JPH0478506B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a brake booster used in a vehicle.

``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 constant 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.

``Problems to be Solved by the Invention'' However, in conventional brake boosters of this type, the reaction force ratio is substantially constant and cannot be changed. Therefore, for example, when a brake booster is used as a brake booster for a truck, there will be a difference in the driver's braking sensation when the vehicle is empty and when the vehicle is loaded, and the braking force may be perceived to be low when the vehicle is loaded. It was often done. Furthermore, even under the same braking condition, some drivers may perceive the braking force to be too large or too small, and there are individual differences in preferred braking sensations.

"Means for Solving the Problems" In view of such circumstances, the present invention provides an auxiliary piston in the valve plunger, forms a pressure chamber partitioned by the auxiliary piston in the valve body, and further provides the above-described method. The pressure chamber on the rear side of the auxiliary piston is selectively communicated with either the variable pressure chamber or the constant pressure chamber, and the pressure fluid at the same pressure as the variable pressure chamber or the same pressure as the constant pressure chamber is supplied to the pressure chamber on the rear side. The system is equipped with a supply device for supplying pressure fluid.

"Function" With such a configuration, the effect on the auxiliary piston depends on whether the pressure fluid with the same pressure as the constant pressure chamber is supplied to the pressure chamber or the pressure fluid with the same pressure as the variable pressure chamber is supplied. The acting force can be changed and therefore the reaction force ratio can be changed.

"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 between the first valve seat 10 and the valve body 14 is communicated with the constant pressure chamber 4 through a passage 15 formed in the valve body 6, and the constant pressure chamber 4 is connected to a negative pressure provided in the shell 1. The inlet pipe 16 communicates with 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 14 is communicated with the atmosphere via a filter 18. In addition, the above-mentioned transformation chamber 5
The valve body 6 is maintained airtight with the outside by a sealing member 19 slidably passing through the valve body 6.

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 communicated with 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 is basically the same as a conventionally known negative pressure type brake booster, and when the brake pedal (not shown) is depressed and the input shaft 25 and valve plunger 11 are moved to the left, the valve body 14 is Seated on the first valve seat 10 of the valve body 6 to cut off communication between the variable pressure chamber 5 and the constant pressure chamber 4,
Since the valve body 14 is separated from the second valve seat 12 of the valve plunger 11 and communicates the atmosphere with the variable pressure chamber 5, the atmosphere is thereby supplied into the variable pressure chamber 5. When a pressure difference is generated before and after the power piston 2 and the power piston 2 is moved forward against the repulsive force of the return spring 29, a braking action is performed.

If the force on the brake pedal is released from this brake operating state, the second valve seat 1 of the valve plunger 11
The power piston 2 is return spring 29
It is returned to its original non-operating position.

When the key member 30 comes into contact with the inner surface of the shell 1 due to the retraction of the power piston 2, the retraction of the valve plunger 11 communicating therewith is stopped.
The power piston 2 and the valve body 6 continue to retreat, and as the valve body 6 retreats, the first valve seat 10 of the valve body 6 approaches the valve body 14, and when the gap between them becomes almost zero, the valve body 6 moves toward the key member 30. It comes into contact with and stops. Therefore, the next time the input shaft 25 is moved forward again, the flow path of the valve mechanism 7 is immediately switched.

However, in this embodiment, the valve body 6 is composed of a stepped cylindrical body 6a and a plate 6b attached to the left end surface of the stepped cylindrical body 6a.
A recess 35 is formed in the center of the left end surface of the recess 3.
5 is sealed with the plate 6b. A generally dish-shaped or umbrella-shaped auxiliary piston 36 is slidably fitted into this recess 35, and is connected to the auxiliary piston by the stepped portion formed on the valve plunger 11 and the snap ring 37 attached to the valve plunger 11. 36 to the valve plunger 11,
A seal member 38 provided on the outer periphery of the auxiliary piston 36
A pair of pressure chambers 39 and 4 are formed inside the recess 35 by
It is partitioned into 0.

