JPH0780450B2 - A braking device that can accurately obtain a braking effect according to the operating force. - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle brake device, and more particularly to a brake device that can obtain a braking effect that accurately corresponds to the operating force of a brake operating member.

Brake devices for automobiles include a brake that suppresses wheel rotation, a brake operating member that is operated to operate the brake, and a brake drive device that operates the brake according to the operation of the brake operating member. It is usually configured to include and. In the conventional brake device, the operating force of the brake is proportional to the operating force of the brake operating member (this proportional constant is referred to as the brake servo ratio). The deceleration and the magnitude of the braking torque generated on the axle are not uniquely determined by the operating force of the brake, and are affected by various conditions such as the load, the gradient of the road surface, and the friction coefficient of the friction material of the brake. Therefore, the driver has to operate the brake operating member in consideration of these conditions.

Therefore, it has been proposed in Japanese Patent Laid-Open No. 188746/1983 that the deceleration of the vehicle, not the actuation force of the brake, be uniquely determined with respect to the actuation force of the brake operating member. The brake drive device is such that the brake servo ratio is changed based on an electric signal, and a deceleration detecting means for detecting a deceleration of an automobile, an operating force detecting means for detecting an operating force of a brake operating member, and a deceleration. Brake drive device control means for controlling the brake drive device so that the actual deceleration detected by the detection means becomes equal to a target deceleration determined by a predetermined ratio with respect to the operating force detected by the operating force detection means. Is provided. The target deceleration is set to a constant value regardless of the elapsed time after the start of the operation of the brake operating member.

Problems to be Solved by the Invention However, it is not preferable to set the target braking effect such as the target deceleration constant regardless of the elapsed time after the start of the operation. For example, if the target braking effect in the initial stage of braking is determined to be the same value as that in the middle period of braking, there is a problem that the delay in the effect in the initial stage of braking becomes large. In the brake device, a certain period of time is required from when the operation of the brake operating member is started to when the brake actually starts, and this is called delay in braking, but this delay in braking becomes large.

Means for Solving the Problems In order to solve this problem, the present invention, as shown in FIG. 1, includes a brake, a brake operating member, an operating force detecting means, a brake drive device, a braking effect detecting means, And (a) an operation start detecting means for detecting an operation start of the brake operating member, and (b) a brake operating member after the operation start is detected by the operation start detecting means. Of the target braking effect with respect to the operating force detected by (c) the operating force detecting means, and the elapsed time measured by the measuring means is preset. The target braking effect determiner for determining the target braking effect is set to be larger than the predetermined ratio while the time is within the time period and set to the predetermined ratio after the initial time. It is provided with steps.

In the brake device configured as described above, the target braking effect is determined to be large by the target braking effect determination means at the beginning of when the operation start detection means detects the operation start of the brake operation member, that is, in the initial period. To be done. Within the initial time, a braking effect larger than the initial braking effect is determined as the target value. Then, the brake drive device control means controls the brake drive device so that the actual braking effect detected by the braking effect detection means becomes substantially equal to the target braking effect.

Therefore, in the initial stage of the braking effect control, the shortage amount of the actual braking effect detected by the braking effect detecting means with respect to the target braking effect becomes large, and the brake control drive device increases the braking operation force accordingly. Since the control for abruptly increasing is performed, a braking effect close to the desired braking effect from the initial stage of the braking control can be obtained, and the effect of reducing the braking delay can be obtained.

Embodiment Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 2, reference numeral 10 indicates a brake pedal as a brake operating member. The brake pedal 10 operates a master cylinder 14 via a hydraulic booster 12. A reservoir 16 is attached to the upper part of the master cylinder 14, and a pump 18 pumps up the brake fluid from the reservoir 16 and stores it in an accumulator 20 at a high pressure, and the booster 12 is connected to the accumulator 20 by a fluid passage 22. Has been done.

The booster 12 and the master cylinder 14 share a housing 30 as shown in FIG. Pistons 32 and 34 are fitted in the housing 30 in a liquid-tight and slidable manner,
As a result, pressure chambers 36 and 38 are formed. In these pressurizing chambers 36 and 38, the pistons 32 and 34 are spring-loaded.
40 and 42 are communicated with the reservoir 16 in a state of being retracted to the retracted end positions where they abut the stoppers 44 and 46, respectively.

