JPH03217360A - Combined braking system for automobile - Google Patents

Abstract

PURPOSE:To secure a sufficiently high braking effect as well as to smooth a variation in braking effort and improve the extent of riding comfortableness by installing plural types of auxiliary brakes in addition to a friction brake, and controlling each timing of the start and end of working in each auxiliary brake independently with each other. CONSTITUTION:A braking system has a friction brake A controlling the rotation of a wheel by means of friction and its auxiliary brake B. In the above constitution, there are provided with plural types B1, B2 and so on of the auxiliary brake B. These auxiliary brakes B1, B2 make each action independent of each other in accordance with a control rule prescribing each timing of the start and end of each action, and it is controlled by an auxiliary brake control means C. With this constitution, these auxiliary brakes B1, B2 are combined together, thereby making them work and bringing a sufficiently high braking effect into full play, and simultaneously each action of these auxiliary brakes B1, B2 is shifted with each other, and a variation in braking effort is smoothed, thus the extent of riding comfortableness is improved.

Description

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

Conventional friction brakes include disc brakes, drum brakes, etc. Friction brakes are typically designed to operate in response to operation of a brake operating member such as a brake pedal. The auxiliary brake is a brake that assists braking by such a friction brake, and is disclosed in Japanese Patent Application Laid-Open No. 61-2
Exhaust brake described in Publication No. 5929 and Japanese Unexamined Patent Publication No. 1983
The aerodynamic brake described in Japanese Patent No. 1-1 25865 is one example. An exhaust brake is a brake that closes a hub installed in the middle of an engine's exhaust pipe, blocking the flow of exhaust gas and increasing the internal resistance of the engine to slow the vehicle.Aerodynamic brakes are brakes that slow down the vehicle by increasing the internal resistance of the engine This is a brake that decelerates a car by applying air flowing through it to a baffle plate and using air resistance.If an auxiliary brake is provided, the burden on the friction brake can be reduced.

Problems to be Solved by the Invention However, in conventional composite brake systems, only one type of auxiliary brake is provided, and there is a problem in that it is not always possible to obtain sufficient effects.

An object of the present invention is to provide a composite brake system that can more effectively reduce the burden on friction brakes.

Means for Solving the Problems In order to solve the above problems, the present invention provides a plurality of types of auxiliary brakes as shown in FIG. The present invention is characterized by the provision of auxiliary brake control means for controlling the action of each auxiliary brake in accordance with control rules that define the start time and end time of their action.

Functions and Effects of the Invention In the composite brake system configured as described above, a plurality of types of auxiliary brakes are provided, so that sufficient braking force can be obtained by the actions of these auxiliary brakes. Moreover, each of the multiple types of auxiliary brakes can start and end its action according to its own preset control rules, so this control rule is applied at the time when each auxiliary brake exerts its braking effect most effectively. By setting this, a high braking effect can be obtained. Further, by staggering the start and end timings of the plurality of types of auxiliary brakes, the change in braking force becomes smoother than in the case where they are not staggered, resulting in an effect of improving ride comfort.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

In FIG. 2, reference numeral 10 denotes a hydraulic disc brake as a friction brake, which is provided on each of the four wheels of an automobile to suppress their rotation.

The wheel cylinders 12 of the disc brakes 10 on the left and right front wheels (see Figure 3) and the disc brakes 1 on the left and right rear wheels.
0 wheel cylinder 14 (see Fig. 3), a pressure is generated in the mask cylinder 18 (see Fig. 3) by depressing the brake pedal 16, and is controlled to an appropriate height by the hydraulic linear control valve 20. Hydraulic pressure is supplied.

Furthermore, the hydraulic pressure in the wheel cylinders 12, 14 is switched between an increased pressure state, a reduced pressure state, and a hydraulic pressure maintained state by the anti-skid actuator 22, and the four wheels are subjected to anti-skid control.

24 is a gasoline engine (hereinafter simply referred to as the engine)
The engine 24 is provided with an intake manifold 26 and an exhaust manifold 28. The intake manifold 26 is provided with a butterfly two throttle valve 30 and an injector 32 for injecting gasoline as fuel into the intake manifold 28 on the upstream side and the downstream side, respectively. The throttle valve 30 is the motor 3
4, it is opened by an amount corresponding to the amount of depression of the accelerator pedal which is not rotated, and the opening degree during this time is detected by the throttle opening sensor 36. 37 is an ignition device, and an engine rotation speed sensor 38 detects an engine rotation speed of 240. In addition, in this vehicle, the engine 24
The output of is transmitted to the wheels by a power transmission device having an automatic transmission 39. In the automatic transmission 39, the hydraulic control device that determines the shift timing has an oil passage switched by switching a solenoid valve, and controls the gear ratio and lock-annob control.

