JPH08189384A - Retarder for vehicle - Google Patents

Abstract

PURPOSE: To stop the operation of a compression open type retarder or a retarder comprising an exhaust brake under the condition that fuel is injected. CONSTITUTION: The position of a control rack 16 of a fuel injection pump 11 is detected by a rack position sensor 24 as well as the detection of the speed of an engine 10 by a speed sensor 23. Thus a retarder can be operated only when the position of the control rack 16 is moved only within a specified stroke to an incremental side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle retarder,
In particular, the present invention relates to a vehicle retarder that generates a braking force by opening an engine compression or closing an exhaust pipe.

[0002]

2. Description of the Related Art A compression open retarder or an exhaust brake retarder is used to enhance the braking ability of an engine which is mounted on a vehicle and is composed of an internal combustion engine for driving drive wheels via a power line. There is.

The compression open type retarder is designed to stop the supply of fuel to the engine and open the exhaust valve to release the compressed air almost in synchronism with the piston reaching the top dead center. is there. At this time, the engine operates as an air pump, and since the engine that constitutes this pump is driven by the kinetic energy of the vehicle, it absorbs the compression work that is applied to the engine from the outside, so that the engine receives the braking force. Cause

The exhaust brake that closes the exhaust pipe of the engine is operated by stopping the supply of fuel to the engine and closing the exhaust brake valve provided in the middle of the exhaust pipe. When the exhaust brake valve is closed, the exhaust system of the engine is closed and the resistance of the engine increases. Therefore, the braking force of the engine brake is increased by closing the exhaust brake valve.

[0005]

In a diesel engine equipped with such a compression open type retarder or exhaust brake type retarder, if fuel injection is performed during operation of the retarder as described above, the exhaust temperature rises and the exhaust valve May cause a malfunction. Further, since the incomplete combustion is performed in the cylinder due to the fuel injection during braking, black smoke or white smoke is generated in the exhaust gas, which may be discharged together with the exhaust gas.

Conventionally, therefore, as shown in FIG. 8, the rotation speed of the engine is detected by a rotation sensor and only when the rotation speed of the engine is higher than a predetermined rotation speed No, a compression open type retarder or an exhaust brake is used. I tried not to activate the expression retarder.

As described above, the conventional retarder control is controlled only by the engine speed and does not necessarily correspond to the non-injection state. As shown in FIG. 9, in the graph of the position characteristics of the control rack of the fuel injection pump with respect to the engine speed, the area above the rack characteristics in the idle state and above the non-injection position of the control rack. In, fuel injection is performed. Therefore, if the braking operation is performed in the region where the engine speed is higher than No as shown in FIG. 8, the idle state is set in the hatched region shown in FIG. 9, that is, the region where the engine speed is higher than No. There is a possibility that fuel may be injected at the time of braking in an area above the rack characteristics of No. 1 and above the non-injection position of the control rack. In this case, the above problems will be brought about.

When braking is performed only by determining whether the engine speed is higher or lower than No, when the control computer cannot recognize the engine speed due to a malfunction of the rotation sensor or the like. Had the problem of having to shut down the retarder system.

The present invention has been made in view of the above problems, and a compression open type retarder or an exhaust brake type retarder is operated only in a non-injected state of fuel, or the engine speed is changed. It is an object of the present invention to provide a vehicle retarder in which the control of the retarder described above can be continued even when the rotation sensor for detecting the failure occurs.

[0010]

According to the present invention, in a retarder for a vehicle in which a braking force is generated by opening the compression of an engine or closing an exhaust pipe, the rotation speed of the engine is detected by a rotation detecting means, and The position of the control rack of the fuel injection pump for injecting fuel to the engine is detected by the position detecting means, and the engine speed is equal to or higher than a predetermined value and the position of the control rack is increased by a predetermined stroke. The above braking operation is performed only when the vehicle is moving only within the range, and the braking operation is not performed in other cases.

[0011]

The vehicle retarder is activated only when the number of revolutions of the engine is equal to or higher than a predetermined value and the position of the control rack is moved to the amount increasing side within a predetermined stroke.