The piston 52, which is the output piston of the booster 12, is integrated with the piston 34 of the master cylinder 14. Housing 30
A cylindrical auxiliary member 54 is fixed to the end portion of the side opposite to the master cylinder side, and functions as a part of the housing 30. A piston 56, which is an input piston of the booster 12, is fluid-tightly and slidably fitted to the auxiliary member 54, and a hydraulic chamber 58 is formed between the pistons 52 and 56. A valve 62 is provided at the end of the piston 56 on the piston 52 side.
Is fixed by screwing, and the large diameter portion 64 of this valve element 62 is
A spring 66 is provided between the piston 52 and the piston 52 to urge the pistons 52 and 56 in a direction in which they are separated from each other.

The valve element 62 is slidably and substantially fluid-tightly fitted in a valve hole formed in the center of the piston 52, and is always in the state shown in FIG. Although it communicates with the reservoir 16 through the formed liquid passage 70, the liquid passage 72 formed in the piston 52, and the annular chamber 74, it moves forward by a certain distance with respect to the piston 52 (moves leftward in FIG. 3). In this state, the communication between the liquid passages 70 and 72 is blocked, and in the state where the liquid passage 70 is further advanced by a certain distance, the liquid passage 70 is connected to the port 79 via the liquid passage 76 formed in the piston 52 and the annular chamber 78. Has become. The accumulator 20 is connected to the port 79 by the liquid passage 22. That is, the valve element 62, together with the piston 52, can be switched between a state in which the fluid pressure chamber 58 communicates with the reservoir 16, a state in which the fluid pressure chamber 58 communicates with the accumulator 20 serving as a fluid pressure source, and a state in which neither the reservoir 16 nor the accumulator 20 communicate. That is, a possible switching valve 80 is configured.

As is apparent from FIG. 2, the pressurizing chamber 36 of the master cylinder 14 is formed by the main liquid passage formed by the liquid passages 90 and 92.
It is connected to the wheel cylinder 96 of the brake that brakes 94. On the other hand, the pressurizing chamber 38 is connected to a wheel cylinder of a brake that brakes the rear wheels, but since the configuration of this rear wheel system is the same as the configuration of the front wheel system, illustration and description thereof will be omitted. Will be described only.

The liquid passage 90 is bifurcated after passing through the check valve 98, and a sudden increase / decrease valve 100 and a gradual increase / decrease valve 102 are provided in each branch passage.
Is provided. The rapid increase / decrease valve 100 is always connected to the liquid passages 90 and 9
2, that is, the master cylinder 14 and the wheel cylinder 96 are in a pressure-increasing allowable state in which they communicate with each other, but an intermediate current is supplied to the solenoid 104, so that the master cylinder 14
Is a three-position solenoid valve that is switched to a pressure-holding state that cuts off the communication between the wheel cylinder 96 and the wheel cylinder 96, and is further switched to a depressurization allowable state that allows the wheel cylinder 96 to communicate with the reservoir 16 by supplying a large current to the solenoid 104. ing. The slow increase / decrease valve 102 is also a three-position solenoid valve having the same structure as the rapid increase / decrease valve 100, but the control of the current supplied to the solenoid 106 is different. That is, when it is necessary to gently increase the hydraulic pressure of the wheel cylinder 96, a current is supplied to the solenoid 106 that alternately switches the slow increase / decrease valve 102 between the pressure increase allowing state and the pressure maintaining state in a short cycle. When it is necessary to gently reduce the hydraulic pressure of the wheel cylinder 96, the solenoid 106 is supplied with a current that alternately switches the slow increase / decrease valve 102 between the pressure reduction allowable state and the pressure holding state in a short cycle. .

A bypass passage 110 provided with a check valve 108 and bypassing the rapid increase / decrease valve 100 and the gradual increase / decrease valve 102 is provided, and the brake fluid of the wheel cylinder 96 can flow back to the master cylinder 14 via the bypass passage 110. Is being done.

