JPH0569034B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a manual brake device, and more particularly to a manual brake device equipped with a brake booster.

``Prior Art'' In general, a brake booster includes a power piston slidably disposed within a shell, a valve mechanism housed within a valve body of the power piston shaft,
A low pressure chamber formed on the front side in the operating direction of the power piston, a variable pressure chamber formed on the rear side, and a valve plunger constituting the valve mechanism are operated to switch the flow path and supply pressure fluid to the variable pressure chamber. and an input shaft that moves the power piston forward.

In conventional brake boosters of this type, braking is performed by stepping on the brake pedal that is linked to the above input, and the brake booster is manually operated to perform braking. When used as an actuated brake device that allows for
I was becoming unable to operate the brakes with my feet.

As a brake booster to solve such problems, the inventor of the present invention has already proposed in Japanese Patent Application No. 60-24607, etc., an auxiliary piston is attached to the valve plunger, and this auxiliary piston increases pressure within the valve body. A brake booster has been proposed that has a chamber defined and further provided with a supply-side on-off valve for supplying pressure fluid to the pressure chamber and a discharge-side on-off valve for discharging pressure fluid from the pressure chamber.

According to such a brake booster, the supply side on-off valve is opened with the discharge side on-off valve shut off to supply pressure fluid to the pressure chamber, and the auxiliary piston and valve plunger are advanced by the pressure. By switching the flow path of the above mechanism, the brake can be applied without moving the input shaft forward. Therefore, it can be used as a manual brake device while ensuring that the brake can be applied by pressing the brake pedal. You will be able to do this.

"Problems to be Solved by the Invention" However, when a substantially constant fluid pressure is supplied to the pressure chamber to perform a braking action, thereby reducing the vehicle speed to a low speed region or stopping the vehicle, Even though the output of the brake booster is substantially constant, as the speed of the vehicle decreases, its output becomes relatively stronger, resulting in sudden braking and causing the driver to experience problems. There were times when I felt uncomfortable.

"Means for Solving the Problem" In view of such circumstances, the present invention provides a manual brake device equipped with a brake booster that reduces the brake output when the speed of the vehicle falls below a predetermined value. It is something to do.

That is, the present invention provides the above-mentioned brake booster including an auxiliary piston attached to the plunger, and a section formed on the rear side of the auxiliary piston,
a pressure chamber that moves the auxiliary piston and valve plunger forward by the introduced fluid pressure to switch the flow path of the valve mechanism to perform a braking action;
A vehicle speed sensor that detects the speed of the vehicle, an operation amount detector that detects the operation amount applied to the manual brake operation member, and a communication path that communicates the pressure chamber with the pressure fluid supply source. a supply-side on-off valve that opens and closes; a discharge-side on-off valve that opens and closes the communication passage that communicates the pressure chamber with a discharge source that discharges the pressure introduced therein; a control device that inputs a signal to control the opening and closing of the supply side on-off valve and the discharge side on-off valve, and supplies pressure to the pressure chamber according to the amount of operation applied to the manual brake operation member, When the speed of the vehicle detected by the vehicle speed sensor becomes equal to or less than a predetermined value while pressure is being supplied to the pressure chamber, the control device opens the discharge side on-off valve for a predetermined time to reduce the pressure. This is designed to reduce the pressure in the chamber.

"Operation" According to such a configuration, when the speed of the vehicle falls below a predetermined value due to the operation of the manual brake device,
It is possible to lower the fluid pressure introduced into the pressure chamber that moves the auxiliary piston and valve plunger forward to perform braking, thereby reducing the output of the brake booster to achieve smooth braking without the feeling of sudden braking. I can make you do it.

"Example" The present invention will be described below with reference to the illustrated example.
In FIG. 1, a power piston 2 is slidably provided in a shell 1 of a brake booster, and a diaphragm 3 is stretched on the back surface of the power piston 2. The interior of the shell 1 is divided into a constant pressure chamber 4 at the front and a variable pressure chamber 5 at the rear. A valve body 6 is integrally provided on the shaft portion of the power piston 2, and a valve mechanism 7 for switching the flow path is housed within the valve body 6.

