JPH04303060A - Braking servo device - Google Patents

Abstract

PURPOSE:To keep off any movement of a brake pedal at the time of setting it down to an automatic braking device by constituting a valve body with a retractably fitted cylindrical member, and installing a power piston and a constant pressure passage front side in a first cylindrical member and a constant pressure passage rear side part, a valve mechanism and a variable pressure passage in a second cylindrical member, respectively. CONSTITUTION:A valve body 7 is composed of a first cylindrical member 44 at the front side and a second cylindrical member 43 at the rear side, while the end of a bellows 17, two power pistons 9, 10 and two diaphragms 11, 12 are all attached to the first cylindrical member 44, and a valve mechanism 16 is housed in the second cylindrical member 45. When atmospheric air is conducted into an internal space A' of the bellows 17 and a tandem braking servo unit is made to function as an automatic braking device, the first cylindrical member alone is advanced forward and the second cylindrical member 45 will not move at all, so that an input shaft 32 and a brake pedal are not moved as well.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a brake booster having the function of an automatic braking device.

[Prior Art] Conventionally, a brake booster with the function of an automatic braking device has a valve body slidably provided in a shell, a power piston provided in the valve body, and a brake booster formed on the front side of the power piston. Communication between a constant pressure chamber, a variable pressure chamber formed on the rear side of the power piston, a constant pressure passage provided in the valve body and communicating with the constant pressure chamber, a variable pressure passage communicating with the variable pressure chamber, and a pressure passage communicating with a pressure fluid source. an input shaft having a tip end connected to a valve plunger constituting the valve mechanism, an input shaft provided in the constant pressure chamber, a rear end connected to the constant pressure passage, and a front end connected to the constant pressure passage. A device is known that includes a bellows attached to the wall surface of the shell and is capable of supplying pressure fluids of different pressures to the internal space of the bellows (for example, Japanese Patent Application Laid-Open No. 1-127446). In the brake booster, the valve body and power piston are moved forward by supplying atmospheric air into the bellows when necessary, thereby operating the brake booster even when the brake pedal is not depressed. can be done.

[Problems to be Solved by the Invention] However, in the conventional brake booster, the valve body is constructed from a single member, so that the brake booster does not function as an automatic brake device as described above. When the valve body is moved forward, the input shaft is also moved forward in conjunction with the forward movement of the valve body. In this way, when the input shaft is moved forward, the brake pedal that is linked thereto also automatically moves. In other words, when the brake booster functions as an automatic braking device, the brake pedal moves automatically even though the driver does not press the brake pedal, so the driver's brake feedback is reduced. There was a drawback that the ring was obstructed.

[Means to solve the problem] In view of these circumstances,
The present invention includes a valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber formed on the front side of the power piston, a variable pressure chamber formed on the rear side of the power piston, and the above valve body. a valve mechanism for controlling communication between a constant pressure passage communicating with the constant pressure chamber, a variable pressure passage communicating with the variable pressure chamber, and a pressure passage communicating with a pressure fluid source; and a valve plunger constituting the valve mechanism having a tip end. A bellows is provided in the constant pressure chamber, the rear end is connected to the constant pressure passage, and the front end is attached to the wall of the shell, and the bellows is provided in the internal space of the bellows. In the brake booster capable of supplying pressure fluids of different pressures, the valve body is composed of a first cylindrical member and a second cylindrical member that are fitted to each other so as to be movable in the axial direction, A first cylindrical member is provided with the power piston and a front side portion of the constant pressure passage, a rear end of the bellows is connected to the constant pressure passage of the first cylindrical member, and the second cylindrical member is further provided with a front side portion of the power piston and a constant pressure passage. , the rear side portion of the constant pressure passage, the above-mentioned valve mechanism, and the variable pressure passage are provided.

[Operation] According to such a configuration, when the brake booster functions as an automatic brake device by introducing atmospheric air into the internal space of the bellows, the first cylindrical member of the valve body provided with the power piston The second cylindrical member of the valve body is not moved. Therefore,
The input shaft and the associated brake pedal are never moved. In this way, when the brake booster functions as an automatic braking device, the brake pedal does not move automatically, so the driver's brake feeling is not impaired.