The accumulator 20 is connected to a portion of the liquid passage 90 after passing through the check valve 98 via an electromagnetic opening / closing valve 112. The solenoid on-off valve 112 is always in a state of disconnecting the connection between the accumulator 20 and the liquid passage 90, but
After a certain short time T _{1 has} elapsed from the start of depressing 10, the high pressure brake fluid is supplied from the accumulator 20 to these valves 100 and 102.
However, the high-pressure brake fluid supplied from this accumulator 20 cannot flow into the master cylinder 14 because
Blocked by 98.

As is clear from the above description, the booster 12, master cylinder 14, pump 18, accumulator 20, solenoid on-off valve 112,
The sudden increase / decrease pressure reducing valve 100, the slow increase / decrease pressure reducing valve 102, and the like constitute a brake drive device.

The brake drive device is controlled by the control device 120. The control device 120 is mainly composed of a computer. The control device 120 includes a rotation sensor 122 for detecting the rotation speed of the front wheels 94, a brake switch 124 for detecting that the brake pedal 10 is depressed, and a brake pedal 10.
A load cell 126 for detecting the operating force of the control unit and a manual operation unit 128 for manually changing the control characteristics of the control device 120 are connected. The control device 120 determines the target braking effect corresponding to the operating force of the brake pedal 10 based on the information supplied from these, and the sudden increase / decrease valve 100, the slowly increasing / decreasing valve 102.
By controlling the solenoid opening / closing valve 112, the hydraulic pressure of the wheel cylinder 96 is controlled so that the braking effect of the front wheels 94 becomes equal to the target braking effect. Brake switch 124
Represents the braking start detecting means, the load cell 126 constitutes the operating force detecting means, and the control device 120 constitutes the target braking effect determining means and the brake drive device controlling means. The control device 120 also constitutes a vehicle speed detecting means and a braking effect detecting means together with the rotation sensor 122. That is, the control device 120 is configured to calculate the vehicle speed and the deceleration based on the output signal of the rotation sensor 122,
In this embodiment, the braking effect can be grasped based on this deceleration. As will be apparent from the description below, the control device 120 also constitutes a time measuring means for measuring the elapsed time from the start of the braking operation.

The ROM of the computer that is the main body of the control device 120 has a fourth
The initial map shown in the figure, the low speed map shown in FIG. 5 and the high speed map shown in FIG. 6 are stored. The initial map is a map for control within the initial time T ₀ immediately after the brake pedal 10 is depressed, and the low speed map and the high speed map are maps for control after the initial time T _{0 has} elapsed. The high-speed map is for control when the vehicle is traveling at a high speed that is higher than the high-speed set value V ₀ (for example, 50 km / h), and the low-speed map is for control when it is traveling at a low speed that is less than the high-speed set value V _0. Is a map of.

The initial map is 1As, 1Bs spread on both upper and lower sides as shown in FIG. 7, centered on a straight line representing the desired relationship between the operating force F of the brake pedal 10 and the target deceleration g _S , g _S = αF, at the initial stage of braking. , Cs, 2Bs and 2As areas,
This is a map. That is, the entire range of the operating force F of the brake pedal 10 is divided into a plurality of stages, and the width of the above region is set stepwise for each stage. Region C _S is a region where deceleration g is appropriate,
1B _S is a region where the deceleration g is slightly excessive, and 1A _S is a region where the deceleration g is excessive. On the other hand, the region 2B _S is a region where the deceleration g is slightly too small, and the region 2A _S is the deceleration g
Is an area that is too small.

Further, the low speed map of FIG. 5 and the high speed map of FIG. 6 show that the brake pedal 10 is used when the vehicle is traveling at a speed lower than or equal to the high speed set value V _0.
As shown in FIGS. 8 and 9 with respect to the proper relationship between the operating force F and the deceleration g _L when the is operated, and the straight lines representing g _L = βF and g _H = γF, respectively, as shown in FIGS. Region 1A _L , 1B _L , C _L , 2B _L , 2A _L and 1A _H , 1B _H ,
C _H , 2B _H , 2A _H are set and these are mapped. In the present embodiment, the above constants α, β, γ
The width of each area shown in FIGS. 4 to 6 and the initial time T ₀ and the high speed set value V ₀ can be changed within a certain limit by the operation of the manual operation unit 102.

