JPH03199631A - Automotive combination brake system - Google Patents

Abstract

PURPOSE:To effectively reduce the speed of an automobile by constituting the brake system so that when the engine brake action is hardly increased due to the decrease in the opening of the throttle valve of the engine and when the opening of the throttle valve does not reach 0, the action of an auxiliary brake is started. CONSTITUTION:The intermediate time between the time when the engine brake force cannot be increased and the time when the opening of the throttle valve reaches 0 is selected as the operation start time for an air brake 56 and for an exhaust brake 38, and also it is so designed that these brakes 56 and 38 are not simultaneously operated, but are started in this order. Thus, after a lapse of a short time after the engine brake force is not increased, the operation of an auxiliary brake is started, so that the automobile can be effectively braked, and also the braking force can be smoothly changed for enhancing operation feeling.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a composite brake for an automobile including a friction brake and an auxiliary brake for braking an automobile driven by an engine, and in particular to an improvement in the control of the auxiliary brake. It is related to.

Conventional technology An example of the above friction brake is a disc brake.

Such as drum brakes. Friction brakes are generally designed to operate in response to operation of a brake operating member such as a brake pedal.

On the other hand, examples of the auxiliary brakes include an exhaust brake (also referred to as an exhaust retarder), an aerodynamic brake, and a fluid retarder. The auxiliary brake is applied when a speed increasing operating member such as an accelerator pedal that controls the opening of the engine's throttle valve is operated from an applied position to a non-active position, or when a brake operating member is operated from a non-active position to an active position. It is generally designed to start operating at a certain time. JP-A No. 61-25929 describes an exhaust brake that starts operating when the driver releases the accelerator pedal to decelerate the vehicle and the accelerator switch changes from the OFF state to the ○N state. .

Problems to be Solved by the Invention When reducing the opening degree of the throttle valve (hereinafter referred to as throttle opening degree) in order to cause the engine to perform a braking action, the throttle valve reaches the most closed position where the throttle opening degree is O. The engine braking effect does not continue to increase until then. FIG. 7 is a graph showing an example of the relationship between the throttle opening degree and the output torque of the engine in a gasoline engine. The period in which negative output torque is generated is the period in which the engine performs a braking action, but as is clear from the graph, the throttle opening remains constant until it reaches a certain value greater than 0. Negative output torque, that is, engine braking torque, increases with the decrease, but after that, the engine braking torque is maintained almost constant despite the decrease in throttle opening. The hatched region in the figure is the constant region of engine brake torque.

Due to the existence of such engine braking characteristics, in a combined brake system that operates the auxiliary brake when the throttle valve is in the most closed position, the auxiliary brake is activated after a certain period of time has elapsed from the end of the engine brake torque increase. The problem is that the vehicle cannot be effectively decelerated.

Similarly, a composite brake system in which the auxiliary brake is operated when the brake operating member is operated from the non-operating position to the operating position cannot effectively decelerate the vehicle.

The present invention has been made with the object of solving the above-mentioned problem by appropriately determining the start timing of the auxiliary brake in consideration of the engine braking characteristics.

Means for Solving the Problems And, the gist of the present invention is, as shown in FIG. The present invention provides an auxiliary brake control means for starting the operation of the auxiliary brake at a time when there is almost no increase in the opening of the throttle valve and when the opening degree of the throttle valve does not reach O.

Incidentally, the friction brake is generally operated in response to the operation of the brake operating member, but
In constant-speed driving control that automatically drives a car at a constant speed, follow-up driving control that automatically follows the car in front, etc., the need for friction brake activation is automatically determined and the judgment result is used. It is also possible to use a type that is activated based on the

In addition, although the throttle valve is generally controlled in accordance with the operation of the speed increasing operation member, it automatically determines the necessity of engine braking and uses the engine brake function based on the determination result. It is also possible to adopt a type in which the throttle opening degree is reduced in order to perform an engine braking action.

Further, the throttle valve may be a butterfly type or a slide type.

Operation and Effects of the Invention In the device of the present invention, the operation of the auxiliary brake is started at a time when the engine braking action hardly increases, and earlier than the start time of the auxiliary brake in the conventional combined brake system, so that the vehicle can be It can be effectively slowed down.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 2, numeral 10 indicates a gasoline engine (hereinafter simply referred to as engine). The engine IO is provided with an intake manifold 12 and an exhaust manifold 14. The intake manifold 12 is provided with a butterfly-type throttle valve 16 and an injector 18 for injecting gasoline as fuel into the intake manifold 12 on the upstream side and the downstream side, respectively. The throttle valve 16 is controlled to an opening degree according to the amount of depression of an accelerator pedal (not shown). On the other hand, the exhaust manifold 14 is provided with a butterfly type exhaust valve 22 for blocking the exhaust passage 20 thereof.

