There is a problem that black smoke is likely to be generated.

  Regarding the point of preventing the generation of the black smoke, as described in Patent Document 3, it is conceivable to apply a technique for reducing the fuel injection amount at the time of releasing the brake by the exhaust brake, but only reducing the fuel injection amount is considered. If the exhaust gas amount in the exhaust passage is not adjusted, there is a risk that an inert atmosphere may still be formed in the cylinder due to the presence of the exhaust gas, and the generation of black smoke cannot be effectively suppressed. .

That is, in each of the above conventional techniques, no special consideration is given to suppressing the generation of black smoke while smoothly opening the exhaust brake valve when releasing the brake by the exhaust brake.
The present invention has been made in view of such a problem, and at the time of releasing the brake by the exhaust brake, the exhaust responsiveness of the exhaust brake valve can be further improved and the generation of black smoke can be suppressed. An object is to provide a brake device.

In order to achieve the above object, an exhaust brake device according to claim 1 is provided in an exhaust passage communicating with a cylinder of an internal combustion engine and generating a braking force by closing the exhaust passage, an exhaust passage and a cylinder An EGR passage that connects an intake passage communicating with the EGR passage, an EGR valve that is interposed in the EGR passage and controls the flow rate of EGR gas, a brake release detecting means that detects the release of braking by an exhaust brake, and the operating state of the internal combustion engine When the release of braking is detected by the operating state detecting means for detecting the brake and the brake release detecting means , the EGR valve is opened at a predetermined opening for a predetermined valve opening time and then closed to reduce the exhaust pressure. together is, this having the opening and opening time of the EGR valve, and a valve control means for Gosuru in system according to the output signal from the operating condition detecting means in the detection time of release It is characterized in.

The brake release detecting means preferably detects an accelerator depression signal or an OFF signal of a brake switch of the exhaust brake device. This is because the driver's intention to accelerate the vehicle is accurately reflected.
In the second aspect of the invention, the operating state detecting means detects and outputs the rotational speed of the internal combustion engine or the amount of fuel injected into the cylinder, and the valve control means provides the optimum release brake valve release response. In order to obtain, it is characterized in that the opening degree of the EGR valve is controlled to be large or the valve opening time is controlled to be long according to the increase in the rotational speed or the fuel injection amount.

According to the third aspect of the present invention, the operating state detection means detects and outputs the exhaust pressure upstream of the position where the exhaust brake valve is disposed, and the valve control means provides an optimal exhaust brake valve release response. In order to obtain the characteristics, the opening degree of the EGR valve is set to be large or the valve opening time is controlled to be long as the exhaust pressure increases .
According to a fourth aspect of the present invention, the EGR valve is a multi-stage EGR valve.

  Further, the invention according to claim 5 further includes an injection amount control means for controlling the fuel injection amount to the cylinder, and the injection amount control means reduces the fuel injection amount in accordance with the operation signal of the exhaust brake valve. It is a feature.

  Therefore, according to the exhaust brake device of the present invention described in claim 1, since the valve control means determines the opening of the EGR valve in consideration of the operating state of the internal combustion engine at the time of release of braking by the exhaust brake. It is possible to obtain an optimal brake release response that quickly reduces the exhaust pressure, and it is possible to further improve the release response of the exhaust brake valve.

Moreover, since the opening time of the EGR valve considering the operation state at the time of releasing the brake is also determined, the exhaust gas recirculation amount (EGR amount) can be adjusted appropriately, and black smoke is generated due to excessive EGR amount. Can be prevented. In addition, deterioration of engine performance can be prevented.
According to the second aspect of the present invention, the upstream side exhaust pressure is controlled based on the rotational speed of the internal combustion engine or the amount of fuel injected into the cylinder, which is correlated with the exhaust pressure upstream of the exhaust brake valve position. It becomes possible to properly grasp and control the opening degree of the EGR valve, and further improve the release responsiveness of the exhaust brake valve and suppress the generation of black smoke without deteriorating drivability. be able to.