[Embodiment] The present invention will be explained below with reference to the illustrated embodiment. In FIG. 1, a shell 1 of a tandem brake booster is shown.
It is composed of a front shell 2 formed into a roughly cup shape, and a rear shell 3 having a roughly dish shape that seals an opening of the front shell 2. A center plate 4 formed into a roughly cup shape is fitted into the interior of the front shell 2, and a front chamber 5 and a rear chamber 6 are formed in front and behind the wall surface of the center plate 4. The center plate 4 and the rear shell 3 each have a through hole formed in their respective central shaft portions, and a cylindrical valve body 7 is slidably passed through each through hole, and a seal member 8 is attached to each of the through holes. Airtightness between the through hole and the valve body 7 is maintained. A front power piston 9 and a rear power piston 10 are arranged in each of the front chamber 5 and rear chamber 6, and each power piston 9, 10
The inner circumference of the piston is connected to the valve body 7, and a front diaphragm 11 and a rear diaphragm 12 are stretched on the rear side surfaces of each power piston 9 and 10, respectively.
The inner peripheral portions of each of the diaphragms 11 and 12 are also connected to the valve body 7. The outer peripheral bead portion 11a of the front diaphragm 11 is held by an annular wall portion 2a of the front shell 2 and an opposing wall portion 4a of the center plate 4 facing thereto. The front diaphragm 11 divides the inside of the front chamber 5 into a constant pressure chamber A on the front side and a variable pressure chamber B on the rear side. The outer peripheral bead portion 12a of the rear diaphragm 12 is held by an annular groove 3a formed in the outer peripheral portion of the rear shell 3 and a cylindrical portion 4b of the center plate 4. and,
The rear diaphragm 12 divides the inside of the rear chamber 6 into a constant pressure chamber C on the front side and a variable pressure chamber D on the rear side. A valve mechanism 16 having a conventionally well-known configuration is provided in the valve body 7, and when a bellows 17, which will be described later, is not provided, this valve mechanism 16 controls the two constant pressure chambers A and C and the two variable pressure chambers B, It is designed to switch the fluid circuit between it and D. The valve mechanism 16 is formed at the right end of an annular first valve seat 18 formed on the valve body 7 and a valve plunger 19 slidably provided on the valve body 7 inside the annular first valve seat 18. The second valve seat 20 is provided with an annular second valve seat 20, and a valve body 22 that is seated on both valve seats 18 and 20 from the right side in FIG. 1 by a spring 21. The space on the outer circumferential side of the annular seat portion where the first valve seat 18 and the valve body 22 come into contact is a first space in the axial direction formed in the valve body 7 when the bellows 17 is not provided.
It communicates with the constant pressure chamber A via a constant pressure passage 23. Constant pressure chamber A is a negative pressure introduction pipe 24 connected to the front shell 2.
Negative pressure is introduced from the negative pressure source through It is constantly connected to room C. Therefore, when negative pressure is introduced into the constant pressure chamber A, negative pressure is also introduced into the constant pressure chamber C via the second constant pressure passage 25. On the other hand, a portion on the inner circumference side of the annular seat portion where the first valve seat 18 and the valve body 22 contact, and on the outer circumference side of the annular seat portion where the second valve seat 20 and the valve body 22 contact; In other words, the space between the inner and outer annular seat portions is communicated with a variable pressure chamber D via a radial variable pressure passage 26 formed in the valve body 7, and the variable pressure chamber D is connected to another axial variable pressure chamber formed in the valve body 7. It communicates with the variable pressure chamber B via a passage 27. Furthermore, the space on the inner circumferential side of the inner annular seat portion where the second valve seat 20 and the valve body 22 contact is formed through a pressure passage 28 formed in the valve body 7 and a filter filter 29 provided therein. It communicates with the atmosphere. Further, the right end portion of the valve plunger 19 slidably provided on the valve body 7 is connected to an input shaft 32 that is linked to a brake pedal (not shown), and the left end portion of the valve plunger 19 is connected to a recessed portion of the push rod 33. It is made to oppose the right end surface of the reaction disk 34 accommodated in 33a. The left end of the push rod 33 is connected to the master cylinder 3 which is passed through the opening 2b of the shaft of the front shell 2.
It is linked to the piston 35a of No. 5. A seal member 36 maintains airtightness between the opening 2b and the piston 35a. Since a return spring 37 is elastically mounted between the valve body 7 and the shaft portion of the front shell 2, the valve body 7 is normally held at the non-operating position shown in the drawing. In this non-operating state, the valve body 2