The exhaust brake valve 22 is connected to a diaphragm 24 via a link mechanism (not shown).

The diaphragm 24 is normally placed in the open position by the spring 26 so that the exhaust brake valve 22 does not block the exhaust passage 20, but when negative pressure is generated in the air chamber 26, the diaphragm 24 resists the biasing force of the spring 26. Then, the exhaust brake valve 22 moves to the closed position where it blocks the exhaust passage 20. Note that the figure shows the diaphragm 24 in the closed position.

The air chamber 26 is an electromagnetic directional switching valve 32 (hereinafter simply referred to as the switching valve 3).
2) via vacuum pump 34 and filter 3
6. The switching valve 32 is always connected to the air chamber 26.
The pressure in the air chamber 26 is controlled to a level equal to atmospheric pressure by cutting off the vacuum pump 34 and communicating it with the filter 36. However, when a solenoid (not shown) is energized, the vacuum pump 36 is cut off and the vacuum pump 3
4 to generate negative pressure in the air chamber 26. That is, in this embodiment, the exhaust brake valve 22. Diaphragm 24. A switching valve 32, a vacuum pump 34, a filter 36, and the like constitute an exhaust brake 38.

The switching valve 32 is controlled by a controller 40 mainly composed of a computer including a CPU, ROM, RAM, and bus. The controller 40 also includes a throttle opening sensor 42 that detects the opening degree (opening/closing angle) of the throttle valve 16, and an engine sensor 42 that is provided in the housing of the distributor 44 of the engine 10 to detect the rotational speed of the engine 10. It is connected to the rotational speed sensor 46.

The automobile is equipped with a hydraulically actuated disc brake 50 as a friction brake, which restrains the rotation of each of its four wheels. Each of these disc brakes 50 is operated in response to depression of a brake pedal (not shown).

Furthermore, the motor vehicle is provided with an aerodynamic brake 56 having a baffle plate 54 . The baffle plate 54 is attached to the roof of the automobile so as to be rotatable around an axis extending in the left-right direction of the automobile, and is normally in a non-operating position in close contact with the upper surface of the roof.
When activated, it rotates counterclockwise in the figure from the non-operating position (rotated to the operating position in the figure) to increase the air resistance of the vehicle.

The ROM of the controller 40 stores various control routines including the auxiliary brake control routine shown in the flowchart of FIG. The ROM also contains the engine rotational speed and exhaust brake 3, as shown in the graph in Figure 4.
8 and the throttle opening at which the aerodynamic brake 56 should start operating. Note that this relationship is set so that the aerodynamic brake 56 and the exhaust brake 38 start operating in that order during a period in which the engine brake torque does not increase and the throttle opening does not reach O. The throttle opening corresponding to each engine speed is larger for the aerodynamic brake than for the exhaust brake.

Next, the operation will be explained.

When the controller i-roller 40 is not powered on, the switching valve 32 is not energized and the actuator 60 is not operated, so that the exhaust brake 38 and the aerodynamic brake 56 are inactive.

When the controller 40 is powered on in this state, the auxiliary brake control routine shown in FIG. 3 is executed at predetermined intervals. When this routine is executed each time, first, in step Sl (hereinafter simply referred to as Sl; the same applies to other steps), the current throttle opening TA is detected based on the output signal of the throttle opening sensor 42. after that,
In S2, the current engine rotation speed NE is detected based on the output signal of the engine rotation speed sensor 46.

Subsequently, in S3, the aerodynamic brake operation start opening degree TAI corresponding to the current engine speed NE is determined using the relationship shown in FIG.

Thereafter, in S4, it is determined whether the current throttle opening TA is less than or equal to the aerodynamic brake operation start opening TA1. Assuming that this time, the aerodynamic brake 56
It is determined that it is necessary to activate the
Then, in S5, the actuator 60 is actuated to actuate the aerodynamic brake 56.

On the other hand, if it is assumed that the current throttle opening TA is larger than the aerodynamic brake activation start opening TAI, it is determined that there is no need to operate the aerodynamic brake 56, and the determination result in S4 becomes NO, and in S6, the actuator 60
The aerodynamic brake 56 is released by issuing a release signal that returns it to its inactive position.

In either case, in S7, the exhaust brake operation start opening degree TA2 corresponding to the current engine rotational speed NE is determined.
is determined using the relationship shown in FIG. Next, S8
In this step, it is determined whether the current throttle opening TA is less than or equal to the exhaust brake operation start opening TA2. Assuming that is the case this time, it will be determined that the exhaust brake 38 needs to be activated, the determination result will be YES, and S9
At this time, the exhaust brake 38 is operated by energizing the switching valve 32. On the other hand, if it is assumed that the current throttle opening TA is larger than the exhaust brake activation start opening TA2, it is determined that there is no need to operate the exhaust brake 38, and the determination result of S8 is NO, and 310
At this time, the exhaust brake 38 is released by issuing a demagnetizing signal to the switching valve 32 to demagnetize it. This completes one execution of this routine.

