JP2002145043A - Hydraulic pressure brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic pressure brake device capable of assist servo control and automatic brake control with a simple construction. SOLUTION: A stepped piston 30 is fitted into a master cylinder to form a pressurizing chamber 31, a supplying chamber 32, and a pressure adding chamber 33. A brake fluid is supplied from the supply chamber 32 to the pressurizing chamber 31, the pressure adding chamber 33 and a wheel cylinder 38, by a pump 41 to an operating force F of a brake pedal 34. A pressure control valve 42 controls a discharge amount of the pump 41 so that the pressure in the supply chamber 32 is 0, thereby allowing assist servo control. A assist servo ratio can be determined by a difference between an effective pressure receiving area to the pressurizing chamber 31 in a small diameter portion of the piston 30 and an effective pressure receiving area to the pressure adding chamber 33 in a large diameter portion 28 of the piston 30. By half-opening a proportional solenoid valve 40, the pressure in the pressure adding chamber 33 is increased to advance the piston 30, thereby operating an automatic brake.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic brake device capable of boost control and automatic brake control.

[0002]

2. Description of the Related Art A conventional hydraulic brake device for an automobile will be described with reference to FIGS. The hydraulic brake device 1 shown in FIG. 6 is an example in which an automatic brake operation function is provided with the simplest configuration. Referring to FIG. 6, a large-diameter piston 3 is slidably fitted in the master cylinder 2, and a small-diameter rod portion 4 integrally connected to the piston 3 is extended to the outside, and the master cylinder Pressurizing chamber 5 and pressure adding chamber 6 in 2
Two chambers are formed. A brake pedal 7 is connected to the rod portion 4, and a return spring 8 is provided in the pressurizing chamber 5.

The pressurizing chamber 5 is connected to a wheel cylinder 9 and to a reservoir 11 through a reservoir port 10. The pressure addition chamber 6 is connected to the reservoir 11 via the pump 12, and is pressurized by the discharge pressure of the pump 12. An electromagnetic pressure control valve 13 is provided between the pressure addition chamber 6 and the reservoir 11 in parallel with the pump 12.

The operation of the hydraulic brake device 1 will now be described.
explain. If only the operating force of a normal driver is
Key 7 is depressed with the operating force F and the return spring 8
Sleeping force F _kWhen piston 3 moves forward against
Is closed, the pressurizing chamber 5 is pressurized, and the pressure
On the cylinder 9. At this time, the pressure P_a
Is the pressure receiving area of the piston 3 with respect to the pressure chamber 5_aTo be
And P_a= (F-F_k) / S_a Becomes

In the case of automatic brake control without operation by the driver, the pump 12 is started, the pressure adding chamber 6 is pressurized, and the piston 3 is advanced against the spring force of the return spring 8 to move the pressurizing chamber 5. Press. The pressure in the pressure addition chamber 6 is controlled by adjusting the discharge pressure of the pump 12 by the electromagnetic pressure control valve 13. At this time, the pressure P _a of the pressure chamber 5, the effective pressure-receiving area with respect to the pressure addition chamber 6 of the piston 3 S _c, the pump
The discharge pressure of 12 Then P _c, the _{P a = (S c × P} c -F k) / S a.

When the operating force by the driver and the operating force by the automatic brake act simultaneously, these can be added to make P _a = (F + S _c × P _c −F _k ) / S _a . Alternatively, the pressure in the pressurizing chamber 5 is detected by a pressure sensor, or the vehicle deceleration is detected by an acceleration sensor, and the discharge pressure of the pump 12 is adjusted so as not to exceed the target pressure or the target deceleration by the automatic brake. By doing so, by supplying the required pressure of the greater of the operating force by the driver or the operating force by the automatic brake to the wheel cylinder 9, it is possible to reduce the uncomfortable feeling of the braking operation by the driver.

Further, the pressure of both the pressurizing chamber 5 and the pressure added chamber 6 detected by the pressure sensor, by _{F = S a × P a -S} c × P c + F k, calculates the operating force F, multiple By controlling the pressure _Pc of the pressure addition chamber 6 by adjusting the discharge pressure of the pump 12 by the electromagnetic pressure control valve 13 so that P _a = α × F / S _{a where the} force ratio is α. It is also possible to perform boost control.

However, when performing the boosting control in this manner, it is necessary to use two expensive pressure sensors, and since the operating force F is calculated based on the outputs of the two pressure sensors, the accuracy is reduced. With the problem that it is difficult to raise.