[0012]

1 shows a diesel engine 10 equipped with a vehicle retarder according to a first embodiment, and a fuel injection pump 11 is attached to a side surface of a cylinder block of the diesel engine 10. . A timer 13 is attached to the camshaft 12 of the fuel injection pump 11, and the timing of injection of the fuel injection pump 11 is adjusted by adjusting the phase angle of the camshaft 12 by the timer 13.

An electronic governor 14 is attached to the rear side of the fuel injection pump 11. The electronic governor 14 includes an actuator 15, and the actuator 15 moves the control rack 16 in the front-rear direction, thereby adjusting the supply amount of fuel injected at one time.

The actuator 15 of the electronic governor 14
Is controlled by an electronic control unit 20 composed of a computer. An accelerator sensor 22 for detecting the depression amount of an accelerator pedal 21 is provided on the input side of the electronic control unit 20, an engine rotation sensor 23 mounted on the front side of the engine 10 for detecting the number of revolutions of the engine 10, a fuel injection. A rack position sensor 24 for detecting the position of the control rack 16 of the pump 11 and a retarder switch 25 operated by the driver are connected to each other. Then, the electronic control unit 20 uses the electronic governor 14
A control signal is supplied to the actuator 15 and the position of the control rack 16 is adjusted by this.

Next, the compression open type retarder provided in each cylinder of the engine 10 will be described. Figure 2
As shown in, the piston 30 is slidably held in the cylinder 29, and the piston 30 is connected to the upper end of the connecting rod 32 via the piston pin 31. The other end of the connecting rod 32 is connected to the crankshaft.

The upper part of the cylinder 29 is a cylinder head 33.
The cylinder head 33 is provided with an exhaust port 34 while being closed. And each cylinder is equipped with two exhaust valves 35, 36,
The exhaust port 34 is opened and closed by means of 5, 36. Opening / closing of the exhaust valves 35 and 36 is controlled by a rocker arm 37 via a pusher 38.

Further, this engine is provided with a hydraulic cylinder 42, and a piston rod 43 thereof penetrates the pressing element 38 and presses the upper end of one exhaust valve 36. The hydraulic cylinder 42 is designed to open the exhaust valve 36 independently of the valve opening operation by the rocker arm 37, and in particular, the exhaust valve 36 is opened in synchronization with the piston 30 almost reaching the top dead center to open the compression opening type. It is designed to perform braking operation using a retarder.

Particularly, this compression open type retarder is connected to a rocker arm 37 of another cylinder which performs a valve opening motion almost in synchronization with the piston 30 of the cylinder 29 having an engine compressing air to reach the top dead center. The exhaust valve 36 is opened by utilizing the movement of the push rod 39 that is being operated to obtain a braking operation. That is, the master cylinder 59
Is provided, the piston 60 of the cylinder 59 is pushed up by another push rod 39, and the master cylinder 59 is connected to the hydraulic cylinder 42.

A hydraulic pump 62 supplies a relatively low hydraulic pressure to the master cylinder 59 and the hydraulic cylinder 42 through a switching valve 44 and a control valve 61. The control valve 61 has the functions of a one-way valve and an on-off valve, and the switching valve 4
Only the flow of oil from the 4th side to the hydraulic cylinder 42 side is allowed, and it closes when the pressure on the hydraulic pump 62 side decreases. A relief valve 63 is connected to the discharge side of the hydraulic pump 62, and the relief valve 63 keeps the discharge pressure at a stable pressure.

In the above configuration, the electronic control unit 20 reads the depression amount of the accelerator pedal 21 from the accelerator sensor 22 and the rotation speed of the engine 10 from the rotation sensor 23, and based on these information. The actuator 15 of the electronic governor 14 is controlled and the control rack 16 is moved to adjust the injection amount of fuel injected at one time. The timing of injection at this time is controlled by the timer 13.