By forming the auxiliary piston 36 into an umbrella shape, the pressure receiving area can be increased without interfering with the passage 15, and the auxiliary piston 36 can
The reaction disk 27 can be inserted into the umbrella-shaped inside of valve body 6.
The axial length of can be shortened. Further, since the auxiliary piston 36 has an umbrella shape, it is stronger than a flat plate shape against bending force due to a pressure difference, and the piston can be made thinner.

The pressure chamber 39 located behind the auxiliary piston 36 includes 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 shell 1.
a conduit 43 connected to the conduit 42 on the exterior of the
It is connected to a flow path switching mechanism 45 of a supply device 44 that supplies pressure fluid to the pressure chamber 39 via.

Similarly, the pressure chamber 40 located in front of the auxiliary piston 36 also has a passage 46 formed in the valve body 6,
Connected to the flow path switching mechanism 45 of the supply device 44 via a flexible conduit 47 spirally arranged in the constant pressure chamber 4 and a conduit 48 outside the shell 1,
The flow path switching mechanism 45 is further connected to a negative pressure source (not shown) which is communicated with the constant pressure chamber 4 via a conduit 49, and is connected to the variable pressure chamber 5 via a conduit 50.
are communicated.

The supply device 44 switches the flow path of the flow path switching mechanism 45 in response to a detection signal from a vehicle weight sensor 55 that detects the loaded state of the vehicle, and connects each pressure chamber 39, 40 to a negative pressure source or a transformer. A control device 56 including a microcomputer communicated with the chamber 5 is provided. The vehicle weight sensor 55 may have an appropriate configuration, such as one that detects the load amount from the suspension stroke between the vehicle body and the axle, or one that detects the load amount from a load switch installed on the seat. Can be used.

In the brake booster having the above configuration, as shown in FIG. 2, the pressure chambers 39, 40 before and after the auxiliary piston 36 are switched to communicate with the negative pressure source or the variable pressure chamber 5, so that the pressure chambers 39, 40 are connected to the negative pressure source or the variable pressure chamber 5. The reaction force ratio can be changed in three stages.

In other words, if the vehicle has a large load capacity,
The control device 56 of the supply device 44 detects the state using the vehicle weight sensor 55 and controls the flow path switching mechanism 45.
The flow path of the auxiliary piston 36 is switched, and the pressure chamber 39 on the rear side of the auxiliary piston 36 is communicated with the inside of the variable pressure chamber 5 via the passage 41, the conduits 42, 43, the flow path switching mechanism 45, and the conduit 50. A conduit 49 and a flow path switching mechanism 4 are provided in the pressure chamber 40 on the front side.
5. Negative pressure is introduced via conduits 48, 47 and passage 46.

In this state, the pressure inside the variable pressure chamber 5 is introduced into the pressure chamber 39 on the rear side of the auxiliary piston 36, and the negative pressure, that is, the pressure inside the constant pressure chamber 4, is introduced into the pressure chamber 40 on the front side of the auxiliary piston 36. Therefore, as mentioned above, when the brake booster is activated and a pressure difference occurs between the front and rear of the power piston 2, the same pressure difference as the pressure difference between the front and rear of the power piston 2 is created between the front and rear of the auxiliary piston 36. A pressure difference begins to occur. As a result, the valve plunger 11 and the input shaft 25 receive the forward force of the auxiliary piston 36, allowing the driver to obtain strong braking force with a light pedal effort. The force ratio becomes large.

Next, when the loading capacity of the vehicle becomes medium, the supply device 44 detects this state with the vehicle weight sensor 55 and closes the pressure chamber 39 on the rear side of the auxiliary piston 36, which has been in communication with the variable pressure chamber 5. Negative pressure is introduced inside. In this state, the auxiliary piston 36
Negative pressure is introduced into both the front and rear pressure chambers 39 and 40, and when the brake booster is activated, the auxiliary piston 3
Since no pressure difference occurs before and after the piston 36, the reaction force is transmitted to the driver at an originally determined intermediate reaction force ratio, similar to the case without the auxiliary piston 36.