On the other hand, the automotive hydraulic brake device shown in FIG. 7 is an example in which boost control can be performed with a simple structure. Note that the same parts as those shown in FIG. 6 are described with the same reference numerals. Referring to FIG. 7, a stepped piston 17 having a small-diameter portion 15 and a large-diameter portion 16 is slidably fitted in a master cylinder 14, and a pressurizing chamber 18 and a supply chamber 19 are provided.
A chamber is formed. A rod portion 20 is connected to the piston 17, and extends outside the master cylinder 14,
The brake pedal 7 is connected to the rod portion 20.
The pressurizing chamber 18 is provided with a return spring 8.

The pressurizing chamber 18 is connected to the wheel cylinder 9 and communicates with the supply chamber 19 via a port 21. The supply chamber 19 is connected to the reservoir 11 through the reservoir port 22.
It is connected to the. The supply chamber 19 is connected to the suction side of the pump 23, and the discharge side of the pump 23 is connected to a wheel cylinder.
Connected to 9. The suction side and the discharge side of the pump 23
It is connected via a pilot-type pressure control valve 24.
The pressure control valve 24 is connected to the suction side of the pump 23, that is, the supply chamber.
When the pressure of 19 is higher than almost 0, it closes and when it is low, it opens.

The operation of the hydraulic brake device 14 will now be described. When the brake pedal 7 is depressed with the operating force F,
When the piston 17 moves forward against the spring force F _k of the return spring 8, the port 21 and the reservoir port 22 is closed, the pressure chamber 1
8, a closed space is formed by the supply chamber 19 and the wheel cylinder 9, and thereafter, the amount of liquid supplied to the wheel cylinder 9 is determined according to the stroke of the piston 17.

When the piston 17 advances, the pressurizing chamber 18 and the supply chamber 19 are pressurized, and the brake fluid is supplied to the wheel cylinder 9. At the same time, the pump 23 starts to move from the supply chamber 19 to the pressurizing chamber 18. Brake fluid is supplied. At this time, S _a the effective pressure-receiving area against compression chamber 18 of the small-diameter portion 15 of the piston 17, the effective pressure receiving area for the supply chamber 19 of the large-diameter portion 16
S _b, the pressure in the compression chamber 18 P _a, when the pressure in the supply chamber 19 and P _b, the following equation holds from the balance of forces acting on the piston 17. F = S _a × P _a + S _b × P _b + F _k

Here, when the pressure of the supply chamber 19 becomes positive, the pressure control valve 24 is closed, and the pressure is reduced by the suction of the pump 23. When the pressure becomes almost zero, the pressure control valve 24 is opened. Since the pump 23 is unloaded, its pressure becomes almost zero. Thus, in the formula, when P _b = 0, the pressure P _a of the compression chamber 18 becomes _{P a = (F-F k} ) / S a. On the other hand, there is no pump 23 and pressure control valve 24, the pressure P _a of the pressure chamber 18 when the pressure directly pressurizing the wheel cylinder 9 by piston 17 _{', P a' = (F-} F k) / (S a + S because it is _b), boost ratio alpha _{is, α = P a / P a} '= (S a + S b) / S a next, it is possible to perform the boost control. The amount of brake fluid supplied to the wheel cylinder 9 is (S _a + S _b ) × L, where L is the stroke of the piston 17. A brake system for performing boost control in this way is described in, for example, German Patent No. 19716404.

[0014]

However, in the conventional example shown in FIG. 7, when the brake is not applied (in a state where the operating force by the driver is not acting on the brake pedal 7), the pressurizing chamber is not operated.
Since both the supply chamber 18 and the supply chamber 19 are communicated with the reservoir 11, and no thrust can be applied to the piston by the pump, there is a problem that automatic brake control such as traction control cannot be performed.

The present invention has been made in view of the above points, and has as its object to provide a hydraulic brake device capable of performing boosting control and automatic brake control with a simple structure.