The fuel injected into each cylinder is spontaneously ignited by the heat of the intake air compressed by the piston 30 shown in FIG. 2, whereby the air-fuel mixture is burned in the cylinder and the engine 10 produces an output. . After the combustion, the rocker arm 37 opens the pair of exhaust valves 35, 36 via the pusher 38 to exhaust the exhaust gas through the exhaust port 34.

Next, the operation of the compression open type retarder will be described. When not braking, the switching valve 4 is operated by the computer 20.
4 is switched to the reservoir side, and even if the piston 60 is pushed up by the push rod 39 of the other cylinder and the hydraulic pressure rises in the master cylinder 59, this hydraulic pressure passes through the control valve 61 and the switching valve 44. The hydraulic pressure is not applied to the hydraulic cylinder 42, so that the exhaust valve 36 causes the piston 3 to move.
It is not opened in synchronization with 0 reaching top dead center.

On the other hand, the driver operates the retarder switch 2
When 5 is operated, the computer of the electronic control unit 20 determines whether or not the condition for operating the retarder is satisfied. If the condition is satisfied, the switching valve 44 is set to the hydraulic pump 62 by the electronic control unit 20.
Switch to the side. Therefore, the pressures set by the relief valves 63 are applied to the master cylinder 59 and the hydraulic cylinder 42 through the hydraulic pump 62, respectively. This pressure is a relatively low and stable pressure, and the hydraulic cylinder 42 is not operated.

Then, in synchronization with the piston 30 of the cylinder 29 reaching the top dead center, the push rod 3 connected to the rocker arm 37 of the other cylinder of this engine.
The piston 60 is pushed up by the movement of 9, and the master cylinder 59 generates a sudden hydraulic pressure. This hydraulic pressure is supplied to the hydraulic cylinder 42, its piston rod 43 is pushed out, and only the exhaust valve 36 is opened. As a result, the braking operation for releasing the compression is performed. Ie piston 30
The compressed air is discharged to the exhaust port 34 side through the gap between the exhaust valve 36 and the valve seat, and absorbs the work done from the outside by the pump action performed by the cylinder 29 at this time. As a result, braking force is generated.

When the push rod 39 descends and the piston 60 of the master cylinder 59 returns, the oil in the hydraulic cylinder 42 flows to the master cylinder 59, and the piston rod 43 of the hydraulic cylinder 42 has the elastic restoring force of the built-in spring. Drawn in by. Therefore, the exhaust valve 36 is closed to prepare for the next compression.

In the graph of FIG. 3, the braking operation of the vehicular retarder by the compression release due to the opening and closing of the exhaust valve 36 in such a non-injection state is shown in the graph of FIG. It is supposed to be performed only when the position is below Ro,
In other states, the braking operation by releasing the compression is not performed. Here, by setting the control rack position Ro to a value equal to the non-injection position where the fuel injection amount becomes substantially 0, fuel injection is not performed in the region where the retarder is operated.

FIG. 4 shows the engine speed No, the control rack position Ro, and the rack characteristics in the idling state. The rack characteristic line in the idling state is set as shown in FIG. 4, and the straight line of Rw = Ro and Ne = N are set.
It is set so that the rack characteristic line in the idling state passes above the intersection with the straight line of o. In this case, since the compression open type retarder is operated only when the control rack position is Ro or lower and the engine speed is No or higher, fuel injection is not performed when the retarder is operated. .

FIG. 5 is a flow chart showing the braking operation by the electronic control unit 20 of such a compression open type retarder. The computer of the electronic control unit 20 determines whether the driver has turned on the retarder switch 25, and then determines whether the output of the engine rotation sensor 23 is normal. That is, when the engine speed is smaller than the maximum value Nmax during normal operation and larger than the minimum speed Nmin during normal operation, it is determined whether the engine speed is No or higher, and then the rack position is Ro. Determine if it is below. The compression opening type retarder is operated only when the engine speed is No or higher and the rack position is Ro or lower.

This retarder is not operated when the engine speed is equal to or lower than No or when the position of the control rack is equal to or higher than Ro.

