JPH0551052B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust brake device, and more particularly to controlling the opening speed of an exhaust brake valve when opening the exhaust brake valve to release the exhaust brake.

[Prior Art] A vehicle exhaust brake device brakes the engine by increasing back pressure by restricting the exhaust passage of the engine using an exhaust brake valve.

[Problems to be Solved by the Invention] In the conventional exhaust brake device, the following problem occurred when the exhaust brake valve was opened to release the exhaust brake.

The exhaust braking force of the exhaust braking device increases as the transmission gear ratio increases (the gear stage is on the lower speed side). Therefore, if the exhaust brake valve is opened instantaneously when the exhaust brake is released, if the transmission gear ratio is large, the feeling of acceleration due to the release of the exhaust brake will be noticeable, which may cause a large shock to the occupants. I was getting used to it.

This also applies to the relationship between the driving state of the vehicle and the exhaust braking force using the engine speed as an intermediary. That is, the exhaust brake force is
It is caused by the exhaust gas pressure accumulated between the exhaust valve of the engine and the exhaust brake valve in the exhaust passage, and the exhaust brake valve is designed to restrict the exhaust passage and accumulate exhaust gas pressure. In the case of such an exhaust brake device, when the engine is rotating at low speed, the exhaust gas flow rate is small, and this exhaust gas sequentially passes through the exhaust brake valve and flows out. Appropriate back pressure cannot be secured between the In addition, when the engine is rotating at high speed, the flow rate of exhaust gas becomes excessive, so the back pressure becomes excessive and the exhaust valve is forced to open, or the leakage of exhaust gas becomes significant, making it difficult to obtain sufficient exhaust braking force. I can't. As can be understood from this, the exhaust brake force also changes depending on the engine speed, and if the exhaust brake valve is opened instantly at the engine speed that generates a sufficiently large exhaust brake force, the above-mentioned The same problem will occur.

On the other hand, in consideration of the above problem, it is conceivable to reduce the shock by uniquely setting the opening speed of the exhaust brake valve to be slow.

However, if the opening speed of the exhaust brake valve is uniquely set to be slow in this way, the opening speed of the exhaust brake valve will become slow even when the transmission gear ratio, which normally causes little shock, is small (on the high speed side). As a result, the release time of the exhaust brake is prolonged, which may cause deterioration of acceleration after release, which may adversely affect the driver's driving sensation.

This also applies to the above-mentioned relationship between engine speed and exhaust brake force, in the operating conditions of the engine in the low and high speed ranges where a sufficiently large exhaust brake force cannot be obtained and there is almost no shock when releasing the exhaust brake. The same is true.

Furthermore, the actuator that drives the exhaust brake valve is structurally equipped with an opening operation control device that controls the opening operation speed of the exhaust brake valve. ) has been proposed. This proposal changes and controls the opening speed of the exhaust brake valve at the initial stage and after the opening operation, but as long as the negative pressure introduced to the actuator is constant, the opening speed of the exhaust brake valve is changed from low to high speed range. The opening speed of the exhaust brake valve remains the same regardless of the gear in which the engine is operated, and therefore it is considered that the above-mentioned problem cannot be solved.

[Means for Solving the Problems] The present invention provides an exhaust brake valve that brakes the engine by restricting the exhaust passage, a gear position detection means that detects the transmission gear ratio, and an engine rotation detection means that detects the rotation speed of the engine. and control means for controlling the opening speed of the exhaust brake valve in accordance with a control map based on the detected values by the engine rotation detection means and the gear stage detection means, As the rotation speed increases, the opening operation speed becomes faster on the medium and high rotation side, and the opening operation speed becomes faster when the gear ratio is small and slow when the gear ratio is large. The content is as follows.

[Function] With the above configuration, the exhaust brake valve opens at a high speed when the gear ratio is small and the rotation speed is idling or near the maximum speed, and when the gear ratio is large and the rotation speed is medium. When the engine is rotating, the exhaust brake valve is opened at a slow speed.

