JPH037256Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for boosting braking force using hydraulic pressure, and particularly to a variable hydraulic booster that can vary the boost ratio.

The braking force of a vehicle varies depending on the hydraulic pressure applied to each wheel cylinder. Pressure oil to this wheel cylinder is generated by the operation of a piston in a brake master cylinder. A known method is to directly apply pedal depression force as a pressing force to the piston, and to double the pressing force by using a power piston formed with a pressure receiving surface for pressurized fluid. Among these, a hydraulic booster that uses oil pressure can be connected in parallel to the power steering hydraulic system, for example.
Attachment rate is increasing. By the way, in a conventional brake hydraulic booster, the area of the hydraulic pressure receiving surface of the power piston that receives high hydraulic pressure is constant, and when the hydraulic pressure is constant, the boost ratio is constant. In other words, as shown in Fig. 1, when no boost is applied to the input transmitted from the brake pedal to the input shaft in the hydraulic booster (which almost matches the pedal force), the output corresponding to the broken line a is It is only transmitted to the master cylinder side, and when boosting is performed, an output corresponding to the solid line b relative to the input is transmitted to the master cylinder side, and a large braking force can be obtained. However, when operating such a conventional brake device equipped with a hydraulic booster, under the same road surface conditions, a larger braking force is required when the vehicle is loaded than when the vehicle is lightly loaded, so that the input, i.e., It also requires a lot of pedaling force. In this way, when the weight of the vehicle is large, it is necessary to apply a large amount of force to the pedal, so if you press the brake pedal when the cargo load is large, your feet will easily become fatigued and brake operability will deteriorate. .

An object of the present invention is to provide a hydraulic variable booster that can reduce the difference in pedal effort when a light vehicle is used and when a vehicle is loaded by regulating the input.

The hydraulic variable booster according to the present invention has an input shaft that moves in the axial direction by the pedal force, an output shaft that applies pressing force to the brake master cylinder, and a hydraulic booster that moves the output shaft in the direction of the brake master cylinder by receiving hydraulic pressure. It has a main hydraulic pressure receiving surface that generates a pressing force to press the input shaft, and a piston part that is provided integrally with the output shaft and moves according to the movement of the input shaft, and a hydraulic pressure source that sends oil to the main hydraulic pressure receiving surface. It consists of a spool valve that is installed in the oil passage and adjusts the hydraulic pressure supplied to the main hydraulic pressure receiving surface according to the movement of the input shaft. an auxiliary oil pressure receiving surface that presses the input shaft in a direction opposite to the output shaft pressing direction of the piston portion; an auxiliary oil path that branches from the oil passage and communicates with the auxiliary oil pressure receiving surface; It consists of a switching valve that opens and closes the auxiliary oil passage, and a controller that sends an open signal to the switching valve when the cargo load is less than a predetermined value based on a signal from a sensor installed on the vehicle body that detects the cargo load. It is characterized by

Such a variable hydraulic booster guides pressurized oil to the main hydraulic chamber that continues to the oil passage side via the spool valve when the cargo load of the vehicle body is below a predetermined value, and applies the hydraulic pressure to the main hydraulic pressure receiving surface of the piston part. At the same time, it is also received by the auxiliary hydraulic pressure receiving surface that presses the input shaft in the opposite direction to the output shaft pressing direction, and a part of the pressing force applied to the input shaft is suppressed by hydraulic pressure, and a part of the pressing force is directed from the piston toward the output shaft. On the other hand, when the load amount of the vehicle body exceeds a predetermined value, the hydraulic pressure to the auxiliary hydraulic pressure receiving surface is cut off, and the pedaling force of the input shaft is directly transmitted to the piston section, which in turn applies an increased pressing force. It acts to transmit information to the output shaft.

The present invention will be described below with reference to the accompanying drawings. Second
The figure shows a hydraulic variable booster 3 installed between a brake master cylinder 1 and a brake pedal 2.
showed that. This hydraulic variable booster 3 is connected in parallel with the power steering to an oil pump 5 and an accumulator (a diversion valve may be added between the pump element and the not shown) 6 used in the power steering 4. be done. The master cylinder 1 is connected to each wheel cylinder 7 via a hydraulic pipe, and each wheel cylinder is configured to apply a braking force to each wheel 8 in conjunction with the pressurizing operation of the master cylinder.