The exhaust manifold 28 has a butterfly type exhaust brake valve 42 for blocking the exhaust passage 40 thereof.
is provided. The exhaust brake pulp 42 is connected to a diaphragm 44 via a link mechanism (not shown). The diaphragm 44 is normally positioned in the open position by the spring 46 so that the exhaust brake valve 42 does not block the exhaust passage 40, but when negative pressure is generated in the air chamber 48, the diaphragm 44 resists the biasing force of the spring 46. Then, the exhaust brake valve 42 moves to the closed position where it blocks the exhaust passage 40. The figure shows diaphragm 4 in six closed positions.
4 is shown.

The air chamber 48 is an electromagnetic directional switching valve 50 (hereinafter simply referred to as a switching valve 5).
It is called 0. ) to the vacuum pump 52 and filter 54. The switching valve 50 is always connected to the air chamber 4.
8 is cut off from the vacuum pump 52 and communicated with the filter 54 to control the pressure in the air chamber 48 to a level equal to atmospheric pressure. However, when a solenoid (not shown) is energized, it is cut off from the filter 54 and communicated with the vacuum pump 54. 52 to generate negative pressure in the air chamber 48. That is, in this embodiment, the diaphragm 4
4, switching valve 50, vacuum pump 52, filter 54
etc. constitute the exhaust control actuator 58 (see FIG. 3), and together with the exhaust brake hub 42 constitute the exhaust brake 60.

Furthermore, an aerodynamic brake 66 with a baffle plate 64 is provided on the roof of the automobile. The baffle plate 64 is attached to the roof of the vehicle so as to be rotatable around an axis extending in the left-right direction of the vehicle, and is normally in a non-active position where it is in close contact with the top surface of the roof, but can be moved to the non-active position by the empty brake actuator 68. is rotated counterclockwise in the figure, increasing the air resistance of the vehicle in the operating position shown.

The above exhaust brake 60. The aerodynamic brake 66 and the like are controlled by a braking force control device 70 shown in FIG. This control device 70 has a controller 72 mainly composed of a computer including a CPU, ROM, RAM, and bus.

This controller 72 includes a brake depression sensor 74 that detects the depression force of the brake pedal 16, a vehicle speed sensor 76 that detects the rotational speed of the wheels, a deceleration sensor 78 that detects the wheel deceleration, and a neutral switch 80.
are connected to each other, and their detection signals are supplied. The controller 72 also includes an exhaust control actuator 58 and an aerodynamic brake actuator 6.
8. A hydraulic linear control well 20 is connected, and as described later, the exhaust brake 60 and the aerodynamic brake 66 are switched between operating and non-operating states based on the vehicle speed detected by the vehicle speed sensor 76. Controls the height of the supply fluid pressure to the cylinders 12.14.

The controller 72 further includes an electronically controlled fuel injection device 82.
, throttle control device 84 and automatic transmission control device 8
6, and an anti-skid control execution signal and a release signal are supplied from an anti-skid control device 88.

The electronically controlled fuel injection device 82 is a device that controls fuel supply to the engine 24, and responds to an ignition cut request, a fuel cut request supplied from the controller 72, an engine rotation speed output request supplied from the throttle control device 84, etc. Based on this, an ignition control signal is supplied to the ignition device 37, an injector drive signal is supplied to the injector 32, and an engine rotation speed NB is supplied to the controller 72. Further, the throttle control device 84 supplies a throttle drive signal to the motor 34 that drives the throttle valve 30, receives a detection signal from the throttle opening sensor 36, and controls the throttle valve 30 according to the amount of depression of an accelerator pedal (not shown). Open amount. The automatic transmission control device 86 is a device that controls switching of a solenoid valve of a hydraulic control device provided in the automatic transmission 39, and performs speed ratio control and candle up control. A plurality of types of shift patterns are stored in advance in the ROM of the computer of this automatic transmission control device 86, and shift and lock-up effects are performed on the automatic transmission 39 according to throttle opening, vehicle speed, selected shift pattern, etc. However, a braking effect can be obtained by performing downshift control to make the gear ratio smaller than the ratio obtained based on the throttle opening and the like. In this vehicle, as will be described later, downshift control is performed during braking, and the exhaust brake 6
0. It is designed to function as an auxiliary brake together with the aerodynamic brake 66.

The RAM of the computer of the controller 72 is provided with flags F, , F2, and F3 together with a working memory as shown in FIG. Various control routines including routines and disc brake control routines are stored. The braking of this vehicle will be explained below.