[0016]

According to a first aspect of the present invention, there is provided a hydraulic brake device in which a stepped piston is slidably fitted in a master cylinder to advance the piston. Forming three chambers of a pressurizing chamber pressurized by a pressurized chamber, a supply chamber and a depressurized pressure adding chamber, the effective pressure receiving area of the piston with respect to the pressurizing chamber is larger than the effective pressure receiving area of the pressure adding chamber with A wheel cylinder is connected to the pressurizing chamber, and a pump for supplying brake fluid from the supply chamber to the pressurizing chamber and the pressure adding chamber is provided, and the discharge amount of the pump is set so that the pressure in the supply chamber becomes substantially zero. Is controlled. With this configuration, boosting control can be performed by pressurizing the pressurizing chamber and the pressure adding chamber connected to the wheel cylinder by the pump in accordance with the operating force on the piston. The boost ratio is determined by the difference between the effective pressure receiving area for the chamber and the effective pressure receiving area for the pressure adding chamber. A hydraulic brake device according to a second aspect is characterized in that, in the configuration of the first aspect, an on-off valve that opens and closes a flow path between the pump and the pressurizing chamber is provided. With this configuration, when the on-off valve is closed, the pump is pressurized,
The pressure in the pressure adding chamber becomes higher than the pressure in the pressurizing chamber, the piston advances, and the automatic brake operates. According to a third aspect of the present invention, there is provided the hydraulic brake device according to the first or second aspect, wherein a discharge side of the pump and a suction side are suctioned based on a differential pressure between a reservoir for replenishing the pressurized chamber with brake fluid and the supply chamber. The discharge amount of the pump is controlled by a pressure control valve that communicates with and shuts off the side. With this configuration, according to the pressure difference between the reservoir and the supply chamber,
The pressure in the supply chamber is adjusted to almost zero by loading and unloading the pump by the pressure control valve. Claim 4
A hydraulic brake device according to any one of claims 1 to 3, wherein a pressure accumulating means is provided in the supply chamber. With this configuration, when the supply chamber is pressurized due to the shortage of the discharge amount of the pump, the pressure of the supply chamber is temporarily accumulated by the pressure accumulating unit, and the increase in the pressure of the supply chamber is suppressed. Reduce the increase in reaction force to the piston.
A hydraulic brake device according to a fifth aspect is characterized in that, in the configuration of the fourth aspect, the pressure accumulating means is built in the piston. With such a configuration, downsizing can be achieved. Further, in the hydraulic brake device according to claim 6, in the configuration according to claim 4, the pressure accumulating unit is configured such that the pressure accumulating means includes a piston portion movably provided in the piston and defining a supply chamber and the pressure addition chamber. It is characterized by becoming. With this configuration, when the supply chamber is pressurized, the piston moves toward the pressure addition chamber, and accumulates the pressure of the supply chamber in the pressure addition chamber.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. A first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the hydraulic brake device 25 of the first embodiment includes a master cylinder 26,
The small diameter portion 27 at the distal end, the large diameter portion 28 at the center, and the rod portion 29 at the proximal end
Are provided slidably, and three chambers of a pressurizing chamber 31, a supply chamber 32 and a pressure adding chamber 33 are formed. The rod part 29 has a larger diameter than the small diameter part 27 and a large diameter part.
A brake pedal 34 is connected to an end of the master cylinder 26 which has a smaller diameter than that of the master cylinder 26 and extends outside. Piston 30
Pressure receiving area S _a of the small diameter portion 27 of the
28 relationship between the effective pressure-receiving area S _c for the pressure adding chamber 33 of the effective pressure receiving area S _b and the large diameter portion 28 to the feed chamber 32 has a S _a> S _c and S _b> S _c. In the pressurizing chamber 31, a return spring 35 is provided.

The pressurizing chamber 31 is connected to a reservoir R via a reservoir port 36. The reservoir port 36 is arranged to open when the piston 30 is in the non-braking position, and to be closed by the small diameter portion 27 when braking is started and the piston 30 moves forward. The pressurizing chamber 31 is connected to a wheel cylinder 38 via a pipe 37.

The pressure adding chamber 33 is connected to a wheel cylinder 38 via a pipe 39. Pipe 39 has a proportional solenoid valve
40 (open / close valves) are provided. The proportional solenoid valve 40 is a normally open solenoid valve having a poppet structure equipped with a push-type linear solenoid, and is capable of adjusting the opening degree in accordance with a current supplied.

The supply chamber 32 is pumped through a pressure control valve 42.
The pump 41 is connected to the suction side, and the discharge side of the pump 41 is connected between the pressure addition chamber 33 of the pipe line 39 and the proportional solenoid valve 40.
The pump 41 is normally stopped and the brake pedal
It is started in conjunction with the operation of 34 or the operation of the automatic brake described later. The pressure control valve 42 is connected to the line 37 by a line 43, and is connected to a reservoir by a line 44.
Connected to R. The pressure control valve 42 is a spool-type pilot-type pressure control valve, and includes a supply chamber 32 and a reservoir R.
When the pressure of the supply chamber 32 is a positive pressure,
The pipe 43 is closed, and the brake fluid in the supply chamber 32 is pumped to the pump 41.
When the pressure in the supply chamber is a negative pressure, the pipe 43 is communicated with the suction side of the pump 41 to
By unloading 41, the pressure in the supply chamber 32 is almost
I keep it at 0. The pressure control valve 42 may be of another type as long as it has the above function, and may be, for example, a poppet type having a differential pressure detection piston.