The valve mechanism 7 has a first valve formed in the valve body 6.
A valve seat 10, a second valve seat 12 formed on the valve plunger 11, and a power piston 2 on both valve seats 10, 12.
A valve body 14 is provided which is seated from the rear side, that is, from the right side in FIG. 1, by the elastic force of a spring 13. The outside of the seat portion of the first valve seat 10 and the valve body 14 is communicated with the constant pressure chamber 4 through a passage 15, and the constant pressure chamber 4 is connected to the constant pressure chamber 4 through a negative pressure introduction pipe 16 provided in the shell 1. It is connected to a negative pressure source such as an engine intake manifold (not shown).

On the other hand, the intermediate portions of the seals between the first valve seat 10 and the valve body 14 and between the second valve seat 12 and the valve body 14 are communicated with the variable pressure chamber 5 through a passage 17 formed in the valve body 6, and further The inner side of the seat portion between the second valve seat 12 and the valve body 4 is communicated with the atmosphere via a filter 18. In addition, the above-mentioned transformer chamber 5 is
A seal member 19 slidably penetrates the valve body 6 to maintain airtightness from the outside.

The valve plunger 11 constituting the valve mechanism 7 is connected to an input shaft 25 linked to a brake pedal (not shown).
The distal end surface of the valve plunger 11 faces a reaction disk 27 housed in a recess formed at the base of the output shaft 26. The output shaft 26 passes through the seal member 28 and projects to the outside of the shell 1, and is linked to a piston of a master cylinder (not shown).

The power piston 2, valve body 6, etc. mentioned above are
Normally, the return spring 29 is used to hold the valve plunger 11 in the non-operating position shown in the figure. This restricts the free movement of the valve plunger 11 to the right with respect to the valve body 6, so that when the input shaft 25 and the valve plunger 11 are operated next, the valve mechanism 7 can immediately switch the fluid circuit.

The above configuration and operation are basically the same as those of the conventionally known negative pressure type brake booster, so a description of the operation will be omitted.

However, in this embodiment, the valve body 6 is composed of a stepped cylindrical body 6a and a stepped cylindrical body 6a.
A disk-shaped auxiliary piston 35 is disposed in a space formed in the large diameter portion of the stepped cylindrical main body 6a. The auxiliary piston 35 is attached to the valve plunger 11 by a snap ring 36 attached to the valve plunger 11, and a diaphragm 37 is stretched between the back surface of the auxiliary piston 35 and the valve body 6.

The diaphragm 37 divides the space into two pressure chambers 38 and 39, and the front pressure chamber 38 is formed by a passage 40 bored in the fixed plate 6b.
The pressure chamber 39 at the rear always communicates with the constant pressure chamber 4 through a passage 41 formed in the valve body 6;
A flexible conduit 42 spirally arranged in the constant pressure chamber 4 and connected to the valve body 6, and a conduit 4 connected to the conduit 42 outside the shell 1.
3 to a flow path switching mechanism 44 that supplies pressure fluid to the pressure chamber 39.

In the illustrated embodiment, the flow path switching mechanism 44 is composed of two electromagnetic on-off valves 50 and 51 that are connected to each other.
At the same time, one supply-side on-off valve 50 is connected to the atmosphere, and the other discharge-side on-off valve 51 is connected to the conduit 5.
2 to a negative pressure source (not shown).
The pair of on-off valves 50 and 51 are controlled to open and close, respectively, by a control device 53 including a microcomputer.
3 inputs a signal from an operation amount detector 56 that detects the amount of operation of the manual brake operating member 55, such as the magnitude of input and the amount of stroke, and switches the flow path switching mechanism according to the signal as will be described in detail later. By switching the flow path 44, atmospheric pressure can be introduced into the pressure chamber 39 on the rear side.

In the brake booster having the above configuration, when the manual brake operating member 55 is not operated, the control device 53 controls the supply side on-off valve 5.
0 is closed, and the discharge side on-off valve 51 is opened. In this state, negative pressure is introduced into both the pressure chambers 38 and 39 before and after the auxiliary piston 35, and no pressure difference occurs between the front and rear of the auxiliary piston 35. Therefore, when the brake pedal (not shown) is depressed, the input shaft 25 By advancing the auxiliary piston 35
It is possible to perform the same operation as a conventionally known brake booster that does not have a brake booster.