As shown in FIG. 3, the hydraulic variable booster 3 includes an input shaft 1 connected to a brake pedal 2 within a frame 9.
0 and an output shaft 11 disposed on the same line as this and applying a pressing force to a piston (not shown) in the master cylinder 1, respectively, are slidably supported. A piston portion 12 is integrally formed at one end of the output shaft, and is pressed and supported by a return spring 20 to a stop position P0. The piston portion 12 has an end face formed as a main hydraulic pressure receiving surface 14, and this is formed as a main hydraulic pressure chamber 15.
It is entering into. The other end of a lever 13, one end of which is connected to a spool valve 16 to be described later, is connected to this main hydraulic pressure receiving surface via a pin 17 that faces perpendicular to the plane of the paper. The lever 13 similarly connects a hollow connecting member 18 on the input shaft 10 side with a pin 19 near the pin 17 side. This connecting member is non-rotatably but slidably fitted into the frame body 9, and presses the main body side of the input shaft 10 in the return direction A via the return spring 21 to the stop position (the position shown by the solid line in FIG. 3). ) Support P1.

The input shaft 10 has one end formed as a pedal connecting end 101 and the other end as a main pressing end 102, which protrudes from inside the connecting member 18 and is connected to both pins 17 of the lever 13,
19 so as to be able to come into contact with each other. Further, an annular hydraulic pressure receiving surface 103 is formed at the center of the input shaft as a sub-hydraulic receiving surface whose outer diameter increases stepwise.
This surface has a tapered shape and is formed to receive hydraulic pressure in the return direction A. Note that when the input shaft 10 is at the stop position P1, a part of the main pressing end 102 side of the small diameter portion is in contact with the small diameter inner wall of the frame 9 side. The large-diameter side of this input shaft is in contact with a part of the large-diameter inner wall on the frame side. Therefore, the portion where the remaining portion of the small diameter portion of the input shaft 10 and the remaining portion of the large diameter inner wall of the frame body 9 face each other is formed as an annular hydraulic chamber 30 . This annular hydraulic chamber 3
The axial length L of 0 is the sliding stroke required until the annular hydraulic pressure receiving surface 103 on the input shaft at the stop position P1 comes into contact with the tapered stopper wall 901 on the frame body 9 side. The annular hydraulic chamber 30 can communicate with the main hydraulic chamber 15 located on the oil path leading to the oil pump 5 via the auxiliary oil path 22 . This auxiliary oil passage is provided with a switching valve 23 that functions as a three-way valve in the middle, and when this switching valve is off, the auxiliary oil passage 22 is in communication, and when it is on, the auxiliary oil passage 22 is cut off, and the annular hydraulic chamber 30 is closed. It communicates with the reservoir 24 side. As shown in FIG. 2, this switching valve is connected to a controller 25. The controller 25 outputs an ON signal to the switching valve 23 based on the output of a load sensor 26 that detects the amount of cargo load of the vehicle, and when this exceeds a set value.
As shown in FIG. 3, a long guide hole 31 is formed in the frame 9 in a direction parallel to the output shaft 11, into which the spool valve 16 is slidably fitted. A connecting hole 161 is formed over almost the entire length of the connecting hole 161, thereby almost eliminating the pressure difference between both ends. This spool valve has one end protruding into the main hydraulic chamber 15, and the upper end of the lever 13.
The pin 27 is engaged with the groove. In this case, since the spool valve 16 receives the pressure within the main hydraulic chamber 15 at both ends, it is operated only by the pressing force from the lever 13 and the pressing force from the return spring 26. An annular recess 162 is formed in the body of the spool valve, and a lateral hole 163 communicating with the connecting hole 161 is opened in the annular recess 162 . When the input shaft 10 is at the stop position P1,
The lever 13 supports the spool valve 16 in a stop position P2 shown in solid line in FIG. In this case, guide hole 3
Of the two openings following 1, the outflow port 28 faces the annular recess 162, and the inflow port 29 is blocked from the annular recess. Note that the inlet 29 communicates with the pump 5 side, and the outlet 28 communicates with the reservoir 24 side.