Furthermore, according to the invention described in claim 3, by directly detecting the exhaust pressure upstream from the position where the exhaust brake valve is disposed , the upstream pressure is surely grasped and the EGR valve is opened. It is possible to control the degree, and it is possible to reliably achieve the improvement of the release responsiveness of the exhaust brake valve and the suppression of the generation of black smoke without deteriorating the drivability.
Further, according to the invention of claim 4, the opening and closing operation of the EGR valve can be performed quickly and precisely at a desired opening degree, the inert atmosphere is positively eliminated, black smoke is generated, and engine performance is reduced. It can prevent more effectively.

  Furthermore, according to the fifth aspect of the invention, the generation of black smoke can be suppressed synergistically by further reducing the fuel injection amount in addition to controlling the EGR valve. In addition, it is possible to shorten the fuel injection amount reduction time by the control according to the operation state of the EGR valve. In this case, it is possible to improve drivability.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Referring to FIG. 1, there is shown a system configuration diagram to which an exhaust brake device according to an embodiment of the present invention is applied, and the configuration of the exhaust brake device according to the present invention will be described based on FIG.
As shown in the figure, each cylinder 2 of a diesel engine (hereinafter simply referred to as an engine) 1 is partitioned by a fuel supply system 16 having a fuel injection device and a piston 3 by opening an intake valve 6. An intake passage 8 for introducing intake air into the combustion chamber 4 and an exhaust passage 28 for deriving exhaust gas from the combustion chamber 4 by opening the exhaust valve 18 are connected.

A supercharger 14 is interposed on the upstream side of the intake passage 8, and an air cleaner (not shown) is connected to the tip of the intake passage 8. An intake throttle 10 is disposed in the intake passage 8 and an intercooler 12 is interposed.
On the other hand, the catalytic converter 22 is connected to the downstream side of the exhaust passage 28. Further, an EGR passage 24 branches and extends from the exhaust passage 28, and a part of the exhaust gas (EGR gas) is recirculated into the intake passage 8 to suppress NOx emission and the like. The tip of the EGR passage 24 is connected to the intake passage 8 on the downstream side of the position where the intake throttle 10 that adjusts the flow passage area of the intake passage 8 is provided. The EGR passage 24 is electrically connected to an EGR cooler 26 for cooling EGR gas and an electronic control unit (ECU) 40, and is a multistage type configured to allow the exhaust passage 28 and the intake passage 8 to communicate with each other. An EGR valve 20 is provided.

The EGR valve 20 of the present embodiment is configured such that the opening area can be changed in eight stages.
Specifically, as shown in FIG. 2, the EGR valve 20 includes a valve body 201 having a bowl-shaped valve body 209 that opens and closes the EGR passage 24, and three pistons 211 that transmit air pressure to the valve body 209 side. And a cylinder 202 having 212 and 213.
The valve main body 201 is provided with an accommodating portion 214 opposite to the position where the cylinder 202 is disposed, and the accommodating portion 214 biases the shaft portion of the valve body 209 and the valve body 209 in the valve closing direction. A spring 208 is accommodated. One end of the spring 208 is in contact with the valve body 201, and the other end is in contact with the stopper 207. The stopper 207 is also brought into contact with the valve body 209.

  The cylinder 202 is provided with three air introduction holes 203, 204, and 205 for receiving air from an actuator (not shown) that supplies air for controlling the opening degree. The valve body 209 is opened and closed via the rod 206 and the stopper 207 by moving in eight stages according to the pressure received by the air from the air introduction holes 203, 204 and 205.

First, the opening degree of the first stage is set by not supplying air to any of the three air introduction holes 203, 204, 205. In this case, the valve element 209 is seated on the seat 210 by the reaction force of the spring 208, and the EGR passage 24 is completely closed.
The opening degree of the second stage is set by supplying air only to the air introduction hole 203. In this case, air pressure is generated between the piston 211 and the piston 212, that is, the back surface of the piston 211, and the piston 211 moves rightward. As a result, the rod 206 and the stopper 207 move rightward against the reaction force of the spring 208, the valve body 209 is separated from the seat 210, and the EGR passage 24 is slightly opened.