Furthermore, when the loading capacity of the vehicle becomes small, the supply device 44 is connected to the pressure chamber 3 on the rear side of the auxiliary piston 36.
The pressure chamber 40 on the front side is communicated with the inside of the variable pressure chamber 5 while introducing negative pressure into the pressure chamber 9. In this state, when the brake booster is activated, a pressure difference opposite to the pressure difference before and after the power piston 2 is generated before and after the auxiliary piston 36, so that the valve plunger 11 is moved away from the auxiliary piston 36 in the forward direction. You will experience an opposite backward force. Therefore, the driver is required to apply a relatively heavy pedal force to obtain a constant output, which prevents excessive braking force from occurring and causing skids and the like. It is clear that in this state, the reaction force ratio is small.

Next, although the above description is an explanation of the operation related to the vehicle weight sensor 55 included in the supply device 44, the supply device 44 is further provided with a plurality of sensors and switches. That is, the control device 56 is capable of detecting the speed of the vehicle based on a signal from a vehicle speed sensor 57 that detects the speed of the vehicle, and at the same time controls the reaction force ratio according to the vehicle weight. Furthermore, the flow path switching mechanism 45 is switched and controlled so that the reaction force ratio becomes smaller as the vehicle speed increases.

Further, the control device 56 is equipped with a manually operated reaction force ratio switching switch 58, and the control point of the flow path switching mechanism 45 can be changed according to the switching position of the switching switch 58. It's becoming like that.

Further, the control device 56 includes a stop brake device 59, and after the control device 56 detects the stopped state of the vehicle using a vehicle speed sensor 57, a brake lamp switch 60 detects that the brake pedal has been continuously depressed for a predetermined period of time. If it is detected by continuous operation of Stop the vehicle.

On the other hand, when the control device 56 detects that the accelerator switch 62 that detects depression of the accelerator pedal or the manual stop brake release switch 63 is operated, the atmospheric pressure introduced into the rear pressure chamber 39 is released. to release the brake booster.

The parking brake device 59 is provided with a parking brake switch 64 and a door switch 65 on the driver's seat side so that the driver does not leave the driver's seat in this state when the vehicle is stopped. If the door is opened without pulling the alarm 6, the control device 56
6 can be operated. Alternatively, if a load switch is provided at the driver's seat as the vehicle weight sensor 55, the door switch 6
Instead of 5, the load switch may be used to issue the alarm.

Further, the control device 56 is equipped with an ultrasonic sensor 67 that detects the presence or absence of an obstacle. from the port 61 of the flow path switching mechanism 45 to the rear pressure chamber 3.
Atmospheric pressure is introduced into the vehicle, and the brake booster is automatically activated to stop the vehicle.

At this time, the stop brake release switch 63
Alternatively, the operation of the brake booster may be released by a manual brake release switch (not shown). Further, when the speed of the vehicle is low, the ultrasonic sensor 67 may be activated even when the vehicle is moving forward, and the vehicle may be automatically stopped.

Furthermore, although not shown, a manual brake switch is provided as necessary, and the flow path switching mechanism 45 is appropriately switched and controlled in accordance with the operating position of the manual brake switch by the hand, separately from the depression operation of the brake pedal by the foot. With this, it is also possible to control the output of the brake booster in three stages.

As described above, the brake booster according to the present invention can be used for various purposes, but if necessary, some of the above-mentioned functions may be omitted or other appropriate functions may be added. Of course, this is a good thing. In any case, a supply device 44 corresponding to various uses or functions is required, and it will be easy for those skilled in the art to obtain such a supply device 44.

Further, the fluid pressure supplied to each pressure chamber 39, 40 is not limited to the above-mentioned negative pressure or the same pressure as that introduced into the variable pressure chamber 5, but a constant pressure controlled to an appropriate pressure. pressure, or a controlled pressure proportional to the pressure introduced into the variable pressure chamber 5, or a controlled pressure of its own pressure for a specific purpose, each pressure chamber 39,
It is clear that by appropriately controlling the fluid pressure supplied to 40, it is possible to control the reaction force ratio in three or more stages as described above.

