JPS6253385B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an antilock brake system.

Conventionally, such a control device includes a control hydraulic chamber provided in a brake device so as to suppress braking force when hydraulic pressure is supplied, an electric hydraulic pump, and a high-pressure oil passage connected to a discharge port of the hydraulic pump. It consists of an oil tank, a low-pressure oil passage connected to the oil tank, and a control valve that alternately controls communication of the control hydraulic chamber with the high-pressure oil passage and the low-pressure oil passage. A known system is known in which a high-pressure oil passage is communicated with a control hydraulic chamber through a switching action, and excessive braking force is suppressed by the discharge pressure of a hydraulic pump, thereby preventing wheel locking. By the way, in this conventional device, the hydraulic pump is always operated and the discharged excess pressure oil is returned to the oil tank via the relief valve, but since there are generally very few opportunities for this control device to operate, However, it is not preferable to keep the hydraulic pump running all the time because of power loss.

In order to solve this problem, a pressure accumulator that accumulates the discharge pressure of the hydraulic pump is connected to the high-pressure oil path, and a pressure switch that responds to the hydraulic pressure of the pressure accumulator controls the energization of the hydraulic pump. It may be possible to drive the hydraulic pump only when the pressure falls below a set value, but in this case, the pressure switch will immediately switch to the ON or OFF state even if the set value is slightly increased or decreased. As a result, the pressure switch ends up turning on and off frequently, which not only shortens the life of the switch itself, but also causes noise due to the repeated starting and stopping of the pump.
Further, there are problems such as a decrease in the durability of the pump.

The present invention has been proposed in view of the above, and it is an object of the present invention to provide a control device for the anti-lock brake device, which can eliminate all of the above-mentioned problems and inconveniences of the conventional devices.

An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows a vehicle braking device equipped with the device of the present invention and a control hydraulic circuit that applies a control hydraulic pressure to the braking device so as to suppress its braking force. In FIG. 1, a brake pedal 30 is connected to a master cylinder 31 so that the master cylinder 31 generates braking hydraulic pressure when the pedal 30 is depressed. A wheel cylinder 33 corresponding to the master cylinder 31 is fixed to the vehicle body near a wheel (not shown), and a pair of pistons 35, 3 are contained in the cylinder 33.
A brake hydraulic chamber 36 is defined between the pistons 35 and 35', which communicates with the hydraulic oil chamber of the master cylinder 31 via an oil passage 32. The rods 37, 37' of each piston 35, 35' extend outwardly through the end wall of the wheel cylinder 33, and the outer end of each rod 37, 37' connects to a brake drum attached to the wheel. A pair of brake shoes 3 close to the inner peripheral surface of (not shown)
9 and 39', respectively. Therefore, the brake pedal 30 is depressed and the master cylinder 3
1 generates a braking hydraulic pressure, this braking hydraulic pressure is transmitted to the braking hydraulic chamber 36 in the wheel cylinder 33 and presses and moves each piston 35, 35' in a direction away from each other, and accordingly, each brake shoe 3
9 and 39' are pressed toward the inner circumferential surface of the brake drum, and a braking force can be applied to the wheels by frictional contact with the inner circumferential surface of the drum.

If the braking force is too large, there is a possibility that the wheels will lock. In order to prevent the wheels from being locked, a pair of control hydraulic chambers 40, 40' are formed between each piston 35, 35' and the end wall of the wheel cylinder 33, and these control hydraulic pressures are The above-mentioned brake hydraulic chamber 36 is provided in the chambers 40 and 40'.
By press-fitting a control hydraulic pressure capable of counteracting the braking hydraulic pressure, the outward movement of each piston 35, 35' is suppressed, thereby suppressing the above-mentioned braking force. Next, a control hydraulic circuit for this purpose will be explained.

At the discharge port of the hydraulic pump P whose suction port is connected to the oil tank T, there is a high pressure oil path 45 with a check valve 44 interposed in the middle.
This high-pressure oil passage 45 is connected to both control hydraulic chambers 40, 40' via the first control valve _V1 and oil passages 48, 49. High pressure oil line 45
A pressure accumulator 46 capable of accumulating the discharge pressure of the hydraulic pump P is connected downstream of the check valve 44, and a return oil passage 50 connected to the oil tank T is connected to the upstream side of the check valve 44. A relief valve 51 is interposed in the middle of the return oil passage 50. The oil tank T also includes a second control valve V ₂ and an oil passage 52,
49, a low pressure oil passage 53 is connected to the control oil pressure chambers 40, 40'. The first and second control valves V ₁ and V ₂ are controlled to be switched depending on the running state of the vehicle based on judgment by a computer (not shown).