The ROM further stores a pressure increasing / decreasing valve control map as shown in FIG. This is because the deceleration error Δg _S (=
g-g _S ), Δg _L (= g-g _L ), and Δg _H (= g-g _H ) in each of the above regions, what state should the rapid increase / decrease valve 100 and the slow increase / decrease valve 102 have? In the drawing, x is a pressure increasing instruction, y is a pressure reducing instruction, and z is a pressure holding instruction. For example, the deceleration error Delta] g _S in early region C _S
If it is, the pressure-holding instruction is given to both the rapid increase / decrease valve 100 and the slow increase / decrease valve 102. However, if the deceleration error Δg _S changes from the value of the region C _{S to} the value of the region 2B _S , the slow increase / decrease valve 102 Is given a pressure increase instruction, and the rapid pressure increase / decrease valve 100 is given a pressure keeping instruction. Then, when the deceleration error Δg _S changes to the value in the region 2A _S, a pressure holding instruction is given to the slow increase / decrease valve 102,
A pressure increase instruction is given to the sudden increase / decrease valve 100. When the deceleration error Δg _S changes from the value in the region 2B _{S to} the value in the region C _S , the pressure increase instruction is given to the slow increase / decrease valve 102 once, and then the pressure holding The instruction is given, and the pressure-holding instruction is continuously given to the rapid increase / decrease valve 100 to which the pressure-holding instruction has been given. Even when the deceleration error Δg _S changes between other regions, a predetermined instruction is similarly given to the rapid increase / decrease valve 100 and the slow increase / decrease valve 102 according to the arrow in FIG.

The ROM further stores various control programs including the control program represented by the flowchart of FIG. The operation of the brake device will be described below with reference to the flowchart of FIG.

When the brake pedal 10 is not depressed, the switching valve 80 shown in FIG. 3 is in a state of communicating the hydraulic chamber 58 with the reservoir 16. In this state, the communication between the hydraulic chamber 58 and the accumulator 20 shown in FIG. 2 is cut off, and
Since the electromagnetic on-off valve 112 is also in the closed state, the brake fluid pumped up from the reservoir 16 by the pump 18 is stored in the accumulator 20 at high pressure. And the accumulator 20
After a certain amount of brake fluid is stored in the pump 18, the pump 18 is stopped based on a signal from a pressure switch (not shown) provided in the accumulator 20. Further, step S1 of FIG. 11 is repeatedly executed in the control device 120.

When the brake pedal 10 is stepped on, the piston 56 advances, but the valve 62 closes the liquid passage 72 before the large diameter portion 64 of the valve 62 that advances together with the piston 56 abuts the piston 52,
Open the fluid passage 76. Therefore, high-pressure brake fluid flows from the accumulator 20 into the fluid pressure chamber 58 through the port 79, the annular chamber 78, and the fluid passages 76 and 70, and the piston 52 is advanced. At this time, the hydraulic pressure of the hydraulic chamber 58 also acts on the piston 55, so that the operating force of the brake pedal 10 increases. The load cell 126 converts this operating force into an electric signal and supplies it to the control device 120.

Further, as the brake pedal 10 is stepped on, an operation start detection signal is supplied from the brake switch 124 to the control device 120. Therefore, the determination result of step S1 in the flowchart of FIG. 11 is YES, step S2 is executed, and the operation force F is taken in. The signal from the load cell 126 is stored in the operating force register of the computer of the controller 120. Also, in step S3,
The actual deceleration g is calculated based on the output signal of the rotation sensor 122.

Then, in S4, the elapsed time after the start of the operation is the initial time.
It is determined whether T ₀ or less. Based on the operation start detection signal from the brake switch 124, whether the timer built in the computer of the controller 120 is started and whether the time T measured by the timer is the initial time T ₀ or less That is, the determination is made. The determination result of S4 performed immediately after the brake pedal 10 is pressed is of course YES, so S5 is executed. The calculation of the target deceleration g _S based on the operation force F stored in the operation force register and the expression g _S = αF, and the calculation of the error Δg _S of the actual deceleration g with respect to the target deceleration g _S are performed. Of.