Next, in the embodiment described above, a fluid pressure higher than that of the other pressure chamber is introduced into the pressure chamber 40 on the front side and the pressure chamber 39 on the rear side of the auxiliary piston 36, for example, as shown in FIG. In this way, the front pressure chamber 140 is always communicated with the constant pressure chamber 104 via the passage 170 formed in the valve body 106, and a higher pressure than the front pressure chamber 140 is introduced only into the rear pressure chamber 139. In this case, a diaphragm-shaped seal member 138 can be used instead of the sliding seal 38 such as an O-ring.

In this case, a pressure higher than that in the rear pressure chamber 139 cannot be introduced into the front pressure chamber 140, so its function is limited compared to the case of FIG. 1, but a diaphragm can be used as the sealing member 138. Therefore, compared to the case where an O-ring is used, there is an advantage that sliding resistance and hysteresis caused by elastic deformation of the O-ring can be eliminated.

Note that the specific configuration of the supply device (not shown) that supplies pressure fluid to the pressure chamber 139 will be different from that of the above embodiment due to the restriction of the function, but other configurations will be the same as those of the above embodiment. The parts that are substantially the same as those in FIG. 1 or corresponding to those in FIG. 1 are designated by the same reference numerals as in FIG.

FIG. 4 shows another embodiment of the present invention,
In this embodiment, the auxiliary piston 236 is a cylindrical stepped piston, and its inner and outer circumferences are sealed with O-ring-shaped seal members 238a, 238b, thereby creating three pressure chambers 271, 27 in the valve body 206.
2,273 was formed. Each of the pressure chambers 271 to 273 is connected to the shell 2 through a passage 274 formed in the valve body and a flexible conduit 275 spirally arranged in the constant pressure chamber 204.
01 is connected to a supply device (not shown) provided outside the drawings.

The supply device is equipped with a flow path switching mechanism and a control device that connect the three pressure chambers 271 to 273 to the negative pressure source and the variable pressure chamber 205, respectively, and therefore its configuration is more complicated than that in FIG. However, the other configuration is substantially the same as the embodiment shown in FIG. 1, and the same or corresponding parts as in FIG. 1 are given the same reference numerals as in FIG. 1 plus 200. It is shown as follows.

In this embodiment, as shown in FIG. 5, the auxiliary piston 23 in each pressure chamber 271 to 273
6, each pressure receiving area is set appropriately, and each pressure chamber 2
It is clear that the reaction force ratio can be changed in seven steps by switching and communicating the pressure points 71 to 273 with the negative pressure source or the variable pressure chamber 205.

Furthermore, FIG. 6 shows a modification of the embodiment shown in FIG. 4, in which diaphragm-shaped seal members 338a, 338b are used instead of O-ring-shaped seal members 238a, 238b, similar to the embodiment shown in FIG.
.

In this embodiment, the auxiliary piston 336 has two
It is composed of two dish-shaped diaphragm plates 380 and 381, and the outer diameter of the diaphragm plate 380 located on the rear side is larger than the outer diameter of the diaphragm plate 381 on the front side. A diaphragm 338a is disposed on the back surface of the diaphragm plate 380 on the rear side, and the outer periphery of the diaphragm 338a is folded back to the outside and then connected to the valve body 306. One end of the other diaphragm 338b is connected to the outer circumference of a diaphragm plate 381 on the front side, and the other end of this diaphragm 338b is connected to the valve body 306 after being folded inward.

Therefore, three pressure chambers 371, 372, 373 are formed in the valve body 306 by the pair of diaphragm plates 380, 381 and the diaphragms 338a, 338b.
Considering the bending direction of 8b, pressure chambers 371 and 37
3 are passages 374 formed in each valve body.
and a flexible conduit 375 disposed spirally within the constant pressure chamber 304, and connected to a supply device (not shown). and the remaining pressure chamber 3
72 is a passage 37 formed in the valve body 306.
It is constantly communicated with the constant pressure chamber 304 via 0.

In such a configuration, the fluid pressure introduced into the pressure chamber 371 urges the auxiliary piston 336 in the forward direction, and the fluid pressure introduced into the pressure chamber 373 urges the auxiliary piston 336 in the backward direction. It becomes like this.