The operation of the present embodiment configured as described above will now be described. Normally, the proportional solenoid valve 40 is fully opened. When the brake pedal 34 is depressed with the operation force F,
When the piston 30 against the spring force F _k of the spring 35 return to advances, the reservoir port 36 is closed by the small-diameter portion 27. When the pump 41 is started, the proportional solenoid valve 40 is open, so that the discharge pressure of the pump 41 causes the pressurizing chamber 31, the wheel cylinder 38, and the pressure adding chamber 33 to be equally applied via the pipes 39 and 37. Pressed.

[0022] At this time, the pressure in the pressure chamber 31 P _a, the supply chamber 32
The pressure P _b, the pressure in the pressure addition chamber 33 and P _c, the following equation holds from the balance of forces acting on the piston 30. In _{F = S a × P a +} S b × P b -S c × P c + F k where supply chamber 32, when the pressure is positive pressure, the pressure control valve 42 closes the conduit 43, the pump 23 When the pressure is reduced to approximately 0 by suction, the pressure control valve 42 connects the pipe 43 to the suction side and unloads the pump 41, so that the pressure becomes approximately 0. Further, the pump 41 pressurizes the pressurizing chamber 31 and the pressure adding chamber 33 equally. Therefore,
In the formula, when _{P b = 0, P a =} P c, the _{= P a (F-F k} ) / (S a -S c). On the other hand, the pressurizing chamber 31 when the pump 41 is not operated and the wheel cylinder 38 is directly pressurized by the piston 30
The pressure P _a 'from _{P a = P b = P c} , P a' of _{= (F-F k) /} (S a + S b -S c) a because, boost ratio alpha is alpha = P _a / P _a ′ = (S _a + S _b −S _c ) / (S _a −S _c ), and boost control can be performed. At this time, the reaction force F of the brake pedal 34, F = a _{(S a -S c) × P} a + F k. The supply amount of the brake fluid to the wheel cylinder 38 is (S _a + S _b −S _c ) × L, where L is the stroke of the piston 30, and S _a + S _b −S _c is the rod of the piston 30. Equal to the cross-sectional area of part 29. In the case where boosting function is lost due to a failure or the like of the pump 41, pressure chamber 31, by the cooperation of the supply chamber 32 and the pressure adding chamber 33, since the pressure P _a 'is obtained, the braking force Can be secured.

Next, the operation of the automatic brake will be described. When operating as an automatic brake, the pump 41 is started, and the proportional solenoid valve 40 is half-closed to pressurize the pressure addition chamber 33. The pressure P _c of the pressure addition chamber 33 rises and becomes _{S c × P c> F k} , the piston 30 moves forward to close the reservoir port 36. Thereafter, as in the above boosting control, the operation of the pump 41 and the pressure control valve 42 causes P _b =
0 because made, the pressure P _a of the pressure chamber 31 becomes _{P a = (S c × P} c -F k) / S a. Corresponding to a differential pressure _{ΔP = P c -P a = (} S a / S c -1) × P a + F k / S c of the pressure adding chamber 33 and pressure chamber 31 the current supplied to the proportional solenoid valve 40 if the current value, the target wheel cylinder pressure P _a is obtained. Since a S _a> S _c, ΔP is always positive, the wheel cylinder pressure P _a, to the increase in the current supplied to the proportional solenoid valve 40, the constant _{1 / (S a / S c} -1) And increases linearly. At this time, the supply amount of the brake fluid to the wheel cylinder 38 is the same as in the boost control.

[0024] During automatic braking, so to supply the brake fluid from the supply chamber 32 to the pressure addition chamber 33, in order to control the same manner as when the boost control is desirably a S _b> S _c, when the pressure control valve 42 the pressure P _b of the supply chamber 32 is zero,
By configuring from the pressurizing chamber 31 side as the brake fluid to flow into the supply chamber 32 side, it is possible to pressurize the pressure adding chamber 33 even S _b <S _c.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The second embodiment is different from the first embodiment in that the master cylinder is tandemly divided into two systems and each system is provided with two wheel cylinders. Portions are denoted by the same reference numerals, and only different portions will be described in detail.