Pump P is connected to relay switch 56 from power source 57.
It is driven by a power motor M which receives power supply through the motor. The relay switch 56 is an electromagnetic actuator 55 whose operation is controlled by a pressure switch S.
The opening/closing is controlled by the The pressure switch S has a pressure detection portion connected to the high pressure oil path 45 downstream of the check valve 44 via a pressure detection oil path 54, and when the oil pressure in the oil path 54 falls below the lower limit set value. When the hydraulic pressure increases to an upper limit setting value higher than the lower limit setting value, the hydraulic pressure is closed and the electromagnetic actuator 55 is opened, and the electromagnetic actuator 55 is opened. This point is a feature of the present invention.

Next, the specific structure of the pressure switch S will be explained based on FIGS. 2 and 3.

The main body 1 of the pressure switch S includes a protruding cylinder part 2 which protrudes in the direction of the center line, and a protruding cylinder part 2.
and a cylindrical portion 3 formed on the opposite side, and a pressure receiving piston 8 in the center of the protruding cylinder portion 2;
A sliding contact hole 4 that supports the pressure receiving piston 8 and a rod 9 extending along the center line of the cylindrical portion 2 so as to be slidably connected in the axial direction extends through the rod 9 in the center line direction. It is formed by At this time, the main body 1 is made of a magnetic material, and the rod 9 is made of a non-magnetic material.

A large diameter portion is formed at the outer end of the sliding contact hole 4, and a seal member 5 is inserted into the large diameter portion.
It has an opening 7 in the center and a pressure receiving piston 8.
A fitting body 6 that slidably supports the tip of the pressure receiving piston 8 and functions as a stopper for the pressure receiving piston 8 is fitted and fixed.

The outer periphery on the distal end side of the protruding cylinder portion 2 is screwed into the engagement hole of the connecting body 11 via the sealing member 10, and the connecting body 11 has the above-mentioned groove that communicates with the end surface of the protruding cylinder portion 2. A pressure detection oil passage 54 is formed. Therefore, the pressure oil introduced through the oil passage 54 further passes through the opening 7 and presses the pressure receiving surface of the pressure receiving piston 8, and as a result, the pressure receiving piston 8 is forced into the high pressure oil passage 45 introduced through the oil passage 54. A force is applied to push the rod 9 outward from the cylindrical portion 3 in accordance with the oil pressure.

A female thread 16 is formed on the inner circumferential surface of the outer end of the cylindrical portion 3, and a male thread 14 is formed on the outer circumferential surface, and a pair of axially elongated holes 1 are formed at positions facing each other in the diametrical direction.
5, 15' spring pressure adjustment cylinder 13
The outer circumference on the inner end side of is the outer circumference of an annular movement limiting plate 20 formed of a magnetic material between the annular step formed on the inner circumference side of the cylindrical part 3 and the inner end surface of the spring pressure adjustment cylinder 13. They are screwed together so that they are held in place.

A large-diameter portion 17 is integrally formed in a portion of the rod 9 near the pressure-receiving piston 8, and the large-diameter portion 17 enters into the stepped portion 18 of the main body 1 when the pressure-receiving piston 8 is not receiving fluid pressure. adjacent to
A magnet 19 is fitted onto the rod 9. Further fitted onto the rod 9, adjacent to the magnet 19, is a spring seat 21 having a boss portion 22 passing through the center hole of the movement limiting plate 20. A spring seat 24 having a pair of protruding arms 25, 25' protruding radially outward from a pair of elongated holes 15, 15' of the spring pressure adjusting cylinder 13 is attached to a portion of the rod 9 near the outer end. A pressing spring 23 is fitted between the spring seat 24 and the spring seat 21 so that the spring seat 24 and the spring seat 21 can be slidably connected to each other.
is interposed. An adjusting ring 26 is screwed onto the external thread 14 of the spring pressure adjusting cylinder 13 so as to come into pressure contact with each of the protruding arms 25, 25'.By rotating the adjusting ring 26,
The pressing force of the pressing spring 23 can be adjusted.

A contact switching device 28 having a contact switching actuator 29 inside is supported on the inner peripheral side of the outer end of the spring pressure adjustment cylinder 13 via a support member 27 . An input terminal of this contact switching device 28 is connected to the electromagnetic actuator 55, and an output terminal thereof is grounded.