When braking is not applied, the exhaust brake 60, aerodynamic brake 66, and disc brake 10 are in a non-operating state, and downshift control of the automatic transmission 39 is not performed. In the braking force control routine, first, in step 31 (hereinafter simply referred to as S1; the same applies to other steps), it is determined whether braking has started based on whether the brake pedal 16 has been depressed. . When not braking, S1 becomes NO and 322, S23, S24 and S2
5 is executed, exhaust brake 60 and aerodynamic brake 6
6 is released, and the downshift control and the hydraulic pressure control of the hydraulic linear control well 20 are not performed.

If the brake pedal 12 is depressed, the determination result in S1 becomes YES, and after the vehicle speed (2) is read in S2, the aerodynamic brake 66 is controlled in S3 to S8. The timing at which the aerodynamic brake 66 is applied is represented by the hatched portion in FIG. 7 in a graph in which the braking start vehicle speed ■8 is plotted on the horizontal axis and the vehicle speed ■7 is plotted on the vertical axis. As is clear from the figure, the aerodynamic brake 66 is
When the brake pedal 16 is depressed when the vehicle speed exceeds m/h, the action starts.
If the speed is 150 km/h or more, the F flag is turned ON in S4 and the start of action of the aerodynamic brake 66 is memorized, and then S5 is executed and the baffle plate 64 is rotated to the action position. If the vehicle speed becomes smaller than 1501 an/h due to braking, S3 becomes No and 36 is executed.
A determination is made as to whether the vehicle speed V, is 134 km/h or less.

Once the aerodynamic brake 66 has started its action, even if the vehicle speed 7 becomes less than 150 klIl/h, the
While the speed is greater than km/h, S6 becomes No, 37 becomes YES, the aerodynamic brake 66 is continuously applied, and 134
When the speed becomes less than km/h, it is brought into a non-operating state in S8 and the F flag is turned off. Also, when the brake pedal 16 is depressed, the vehicle speed ■1 is 150 km/h.
If it is smaller, the flag F will not be turned on, so even if the vehicle speed is greater than 134k+n/h, S3, S6, and S7 will be No, and the aerodynamic brake 66 will not be activated. If the difference between the vehicle speed vB when the brake pedal 12 is depressed and the vehicle speed at the end of the application is small, even if the aerodynamic brake 66 is applied, it will end in a short time and the deceleration effect will be small. It is better not to apply the aerodynamic brake 660, and a predetermined difference is provided between the vehicle speed at which the aerodynamic brake 660 is applied and the vehicle speed at which the aerodynamic brake 660 ends, so that the aerodynamic brake is applied for a certain period of time or longer. Also,
In this way, the baffle plate 64 will not be rotated uselessly to the operating position, and wasteful energy consumption and generation of operating noise due to the rotation of the baffle #tFi64 can be avoided. The setting of the vehicle speed at which the action starts and the vehicles at which the action ends is the control rule for the aerodynamic brake 66, and the vehicle speed at which the action starts is set at a height at which the air force brake 66 exerts its braking effect most effectively.

Following the control of the aerodynamic brake 66, the exhaust brake 60 is controlled in steps 89 to S14. exhaust brake 60
The period of action is indicated by diagonal lines in the graph of Figure 8, and the period when the vehicle speed ■8 is 1501a++/h or higher and 250km/h.
When braking is performed when the vehicle speed is less than be allowed to continue. It is designed to operate when the vehicle speed 8 is lower than the aerodynamic brake 66, and like the aerodynamic brake 66, it is designed not to start and end its action in a short period of time. .

Next to the control of the exhaust brake 60, the downshift control is performed in step 3.
15 to S20. The execution timing of downshift control is indicated by diagonal lines in the graph of Fig. 9, and is executed when braking is performed at a vehicle speed of 130 km/h or more and 180 kl/h or less. After the F3 flag is turned on, the F3 flag continues to act until the vehicle speed (1) becomes equal to or less than 80},n+/h. It is designed to operate when the vehicle speed is lower than the exhaust brake 60, and like the aerodynamic brake 66 and the exhaust brake 60, it is designed so that its operation does not start and end in a short period of time. -ing