Subsequently, step S6 is executed, and the area in the initial map of FIG. 4 is determined based on the operating force F stored in the operating force register and the deceleration error Δg _S calculated in step S5. Further, in step S7, it is determined from which region the deceleration error Δg _S has moved to that region. That is, if the result of the region determination in step S6 is any of 2A _S , C _S , and 1A _S , the 10th
As can be seen, the pressure increase instruction x, indicating the reduction y, although any of the pressure-holding instruction z is the uniquely determined, if the result of the region determination was 2B _S or 1B _S is how Since the instruction is divided into two types depending on whether the area has moved to that area, the passage route is determined. Specifically, the area stored in the area register of the RAM is compared with the area determined in step S6, and if they are the same, execution of the program proceeds to step S8. Whether or not the area has changed to that area is stored in the passage route register, and the content of the area register is updated.

In the following step S8, any one of the pressure increasing instruction x, the pressure reducing instruction y, and the pressure maintaining instruction z in the pressure increasing / reducing valve control map of FIG. Each is selected for 102, and the solenoids 104, 106 are controlled based on the instruction in step S9. Then, in step S10, it is determined whether the braking is completed, that is, the brake pedal 10
It is determined whether or not the depression is released, and if it is released, the electromagnetic opening / closing valve 112 is closed in step S11, and the rapid increase / decrease valve 100 and the slow increase / decrease valve 102 are in the normal state. After returning to step S1, the process returns to step S1, but if not released, steps S2 and thereafter are executed again.

The above is a general description of the control by S2 to S10.
10 The actual deceleration calculated in S3 immediately after stepping on is almost 0
Is. Therefore, the error Δg _S calculated in S5 becomes large, and the areas C _S and 2B _S in the map of FIG.
Since the width of the area is narrow, the result of the area judgment in S6 is 2A _S
Then, in S8, the pressure increase instruction for the sudden increase / decrease valve 100 is determined. Therefore, the solenoid control in S9 maintains the rapid pressure increase / decrease valve 100 in the pressure increase allowable state, the brake fluid is supplied from the master cylinder 14 to the wheel cylinders 96 at a sufficient flow rate, and the delay in the braking effectiveness is reduced.

As described above, S2 to S10 are repeatedly executed even while the rapid pressure increase / decrease valve 100 is maintained in the pressure increase allowable state, and the brake begins to operate so that the actual deceleration g approaches the target deceleration g _S , or When it exceeds, the control of the sudden increase / decrease valve 100 and the gradual increase / decrease valve 102 is performed, and the vehicle is in a state of being braked at the target deceleration g _S.

Since the electromagnetic opening / closing valve 112 is switched to the open state after a certain short time T _{1 has} elapsed since the operation start detection signal was issued from the brake switch 124 as described above, the hydraulic control of the wheel cylinder 96 is thereafter performed. Is performed not by using the master cylinder 14 as a hydraulic pressure source but by using the accumulator 20 as a hydraulic pressure source. However, since the brake fluid is supplied from the master cylinder 14 until the time T ₁ elapses,
The depression amount of the brake pedal 12 is not limited to a remarkably small amount.

Eventually, the elapsed time T after the start of the operation exceeds the initial time T ₀ , the determination result in S4 becomes YES, and S12 is executed. It is determined whether or not the actual vehicle speed V at that time exceeds the high-speed set value V ₀ . If the determination result is NO, S13 to S16 are executed in the same manner as S5 to S8, and the vehicle is braked at the target deceleration g _L. Also,
If the decision result in S12 is YES, S17 to S20 are executed, and the vehicle is braked at the target deceleration g _H. Even if the operating force of the brake pedal 10 is the same, different braking effects can be obtained during low speed traveling and high speed traveling,
Since each braking effect is suitable for each traveling, the driver only has to operate the brake pedal 10 with a constant feeling without being aware of the traveling speed, which facilitates the braking operation. The effect of improving the safety of the automobile can be obtained. Of course, control S1 at high speed
If the actual vehicle speed V becomes smaller than the high speed set value V ₀ while 7 to S20 are executed, the low speed control of S13 to S16 is performed.

Further, the control device 120 controls the sudden increase / decrease valve 100 and the slow increase / decrease valve 102 based on the output signal of the rotation sensor 122, and the front wheel 94
It also has the function of an anti-skid device that prevents the vehicle from falling into the skid state, and this control has priority over the above control. However, since the control in this case is well known, it will be explained. Is omitted.