The axial width of the magnet 19 is smaller than the axial distance between the surface of the main body 1 in contact with the magnet 19 and the movement limiting plate 20, and both the main body 1 and the movement limiting plate 20 are made of a magnetic material. Since it has been
The rod 9 and the magnet 19 always receive the pressing force from the pressing spring 23 via the spring seat 21, and when the pressure receiving piston 8 is not receiving fluid pressure, the magnet 19
9 is pressed onto the main body 1 by magnetic force. At this time, the tip of the rod 9 is separated from the contact switching actuator 29, so that the contact switching device 28 is placed in the contact state.

Now, the pressure receiving piston 8 receives hydraulic pressure from the high pressure oil passage 45, and when the pressure on the pressure receiving piston 8 due to this hydraulic pressure overcomes the pressing force between the magnet 19 and the main body 1 and the pressing force of the pressing spring 23, the rod 9 and magnet 1
9 is pressed and moved toward the contact switching device 28 side, the magnet 19 is pressed against the movement limiting plate 20, and the tip of the rod 9 presses the contact switching actuator 29 to switch the contact switching device 28 to the OFF state. In this state, even if there is some downward fluctuation in the oil pressure acting on the pressure receiving piston 8, the magnet 19 continues to maintain its pressed state against the movement limiting plate 20 due to its magnetic force. Then, the pressing force due to the hydraulic pressure acting on the pressure receiving piston 8 becomes sufficiently small, and even if it cooperates with the pressing force between the magnet 19 and the movement limiting plate 20, it cannot resist the pressing force by the pressing spring 23. When the rod 9 and the magnet 19 move toward the main body 1 side, the magnet 1
9 is again crimped to the main body 1, and the tip of the rod 9 separates from the contact switching actuator 29, switching the contact switching device 28 to the connected state again.

FIG. 4 shows the force exerted on the rod 9 and magnet 19 in the side direction of the main body 1 in response to the axial displacement of the rod 9 and magnet 19, with the horizontal axis representing displacement and the vertical axis representing the magnitude of force. The magnitude of pressure is shown graphically. Here, the point O ₁ on the horizontal axis is
The point corresponds to the position of the rod 9 and the magnet 19 relative to the body 1 when the magnet 19 is crimped to the body 1.
_O2 corresponds to the position of the rod 9 and the magnet 19 relative to the main body 1 when the magnet 19 is pressed against the movement limiting plate 20. A straight line a shows a change in the pressing force of the pressing spring 23, and a curve b shows a change in the algebraic sum of the pressing force of the magnet 19 and the pressing force of the pressing spring 23.
Therefore, the shaded area in the figure is the main body 1 of the magnet 19.
Alternatively, it shows a change in the pressing force against the movement limiting plate 20. As is clear from this figure 4,
Only when the magnitude of the pressing force due to the hydraulic pressure acting on the pressure receiving piston 8 becomes larger than the magnitude of the force indicated by ₁ , the magnet 19 separates from the main body 1 and moves together with the rod 9 to move the movement limiter plate 2.
0, and at the same time the rod 9 is connected to the contact switching actuator 2.
Press 9. Furthermore, in this state, the magnet 19 moves to the movement limiting plate ₂ only when the magnitude of the pressing force due to the fluid pressure acting on the pressure receiving piston 8 becomes smaller than the magnitude of the force indicated by 2.
0, moves together with the rod 9, and presses onto the main body 1, and at the same time, the rod 9 separates from the contact switching actuator 29. Moreover, when the magnet 19 is located at an intermediate position between the main body 1 and the movement limiting plate 20, the balance of forces is extremely unstable, so that as soon as the magnet 19 separates from the main body 1, it is pressed against the movement limiting plate 20. Moreover, the characteristic is exhibited that it is pressed to the main body 1 immediately after being separated from the movement limiting plate 20.

Next, the operation of the embodiment of the present invention will be explained.
While the vehicle is running, when there is no possibility of the wheels locking even when the brakes are not applied or when the brakes are applied, the first control valve V ₁ is closed as shown in FIG. is switched to the right side, and the second control valve V ₂ is switched to the left side. At this time, each control hydraulic chamber 40, 4
0' communicates with the oil tank T via the second control valve V ₂ and the low pressure oil passage 53, so the braking force can be increased freely.