The opening degree of the third stage is set by supplying air only to the air introduction hole 204. In this case, air pressure is generated on the back surface of the piston 212, and the piston 212 moves rightward. As a result, the stopper 207 moves to the right against the reaction force of the spring 208, and the EGR passage 24 is opened.
The fourth stage opening is set by air supply only to the air introduction hole 205, and the fifth stage opening is set by air supply from the air introduction holes 203 and 204, and the sixth stage opening. Is set by the air supply of the air introduction holes 203 and 205, and the opening degree of the seventh stage is set by the air supply of the air introduction holes 204 and 205. Further, the opening degree of the eighth stage is set by supplying air to all three air introduction holes 203, 204, 205. In this case, the air pressure is applied to the back surface of the pistons 211, 212, 213. The rod 206 and the stopper 207 move to the right against the reaction force of the spring 208, and the EGR passage 24 is in the maximum opening state.

As described above, the EGR valve 20 of the present embodiment is configured so that the valve opening degree O _E can be arbitrarily set, and finely adjusted EGR gas can be recirculated to the intake passage 8 side. The opening / closing operation 20 can be performed quickly and precisely, and the inert atmosphere can be actively eliminated.
Next, an exhaust brake valve 30 that generates a braking force by closing the exhaust passage 28 is provided in the exhaust passage 28 upstream of the catalytic converter 22.

  As shown in detail in FIG. 3, the exhaust brake valve 30 includes a valve body 301 having a butterfly valve 306 disposed in the exhaust passage 28, and an air cylinder 302 having a rod 303 that transmits air pressure to the butterfly valve 306 side. And a link 304 that is rotationally connected to the rod 303, and a rotation shaft portion 305 that converts the reciprocating motion of the rod 303 into rotation through the link 304 and rotates the butterfly valve 306.

  When air is supplied into the air cylinder 302 and the rod 303 protrudes outward, the rotation shaft portion 305 rotates around the counter hour hand as shown in the side view of FIG. Also, the exhaust passage 28 is closed by rotating around the counter hour hand. In this case, the butterfly valve 306 receives exhaust pressure over the entire surface thereof. As a result, the exhaust pressure on the upstream side of the position where the butterfly valve 306 is disposed, that is, on the combustion chamber 4 side rises, and this exhaust pressure becomes a force to push back the piston 3, generating negative work and exerting the engine brake. The

  On the other hand, the supply of air into the air cylinder 302 is stopped when the engine brake is requested to be released. The rod 303 is retracted by the reaction force of a spring (not shown) disposed in the air cylinder 302, and the rotation shaft portion 305 rotates around the hour hand as shown in the side view of FIG. The butterfly valve 306 also rotates around the hour hand as shown in the side view of FIG. 4B, and opens the exhaust passage 28 as shown in the front view of FIG.

  By the way, fresh air from the air cleaner enters the intake passage 8 via the supercharger 14 and reaches the intercooler 12. After being adjusted by the intake throttle 10, the fresh air merges with the EGR gas and the combustion chamber 4 of each cylinder 2. Led in. Then, the crankshaft 36 and the flywheel 38 are operated by combustion of fuel supplied from the fuel supply system 16. When combustion ends, the exhaust gas is discharged into the exhaust passage 28 and sent to the catalytic converter 22.

  Various sensors for detecting the operating state of the engine 1 such as a crank angle sensor 32 for detecting the engine rotational speed Ne and an accelerator sensor 34 for detecting the driver's intention for acceleration are electrically connected to the input side of the ECU 40. ing. On the other hand, on the output side of the ECU 40, various actuators such as the fuel supply system 16, the intake throttle 10, the EGR valve 20, and the exhaust brake valve 30 are electrically connected.

The ECU 40 includes an operation state detection unit (operation state detection unit) 42, a brake release detection unit (brake release detection unit) 44, and an exhaust pressure applied to the exhaust brake valve 30 when the exhaust brake is released. And a valve control unit (valve control means) 46 and an injection amount control unit (injection amount control means) 48.
The driving state detection unit 42 electrically converts signals from the various sensors, and particularly in the present embodiment, when a signal indicating that the exhaust brake release condition is satisfied is input from the brake release detection unit 44, immediately before that. The engine rotation speed Ne and the fuel injection amount Q at the time of are output to the valve control unit 46.