Further, FIG. 7 shows a modification of the embodiment shown in FIG. 6, in which the other end of a diaphragm 438b corresponding to the diaphragm 338b is folded back outward instead of folded inward. and 3
Of the three pressure chambers 471, 472, 473, the pressure chambers 471, 472 are communicated with a supply device (not shown), and the other pressure chamber 473 is constantly communicated with the constant pressure chamber 404 via a passage 470 formed in the valve body 406. .

In this embodiment, the fluid pressure introduced into the pressure chamber 471 urges the auxiliary piston 436 in the forward direction, and the fluid pressure introduced into the pressure chamber 472 urges the auxiliary piston 436 in the backward direction. However, when introducing pressure into pressure chamber 472, pressure must also be introduced into pressure chamber 471, otherwise the folded portion of diaphragm 438a will
71 side.

In FIGS. 6 and 7, the configuration of the parts not explained is substantially the same as that of the embodiment shown in FIG. are shown with the same reference numerals as in FIG. 4 plus 100 and 200, respectively.

Furthermore, in each of the above embodiments, if the flow path switching mechanism of the supply device can be made compact, it may be incorporated into the valve body.

"Effects of the Invention" As described above, the present invention provides an auxiliary piston in the valve plunger to form a pressure chamber in the valve body, and supplies pressure fluid to the pressure chamber. The reaction force ratio can be changed depending on the pressure of the fluid, so it is possible to obtain the optimum reaction force ratio according to the load amount, the optimum reaction force ratio according to the vehicle speed, etc. Furthermore, changing the reaction force ratio does not adversely affect the performance of the brake booster.

Furthermore, if necessary, by supplying high-pressure fluid to the pressure chamber, it is possible to operate the brake booster without operating the input shaft, so it can be used as a stopping brake device on slopes. The effect is that various applications are possible, such as being able to do the following.

[Brief explanation of the drawing]

FIG. 1 is a systematic sectional view showing one embodiment of the present invention, FIG. 2 is a diagram showing conditions for changing the reaction force ratio in the brake booster shown in FIG. 1, and FIG. 3 is a diagram showing the conditions for changing the reaction force ratio in the brake booster shown in FIG. 4 is a cross-sectional view showing a further embodiment of the present invention; FIG. 5 is a view showing conditions for changing the reaction force ratio in the brake booster shown in FIG. 4; Figures 6 and 7 are respectively 4th
FIG. 7 is a cross-sectional view showing a modification of the figure. 1,101,201,301,401...Ciel, 2,102,202,302,403...Power Piston, 4,104,204,304,40
4... Constant pressure chamber, 5,105,205,305,40
5...Transformer room, 6,106,206,306,40
6...Valve body, 7,107,207,30
7,407...Valve mechanism, 11,111,211,3
11,411...valve plunger, 25,125,2
25,325,425...Input shaft, 36,136,
236,336,436...auxiliary piston, 38,
138, 238a, 238b, 338a, 338
b, 438a, 438b...Seal member, 39, 4
0,139,140,271,272,273,
371, 372, 373, 471, 472, 47
3... Pressure chamber, 44... Supply device, 45... Channel switching mechanism, 46... Control device.

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 is provided on the valve plunger, a pressure chamber is formed in the valve body divided by the auxiliary piston, and the pressure chamber on the rear side of the auxiliary piston is divided into the variable pressure chamber and the constant pressure chamber. A brake characterized in that a supply device is provided which selectively communicates with one of the rear pressure chambers and supplies a pressure fluid having the same pressure as the variable pressure chamber or a pressure fluid having the same pressure as the constant pressure chamber. booster. 2. The brake booster according to claim 1, wherein the auxiliary piston defines two pressure chambers. 3. The brake booster according to claim 1, wherein the auxiliary piston defines three pressure chambers. 4. The brake booster according to any one of claims 1 to 3, wherein the seal member provided on the auxiliary piston and partitioning the pressure chamber is a sliding seal. 5. The brake booster according to any one of claims 1 to 3, wherein the sealing member provided on the auxiliary piston and partitioning the pressure chamber is composed of a diaphragm.