2 is seated on the second valve seat 20, but a slight gap is maintained between the first valve seat 18 and the valve body 22. Further, a rubber bellows 17 is arranged in the constant pressure chamber A of the front chamber 5, and the front end of the bellows 17 is pressed against the wall surface of the front shell 2 by a cup-shaped support member 38. On the other hand, the rear end of the bellows 17 is connected to the outer periphery of the valve body 7 by being brought into pressure contact with an annular recess provided at the inner periphery of the front power piston 9. The rear outer peripheral portion of the support member 38 is held by being interposed between the annular wall portion 2a of the front shell 2 and the outer peripheral bead portion 11a of the front diaphragm 11. There is no leakage from the front end. The bellows 17 arranged in the constant pressure chamber A in this way
The interior space A' of the reinforcing plate 39 and the front shell 2
The front shell 2 is communicated with the negative pressure source through through holes drilled in the wall of the front shell 2 and a second negative pressure introduction pipe 40 attached to the wall of the front shell 2 . A solenoid valve 41 is provided between the second negative pressure introduction pipe 40 and the negative pressure source to selectively communicate the negative pressure introduction pipe 40 with the atmosphere and the negative pressure source. This solenoid valve 41 is controlled ON-OFF by a controller (not shown), and in a normal state in which it is not operated as shown in FIG.
is connected to a negative pressure source. Therefore, at that time, negative pressure is introduced into the internal space A' of the bellows 17 via the negative pressure introduction pipe 40. On the other hand, as shown in FIG. 2, the solenoid valve 4 is
1 is activated, the atmosphere is introduced into the internal space A' of the bellows 17 via the second negative pressure introduction pipe 40. Then, the atmosphere introduced into the internal space A' of the bellows 17 is transferred to the first constant pressure passage 23 and both variable pressure passages 26, 2.
It is also introduced into both pressure change chambers B and D via 7. As a result, in this embodiment, by operating the solenoid valve 41 from the non-operating state of the tandem brake booster shown in FIG. A tandem brake booster can be activated. Next, both constant pressure chambers A
. The space consisting of and the front diaphragm 11
A through hole 11 bored at a position adjacent to the outer peripheral bead portion 11a of
b and the through hole 4 in the opposing wall 4a of the center plate 4
It is composed of c. Note that a through hole (not shown) is bored in the wall of the support member 38 facing the wall of the front shell 2, so that the constant pressure chamber A of the front chamber 5 and the rear chamber are connected through the second constant pressure passage 25. Constant pressure chamber C in front chamber 5 is in constant communication with constant pressure chamber C in front chamber 5.
When negative pressure is introduced into the constant pressure chamber C of the rear chamber 6, negative pressure is also introduced into the constant pressure chamber C of the rear chamber 6. However, in this embodiment, the valve body 7 has a first cylindrical member 44 located on the front side in the axial direction and a second cylindrical member 45 located on the rear side in the axial direction.
When the atmosphere is introduced into the internal space A' of the bellows 17, only the first cylindrical member 44 on the front side moves toward the front side (see FIG. 2). ). The outer circumferential portion of the first cylindrical member 44 is slidably passed through the through hole of the center plate 4, and the sealing member 8 maintains the airtightness of that portion. Further, on the outer circumference of the first cylindrical member 44 located in the front chamber 5,
The inner peripheral portions of the front power piston 9 and the front diaphragm 11 are connected to the rear end of the bellows 17. The outer circumference of the first cylindrical member 44 located in the rear chamber 6 is connected to the inner circumference of the rear power piston 10 and the rear diaphragm 12. The first cylindrical member 44 also includes the above-mentioned pressure changing passage 27.
is provided to connect both transformer chambers B and D. Large-diameter bottomed holes 44a and 44b are formed in the front side shaft portion and the rear side shaft portion of the first cylindrical member 44, respectively, and the push rod 33 is housed in the bottomed hole 44a on the front side. On the other hand, the second cylindrical member 45 is inserted into the bottomed hole 44b on the rear side.
The outer periphery of the two is slidably fitted. Further, at the bottom of the front-side bottomed hole 44a in the first cylindrical member 44,
One end of the return spring 37 is brought into contact with the bottom, and an annular projection 44c extending toward the front side is formed on the inner side of the bottom where the return spring 37 comes into contact. Recess 33
A is fitted. Recessed portion 3 of this push rod 33
The reaction disk 34 is housed between the annular projection 3a and the annular projection 44c. A stepped through hole 44d whose diameter increases on the front side is bored on the inner side of the annular projection 44c, and the front side outer peripheral portion of the valve plunger 19 is slidably fitted into the through hole 44d. are doing. Said annular projection 4
An axial through hole 44e is also formed on the outer side of the hole 4c so that the bottomed holes 44a and 44b communicate with each other. The front-side bottomed hole 44a of the first cylindrical member 44 and the through hole 44e constitute the front-side portion of the first constant pressure passage 23. Note that, as shown in FIG. 2, when only the first cylindrical member 44 is advanced toward the front side, the bottomed hole 44 on the front side
a and the through hole 44e, as well as the first cylindrical member 4