[Embodiment] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, an exhaust brake valve 3 is provided in an exhaust passage 2 defined by an exhaust pipe 1 of the engine to throttle the exhaust passage 2 and brake the engine. The exhaust brake valve 3 is made of a butterfly valve, and its rotating shaft 4 is rotatably supported by the exhaust pipe 1 so as to be rotated within the exhaust passage 2. Further, an actuator 5 is connected to the rotating shaft 4 of the exhaust brake valve 3. In this embodiment, the actuator 5 is a motor 6 whose speed can be controlled. The exhaust brake valve 3 has its rotating shaft 4 connected to an actuator 5.
is rotated into the exhaust passage 2 to narrow the exhaust passage 2 and generate an exhaust braking force. Further, a potentiometer 7 having a general configuration is connected to the rotating shaft 4 of the exhaust brake valve 3 to detect the amount of rotation thereof and detect the opening/closing degree θ of the exhaust brake valve 3.

On the other hand, FIG.
A control means 10 such as a microcomputer that performs deceleration control according to the detected value detected by the detection means 8 is shown. The transmission gear ratio R and the engine rotation speed N are adopted as indicators indicating the driving state of the vehicle, and the detection means 8 includes a gear stage detection means 11 and Engine rotation speed detection means 12 is installed. These detection means 11 and 12 are connected to the control means 10 and output the detected values R and N to the control means 10. Here, the gear stage detection means 11 is composed of a select switch 11a that is switched in accordance with the operation of the select lever to detect the select position, and a shift switch 11b that is switched in accordance with the operation of the shift lever to detect the shift position. , these switches 11
A and 11b are used to detect the only transmission gear, that is, the transmission gear ratio R.

Further, an exhaust brake switch 13, an accelerator switch 14, and a clutch switch 15 are connected to the control means 10, and the exhaust brake is turned on and off.
The conditions for this are now entered. That is, when the exhaust brake switch 13 is ON, the accelerator switch 14 is OFF (the driver has taken his foot off the accelerator pedal), and the clutch switch 15 is ON (the clutch is connected). The exhaust brake is activated. And these switches 13,
If any one of the conditions 14 and 15 no longer satisfies the above conditions, the exhaust brake valve 3 is opened and the exhaust brake is released.

Further, an actuator 5 for driving the exhaust brake valve 3 is connected to the control means 10, and a control signal Sv for controlling the opening speed V of the exhaust brake valve 3 is output to the actuator 5. Also connected to the control means 10 is a potentiometer 7 that outputs an opening/closing opening θ signal of the exhaust brake valve 3.

By the way, especially in the memory of the control means 10, the third
A control graph as shown in the figure is stored. To explain this graph in detail, as shown in Figure 4, when the exhaust brake is activated, the engine brake is also activated, and the amount of power absorbed by the exhaust brake is equal to the total amount of power absorbed by the exhaust brake and the engine brake (in the figure). , shown as A) to the amount of power absorbed by engine braking (in the figure,
The amount of energy (indicated by the shaded area C surrounded by A and B in the figure) is obtained by subtracting the amount of energy (indicated by B). Here, the total power absorption energy amount A and the power absorption energy amount B due to the engine brake simply increase as the engine speed N increases, whereas the power absorption energy amount C due to the exhaust brake increases as the engine speed N increases. Although it once increases as the engine speed N increases, once it reaches a certain engine speed _N0 , it gradually shows a decreasing tendency beyond that point. This is related to the fact that the exhaust brake valve 3 throttles the exhaust passage 2, thereby increasing the back pressure of the engine and braking the engine. To explain using the graph of engine rotation speed vs. power absorption energy amount by exhaust brake shown in Fig. 5, first, when the engine is at a low rotation speed such as idling, the exhaust gas flow rate per unit time is small. The exhaust gas sequentially passes through the exhaust brake valve 3 and flows out, making it impossible to secure sufficient exhaust gas pressure between the exhaust gas and the exhaust valve of the engine. Therefore, the back pressure of the engine cannot be increased and efficient exhaust braking force cannot be obtained (in the figure,
(denoted by D). On the other hand, as the engine speed N increases sequentially, a correspondingly large amount of exhaust gas flow can be secured, so an appropriate back pressure is generated and the exhaust braking force is gradually increased (in the figure, E indicates show). The engine speed N is further increased to a speed N ₀
If this value is exceeded, the exhaust gas flow rate will become excessive and the back pressure will rise too much, forcing the exhaust valve to open, and the loss due to exhaust gas leakage will increase, resulting in the exhaust braking force gradually decreasing. (indicated by F in the figure).