As shown in FIG. 2, in the hydraulic brake device 45 of the second embodiment, the master cylinder 46 is tandemized by inserting the secondary piston 47 and its return spring 48 into the second pressurizing chamber 49. Are formed. The second pressurizing chamber 49 is connected to a reservoir R via a reservoir port 50, and the second pressurizing chamber 49 is connected to two wheel cylinders 52 via a conduit 51.

[0027] The piston 30 is effective pressure-receiving area to the effective pressure receiving area S _b and pressure adding chamber 33 to the feed chamber 32 of the large-diameter portion 28
S _c is made equal so that S _a + S _b −S _c = S _a . The secondary piston 47 has the same diameter as the small diameter portion 27 of the piston 30 (primary piston).

With this configuration, the pressure chamber 31
Is pressurized, the second pressurizing chamber 49 is similarly pressurized via the secondary piston 47, and the wheel cylinder 52 is pressurized similarly to the wheel cylinder 38 to generate a braking force. At this time, since the small diameter portion 27 of the piston 30 and the secondary piston 47 have the same diameter, the discharge amounts of the pressurizing chamber 31 and the second pressurizing chamber 49 become equal. In addition, the step of the cylinder portion is reduced, and processing and assembly can be easily performed. Incidentally, if the ejection amount varies with the primary side and the secondary side is required, as S _b <S _c, by increasing the diameter of the rod portion 29, it is possible to increase the discharge amount of the primary side.

Next, a third embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The third embodiment is different from the first embodiment in that two wheel cylinders are provided and an ABS (anti-lock brake system) is provided. Are given the same reference numerals and only different parts will be described in detail.

As shown in FIG. 3, in the hydraulic brake device 53 according to the third embodiment, two wheel cylinders 38 are connected to a pipe 37 communicating with the pressurizing chamber 31. In line 37,
For each wheel cylinder 38, a pressure-intensifying valve 54 (a normally open electromagnetic on-off valve) and a check valve 55 that allows only the flow from the pressurizing chamber 31 side to the wheel cylinder side are arranged in parallel. . Each of the wheel cylinders 38 is connected to an accumulator 57 via a pressure reducing valve 57 (a normally closed electromagnetic on-off valve) via a conduit 56, and the accumulator 57 is connected to a check valve 59.
Is connected to the suction side of the pump 41 via the. Check valve 59
Allows only the flow from the accumulator 58 side to the pump 41 side.

With the above configuration, the first
As in the embodiment, the boost control and the automatic brake control can be performed.

The ABS is operated by a wheel cylinder.
When the braking force generated by 38 becomes larger than the frictional force between the road tires and the tires lock, the booster valve that is normally open
Close 54 and open the normally closed pressure reducing valve 57. As a result, the supply of the brake fluid to the wheel cylinder 38 is stopped, the pressurized brake fluid in the wheel cylinder 38 flows out to the accumulator 58, the pressure of the wheel cylinder 38 decreases, and the tire lock is released. Is done. Thereafter, when the pressure reducing valve 57 is closed and the pressure increasing valve 54 is opened, since the pump 41 is operated, the brake fluid stored in the accumulator 58 is discharged by the pump 41 via the check valve 59, and the wheel cylinder is discharged. Pressurize 38 again.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. Note that the fourth embodiment has the same AB as that of the third embodiment in addition to the AB of the second embodiment.
Since S is incorporated, the same parts as those in the second and third embodiments are denoted by the same reference numerals, and only different parts will be described below.

As shown in FIG. 4, in the hydraulic brake device 60 of the fourth embodiment, the pipe 51 communicating with the second pressurizing chamber 49 has
For each wheel cylinder 52, a pressure-intensifying valve 61 (a normally open electromagnetic on-off valve) and a check valve 62 that allows only the flow from the second pressurizing chamber 49 side to the wheel cylinder 52 side are arranged in parallel. Have been. Each of the wheel cylinders 52 is connected to an accumulator 65 via a pressure reducing valve 64 (a normally closed electromagnetic on-off valve) via a conduit 63. Accumulator 65
It is connected to the suction side of a return pump 67 via 66. The discharge side of the pump 67 is connected to the pipeline 51 via a check valve 68. The check valve 68 allows only the flow from the pump 67 side to the pipe line 51 side. Pump 67 has A
When the wheel cylinder 52 is repressurized during the BS operation, a pressure control valve 69 for controlling the discharge amount is provided so that the pressure of the accumulator 65 becomes substantially zero. The primary pump 41 and the secondary pump 67 share a common motor 70
Driven by Restrictor 66 and primary conduit 56
The throttle 71 is provided to prevent sudden movement of the brake fluid from the accumulators 58 and 65 to the suction sides of the pumps 41 and 67 during the ABS operation.