The inner space of the bottomed hole 44b on the rear side in 4 also constitutes the first constant pressure passage 23. Next, the second cylindrical member 45 is set to have the same outer diameter throughout the axial direction, and as already mentioned above, the front side outer peripheral part of the second cylindrical member 45 is different from that of the first cylindrical member. It is slidably fitted into the bottomed hole 44b of the member. On the other hand, the rear outer peripheral portion of the second cylindrical member 45 is slidably fitted into the through hole of the rear shell 3.
The seal member 8 maintains airtightness between both members. The valve mechanism 16, the pressure passage 28, and the filter 29 are provided inside the second cylindrical member 45, and the first constant pressure It forms the rear side portion of the passage 23. Further, in this embodiment, as shown in FIG. 2, the valve plunger 19, which is a component of the valve mechanism 16, is composed of a first member 19a on the front side and a second member 19b on the rear side. . That is, the first member 19a on the front side is formed into a columnar shape that is short in the axial direction, and is fitted into the large diameter side of the stepped hole 44d of the first cylindrical member 44. The front end face of the first member 19a faces the reaction disc 34, and the rear end face of the first member 19a faces the non-operating state and the normal operating state of the tandem brake booster shown in FIG. In this state, it is in contact with the tip of the second member 19b. On the other hand, as will be described later, when the tandem brake booster functions as an automatic braking device, the first member 19a is separated from the second member 19b as the first cylindrical member 44 moves forward. It is supposed to be done. Second member 1 forming the rear side of the valve plunger 19
The outer diameter of the front side of 9b is set smaller than the outer diameter of the first member 19a, and in the non-operating state and the normal operating state of the tandem brake booster shown in FIG. The second member 19 passes through the through hole 45a of 45.
The front side outer peripheral part of b is fitted into the small diameter side of the stepped hole 44d of the first cylindrical member 44, and the second member 19b
The front end portion of the first member 19a is in contact with the rear end surface of the first member 19a. The rear end of the second member 19b is connected to the input shaft 32 as in the conventional case, and the second valve seat 2
0 is formed. An annular bottomed hole is provided in the front end surface of the second cylindrical member 45, and compression is applied between the bottom of the bottomed hole and the bottom of the bottomed hole 44b of the first cylindrical member 44 opposite thereto. A spring 46 is provided. This compression spring 46 is completely housed in the bottomed hole of the second cylindrical member 45 when the tandem brake booster shown in FIG. The bottom of the bottomed hole 44b of the shaped member 44 and the front end surface of the second cylindrical member 45 are in contact with each other. The set load of the compression spring 46 is determined when the first cylindrical member 44 moves forward relative to the second cylindrical member 45 as the atmosphere is introduced into the internal space A' of the bellows 17. The load is set such that the second cylindrical member 45 on the rear side is not moved forward due to the differential pressure between the front and rear sides. In other words, bellows 1
Immediately before atmospheric air is introduced into the internal space A' of the bellows 17, negative pressure is introduced into the internal space A' of the bellows 17, so negative pressure acts on the front end surface of the second cylindrical member 45. ,
On the other hand, since atmospheric pressure is acting on the rear end surface of the second cylindrical member 45, the first cylindrical member 44 resists the elastic force of the return spring 37, as shown in FIG. When moved forward, the second cylindrical member 45 is moved forward by the differential pressure between negative pressure and atmospheric pressure, so the compression spring 46 cannot prevent the second cylindrical member 45 from moving forward. The set load is as high as possible. Furthermore, in this embodiment, in order to maintain airtightness between the bottomed hole 44b of the first cylindrical member 44 and the outer circumference of the second cylindrical member 45 fitted into the bottomed hole 44b, A rubber O-ring 47 is attached to the outer periphery of the two-cylindrical member 45. In addition, in order to maintain airtightness between the through hole 45a of the second cylindrical member 45 and the outer circumference of the valve plunger 19 (second member 19b), the second cylindrical member 45
A rubber O-ring 48 is attached to the through hole 45a. (Operation) The tandem brake booster configured as described above normally has a solenoid valve 41 as shown in FIG.
is not activated, negative pressure is introduced into the internal space A' of the bellows 17 via the negative pressure introduction pipe 40. Further, negative pressure is also introduced into the constant pressure chamber A via the other negative pressure introduction pipe 24, so that all the chambers A, B, C,
