JP2604902B2 - Pressure reducing actuator for anti-skid control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an anti-skid control device having a pump function that pressurizes a working fluid inside a braking cylinder such as a wheel cylinder and discharges the working fluid to a master cylinder side. The present invention relates to an actuator for a skid control device.

[Conventional technology]

As this type of actuator for an anti-skid control device, an actuator having a configuration shown in FIG. 3 is known.

In this conventional example, a cylindrical cylinder block 21 fixed to a fixing portion and having a center opening 21a drilled from the right end face side is provided.
A plunger 22 disposed in the center opening 21a of the cylinder block 21 so as to be able to advance and retreat, a suction valve 23 disposed in the center opening 21a, and a discharge valve 24 connected to the left end of the cylinder block 21. And

In the cylinder block 21, a through hole 21b communicating with the center opening 21a is formed at the left end, and an inlet port 21c reaching the center opening 21a from the outer peripheral surface side is formed at a position facing the plunger 22.

The plunger 22 has a center opening 22a formed from the left end side, and an annular groove 22b formed at a position facing the inlet port 21c on the outer peripheral surface, and furthermore, a light transmission 22c between the bottom of the center opening 22a and the annular groove 22b. Are drilled. The plunger 22 has its right end surface on the outer peripheral surface of the eccentric rotor 26 rotated by a drive motor (not shown) by a return spring 22d interposed between the left end surface and the bottom of the center opening 21a. It is urged to slide.

The suction valve 23 is configured by a sphere 23b that forms a valve body urged rightward by a return spring 23a so as to close the open end of the through hole 22a of the plunger 22.

The discharge valve 24 is provided with a valve housing 24b having a center opening 24a from the right end side connected to the cylinder block 21 and disposed in the center opening 24a of the valve housing 24b. A sphere 2 as a valve urged rightward by a return spring 24c to close it
4d, and an outlet port 24e is formed in the valve housing 24b.

And, the inlet port 21c of the cylinder block 21
Although not shown, it is connected to a wheel cylinder via an electromagnetic direction switching valve, and an outlet port 24e of the discharge valve 24 is connected to the master cylinder.

Thus, the vehicle enters the braking state by depressing the brake pedal, and the brake pressure of the wheel cylinder is increased. As a result, the deceleration of the wheel is increased. When the wheel is stopped and the high pressure side is maintained, and the slip rate of the wheel increases and reaches a predetermined set value, the eccentric rotor 26 is rotated, and the wheel cylinder and the inlet port 21c are communicated by the electromagnetic directional control valve. You. For this reason, plunger 2
2 is driven forward and backward with respect to the cylinder block 21. At this time, when the plunger 22 advances leftward from the state shown in FIG. 3, the urging force of the return spring 23a of the suction valve 23 increases, so that the left end face of the plunger 22 and the bottom of the center opening 21a pass through the through hole 22a. The flow of the working fluid into the pressurizing chamber 21d formed by
When the pressure of d increases and the pressure of the pressurizing chamber 21d exceeds the urging force of the return spring 24c of the discharge valve 24, the sphere 24c
Moves leftward against the return spring 24c, the closed state of the through hole 21b is released, and the working fluid in the pressurizing chamber 21d is discharged to the master cylinder side via the outlet port 24e. Thereafter, when the plunger 22 retreats to the right, the return spring 2 with respect to the sphere 23b of the suction valve 23 is moved.
By reducing the urging force of the pressure chamber 3d, the working fluid in the wheel cylinder flows through the inlet port 21c, the annular groove 22b of the plunger 22, the through hole 22c, and the center opening 22a.
Flows into.

As a result, the plunger 22 repeatedly moves forward and backward, whereby the working fluid in the wheel cylinder is discharged to the master cylinder side, and the brake pressure in the wheel cylinder is reduced.

In addition, as similar to this actuator,
For example, there is one described in JP-A-57-182554.

[Problems to be solved by the invention]

However, in the above-described conventional actuator for an anti-skid control device, since the suction valve 23 is disposed in the pressurizing chamber 21d provided in the cylinder block 21, the plunger 22 moves forward and is actuated. After reducing the volume of the pressure chamber 21d, when the plunger 22 retreats and enters a suction stroke in which the volume of the pressure chamber 21d increases, the working fluid from the suction valve 23 with respect to the increasing speed of the volume is increased. There is an unsolved problem that the inflow speed cannot keep up, cavitation is easily generated in the pressurizing chamber 21d, and noise is generated.