Next, S21 is executed, and the disc brake 10 is controlled. This control will be explained based on the flowchart of FIG. First, in S101, the depression force FB of the brake pedal 10 is read, and in S102, the depression force F. Accordingly, the required deceleration gx desired by the driver is determined. There is a 10th difference between the stepping force FB and the deceleration gx.
A straight line in the diagram! There is a relationship represented by 1, and the controller 72
A straight line stored in the computer's ROM! , gx is calculated based on the formula representing . Then, S10
In step 3, the deceleration g8 obtained by the action of the aerodynamic brake 66 is calculated based on the vehicle speed R read in step S1. There is a curve in Figure 11 between vehicle speed Va and deceleration ga! There is a relationship expressed by 2, and this curve! The deceleration ga is calculated based on 2, which represents 2. Also,
Deceleration ge obtained by the action of the exhaust brake 60, deceleration g5 obtained by downshift control, and vehicle speed ■
8, there are straight lines l3 and ! in FIGS. 12 and 13, respectively. 4, and in S104 and S105, the deceleration speed g obtained by the action of the exhaust brake 60 and the downshift control, respectively.
．． , and gs are calculated. Subsequently, in S106, the target deceleration g to be achieved by the disc brake 10 is calculated. This deceleration gb is obtained by subtracting the decelerations g-, ge+ gS obtained by the three types of auxiliary brakes from the required deceleration gx calculated in S102, and the required deceleration gx is obtained by the action of the auxiliary brakes. In this case, g becomes less than O, S107 becomes NO, and the disc brake 10 is not applied. On the other hand, if the vehicle speed ■, is low, some or all of the auxiliary brakes cannot be applied, and the required deceleration gx cannot be obtained unless the disc brake 10 is applied, g, will be a value larger than 0. . The three types of auxiliary brakes are activated when the vehicle speed ■8 is quite high; if braking is performed while driving normally, the auxiliary brakes are not activated, and g, is less than 0. The value becomes large and braking is performed by the disc brake 1o. g, is larger than 0, S107 becomes YES and 3108 is executed, and the wheel cylinder 12.1 is adjusted based on the target deceleration speed gb.
The hydraulic pressure P, which should be supplied to 4 is calculated. Target speed g,
There is a straight line between and hydraulic pressure P, as shown in Figure 14! There is a relationship expressed by , and this straight line! The hydraulic pressure P, is determined based on the formula representing 5, and in S109, the hydraulic linear control valve 20 is controlled so that the determined hydraulic pressure P, is obtained.

The above steps 31 to S21 are repeatedly executed while the brake pedal 16 is depressed, and the automobile is braked. Then, the vehicle speed vR decreases due to the action of the disc brake 1o and the three types of auxiliary brakes, and when the vehicle speed reaches the end of the action of the auxiliary brake, each action is ended, and when the brake pedal 16 is released, the disc brake 1
The braking caused by o is also released.

As is clear from the above description, in this embodiment, the portion of the ROM of the controller 72 that stores 31 to S20 and the portion of the CPU and RAM that executes these steps constitute the auxiliary brake control means.

Although three types of auxiliary brakes were provided in the above embodiment, two types of auxiliary brakes may be selected from these, or another type of auxiliary brake may be added, or the three types of auxiliary brakes described above may be added. It may be provided in place of any of the brakes.

In addition, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing the configuration of the present invention. FIG. 2 is a system diagram showing a composite brake system for an automobile, which is an embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of a braking force control device of the above-mentioned composite brake system. Figure 4 shows the RAM of the computer of the controller, which is one component of the control device.
It is a Bronok diagram conceptually showing the configuration of the . FIG. 5 is a flowchart showing a braking force control routine stored in the ROM of the computer, and FIG. 6 is a flowchart showing a disc brake control routine. FIG. 7 is a graph showing the timing of application of the aerodynamic brake in the above composite brake system, FIG. 8 is a graph showing the timing of application of the exhaust brake, and FIG. 9 is a graph showing the timing of execution of downshift control. . FIG. 10 is a graph showing the relationship between the depression force of the brake pedal and the deceleration required by the driver. FIG. 11 is a graph showing the relationship between vehicle speed and deceleration obtained by the action of the aerodynamic brake, FIG. 12 is a graph showing the relationship between vehicle speed and deceleration obtained by the action of the exhaust brake, and FIG. The figure is a graph showing the relationship between vehicle speed and deceleration obtained by executing downshift control. FIG. 14 is a graph showing the relationship between the deceleration to be obtained by the action of the disc brake and the hydraulic pressure supplied to the wheel cylinder. 10: Disc brake 39: Automatic transmission 42: Exhaust brake valve 60: Exhaust brake 64: Baffle plate 66: Empty brake 70: Braking force control device

Claims (1)

[Claims] In a composite brake system for an automobile having a friction brake that suppresses rotation of a wheel by friction and an auxiliary brake, a plurality of types of auxiliary brakes are provided, and each of the plurality of types of auxiliary brakes is independently set. is,
A composite brake system for an automobile, comprising an auxiliary brake control means for controlling the action of each auxiliary brake in accordance with control rules that define the start time and end time of each auxiliary brake.