Negative pressure is introduced into D and A'. Further, the valve body 7, which is biased by the return spring 37, is also located at the non-operating position shown in the figure. The front side end surface of the second cylindrical member 45 is in contact with each other, and the first member 19a and second member 19b that constitute the valve plunger 19 are also in contact with each other. When the brake pedal (not shown) is depressed from this non-operating state, the input shaft 32 is moved forward (to the left), and the fluid circuit is switched by the valve mechanism 16, so that atmospheric air is introduced into both variable pressure chambers B and D. be done. As a result, an output with a predetermined servo ratio can be obtained from the push rod 33, similar to the conventionally known tandem brake booster. When the tandem brake booster is to function as an automatic brake device in contrast to the normal brake operation described above, the solenoid valve 41 may be actuated by the controller from the non-operating state in which the input shaft 32 is not advanced as shown in FIG. (Figure 2
reference). As a result, atmospheric air is introduced into the internal space A' of the bellows 17 instead of negative pressure. Therefore, the atmosphere introduced into the internal space A' of the bellows 17 is
The first constant pressure passage 23 and the variable pressure passage 26 communicating therewith
and is introduced into both variable pressure chambers B and D via the variable pressure passage 27. As a result, both constant pressure chambers A and C and both variable pressure chambers B,
Since a pressure difference occurs between the two power pistons 9 and
Only the first cylindrical member 44 connecting the diaphragm 10 and both diaphragms 11 and 12 is moved forward against the resiliency of the return spring 37, and the push rod 33 moves to a predetermined position even though the brake pedal is not depressed. You can get the output of In this embodiment, when the tandem brake booster functions as an automatic brake device in this way,
The second cylindrical member 45, which is the rear side portion of the valve body 7, remains stopped at the non-operating position.
The input shaft 32 and the brake pedal (not shown) linked thereto are not moved. Therefore, when the tandem brake booster functions as an automatic braking device, the input shaft 32 and the brake pedal move automatically, unlike in conventional devices, the brake pedal moves regardless of the driver's intention. Therefore, the brake feeling of the driver is not impaired. FIG. 3 shows the second embodiment of the present invention.
This second embodiment is one in which the present invention is applied to a single type brake booster. In this second embodiment, the support member 138 is formed of a generally disc-shaped member, and its outer peripheral edge supports the front end of the bellows 117, and the outer peripheral cylindrical portion 13 of the reinforcing plate 139
9a. Then, the support member 138 in this state is brought into pressure contact with the end surface of the reinforcing plate 139 from the rear side by one end of the return spring 137. Further, in this second embodiment, the front shell 1
The tip of the push rod 133 is made to protrude to the outside of the shell 101 through the opening 102b of the push rod 102 so as to be interlocked with a piston of a master cylinder (not shown). The other configurations are the same as those of the first embodiment,
In principle, the parts corresponding to those in the first embodiment have 100%
The part number is given by adding . It is clear that even with the configuration of the second embodiment, the same effects as those of the first embodiment described above can be obtained. moreover,
FIG. 4 shows O-rings 47, 48 (14) shown in both of the above embodiments.
7, 148) in which a diaphragm-shaped sealing member is used instead. That is, the outer circumference on the front side of the second cylindrical member 245 is a small diameter portion, and the small diameter portion and the first cylindrical member 24 facing the small diameter portion
A membrane-like sealing member 247 is provided across the inner circumferential surface of the four bottomed holes 244b. This sealing member 247 allows the outer circumference of the second cylindrical member 245 and the first cylindrical member 244 to
The inner peripheral surface of the bottomed hole 244b is maintained airtight. Further, the front end of the through hole 245a of the second cylindrical member 245 has an enlarged diameter, and the inner peripheral surface of the enlarged diameter part and the outer peripheral part of the valve plunger 219 (second member 219b) extend. A membrane-like sealing member 248 is provided, thereby maintaining airtightness between the through hole 245a of the second cylindrical member 245 and the outer circumference of the valve plunger 219. In the non-operating state of the brake booster shown in FIG.
It is housed in a space formed by 5 and 5. On the other hand, when only the first cylindrical member 244 is moved forward, the sealing member 247 is extended in the axial direction.
While allowing the first cylindrical member 244 to move, it is possible to maintain airtightness between the first cylindrical member 244 and the second cylindrical member 245. Further, like the seal member 247, the inner seal member 248 is also bent into a U-shape in the non-operating state, so that the enlarged diameter portion of the through hole 245a of the second cylindrical member 245 and the valve plunger 219 (219b) It is stored between the valve plunger 219 (219b) and the second valve plunger 219 (219b).
When the cylindrical member 245 is moved relative to the axial direction, the seal member 248 extends in the axial direction and the valve plunger 219 (
219b) and the second cylindrical member 245, while at the same time maintaining airtightness between the two members. In the embodiment shown in FIG. 4, the members corresponding to the members shown in FIG. 1 are given component numbers with 200 added.