Next, when the manual brake operating member 55 is operated in a non-operating state of the brake booster in which the brake pedal is not depressed, a signal corresponding to the operated amount is sent from the operated amount detector 56 to the control device 5.
3 is input. Then, the control device 53 calculates the amount of change in manual brake operation per unit time from the signal, and if the change is an increase, that is, if the brake force is to be strengthened, the control device 53 operates the discharge side on-off valve 51.
is shut off, and the opening time t of the supply side on-off valve 50 is calculated according to the magnitude of the amount of change (second a).
2b), the supply side on-off valve 50 is opened for the time t.

In addition, the control device 53 continues to calculate the amount of change in the new manual brake operation, and if it is necessary to immediately open the supply side on-off valve 50 again after the opening time t has elapsed, the opening time Even after t has elapsed, the supply-side on-off valve 50 is not shut off, and the supply-side on-off valve 50 is maintained in an open state until a new opening time t elapses. Note that when the supply side on-off valve 50 is left open until the next opening time elapses without shutting off the supply side on-off valve 50 after the previous opening time has elapsed, the inertia of the flow of pressure fluid should be taken into account. Then, the next opening time may be shortened by a small amount of time.

When the supply side on-off valve 50 is opened in this way, the atmosphere is introduced into the pressure chamber 39 on the rear side of the auxiliary piston 35 via the conduits 43, 42 and the passage 41, and is introduced into the pressure chamber 39. The generated pressure advances the valve plunger 11 via the auxiliary piston 35, so that the flow path of the valve mechanism 7 is switched and manual braking is performed. The supply side on-off valve 50 is opened for an opening time corresponding to the amount of operation of the manual brake operating member 55, so that the pressure supplied to the pressure chamber 39 is equal to the amount of operation applied to the manual brake operating member 55. The pressure is controlled according to the

As described above, when the amount of operation of the manual brake operating member 55 increases, the control device 53 controls the opening time of the supply side on-off valve 50 to manually control the fluid pressure introduced into the pressure chamber 39. Although the pressure is controlled according to the amount of change in brake operation, even if the amount of operation of the manual brake operation member 55 decreases, the discharge side opening/closing valve is controlled in accordance with the amount of change in the decrease, in exactly the same way as described above. By controlling the opening time of 51, the fluid pressure introduced into the pressure chamber 39 is also controlled to a pressure corresponding to the manipulated variable.

However, when the vehicle speed falls below a predetermined speed due to the manual braking action, as shown in FIG. Detect the speed V of the vehicle. If the speed V is not zero, the difference ΔV between the stored initial speed Vo and the current speed V, that is, the degree of deceleration of the vehicle, is calculated and stored in the control device 53 in advance.
The opening time T of the discharge side on-off valve 51 is selected from a table (ΔV-T table) in which the optimum opening time T is determined according to the difference ΔV.

After selecting the opening time T, the control device 53 opens the discharge side on-off valve 51 for the time T to reduce the pressure in the pressure chamber 39, and then changes the initial speed Vo to the current speed V. , the current speed V is detected again after the predetermined interval has elapsed.

Therefore, when the manual brake operation is performed and the speed of the vehicle decreases, and the speed becomes below a predetermined speed, the discharge side on-off valve 51 is opened for an appropriate time T as the speed of the vehicle decreases thereafter. As a result, the brake output from the brake booster is lower than normal, and as a result, when the vehicle is running at low speed or when the vehicle is stopped, the braking force is relatively large even if the output of the brake booster is constant. It is possible to eliminate the feeling of sudden braking.

Note that, of course, such control is canceled when the manual brake operation is canceled. When the operation of the manual brake operating member 55 is completely released, the control device 53 closes the supply side on-off valve 50 and opens the discharge side on-off valve 51, so that the fluid introduced into the pressure chamber 39 The pressure is completely discharged and the flow path of the valve mechanism 7 returns to the non-operating state, thereby releasing the braking action and canceling the manual braking action.