With this configuration, the second
Similarly to the third embodiment, the brake fluid can be supplied to the two wheel cylinders to perform boost control, automatic brake control, and antilock brake control.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In the fifth embodiment, since the hydraulic brake devices of the third embodiment are arranged in parallel to form two systems, the same parts as those of the third embodiment have the same reference numerals. Only different parts will be described in detail.

As shown in FIG. 5, in the hydraulic brake device 72 of the fifth embodiment, two master cylinders 26 similar to those of the third embodiment are arranged in parallel, and , The brake pedal 34 is connected via a lever 74 guided to be able to move forward and backward by a guide 73,
The operating force F of the brake pedal 34 is divided into 1/2,
The power is transmitted to each piston 30.
In addition, the pumps 41 of the respective systems are driven by a common motor 75.

[0038] With this configuration, similar to the third embodiment, two systems of wheel cylinders can be used.
Boost control, automatic brake control, and antilock brake control can be performed. At this time, even if one system fails, the required braking force can be ensured by the other system.

Next, a sixth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In the sixth embodiment, since the accumulator is incorporated in the piston of the first embodiment, the same components as those of the first embodiment shown in FIG. Only parts will be described in detail.

As shown in FIG. 6, in the hydraulic brake device 76 of the sixth embodiment, an accumulator 77 (pressure accumulating means) is built in the small diameter portion 27 of the piston 30. Accumulator 77
A free piston 79 is slidably fitted in a cylinder bore 78 formed in the small diameter portion 27, and the free piston 79
Thereby, the inside of the cylinder bore 78 is defined as two chambers of oil chambers 78A and 78B. The oil chamber 78A is connected to the supply chamber 32 via an oil passage 80, and the oil chamber 78B is connected to the reservoir R via an oil passage 81 and an oil passage 82. Free piston 79 is
Normally, the cylinder bore 78 is in contact with the end on the oil chamber 78A side by the spring force of a return spring 83 provided in the oil chamber 78B.

With this configuration, the first
As in the embodiment, the boost control and the automatic brake control can be performed. In this case, since the pump 41 starts in conjunction with the operation of the brake pedal 34, the pump 41
It takes about 0.1 to 0.2 seconds for the discharge amount of the pump 41 to reach the required specified value after the pressure is depressed. For this reason, in the first embodiment, in the initial stage of braking, the discharge amount of the pump 41 is insufficient, and the pressure in the supply chamber 32 is not maintained at 0, but is temporarily increased. At this time, the pressure P _b of the supply chamber 32 acts on the effective pressure receiving area S _b of the large diameter portion 28, the piston
30 because the reaction force P _b × S _b occurs, the movement of the piston 30 is insufficient, with boosting is delayed in the compression chamber 31 and the pressure adding chamber 33, the reaction force is increased braking operation of the brake pedal 34 Feeling worse.

In the hydraulic brake device 76 of the present embodiment, at this time, the free piston 79 of the accumulator 77 retreats, and the brake fluid in the supply chamber 32 flows into the oil chamber 78A, thereby alleviating the rise in pressure. You. Since the oil chamber 78B on the back side of the free piston 79 is connected to the reservoir R,
The pressure of the supply chamber 32 is maintained at substantially the same pressure as that of the reservoir R, so that an increase in the reaction force of the piston 30 can be reduced, and the brake operation feeling can be improved.

Thereafter, when the discharge amount of the pump 41 reaches a required specified value, the brake fluid in the supply chamber 32 is transferred to the supply chamber 31 and the pressure addition chamber 33 by the pump 41, and the free piston 79 of the accumulator 77 is moved. It returns to the original position, and enters _a pressure balance state of the boost control, that is, a state in which the following equation is satisfied: P _a = (F−F _k ) / (S _a −S _c ). In this way, it is possible to reduce the increase in the reaction force to the brake pedal 34 in the initial stage of braking, and improve the brake operation feeling. Further, since the accumulator 77 is built in the piston 37, the size of the master cylinder 26 can be reduced.

On the other hand, when the automatic brake is activated, the pump 41
Even when the supply chamber 32 is depressurized by the start of the operation, the free piston 79 abuts on the end of the cylinder bore 78 and does not move, and the accumulator 77 does not operate, so that the automatic brake control is executed as in the first embodiment. can do.