To solve this problem, it is conceivable to increase the diameter of the working fluid passage in the plunger 22, but in order to increase the diameter of the working fluid passage, the outer diameter of the plunger must also be increased. However, a new problem arises in that the actuator must be increased in size and cannot be applied when the mounting space of the vehicle is limited.

In view of the above, the present invention has been made by focusing on the unsolved problem of the conventional example, and provides an actuator for an anti-skid control device that can prevent cavitation without changing the outer diameter of a plunger. It is intended to be.

[Means for solving the problem]

In order to achieve the above object, an actuator for an anti-skid control device according to claim (1) has a plunger disposed in an opening formed in a cylinder block so as to be able to advance and retreat, and the plunger is disposed between the plunger and the bottom of the opening. A pressurizing chamber is formed, the pressurizing chamber is connected to a braking cylinder via a suction valve, and the actuator for an anti-skid control device connected to a master cylinder via a discharge valve. It is disposed outside the cylinder block in direct communication with the pressurizing chamber, and the opening area of the suction valve is selected to be large enough to secure an inflow amount corresponding to a volume change of the pressurizing chamber. Features.

The actuator for an anti-skid control device according to claim (2) is characterized in that the opening area of the suction valve is at least 25% of the volume change of the pressurizing chamber.

[Action]

In the invention according to claims (1) and (2), the suction valve is provided outside the cylinder block in direct communication with the pressurizing chamber, and the opening area of the suction valve corresponds to a change in the volume of the pressurizing chamber. The plunger moves forward and the volume of the pressurizing chamber decreases, and then the plunger retreats and the volume of the pressurizing chamber increases. The amount can be set to an amount that can sufficiently follow the rapid increase in the volume of the pressurizing chamber, and the occurrence of cavitation can be reliably prevented without increasing the diameter of the plunger.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

 FIG. 1 is a sectional view showing an embodiment of the present invention.

In the drawing, reference numeral 1 denotes a cylinder block in which a central opening 1a is formed from the right end side of a cylindrical shape. In the cylinder block 1, a through hole 1b is formed concentrically with the center opening 1a at the left end so as to communicate with the center opening 1a. In addition, an inlet port 1c is formed to communicate between the outer peripheral surface and the center opening 1a.

A cylindrical plunger 2 is disposed in the center opening 1a of the cylinder block 1 so as to be able to advance and retreat, a suction valve 3 is communicated with an inlet port 1c, and a discharge valve 4 is provided on the left end side of the cylinder block 1. The cylinder block 1 and the discharge valve 4 are fixed in a cylindrical housing 5 and the suction valve 3 is attached to the housing 5.

The plunger 2 has a stepped portion 2c formed between a large-diameter portion 2a on the right end side and a small-diameter portion 2b on the left end side, and is inserted between the stepped portion 2c and the bottom of the center opening 1a of the cylinder block 1. The right end of the plunger 2 is slidably in contact with the outer peripheral surface of the eccentric rotor 6 which is rotationally driven by a drive motor (not shown).

The suction valve 3 has a frusto-conical valve housing 3a integrally screwed to the outer peripheral surface of the housing 5 facing the inlet port 1c of the cylinder block 1, and a center opening screwed to the front end side of the valve housing 3a. A cylindrical body 3c having a hole 3b and a cylindrical body 3c formed by a return spring 3d in the valve housing 3a.
And a spherical body 3e as a valve urged so as to close the center opening 3b of the cylindrical body 3c.
The inlet port 3f is formed on the opposite side from the inlet port 3f. Here, the opening area of the central opening 3b is sufficient to secure an inflow amount that follows the volume change of the pressurizing chamber 1d formed by the bottom of the central opening 1a of the cylinder block 1 and the small diameter portion 2b of the plunger 2. It is selected for more than 25% of the volume change, which is a large area.

The discharge valve 4 is provided in the valve housing 4a connected to the cylinder block 1 in the same manner as in the conventional example described above.
A ball 4d as a valve body for closing the opening of the through hole 1c by a return spring 4c is disposed in a center opening 4b formed opposite to the through hole 1b of the valve housing 4a. An outlet port 4e communicating with 4b is formed.