In this way, the exhaust braking force has a correlation with the engine speed. The fact that the effectiveness of the exhaust brake varies depending on the engine speed N means that depending on the engine speed, opening the exhaust brake valve 3 instantaneously may give a shock feeling, or it may open slowly. Doing so may impair the sense of acceleration. Therefore, as shown in FIG. 3, the memory of the control means 10 stores a graph in which the opening speed V of the exhaust brake valve 3 is plotted on the vertical axis and the engine speed N is plotted on the horizontal axis. In other words, the control means controls the opening speed of the exhaust brake valve according to the control map shown in FIG. The speed increases as the rotation speed increases on the medium and high rotation side, and the opening operation speed increases on the side with a small gear ratio and increases on the side with a large gear ratio. It is designed to be slow. In this example, the slope of the graph is gentler on the smaller side and steeper on the larger side, so that the opening operation speed is the fastest regardless of the gear ratio at idle rotation and maximum rotation. I have to.

Next, the operation of the embodiment will be described.

This will be explained according to the control flow shown in FIG.

First, ON-OFF signals of the engine speed N, transmission gear ratio R, and other switches 13 to 15 are output from the engine speed detection means 12, gear position detection means 11, exhaust brake switch 13, clutch switch 15, and accelerator switch 14. Load and proceed to the next step.

Here, the normal closing operation of the exhaust brake valve 3 will be explained according to the control flow [G]. First, if the exhaust brake switch 13 is ON, the transmission gear ratio R is 0 and the gear is in the neutral position, the clutch switch 15 is ON, and the accelerator switch 14 is OFF, then proceed to the next step to operate the exhaust brake.

Read the opening degree θ of the exhaust brake valve 3 from the potentiometer 7 and proceed to the next step.

If the opening degree θ of the exhaust brake valve 3 is not fully closed, a closing signal Sc is output to the actuator 5. At this time, the opening degree θ of the exhaust brake valve 3 is sequentially detected by the potentiometer 7 and fed back to the control means 10.

Finally, when the exhaust brake valve 3 is fully closed, a stop signal Ss is output to the actuator 5 to maintain the exhaust brake in the operating state.

On the other hand, the opening operation of the exhaust brake valve 3 will be explained according to control flow [H].

If the exhaust brake switch 13 is OFF, the transmission gear ratio R is not 0 and the gear is not in the neutral position, the clutch switch 15 is OFF, or the accelerator switch 14 is ON, proceed to the next step in order to release the exhaust brake. .

A graph corresponding to the speed change gear ratio R (gear stage) is read from the memory of the control means 10, and the process proceeds to the next step.

The opening speed V of the exhaust brake valve 3 corresponding to the current engine speed N is set for the read graph, and the process proceeds to the next step.

Read the opening degree θ of the exhaust brake valve 3 from the potentiometer 7 and proceed to the next step.

If the opening degree θ of the exhaust brake valve 3 is not fully open, a release signal Sv having a previously set opening operation speed V is output to the actuator 5. As a result, the exhaust brake valve 3 is opened at an opening speed V that does not give a shock feeling and does not adversely affect the feeling of acceleration. At this time, the opening degree θ of the exhaust brake valve 3 is sequentially detected by the potentiometer 7, and the control means 10
Feedback will be provided to

Finally, when the exhaust brake valve 3 is fully opened, a stop signal Ss is output to the actuator 5 to maintain the exhaust brake in the released state.