Next, FIG. 4 shows another embodiment of the present invention. In this embodiment, when the speed of the vehicle decreases by a predetermined value A, the discharge side on-off valve 51 is opened for a predetermined time T. It was designed to be open.

In other words, the vehicle speed is
When Vo becomes equal to or less than a predetermined speed, the control device 53 stores the vehicle speed as the initial speed Vo, and then detects the current speed V. and its speed V
If not zero, the difference ΔV between the stored initial velocity Vo and the current velocity V is calculated, and the current velocity V is continuously detected until the difference ΔV becomes equal to or greater than a predetermined value A.

When the difference ΔV becomes equal to or greater than the predetermined value A, the control device 53 opens the discharge side on-off valve 51 for a predetermined time T, then replaces the initial speed Vo with the current speed V, and then restarts the discharge side opening/closing valve 51. The current speed V is newly detected and the operation is repeated until the speed becomes zero. Therefore, even in such control, the same effects as described above can be obtained.

In the above embodiment, the normal braking action by the brake pedal and the manual brake operation member 5
It is clear that the manual braking action according to 5 can be carried out simultaneously.

``Effects of the Invention'' As described above, according to the present invention, when the speed of the vehicle falls below a predetermined value due to the operation of the manual brake device, the output of the brake booster is reduced to provide smooth braking without the feeling of sudden braking. This provides the advantage of being able to perform a braking action.

[Brief explanation of the drawing]

FIG. 1 is a systematic sectional view showing one embodiment of the present invention, FIGS. 2a and 2b are explanatory diagrams illustrating the opening and closing states of the supply side on-off valve 50 and the discharge side on-off valve 51, respectively, and FIG. , and FIG. 4 are flowcharts according to the present invention. 1... Ciel, 2... Power Piston, 4...
Constant pressure chamber, 5... Variable pressure chamber, 6... Valve body, 7
... Valve mechanism, 11 ... Valve plunger, 25 ... Input shaft, 35 ... Auxiliary piston, 39 ... Pressure chamber,
44... Flow path switching mechanism, 50... Supply side on-off valve,
51... Discharge side on-off valve, 53... Control device, 55
...Manual brake operating member, 56...Manipulation amount detector.

Claims (1)

[Scope of Claims] 1. A power piston slidably disposed in a shell, a valve mechanism housed in a valve body of the power piston shaft, and a constant pressure chamber formed on the front side of the power piston in the operating direction. A brake booster comprising a variable pressure chamber formed on the rear side, and an input shaft that operates a valve plunger constituting the valve mechanism to switch the flow path and supply pressurized fluid to the variable pressure chamber to advance the power piston. In the device, an auxiliary piston attached to the valve plunger;
A pressure chamber is defined on the rear side of the auxiliary piston, and uses the introduced fluid pressure to advance the auxiliary piston and valve plunger, switch the flow path of the valve mechanism, and perform a braking action, and detect the speed of the vehicle. a vehicle speed sensor that detects the amount of operation applied to the manual brake operating member; and a supply side opening/closing device that is provided in a communication path that communicates the pressure chamber with the pressure fluid supply source and opens and closes the communication path. A valve, a discharge side on-off valve that is provided in a communication path that communicates the pressure chamber with a discharge source that discharges the pressure introduced into the pressure chamber and opens and closes the same, and a signal from the manipulated variable detector is inputted. a control device that controls the opening and closing of the supply side on-off valve and the discharge side on-off valve to supply pressure to the pressure chamber according to the operation amount applied to the manual brake operation member; When the speed of the vehicle detected by the vehicle speed sensor falls below a predetermined value while pressure is being supplied to the pressure chamber,
A manual brake device equipped with a brake booster, characterized in that the discharge side on-off valve is opened for a required period of time to reduce the pressure in the pressure chamber. 2. A manual brake device equipped with a brake booster according to claim 1, wherein the operation amount detector detects the magnitude of an input applied to a manual brake operation member. 3. A manual brake device equipped with a brake booster according to claim 1, wherein the operation amount detector detects a stroke amount of a manual brake operation member.