If there is a possibility of wheel locking during braking, the first control valve V ₁ remains switched to the right;
The second control valve V ₂ is switched to the right. At this time, the control oil in each control hydraulic chamber 40, 40' is placed in a sealed state, and each piston 35, 3
Since the outward movement of 5' is inhibited, the braking force is kept constant so as not to increase further.

When the braking force increases further and the wheels are about to lock, the first control valve _V1 is switched to the left, and the second control valve _V2 remains switched to the right. At this time, each control hydraulic chamber 40, 40' is cut off from the oil tank T, and in each control hydraulic chamber 40, 40', a high pressure oil passage 45 and a first control valve _{V1 are} connected from the pressure accumulator 46.
Since control oil is injected through the piston 3, each piston 3
5 and 35' move toward each other, and the braking force decreases.

Throughout the above-mentioned operating processes, the high-pressure oil passage 45 and therefore the pressure accumulator 46 must always maintain the control oil pressure necessary to properly perform anti-lock brake control; is adjusted and controlled as follows. That is, when this control oil pressure falls below the lower limit set value, the contact switching device 28 of the pressure switch S becomes connected and energizes the electromagnetic actuator 55, thereby closing the relay switch 56, energizing the electric motor M, and pump P. to drive. As a result, the pressure accumulator 46
Pressure oil is supplied from the hydraulic pump P via the high pressure oil passage 45, and the control oil pressure in the pressure accumulator 46 increases.

When the control oil pressure exceeds the upper limit set value, which is higher than the lower limit set value, the contact switching device 28 of the pressure switch S is turned off, stopping energization to the electromagnetic actuator 55, and thereby the relay switch 56 is opened, the power supply to the electric motor M is stopped, and the pump P is also stopped.

During this time, even if the control oil pressure fluctuates up and down within a range that does not exceed the upper and lower limit set values, the electric motor M and therefore the pump P will not repeatedly start and stop, and their activation or deactivation will not occur. The condition continues.

As described above, according to the present invention, a pressure accumulator is connected to a high-pressure oil passage in a control device for an anti-lock brake system, and this pressure accumulator is operated by an electric motor that is energized and controlled by a pressure switch that responds to the oil pressure of the high-pressure oil passage. Since pressure oil is supplied and replenished from the hydraulic pump in a timely manner, there is no need to constantly drive the hydraulic pump while the vehicle is traveling, and the operating cost can be reduced.

The pressure switch energizes the hydraulic pump when the oil pressure in the high-pressure oil path falls below a lower limit set value, and when the oil pressure rises to an upper limit set value higher than the lower limit set value, the pressure switch energizes the hydraulic pump. Since the pump is configured to stop energizing the pump, as long as the oil pressure in the high-pressure oil passage fluctuates between the above upper and lower limit set values, the pressure switch will not be switched. There is no risk of malfunctions occurring when the switch is repeatedly operated and the pump starts and stops even if there is a slight fluctuation, and the durability of not only the switch itself but also the pump can be increased. It is also possible to suppress noise generation due to repeated starting and stopping of the pump.

[Brief explanation of the drawing]

Fig. 1 is an overall schematic diagram showing an embodiment of an anti-lock brake system equipped with the device of the present invention, Fig. 2 is a longitudinal sectional front view of a pressure switch used in the embodiment, and Fig. 3 is a diagram of the same pressure switch. The side view, FIG. 4, is a graph showing the operating characteristics of the same pressure switch. P...Hydraulic pump, S...Pressure switch, T...Oil tank, _V1 , _V2 ...Control valve, 40, 40'...Control hydraulic chamber, 45...High pressure oil path, 46...Pressure accumulator, 53...Low pressure oil path.

Claims (1)

[Claims] 1. A control hydraulic chamber provided in the brake device to suppress braking force when hydraulic pressure is supplied, an electric hydraulic pump, a high-pressure oil path connected to the discharge port of this hydraulic pump, an oil tank, and a A series of low-pressure oil passages, a control valve that alternately controls communication of the control hydraulic chamber with the high-pressure oil passage and the low-pressure oil passage, a pressure accumulator connected to the high-pressure oil passage, and a pressure accumulator that responds to the pressure of the high-pressure oil passage. and a pressure switch that controls energization of the hydraulic pump, and the pressure switch energizes the hydraulic pump when the oil pressure in the high-pressure oil passage falls below the lower limit setting, and 1. A control device for an anti-lock brake device, characterized in that the controller is configured to stop energization of the hydraulic pump when the value rises above an upper limit setting value.