The housing 5 has a through hole 5a communicating with the inlet port 1c of the cylinder block 1 and the outlet port 3f of the suction valve 3, and an outlet boat 5b communicating with the outlet port 4e of the discharge valve 4. Have been.

An inlet port 3f of the suction valve 3 is connected to a wheel cylinder 9 as a braking cylinder via an electromagnetic directional switching valve 8, and an outlet port 5b of the housing 5 is provided.
Is connected to a master cylinder 11 connected to the brake pedal 10, a reservoir tank 12 is connected between the inlet port 3f and the electromagnetic directional control valve 8, and an accumulator 13 is connected between the outlet port 5b and the master cylinder 11. Is connected. Here, the electromagnetic directional switching valve 8
Has a configuration of a 3 port 3 position directional control valve, the P port is connected to the master cylinder 11, the A port is connected to the wheel cylinder 9, the B port is connected to the inlet port 3f, and the solenoid 8a Exciting current value supplied from the anti-skid control circuit 14 allows the pressure increasing position to connect the P port and the A port on the left end, the holding position to cut off each port at the center, and the A and B ports on the right end. To be reduced.

 Next, the operation of the above embodiment will be described.

When the vehicle is not braking, the electromagnetic directional control valve 8 is held at the pressure increasing position. In this state, the brake pedal 10 is depressed to shift to the braking state, whereby the brake pressure of the master cylinder 11 is changed via the electromagnetic directional control valve 8. Since the pressure is supplied to the wheel cylinder 9, the pressure of the wheel cylinder 9 is increased.
As a result, the deceleration of the wheels increases. When the deceleration exceeds a predetermined set value, a medium-level exciting current is supplied from the anti-skid control circuit 14 to the solenoid 8a, so that the electromagnetic directional control valve 8 is held at the holding position. And the high pressure side holding state in which the pressure increase of the wheel cylinder 9 is stopped. Thereafter, when the slip ratio of the wheel increases and reaches a predetermined set value, anti-skid control is started by the anti-skid control circuit 14, a high-level excitation current is supplied to the solenoid 8a, and the drive motor is driven to rotate. Then, the eccentric rotor 6 rotates. Therefore, the electromagnetic directional control valve 8
Is switched to the decompression position, and the eccentric rotor 6 is driven to rotate, whereby the plunger 2 is driven forward and backward with respect to the cylinder block 1. As described above, when the plunger 2 is driven forward and backward to retract the plunger 2 rightward from the state shown in FIG. 1, the volume of the pressurizing chamber 1d rapidly increases as shown in FIG. 2 (c). At this time, the discharge valve 4 is a sphere 4d
Is urged by the return spring 4c to close the through hole 1b, so that the inflow of the working fluid from the discharge valve 4 is prevented, so that the pressure in the pressurizing chamber 1d becomes negative. Further, since the wheel cylinder 9 is in the holding state on the high-pressure side, the high-pressure working fluid of the wheel cylinder 9 presses the sphere 3e of the suction valve 3 backward against the return spring 3d, and the center opening 3b Is opened, and the high-pressure working fluid flows into the pressurizing chamber 1d through the through hole 5a and the inlet port 1c. At this time, since the opening area of the central opening 3b of the suction valve 3 is selected to be 25% or more of the volume change of the pressurizing chamber 1d,
As shown by the solid line in FIG. 2 (b), the amount of hydraulic oil in the pressurizing chamber 1d increases substantially with the increase in the volume of the pressurizing chamber 1d. Almost no difference from the amount of hydraulic oil in the chamber 1d. For this reason, the occurrence of cavitation can be reliably prevented, and the generation of noise and vibration due to cavitation can be prevented. Moreover, the suction valve 3
Due to the large opening area of the center opening 3b, the flow velocity of the hydraulic oil flowing into the pressurizing chamber 1d is reduced, which can also reduce noise.