The operation of such variable hydraulic booster 3 will be explained. Hydraulic pump 5 is operated by the drive of an engine (not shown), and hydraulic variable booster 3 receives pressure oil through accumulator 6 together with power steering device 4 . First, if the amount of cargo load is small, the controller 25 does not issue an on signal. When the brake pedal 2 is depressed in this state, the input shaft 10 receives the depression force F1 as an input and is initially activated. This operation is transmitted to the connecting member 18 via the return spring 21, and this operation moves the lever 13 counterclockwise using the pin 17 as a fulcrum.
is rotated to slide the spool valve 16 from the stop position P2 toward the operating position P3 shown in FIG. 4 in accordance with the value of the pedal force F1. Then, the outflow port 28 is closed, the inflow port 29 faces the annular recess 162 by a predetermined amount, and pressure oil of a value corresponding to the opening amount of this inflow port flows into the main hydraulic chamber 15. At this time, the main hydraulic chamber 15 and the annular hydraulic chamber 30
are in communication via the auxiliary oil passage 22, so the annular hydraulic pressure receiving surface 103 receives the hydraulic pressure, and a regulating force F11 that reduces the pedal force in the opposite direction to the pedal force F1 acts on the input shaft 10 (see Fig. 5). ). For this reason, the piston portion 12
receives the regulated pedal force F2 (=F1-F11) from the main pressing end 101 of the input shaft via the lever 13, and also receives the hydraulic pressure F3 on the main hydraulic pressure receiving surface 14, and the light vehicle output F4 which is the resultant force of these is received. Act on master cylinder 1. The pressure oil from the master cylinder 1 causes each wheel cylinder 7 to generate a braking force. On the other hand, if the load capacity exceeds the set value,
Since the controller 25 outputs an ON signal to the switching valve 23, the annular hydraulic chamber 30 communicates with the reservoir 24. When the brake pedal 2 is depressed in this state, the spool valve 16 is first operated to switch by an amount corresponding to the value of the pedal force F1, and a predetermined level of pressure oil is supplied to the main hydraulic chamber 15. At this time, the main hydraulic chamber 15
The annular hydraulic chamber 30 is isolated from the input shaft 10, and the input shaft 10 transmits the pedal force F1 almost unchanged to the piston portion 12 without being subjected to any regulating force. For this reason, the piston part has a pedal force F1
and the hydraulic pressure F3, and the resultant force of these forces, output F5 during loading, is applied to the master cylinder 1. The piston section 12 generates hydraulic pressure in the master cylinder 7 based on the hydraulic pressure F3 received by the piston section and the input pedal force, so that almost sufficient braking force can be applied to the vehicle when the vehicle is lightly loaded. , the area of the main hydraulic pressure receiving surface 14 is formed to be sufficiently large.

According to the above-mentioned hydraulic variable booster 3, as shown in FIG. 6, even if the pedal force F1 is constant, when the load is light, this is always reduced by the regulating force F11 and applied to the piston part 12, as shown by the broken line. Only the regulated pedal force F2 (=F1-F11) is added as an input, and the light vehicle output F4, which is made up of this and the hydraulic pressure F3, is output. On the other hand, even with the same pedal force F1, when loading a car, a multiplied output F5 is output when the car is loaded, which is made up of the pedal force F1 and the hydraulic pressure F3. Therefore, if the pedal force F1 is set in advance to a value that does not cause driver fatigue, the regulating force F11 can be adjusted even if the pedal force F1 is constant.
The loaded output F5 increases accordingly, and the braking force increases accordingly. Moreover, the brake pedal operating force is the same when the vehicle is lightly loaded and when the vehicle is loaded, which has the advantage of keeping fatigue levels low.

[Brief explanation of the drawing]

Figure 1 is an input-output characteristic diagram of a conventional hydraulic booster, Figure 2 is a schematic configuration diagram of a variable hydraulic booster as an embodiment of the present invention, and Figure 3 is a cross-section of the main parts of the same device. 4 is an enlarged explanatory diagram of the operation of the spool valve of the above device, FIG. 5 is an explanatory diagram of the operation of the input shaft of the same device, and FIG. 6 is an input-output characteristic diagram of the same device. 1... Master cylinder, 2... Brake pedal, 3... Hydraulic variable booster, 10... Input shaft,
11... Output shaft, 103... Annular hydraulic pressure receiving surface, 12
... Piston part, 13 ... Lever, 14 ... Main oil pressure receiving surface, 15 ... Main oil pressure chamber, 16 ... Spool valve, 22 ... Sub-oil passage, 23 ... Switching valve.

Claims (1)

[Scope of utility model registration request] An input shaft that moves in the axial direction according to the force of the pedal, an output shaft that applies a pressing force to the brake master cylinder, and a main shaft that generates a pressing force that presses the output shaft in the direction of the brake master cylinder by receiving hydraulic pressure. A piston part has a hydraulic pressure receiving surface and is provided integrally with the output shaft and moves according to the movement of the input shaft, and a piston part is provided in an oil passage that sends oil from the hydraulic source to the main hydraulic pressure receiving surface of the input shaft. and a spool valve that adjusts the hydraulic pressure supplied to the main hydraulic pressure receiving surface according to the movement, and is formed on the input shaft and receives hydraulic pressure to move the input shaft in the direction in which the output shaft of the piston section is pushed. an auxiliary oil pressure receiving surface that presses in the opposite direction to the auxiliary oil pressure receiving surface; a auxiliary oil passage that branches from the oil passage and communicates with the auxiliary oil pressure receiving surface; and a switching valve that is provided in the auxiliary oil passage and opens and closes the auxiliary oil passage; A variable hydraulic booster comprising: a controller that sends an open signal to the switching valve when the load amount is less than a predetermined value based on a signal from a sensor that detects the load amount provided on the vehicle body.