When it is determined that the engine speed is abnormal in the above-described detection of the engine speed, that is, whether the engine speed is equal to or higher than the maximum value Nmax during normal operation, or the engine speed is minimum value Nmin during normal operation. In the following cases, the computer determines that the rotation sensor 23 is out of order, and in this case, controls the retarder ON / OFF by determining only the position of the control rack 16. That is, the retarder is activated only when the control rack is Ro or lower, and the retarder is not activated when the control rack is Ro or higher.

By performing such control, even when the control computer 20 becomes unable to recognize the rotation speed of the engine 10, that is, when the rotation sensor 23 or a system attached to the rotation sensor 23 fails, this retarder system is used. The control can be continued without stopping.

Next, a second embodiment will be described with reference to FIG. In this embodiment, in addition to the exhaust valve 36 that performs exhaust operation during normal operation, the exhaust valve 5 dedicated to braking
0 is provided in each cylinder of the engine, and only the exhaust valve 50 is opened by the hydraulic cylinder 42 in synchronization with the piston 30 reaching the top dead center, whereby the engine 10 is pumped. Is used to generate braking force.

Moreover, here, in order to open the exhaust valve 50 for braking, the exhaust cam 47 for opening and closing the exhaust valve 36 is used. That is, the master cylinder 46 is arranged so as to operate 90 ° before the exhaust cam, and the master cylinder 46 is connected to the hydraulic cylinder 42 via the switching valve 44. The exhaust cam 47 is connected to the rocker arm 37 via the tappet 48 and the rocker arm 39.

In the above-described structure, the switching valve 44 is switched to the reservoir 51 side by the computer 20 during non-braking. Therefore, even if the exhaust cam 47 intermittently presses the piston rod of the master cylinder 46 to raise the hydraulic pressure by the master cylinder 46, this hydraulic pressure will escape to the reservoir 51 side, and the hydraulic pressure will be applied to the hydraulic cylinder 42. There is no. Therefore, during non-braking, the opening / closing operation of the braking exhaust valve 50 by the hydraulic cylinder 42 is not performed, the exhaust valve 50 is maintained in the closed state, and only the normal exhaust operation by the exhaust valve 36 is performed.

On the other hand, the driver operates the retarder switch 2
When 5 is turned on, the electronic control unit 20 is a condition for braking, and the engine speed and the position of the control rack are the same as those in the first embodiment, that is, are the ON regions shown in FIG. While making a decision,
Only when the condition is satisfied, the electronic control unit 20 switches the switching valve 44 to the hydraulic cylinder 42 side.

Since engine lubricating oil is supplied from the bearing portion of the exhaust cam 47 into the master cylinder 46 via the check valve, the piston of the master cylinder 46 is intermittently pushed up by the exhaust cam 47. The oil rising in the master cylinder 46 is added to the hydraulic cylinder 42 through the switching valve 44. Therefore, the hydraulic cylinder 42
Piston rod 43 is pushed out, and the exhaust valve 5 for braking
0 will be opened intermittently. Exhaust valve 5 for braking
The closing operation of 0 is performed by the computer 20 by the switching valve 44.
Is controlled and the switching valve 44 is switched to the reservoir side.

In this way, the exhaust valve 5 dedicated to the retarder
In a vehicle in which 0 is opened to operate the compression open type retarder, when the fuel injection pump 11 is injecting fuel, the exhaust valve 50 is prevented from being opened by the control of the computer 20, and the retarder of this retarder is opened. It is possible to prevent problems caused by fuel injection during operation.

Next, a third embodiment will be described with reference to FIG. In this embodiment, an exhaust brake valve 55 is rotatably attached at a position in the middle of an exhaust pipe 54, and a lever 56 fixed to a support shaft of the valve 55 is controlled to open and close by an air cylinder 57. . The air cylinder 57 is connected to the air tank 5 via the switching valve 44.
8 is connected.