Thereafter, when the plunger 2 reaches the top dead center and then reverses to the forward state, the volume of the pressurizing chamber 1d decreases,
The pressure in the pressurizing chamber 1d rises, and the increased pressure acts on the sphere 3e of the suction valve 3 communicating with the pressurizing chamber 1d,
The central opening 3b is closed, and the inflow of hydraulic oil from the inlet port 3f is prevented. When the pressure of the pressurizing chamber 1d exceeds the urging force of the return spring 4d of the discharge valve 4, the sphere 4d operates against the return spring 4c, and the closed state of the through-hole 1b is released. 2A, the working fluid in the pressurized chamber 1d is discharged to the master cylinder 11 through the outlet port 4e and the outlet port 5b of the housing 5, as indicated by the solid line in FIG. At this time, as described above, the amount of hydraulic oil flowing into the pressurizing chamber is substantially equal to the volume of the pressurizing chamber, so that the discharge amount in the discharge stroke increases, and the pressure reduction speed of the wheel cylinder 9 can be improved. .

Thereafter, when the plunger 2 retreats after reaching the bottom dead center, hydraulic oil flows from the suction valve 3 with the increase in the volume of the pressurizing chamber 1d, as described above.

As a result, the plunger 2 repeatedly moves forward and backward, so that the working fluid in the wheel cylinder 9 is
It is discharged to the 11 side, and the brake pressure of the wheel cylinder 9 is reduced.

Incidentally, in the case where the suction valve is provided in the pressurizing chamber 1d as in the conventional example, the opening area of the suction valve cannot be increased. As shown in the dashed line in FIG. 2B, the amount of hydraulic oil flowing from the wheel cylinder into the pressurizing chamber becomes extremely small with respect to the increase in the volume of the pressurizing chamber, causing cavitation and generating large noise and vibration. At the same time, since the amount of hydraulic oil flowing into the pressurized chamber is small, the amount of hydraulic oil discharged to the master cylinder side also decreases as shown by the chain line in FIG. 2 (a), and the pressure reduction speed of the wheel cylinder decreases.

In the above embodiment, the suction valve 3 and the discharge valve 4
Although the case where a sphere was applied as the valve body of the above was explained,
The present invention is not limited to this, and a conical valve body may be used.

Further, in the above-described embodiment, the case where one plunger 2 is brought into sliding contact with the eccentric rotor 6 has been described. However, the present invention is not limited to this, and plungers of a plurality of actuators are brought into sliding contact, and these are driven forward and backward. Is also good.

〔The invention's effect〕

As described above, according to the actuator for an anti-skid control device according to claims (1) and (2), the suction valve that allows the working fluid to flow into the pressurizing chamber is provided outside the cylinder block in which the pressurizing chamber is formed. In this configuration, the opening area of the switching valve is selected to be large enough to secure the inflow amount following the change in the volume of the pressurizing chamber, so that the diameter of the plunger is increased. In the suction stroke in which the plunger is retracted and the volume of the pressurizing chamber increases, the volume of the pressurizing chamber and the amount of working fluid flowing into the chamber can be made substantially equal, thereby reliably preventing the occurrence of cavitation. Noise and vibration can be suppressed, and the large opening area of the suction valve reduces the inflow speed of the working fluid flowing into the pressurized chamber, thereby also suppressing noise. Do Doo is an effect that it can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a time chart for explaining the operation of the present invention, and FIG. 3 is a sectional view showing a conventional example. In the figure, 1 is a cylinder block, 1d is a pressurizing chamber, 2 is a plunger, 3 is a suction valve, 3a is a valve housing, 3c is a cylindrical body, 3d
Is a return spring, 3e is a sphere, 3f is an inlet port, 4 is a discharge valve, 6 is an eccentric rotor, 8 is an electromagnetic direction switching valve, 9 is a wheel cylinder, and 11 is a master cylinder.

Claims (2)

(57) [Claims] 1. A plunger is provided in an opening formed in a cylinder block so as to be able to advance and retreat, and a pressurizing chamber is formed between the plunger and the bottom of the opening. The pressurizing chamber is braked via a suction valve. In the anti-skid control device actuator connected to the master cylinder via a discharge valve while being connected to the cylinder, the suction valve is disposed outside the cylinder block in direct communication with the pressurizing chamber,
An actuator for an anti-skid control device, wherein an opening area of the suction valve is selected to be large enough to secure an inflow amount corresponding to a volume change of the pressurizing chamber. 2. An opening area of said suction valve is at least 25% of a volume change of said pressurizing chamber.
An actuator for an anti-skid control device as described in the above.