The brake release detection unit 44 detects the ON signal of the accelerator sensor 34, and by detecting this signal, it is determined that the driver's intention to accelerate the vehicle is displayed and the brake release condition by the exhaust brake is satisfied, To the operating state detection unit 42 and the valve control unit 46.
In the valve control unit 46, when the brake release condition by the exhaust brake is satisfied, the opening degree O _E and the valve opening time T _{E of the} EGR valve 20 are based on the engine speed Ne and the fuel injection amount Q immediately before the release. And a drive signal is output to the EGR valve 20. By using the engine rotational speed Ne and the fuel injection amount Q at this time, the exhaust pressure in the exhaust passage 28 affected by the engine rotational speed Ne and the like is properly grasped, and black smoke is generated while maintaining drivability. A control amount of the EGR valve 20 that is necessary and sufficient for the suppression is required.

That is, the opening degree O _E of the EGR valve 20 is immediately determined and outputted as a value corresponding to the operating condition of the engine 1 in order to obtain an optimal release response. More specifically, when the engine rotational speed Ne is high or when the fuel injection amount Q is large, the exhaust pressure is high because the exhaust pressure is high, so the opening degree _OE is increased, and when the engine rotational speed Ne is low or the fuel injection amount Q is If it is smaller, the opening degree O _E is determined to be smaller. As a result, the exhaust pressure at the time of release is appropriately and quickly reduced, and the release responsiveness of the exhaust brake valve 30 is improved.

Further, the valve opening time T _E of the EGR valve 20 is necessary to determine the valve closing timing of the EGR valve 20, and is a value sufficient to prevent the amount of EGR from becoming excessive and black smoke from being generated. Is determined and output. More specifically, when the engine speed Ne is high or the fuel injection amount Q is large, the valve opening time _TE is lengthened, but when the engine speed Ne is low or the fuel injection amount Q is small. It is as determined to reduce the open time T _E. As a result, in an EGR valve that is performed with only two signals of fully open and fully closed as in the prior art, for example, even when the exhaust pressure is low, a large amount of EGR gas can be recirculated into the cylinder. In the present embodiment, when the exhaust pressure is low, a slight valve opening time is set, so that only a small amount of EGR gas recirculates, so that generation of black smoke can be prevented.

Moreover, by setting the opening degree O _E and the valve opening time T _E , the combustion chamber 4 is less susceptible to the influence of the exhaust pressure at the time of braking release and the recirculation amount of the EGR gas, and the operation of the engine 1 is prevented. Fluctuation is suppressed and engine output performance is not degraded.
The injection amount control unit 48 controls the fuel injection amount to the cylinder 2, and particularly in this embodiment, the fuel injection amount is reduced from the time when the operation signal of the exhaust brake valve 30 is output to the fuel injection system 16. Output. Specifically, the injection amount control unit 48 sets the reduced fuel injection amount until a predetermined injection holding time _TQ elapses after the exhaust brake is released.

The predetermined injection holding time T _Q, is the time at which the driver does not perform the fuel injection amount along with the request even though the driver is depressing the accelerator. This is because if there is a time delay in the actual operation of the exhaust brake valve 30 and if fuel injection is performed in accordance with the driver's request, the amount of fuel in the cylinder will be excessive with respect to the amount of intake air. In view of the fact that a large amount of fuel is generated, a filter is applied to the fuel injection amount to prevent the generation of black smoke when the time delay is present.

Thus, if the control of the EGR valve 20 and the reduction of the fuel injection amount are performed together, the generation of black smoke can be suppressed synergistically.
In addition, when this injection holding time _TQ becomes long, a driver | operator will recognize more clearly that the acceleration feeling according to his intention cannot be obtained, and drivability will also deteriorate. However, in the present embodiment, the opening degree _{E E} of the EGR valve 20 that achieves an optimal release response and the valve opening time T _E that aims to generate black smoke are determined by the valve control unit 46, so the injection holding time it is possible to achieve a further reduction of T _Q. That is, it is possible to quickly return to normal fuel injection, and in this case, the accelerator response is improved.

Referring to FIG. 4, there is shown a control flowchart of brake release of the exhaust brake device.
In step S401 in the figure, the operating state detection unit 42 sequentially reads the engine speed Ne and the fuel injection amount Q and proceeds to step S402.
In step S402, the brake release detection unit 44 determines whether or not a brake release condition by the exhaust brake is satisfied, specifically, whether or not an ON signal of the accelerator sensor 34 is detected. When it is determined that the driver's intention to accelerate is displayed, that is, when the determination is YES, the process proceeds to step S403. That is, referring to FIG. 5, a timing chart in the case where the brake release control is performed is shown. At the time indicated by the one-dot chain line in FIG. Note that if the ON signal of the accelerator sensor 34 is not detected in step S402, the process returns to step S401.