That is, the present invention relates to a retarder composed of an exhaust brake. The control of the air cylinder 57 is performed by the electronic control unit 20 including a computer based on the flowchart shown in FIG. 5, as in the first embodiment.

The driver uses the exhaust brake switch 2
When 5 is turned on, the electronic control unit 20 determines the condition for braking, that is, whether the engine speed and the position of the control rack are in the ON region shown in FIG. 3, and when the condition is satisfied, Only by the electronic control unit 20 switching the switching valve 44 and supplying compressed air to the air cylinder 57, the exhaust pipe 54 is closed by the exhaust brake valve 55 to achieve the braking operation.

Therefore, also in this embodiment, when the fuel is being injected by the fuel injection pump 11,
Since the retarder including the exhaust valve 55 does not operate, it is possible to prevent problems caused by fuel injection during braking. Therefore, it is possible to obtain the same effect as that of the above embodiment.

[0042]

As described above, according to the present invention, the compression release or the exhaust pipe is performed only when the engine speed is equal to or higher than a predetermined value and the position of the control rack is moved to the increasing side within a predetermined stroke. The braking force is generated by closing the block.

Therefore, according to the present invention, by controlling the operation of the retarder in conjunction with the detection of the engine speed and particularly the detection of the position of the control rack, the braking operation in the state where the fuel injection is being performed. It becomes possible to prevent the rise of exhaust temperature,
This prevents malfunctions such as valve malfunctions and prevents black smoke or white smoke from being emitted into the exhaust gas.

Further, even if the rotation detecting means for detecting the number of revolutions of the engine fails, the control can be continued only by detecting the position of the control rack. Therefore, the system accompanying the failure of the rotation detecting means can be achieved. It will be possible to prevent the stoppage of.

[Brief description of drawings]

FIG. 1 is a side view of an engine including a vehicle retarder according to a first embodiment.

FIG. 2 is a vertical sectional view of a cylinder showing a retarder.

FIG. 3 is a graph showing a region where braking operation is possible.

FIG. 4 is a graph showing a relationship between a region where braking operation is possible and a rack characteristic line.

FIG. 5 is a flowchart showing a control operation of the retarder.

FIG. 6 is a vertical cross-sectional view of a main part of a vehicle retarder according to a second embodiment.

FIG. 7 is a vertical cross-sectional view of a main part of a vehicle retarder according to a third embodiment.

FIG. 8 is a graph showing a braking possible area of a conventional retarder.

FIG. 9 is a graph showing a relationship between a brakeable area of a conventional retarder and a rack characteristic line.

[Explanation of symbols]

 10 Diesel Engine 11 Fuel Injection Pump 12 Camshaft 13 Timer 14 Electronic Governor 15 Actuator 16 Control Rack 20 Electronic Control Unit 21 Accelerator Pedal 22 Accelerator Sensor 23 Engine Rotation Sensor 24 Rack Position Sensor 25 Retarder Switch 29 Cylinder 30 Piston 31 Piston Pin 32 Connecting Rod 33 Cylinder Head 34 Exhaust Ports 35, 36 Exhaust Valve 37 Rocker Arm 38 Pusher 39 Push Rod 42 Hydraulic Cylinder 43 Piston Rod 44 Switching Valve 46 Master Cylinder 47 Exhaust Cam 48 Tappet 50 Exhaust Valve 51 Reservoir 52 Relief Valve 54 Exhaust Pipe 55 Exhaust Brake Valve 56 Lever 57 Air cylinder 58 Air tank 59 Master cylinder 6 0 Piston 61 Control valve 62 Hydraulic pump 63 Relief valve

Claims (1)

[Claims] 1. A retarder for a vehicle, wherein a braking force is generated by opening the compression of an engine or closing an exhaust pipe, a means for detecting an engine speed, and a means for detecting a position of a control rack of a fuel injection pump. And a control means for controlling the opening and closing of the exhaust valve, wherein the engine speed is equal to or higher than a predetermined value and the position of the control rack is moved toward the increasing side within a predetermined stroke. A vehicle retarder characterized in that it is adapted to operate only on the.