Next, a seventh embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. Note that the hydraulic brake device of the seventh embodiment has a structure generally similar to that of the sixth embodiment, except that the structure of an accumulator built in the piston is different. The same parts as in the sixth embodiment shown in FIG.
Only different parts will be described in detail.

As shown in FIG. 7, an accumulator built in a piston 30 of a hydraulic brake device according to a seventh embodiment.
84 (pressure accumulating means) has a free piston 86 slidably fitted in a cylinder bore 85 formed through the large diameter portion 28, and the free piston 86 divides the inside of the cylinder bore 85 into two oil chambers 85A and 85B. Is defined. Oil chamber 85A has oil passage 87
The oil chamber 85B is in communication with the supply chamber 32 through
It communicates with the pressure addition chamber 33 via 8. The free piston 86 is normally in contact with an end of the cylinder bore 85 on the oil chamber 85A side by a spring force of a return spring 89 provided in the oil chamber 85B.

With this configuration, when the supply chamber 32 is pressurized at the initial stage of braking and becomes higher in pressure than the pressurizing chamber 31 and the pressure adding chamber 33, the free piston 86 of the accumulator 84 retreats and the supply is stopped. The brake fluid in the chamber 32 is
By flowing into 85A, the rise in pressure is mitigated.
The oil chamber 85B on the back side of the free piston 86 is
(The same pressure as the pressurizing chamber 33), the pressure in the supply chamber 32 is maintained at substantially the same pressure as the pressurizing chamber 31 and the pressure adding chamber 33, and the reaction force to the piston 30 increases. As a result, the brake operation feeling can be improved as in the sixth embodiment. Thereafter, when the discharge amount of the pump reaches the required specified value, the supply chamber 32 is depressurized and the boosting control can be executed under a predetermined pressure balance, as in the sixth embodiment.

In this case, the pressure in the supply chamber 32 is substantially the same as the pressure in the pressurizing chamber 31 and the pressure adding chamber 33, and is higher than that in the sixth embodiment in which the pressure is the same as the pressure in the reservoir R.
The effect of reducing the brake reaction force is slightly smaller than in the sixth embodiment.

At the time of automatic brake operation, even if the supply chamber 32 is depressurized by the activation of the pump 41, the free piston 86
Does not move in contact with the end of the cylinder bore 85 and the accumulator 84 does not operate, so that the automatic brake control can be executed in the same manner as in the sixth embodiment.

In the sixth and seventh embodiments,
Although the accumulator is described as being built in the piston, the accumulator may be arranged outside the mass cylinder and connected to the supply chamber, the reservoir, and the pressure addition chamber.

Next, an eighth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In the eighth embodiment, the first embodiment
Since the large diameter portion of the piston of the embodiment incorporates the function as the accumulator of the seventh embodiment,
The same parts as those in the first and seventh embodiments are denoted by the same reference numerals, and only different parts will be described in detail.

In the hydraulic brake device 90 according to the eighth embodiment,
The large diameter portion 91 (piston portion) of the piston 30 defining the supply chamber 32 and the pressure addition chamber 33 is formed of an annular member through which the small diameter portion 27 is slidably inserted. On the other hand, it is supported movably along the axial direction. A stopper 92 is attached to the small diameter portion 27 of the piston 30 so as to contact the large diameter portion 91.The large diameter portion 28 is composed of the large diameter portion 28 and the rod portion 29.
By the spring force of the disc spring 93 provided between the shoulder of
Usually, it is in contact with the stopper 92.

With this configuration, when the supply chamber 30 is pressurized in the initial stage of braking, the large-diameter portion 91 retreats against the spring force of the disc spring 93, thereby acting as an accumulator. Thus, the pressure in the supply chamber 30 is reduced.
Thereby, the same operation and effect as those of the seventh embodiment can be obtained.

Next, a ninth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. As shown in FIG. 9, the hydraulic brake device 94 according to the ninth embodiment is the same as the tandem hydraulic brake device according to the second embodiment, except that an accumulator similar to that of the eighth embodiment is provided at the large-diameter portion of the piston. It incorporates the function as. In FIG. 9, the second and
The same parts as those of the eighth embodiment are denoted by the same reference numerals. In the eighth embodiment, a disc spring 93 is used as a spring for biasing the large-diameter portion 91, whereas a coil spring 95 is used in the present embodiment.