When a failure occurs in the control system mainly including the control device 120, the pump 18, or the like, the piston 56 of the booster 12 comes into contact with the piston 52 to directly actuate the piston 34 of the master cylinder 14, and the sudden increase Pressure reducing valve 100 and slow increasing pressure reducing valve 1
In 02, since the master cylinder 14 and the wheel cylinder 96 are kept in communication with each other when the solenoids 104 and 106 are not excited, the hydraulic pressure of the wheel cylinder 96 is raised in accordance with the operating force of the brake pedal 10, and the brake is applied. Can be operated without any problems.

In the embodiment described in detail above, by utilizing the control device 120, which is a constituent element of the anti-skid device, the rapid increase / decrease valve 100 and the slow increase / decrease valve 102, it is appropriate during normal braking operation without fear of falling into a skid state. Although the braking effect is not obtained, the object of the present invention can also be achieved by making the booster 12 capable of changing the boosting factor by an electric signal. The present invention can be applied to any vehicle brake device provided with a brake drive device that can be changed based on a signal.

Further, in the above-described embodiment, when the brake operation is performed while the vehicle is traveling at high speed, first, control is performed so that a braking effect suitable for high-speed traveling is obtained, and the actual vehicle speed V is set to the high-speed set value. a decline in V ₀ below, had been to a braking effect suitable during low-speed traveling is automatically switched to the control obtained, after once control suitable for high-speed running is started, the vehicle speed is reduced However, it is also possible to continue the control as it is.

Further, in the above embodiment, the target braking effect can be changed in two steps before and after the initial time T ₀ has passed, but the range of the elapsed time after the start of the operation is further divided into three or more steps. Thus, it is possible to change the target braking effect for each stage. Further, from the time when the actual vehicle speed V is reduced to an extremely low value immediately before the stop, the target braking effect is smoothly reduced with the lapse of time so that the deceleration becomes 0 at the same time as the vehicle stops, so-called shaking. It is also possible to prevent the occurrence of a return.

Further, the braking effect grasping means is not limited to the deceleration detecting means, and a braking torque detecting means or the like can be adopted.

In addition, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art, such as by appropriately changing control programs and control maps.

[Brief description of drawings]

FIG. 1 is a diagram conceptually showing the structure of the present invention. FIG. 2 is a system diagram showing a vehicle brake device according to an embodiment of the present invention, and FIG. 3 is a front sectional view showing a master cylinder and a booster used therein. 4 to 6 are diagrams showing an initial map, a low speed map and a high speed map stored in the control device of FIG.
FIG. 9 to FIG. 9 are graphs for explaining the meaning of the initial map, the low speed map and the high speed map, respectively. First
FIG. 10 is a diagram showing a pressure increasing / decreasing valve control map stored in the control device of FIG. FIG. 11 is a flow chart showing only a part of the control program of the control device, which is deeply related to the present invention. 10: Brake pedal, 12: Booster 14: Master cylinder, 16: Reservoir 18: Pump, 20: Accumulator 96: Wheel cylinder, 100: Rapid increase / decrease valve 102: Slow increase / decrease valve, 112: Electromagnetic on-off valve 120: Control device, 122 : Rotation sensor 124: Brake switch, 126: Load cell

Claims (1)

[Claims] 1. A brake for suppressing rotation of wheels of an automobile, a brake operating member operated for operating the brake, an operating force detecting means for detecting an operating force of the brake operating member, and the brake operation. A brake drive device that actuates the brake according to the operation of a member, and the ratio of the operating force of the brake and the operating force of the brake operating member can be changed based on an electrical signal, and detects the braking effect of a vehicle The braking effect detecting means, and the actual braking effect detected by the braking effect detecting means are substantially equal to the target braking effect determined by a predetermined ratio with respect to the operating force detected by the operating force detecting means. A brake drive device control means for controlling the brake drive device; An operation start detecting means for detecting an operation start, a time measuring means for measuring an elapsed time during which the operation start detecting means detects the operation start and the brake operation member is continuously operated, and an operation force detecting means for detecting the elapsed time. The ratio of the target braking effect to the operated force is increased compared to the predetermined ratio while the elapsed time measured by the timing means is within a preset initial time, and is outside the initial time. After that, a target braking effect determining means for determining the target braking effect is provided as the predetermined ratio, and a braking device capable of accurately obtaining a braking effect according to an operating force.