In step S403, the valve control unit 46 calculates the opening degree O _E of the EGR valve 20 based on the engine rotational speed Ne and the fuel injection amount Q immediately before the brake release condition is satisfied, and outputs it to the EGR valve 20. The process proceeds to step S404. That is, as shown in FIG. 5, immediately EGR valve 20 when the brake release signal of the exhaust brake is outputted to open at the opening O _E. As a result, the exhaust pressure in the exhaust passage 28 is immediately reduced, and the exhaust brake valve 30 is instantly opened.

In step S404, in valve control unit 46 calculates a valve opening time T _E of the EGR valve 20 based on the engine rotational speed Ne and the fuel injection amount Q immediately before the brake releasing condition is satisfied, and outputs the EGR valve 20 Then, the process proceeds to step S405.
In step S405, in the injection amount control unit 48 proceeds to step S406 to calculate the predetermined injection hold time T _Q. That is, as shown in FIG. 5, fuel injection is performed with a reduced fuel injection amount as the exhaust brake valve 30 is opened. The predetermined injection hold time T _Q is the amount of depression of the accelerator pedal by the driver, in other words, is set as appropriate in accordance with the acceleration of the vehicle is required.

In step S406, it is determined whether or not the valve opening time T _E of the EGR valve 20 has elapsed, when it is determined that the opening time T _E has elapsed, i.e., the flow proceeds to step S406 when YES, the The EGR valve 20 is closed. When the valve opening time T _E has not elapsed, this determination operation is repeated until it has elapsed.
In step S407, if the injection holding time T _Q is determined whether or not elapsed, it is determined as the injection holding time T _Q has elapsed, i.e., to return to normal fuel injection amount when the YES this Exit control routine. Incidentally, when the injection holding time T _Q has not passed, maintains the fuel injection amount that has been reduced to elapsed, it repeats the determination operation.

As described above, in the present embodiment, the EGR valve 20 is determined as the opening degree O _E using the engine speed Ne or the like at the time of release of the exhaust brake, and before the actual opening operation of the exhaust brake valve 30. Alternatively, the exhaust pressure on the upstream side of the position where the exhaust brake valve 30 is disposed is reduced in advance, so that the time until the exhaust brake valve 30 is fully opened can be shortened. That is, even in the existing configuration including an exhaust brake valve, an actuator, a cylinder, etc., the exhaust brake valve is fully opened in a short time. More specifically, it is an experiment that the return time from exhaust valve closing to full opening is shortened from about 0.8 seconds to about 0.3 seconds even when the same spring reaction force is used. Proven in

Further, it has been proved by experiments that the generation rate of black smoke can be reduced to more than about 30% by opening the EGR valve 20 at the opening degree O _E for the valve opening time T _E.
In addition, the setting of the opening degree O _E and the valve opening time T _E by the valve control unit 46 and the setting of the injection holding time T _Q by the injection amount control unit 48 are performed together, thereby dramatically increasing the generation rate of black smoke. Can be reduced.

FIG. 6 is a diagram showing the effect of releasing the brake of the exhaust brake by the exhaust brake device of the present invention.
If the fuel injection amount is simply reduced at the time of releasing the brake by the exhaust brake as in the prior art, as shown by the black circle in the figure, the generation of black smoke with an injection holding time of 0 seconds, which was about 85% The rate is about 60% when the injection holding time is 0.5 seconds. Further, the injection holding time of 1.0 second becomes about 45%, and can be further suppressed. However, as indicated by the chain line in the figure, the slope of the black smoke generation rate with respect to the injection holding time is substantially constant. In other words, a reduction in the generation rate of black smoke can be achieved by making the injection holding time longer, but this will give the driver a sense of rattling and drivability will deteriorate. It is hard to say that can be effectively suppressed.

Therefore, as in the exhaust brake device of the present invention, the opening degree O _E and the valve opening time T _E of the EGR valve 20 are set in consideration of the exhaust pressure upstream of the position where the exhaust brake valve 30 is disposed, and the like. If the injection holding time T _Q (for example, 0.5 seconds) is set, the black smoke generation rate at the injection holding time of 0.5 seconds is about 85% to about 14% as shown by white circles in the figure. It can be seen that the slope of the generation rate of black smoke becomes steep. Moreover, the injection holding time T _Q of 0.5 seconds does not worsen the drivability.