[Effects of the Invention] As described above, according to the present invention, when the brake booster functions as an automatic brake device, the input shaft does not move forward, so the driver's brake feeling is not hindered. The effect is that there is no

[Brief explanation of the drawing]

[Fig. 1] Cross-sectional view showing one embodiment of the present invention

[Fig. 2] A sectional view showing the operating state of the embodiment shown in Fig. 1.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a cross-sectional view of essential parts showing another embodiment of the present invention.

[Explanation of symbols]

1 shell
7 Valve body 9 Front power piston
10 Rear power piston 11 Front diaphragm 12 Rear diaphragm 16 Valve mechanism
17 Bellows 19 Valve plunger
23, 25 Constant pressure passage 26, 27 Variable pressure passage 32 Input shaft 44 First
Cylindrical member 45 Second cylindrical member A, C Constant pressure chamber
B, D Transformer chamber A' Internal space of bellows 17

Claims (1)

[Claims] Claim 1: A valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber formed on the front side of the power piston, a variable pressure chamber formed on the rear side of the power piston, and the above-mentioned. A valve mechanism that is provided in the valve body and controls communication between a constant pressure passage that communicates with the constant pressure chamber, a variable pressure passage that communicates with the variable pressure chamber, and a pressure passage that communicates with the pressure fluid source, and a valve plunger that constitutes the valve mechanism has a tip end. and a bellows, which is provided in the constant pressure chamber and has a rear end connected to the constant pressure passage and a front end attached to the wall of the shell, and has an internal space of the bellows. In the brake booster capable of supplying pressure fluids of different pressures to the valve body, the valve body is constituted by a first cylindrical member and a second cylindrical member that are fitted to each other so as to be movable in the axial direction, The first cylindrical member is provided with the power piston and a front side portion of the constant pressure passage, the rear end of the bellows is connected to the constant pressure passage of the first cylindrical member, and the second cylindrical member is further provided with a front side portion of the constant pressure passage. A brake booster characterized in that the rear side portion of the constant pressure passage, the above-mentioned valve mechanism, and the variable pressure passage are provided.