With this configuration, the second
In the tandem-type hydraulic brake device of the embodiment, the same operations and effects as those of the eighth embodiment can be obtained.

[0056]

As described in detail above, according to the hydraulic brake device of the first aspect, the pressurizing chamber and the pressure adding chamber connected to the wheel cylinder are pressurized by the pump according to the operating force on the piston. Boost control can be performed. At this time, the boost ratio can be determined by the difference between the effective pressure receiving area of the piston with respect to the pressurizing chamber and the effective pressure receiving area of the piston with the pressure adding chamber. According to the hydraulic brake device of the second aspect, by closing the on-off valve, the pressure of the pressure adding chamber can be made higher than the pressure of the pressurizing chamber by pressurizing the pump. Then, the automatic brake can be operated. According to the hydraulic brake device of claim 3, the pressure in the supply chamber is adjusted to almost 0 by loading and unloading the pump by the pressure control valve according to the differential pressure between the reservoir and the supply chamber. Can be. According to the hydraulic brake device of claim 4, when the supply chamber is pressurized due to a shortage of the discharge amount of the pump at the start of the pump at the beginning of braking, the pressure of the supply chamber is temporarily accumulated by the accumulator. Since the increase in the pressure in the supply chamber can be suppressed and the increase in the reaction force to the piston can be reduced, the operational feeling of the brake can be improved. According to the hydraulic brake device of claim 5, since the pressure accumulating means is built in the piston, the size of the device can be reduced. According to the hydraulic brake device of claim 6, when the supply chamber is pressurized, the piston moves to the pressure addition chamber side,
By accumulating the pressure of the supply chamber in the pressure addition chamber, the pressurized pressure of the supply chamber can be substantially maintained at the pressure of the pressure addition chamber, and an increase in the reaction force to the piston can be reduced. Further, by providing the pressure accumulating means on the piston, the size of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a hydraulic brake device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a hydraulic brake device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a hydraulic brake device according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a hydraulic brake device according to a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram showing a hydraulic brake device according to a fifth embodiment of the present invention.

FIG. 6 is a circuit diagram showing a hydraulic brake device according to a sixth embodiment of the present invention.

FIG. 7 is a longitudinal sectional view showing a schematic configuration of a piston of a hydraulic brake device according to a seventh embodiment of the present invention.

FIG. 8 is a circuit diagram showing a hydraulic brake device according to an eighth embodiment of the present invention.

FIG. 9 is a circuit diagram showing a hydraulic brake device according to a ninth embodiment of the present invention.

FIG. 10 is a circuit diagram showing a conventional hydraulic brake device having an automatic braking function.

FIG. 11 is a circuit diagram showing a conventional hydraulic brake device having a boost control function.

[Explanation of symbols]

 25,45,53,60,72,76,90,94 Hydraulic brake device 26 Master cylinder 30 Piston 31 Pressurization chamber 32 Supply chamber 33 Pressure addition chamber 38,52 Wheel cylinder 41 Pump 42 Pressure control valve 40 Proportional solenoid valve (On-off valve) 77,84 Accumulator (pressure accumulating means) 91 Large diameter part (piston part) R Reservoir

Claims (6)

[Claims] 1. A stepped piston is slidably fitted in a master cylinder to form three chambers, a pressurizing chamber pressurized by the advance of the piston, a supply chamber, and a pressure adding chamber depressurized. The effective pressure receiving area of the piston with respect to the pressurizing chamber is made larger than the effective pressure receiving area of the pressure adding chamber, a wheel cylinder is connected to the pressurizing chamber, and the pressurizing chamber and the pressure adding chamber are supplied from the supply chamber. And a pump for supplying a brake fluid, and controlling a discharge amount of the pump so that a pressure of the supply chamber becomes substantially zero. 2. The hydraulic brake device according to claim 1, further comprising an on-off valve for opening and closing a flow path between the pump and the pressurizing chamber. 3. A pressure control valve for communicating and shutting off a discharge side and a suction side of the pump based on a pressure difference between a reservoir for replenishing the pressurized chamber with brake fluid and the supply chamber.
The discharge amount of the pump is controlled.
3. The hydraulic brake device according to 1 or 2. 4. The hydraulic brake device according to claim 1, wherein an accumulator is provided in the supply chamber. 5. The hydraulic brake device according to claim 4, wherein the pressure accumulating means is built in the piston. 6. The hydraulic brake according to claim 4, wherein said pressure accumulating means comprises a piston portion defining said supply chamber and said pressure addition chamber movably provided on said piston. apparatus.