FIG. 6 shows the effect when the injection holding time T _Q is set to 0.5 seconds. However, if the EGR valve 20 is controlled as in the present embodiment, the injection holding time T _Q is set. It is possible to shorten the time shorter than 0.5 seconds. That is, this means that a fuel injection amount that is closer to the driver's intention to accelerate can be obtained, and thus the drivability can be improved in the present invention.

The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the operating state detection unit 42 uses a value such as the engine rotational speed Ne and also arranges an exhaust pressure sensor in the exhaust passage upstream of the position where the exhaust brake valve 30 is disposed. May be directly detected and used to calculate the opening degree O _E and the valve opening time T _E of the EGR valve 20. Even in this case, it is possible to improve the release responsiveness and suppress the generation of black smoke without deteriorating drivability.

  In the above embodiment, the brake release detection unit 44 determines whether the brake release condition by the exhaust brake is satisfied by detecting the ON signal of the accelerator sensor 34. However, the present invention is not necessarily limited to this. Instead, for example, the driver's intention to accelerate may be determined by detecting the OFF signal of the exhaust brake switch disposed in the passenger compartment. It has the effect of reducing the incidence.

1 is a configuration diagram of an engine to which an exhaust brake device according to an embodiment of the present invention is applied. It is a block diagram of the EGR valve of FIG. It is a block diagram of the exhaust brake valve of FIG. FIG. 2 is a control flowchart of exhaust brake braking release by the exhaust brake device of FIG. 1. FIG. 2 is a timing chart of brake release of the exhaust brake by the exhaust brake device of FIG. 1. It is a figure which shows the effect of the brake release of the exhaust brake by the exhaust brake device of FIG.

Explanation of symbols

1 Diesel Engine 2 Cylinder 8 Intake Passage 16 Fuel Supply System 20 EGR Valve (Multi-stage EGR Valve)
24 EGR passage 28 Exhaust passage 30 Exhaust brake valve 32 Crank angle sensor 40 Electronic control unit (ECU)
42 Operation state detection unit (operation state detection means)
44 Brake release detection unit (brake release detection means)
46 Valve control unit (valve control means)
48 Injection amount control unit (injection amount control means)

Claims (5)

An exhaust brake valve disposed in an exhaust passage communicating with a cylinder of the internal combustion engine and generating a braking force by closing the exhaust passage;
An EGR passage connecting the exhaust passage and an intake passage communicating with the cylinder;
An EGR valve that is interposed in the EGR passage and controls the flow rate of EGR gas;
Braking release detecting means for detecting release of braking by the exhaust brake;
An operating state detecting means for detecting an operating state of the internal combustion engine;
When release of braking is detected by the brake release detecting means , the EGR valve is opened at a predetermined opening for a predetermined valve opening time and then closed in order to reduce the exhaust pressure. and by system Gosuru valve control means according to an output signal of the opening and the valve opening time, from the operating condition detecting means in the detection time of the release,
An exhaust brake device comprising: The operating state detecting means detects and outputs a rotational speed of the internal combustion engine or a fuel injection amount to the cylinder,
The valve control means largely controls the opening of the EGR valve or lengthens the valve opening time in accordance with an increase in the rotational speed or the fuel injection amount in order to obtain an optimal release response of the exhaust brake valve. The exhaust brake device according to claim 1, wherein the exhaust brake device is controlled. The operating state detection means detects and outputs the exhaust pressure upstream of the exhaust brake valve position.
The valve control means largely controls the opening of the EGR valve or controls the valve opening time to be long in accordance with the increase of the exhaust pressure in order to obtain the optimal release brake valve responsiveness. The exhaust brake device according to claim 1. The exhaust brake device according to any one of claims 1 to 3, wherein the EGR valve is a multistage EGR valve. 2. The fuel injection control device according to claim 1, further comprising injection amount control means for controlling a fuel injection amount to the cylinder, wherein the injection amount control means reduces the fuel injection amount in accordance with an operation signal of the exhaust brake valve. The exhaust brake device according to any one of 1 to 4.

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