Modifications regarding the actuator 5 are shown in FIGS. 7 to 10.

What is shown in FIGS. 7 and 8 is the cylinder 16
A piston 17 provided inside defines an air pressure chamber 18 and a spring chamber 19, and a piston rod 20 extending toward the spring chamber 19 is connected to the rotating shaft 4 of the exhaust brake valve 3 via a drive link 21. , the air pressure source 23 or the atmosphere side is connected to the air pressure chamber 18 via a solenoid valve 22. Then, when releasing the exhaust brake, the air pressure source 2
3 to the pneumatic chamber 18 to close the exhaust brake valve 3. The time ratio of the pulse signal (ON) to the solenoid valve 22 is gradually decreased (the duty ratio is gradually reduced to 100%). →0%), thereby achieving control of the opening speed of the exhaust brake valve 3. The control means 10 outputs a signal for controlling this duty ratio. Note that instead of controlling the solenoid valve 22, a variable flow rate restrictor 24 may be interposed between the solenoid valve 22 and the air pressure chamber 18, and this restrictor may be controlled.

9 and 10, a pair of cylinders 16, 16 similar to those described above are arranged side by side, and a piston rod 20, which serves as the output end of these cylinders 16, 16, is shown.
20 are connected by a first link 27, and a second link 28 connected to the drive link 21 is connected at a position where the first link 27 is appropriately distributed. Then, when the exhaust brake valve 3 is maintained in a closed state by supplying working air from the air pressure source 23 to both cylinders 16, 16, first, the first solenoid valve 2 with a larger lever distribution ratio is
5 is turned OFF, and then the first solenoid valve 2 is turned OFF.
control the solenoid valves 25 and 26 so as to turn on the solenoid valve 5 again, turn off the other second solenoid valve 26 that was in the on state, and finally turn off the first solenoid valve 25 that was turned on again. Accordingly, the exhaust brake valve 3 is opened in stages. The control means 10 includes such electromagnetic valves 25, 2.
6 switching periods are output as control signals.

[Effects of the Invention] In summary, according to the present invention, the following excellent effects are achieved.

comprising a control means for controlling the opening speed of the exhaust brake valve according to the speed change gear ratio and the rotation speed of the engine;
Since the opening operation speed is changed depending on the height of the rotation range, the rotation speed, and the transmission gear ratio,
The opening operation can be performed at a speed commensurate with the exhaust braking force in all driving conditions, appropriately eliminating the feeling of shock when the brake is released, and extremely effectively preventing deterioration of acceleration performance.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a preferred embodiment of the present invention;
Fig. 2 is a configuration diagram showing the control system, Fig. 3 is a graph showing the relationship between the engine speed stored in the memory of the control means and the opening speed of the exhaust brake valve, and Fig. 4 is a graph showing the amount of power absorbed energy and the opening speed of the exhaust brake valve. FIG. 5 is a graph showing the relationship between the amount of energy absorbed by the exhaust brake and the engine speed; FIG. 6 is a flowchart showing an example of the control flow by the control means; FIG. 8 is a waveform diagram showing an example of the control pulse signal, FIG. 9 is a block diagram showing another modification of the actuator, and FIG. 10 is a diagram of the control pulse signal. FIG. 3 is a waveform diagram showing an example. In the figure, 2 is an exhaust passage, 3 is an exhaust brake valve, and 8
1 is a detection means, 10 is a control means, 11 is a gear position detection means, and 12 is an engine rotation speed detection means.

Claims (1)

[Claims] 1. An exhaust brake valve that brakes the engine by restricting the exhaust passage, a gear position detection means that detects the transmission gear ratio, an engine rotation detection means that detects the rotational speed of the engine, and the engine rotation detection means and the gear position detection means. control means for controlling the opening operation speed of the exhaust brake valve according to a control map based on a detected value by As the rotation speed increases, the opening speed increases,
An exhaust brake device characterized in that the opening operation speed is fast when the gear ratio is small and slow when the gear ratio is large.