The fifth example shows an example of the change in braking force when the brake pedal is started to be depressed after the accelerator pedal is released in order to brake a car using a conventional composite brake system.
It is represented by a dashed-dotted line in the figure. Note that this composite brake system operates the aerodynamic brake 56 and the exhaust brake 38 simultaneously when the throttle opening reaches zero.

As is clear from the figure, in this conventional example, the braking force caused by the auxiliary brake is generated after the braking force caused by the engine braking action (hereinafter referred to as engine braking force) is kept constant for a rather long time. It is not possible to brake a car effectively, and the braking force decreases over time i1!54
Driving feeling is not good enough as it is stiff and does not change smoothly. In addition, in the figure, the idle period from when the throttle opening reaches O until the braking force starts to be generated in response to the operation of the brake pedal is the period required for the driver to switch his foot from the accelerator pedal to the brake pedal. It is.

On the other hand, in the present embodiment, the intermediate time between the time when the engine braking force stops increasing and the time when the throttle opening reaches O is the time when the aerodynamic brake 56 and the exhaust brake 38 start operating. The aerodynamic brake 56 and the exhaust brake 38 are selected and designed so that the aerodynamic brake 56 and the exhaust brake 38 do not begin operation at the same time, but in that order. Therefore, as is clear from the solid line graph in the same figure showing an example of the change in braking force by the device of this embodiment, the operation of the auxiliary brake starts a short time after the engine braking force stops increasing. As a result, the vehicle can be braked effectively, and the braking force changes smoothly, improving the driving feeling.

Further, other examples of changes in braking force by the device of this embodiment are graphically shown in FIG. The figure shows the current engine rotational speed N
E is 2000rpm, 4000rpm and 6 respectively
Three graphs are shown, each showing an example of 0.000 rpm.

As is clear from the above explanation, in this example,
The part of the computer in the controller 40 that executes the routine shown in FIG. 3 is the throttle opening sensor 42. Engine rotation speed sensor 46. It constitutes an auxiliary brake control means in cooperation with a part of the computer that stores the relationships shown in FIG.

Although one embodiment of the present invention has been described above in detail based on the drawings, the present invention can be implemented in other embodiments.

For example, in the embodiment, the exhaust brake valve 2
2 was described as a butterfly type, but it is also possible to use a sliding type.

Further, in the embodiment, the exhaust brake valve 22
was said to be pneumatically operated, but it is now hydraulically operated,
It can also be electromagnetically actuated.

Further, in the above embodiment, the timing to start operating the auxiliary brake was selected to be after the timing when the engine braking force stopped increasing; however, when the engine braking force stopped increasing,
It is also possible to select a period before that period when the rate of increase in engine braking force begins to decrease.

Furthermore, in order to ensure that the braking force changes smoothly over time, it is not possible to design the aerodynamic brake 56 and the exhaust brake 38 to start operating at different times as in the embodiment described above. Although it is not essential, even if you insist that the brakes start operating at the same time, the change in braking force will be clearer than if the brakes were designed to start operating when the throttle opening reaches 0. Become.

Furthermore, it is also possible to provide only one type of auxiliary brake, and it is also possible to provide another type of auxiliary brake.

In addition to these, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a block diagram conceptually showing the configuration of the present invention. FIG. 2 is a system diagram showing a composite brake system which is an embodiment of the present invention. FIG. 3 is a flow chart showing the auxiliary brake control routine stored in the ROM of the computer of the controller in FIG. Fourth
The figure is a graph showing the aerodynamic brake operation start conditions and the exhaust brake operation start conditions stored in the ROM. FIG. 5 is a graph showing an example of the control results obtained by the above-mentioned embodiment device together with an example of the control results obtained by the conventional composite brake system. FIG. 6 is a graph showing some examples of changes in braking force when braking an automobile using the above embodiment. FIG. 7 is a graph for explaining the relationship between throttle opening and engine torque in a gasoline engine. lO: Gasoline engine 16: Throttle valve 38: Exhaust brake 40: Controller 42: Throttle opening sensor 46: Engine speed sensor 56: Aerodynamic brake

Claims (1)

[Scope of Claims] In a composite brake system for an automobile including a friction brake and an auxiliary brake for braking an automobile driven by an engine, a period when there is almost no increase in the engine braking action due to a decrease in the opening of the throttle valve of the engine. A composite brake system for an automobile, comprising an auxiliary brake control means for starting the operation of the auxiliary brake at a time when the opening degree of the throttle valve does not reach zero.