JPS6246610Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a tandem brake booster, which includes a valve body with a built-in valve mechanism that controls the opening and closing of a pressure fluid flow path according to the forward and backward movement of an input shaft, and a valve body incorporating the valve mechanism. The key member that prevents the valve plunger from coming out of the valve body does not come into constant contact with the valve plunger, thereby reducing the size and weight of the valve body.

As a conventional tandem type brake booster, a valve body housing the above-mentioned valve mechanism and a hub into which the end portion of the push rod is fitted are constructed separately,
A distal end of the hub is fitted into the valve body, and a valve plunger of the valve mechanism is slidably fitted into the distal end of the hub, and a key member is inserted through the valve body and the hub to lock the hub. It is known that the valve plunger is engaged with the valve plunger and the key member prevents the valve plunger from coming out of the hub.

By the way, cracks generally occur when the wall thickness of the synthetic resin valve body is made thinner in order to reduce the size and weight of brake boosters. As a result of detailed analysis, one of the reasons for this is that if a pedal force greater than the pedal force required for the brake booster to reach full load is applied to the input shaft, the pedal force applied from the input shaft to the valve plunger will be applied to the key member. It was discovered that this was transmitted to the valve body through the valve body, causing the crack.

The present invention was made based on this knowledge, and the hub is connected to the valve body at a position rearward of the key member so as not to be pulled out forward from the valve body, and the hub is connected between the valve body and the push rod side end surface of the key member. A gap is formed so that the valve body and the push rod side end surface of the key member do not come into contact with each other at all times, and when the input shaft is further advanced under the full load state of the brake booster, the forward force is transferred to the valve plunger, The information is transmitted to the valve body via the key member and the hub.

According to such a configuration, the forward force is not transmitted directly from the key member to the valve body, but is transmitted to the valve body at a position rearward of the key member via the hub. Therefore, even if the wall thickness of the valve body on the front side of the key member becomes thinner due to the thinning of the valve body, the forward force transmission section is located rearward of the key member, so the valve body can be made sufficiently large. The wall thickness can be ensured, thereby effectively preventing the occurrence of cracks in the valve body.

The present invention will be explained below with reference to the illustrated embodiments.
In Figure 1, 1 is a front shell, 2 is a rear shell, and inside the sealed container composed of both shells 1 and 2 is a center plate 3, a front diaphragm 4
and four chambers A by the rear diaphragm 5,
It is divided into B, C, and D. The above-mentioned front shell 1 has a cup-like shape as a whole, and has a stepped portion 1a formed in the middle of the cylindrical portion, a medium diameter cylindrical portion 1b on the opening side, and a small diameter cylindrical portion 1c on the opposite side. An engaging stepped portion 1d is formed at the open end of the diameter cylindrical portion 1b, and the opening portion serves as a large diameter cylindrical portion 1e.

The center plate 3 has a cup shape with a depth approximately half that of the front shell 1, and its cylindrical portion 3
A is fitted into the medium-diameter cylindrical portion 1b of the front shell 1, and a flange portion 3b bent radially outward is formed at the open end of the cylindrical portion 3a, and this is brought into contact with the engagement step portion 1d. Positioning is performed by bringing them into contact. An annular engagement groove 3d that opens approximately radially outward is formed in the bent portion of the cylindrical portion 3a of the center plate 3 and the end wall portion 3c connected thereto. The outer circumferential bead portion 4a of the front diaphragm 4 is held between the inner surface of the cylindrical portion 3d and the inner surface of the small diameter cylindrical portion 1c of the front shell 1 to maintain airtightness of that portion.

Further, an annular engagement groove 2a corresponding to the annular engagement groove 3d is formed on the outer circumference of the substantially dish-shaped rear shell 2, and an outer circumferential end continuous with the annular engagement groove 2a is extended radially outward. The flange portion 2b is directed toward the flange portion 2b. The outer circumferential bead portion 5a of the rear diaphragm 5 is held between the inner surface of the annular engagement groove 2a and the inner surface of the cylindrical portion 3a of the center plate 3 to keep that portion airtight, and the flange portion 2b of the rear shell 2 is The outer surface of the flange portion 2b of the rear shell 2 is supported by a plurality of engaging pawls 1f formed on the large diameter cylindrical portion 1e of the front shell 1 in a state in which the rear shell 2 is overlapped on the flange portion 3b of the center plate 3. This is to prevent it from slipping out.

However, 6 is a synthetic resin valve body housing a conventionally well-known valve mechanism 7 inside, and the cylindrical portion 6
a is slidably protruded outward from an opening 2c formed in the shaft portion of the rear shell 2 via a seal member 8, and a dust cover 9 is attached between the protruding end and the opening 2c. A small diameter portion 10a at the right end of a reaction disk hub 10 made of metal is slidably fitted into the shaft portion of the valve body 6, and a stopper 11 attached to the end of the small diameter portion 10a is brought into contact with the stepped portion of the valve body 6. This prevents the reaction disk hub 10 from slipping out to the left. The inner peripheries of the rear diaphragm 5 and the rear power piston 13 are inserted between the right end surface of the synthetic resin center body 12 slidably fitted around the outer periphery of the hub 10 and the left end surface of the valve body 6. The front diaphragm 4 and the front power piston 1 are sandwiched between the left end surface of the center body 12 and the nut 14 screwed onto the hub 10.
5, and in this state, tighten the nuts 14.
By tightening, the valve body 6, rear diaphragm 5, rear power piston 13, center body 12, front diaphragm 4, and front power piston 15 are integrally fastened between the stopper 11 and the nut 14.
The center body 12 slidably passes through the shaft portion of the center plate 3 while maintaining airtightness with a seal member 16 attached thereto.

By the way, in this embodiment, a notch 10b is formed at the tip of the hub 10, that is, the threaded part of the nut 14, and the front power piston 15 is inserted into this notch.
When the nut 14 is tightened, the front power piston 15 is prevented from rotating along with the nut 14 by engaging the engaging portion 15a formed on the inner circumference of the front power piston 15. This prevents the front diaphragm 4 from being assembled in a twisted state due to the rotation of the front diaphragm 4. FIG. 2 is a cross-sectional view taken along the line - in FIG.
On the other hand, the engaging portion 15 of the front power piston 15
A is a hole 15b which connects both notches 10b and has a hole 15b in the center thereof through which the rod part 17a of the push rod 17 is loosely fitted. As shown in FIG.
The rod portion 17a is brought into contact with the end surface of the reaction disk 18 housed in the rod portion 0c, and the tip of the rod portion 17a is slidably projected to the outside from the shaft portion of the front shell 1 via the seal member 19.

In such a configuration, the hub 10 and the front power piston 15 have their cutouts 10b.
The front power piston 15 does not rotate with the rotation of the nut 14 when the nut 14 is tightened because the front power piston 15 is integrally connected in the rotational direction by engagement with the engaging portion 15a. Therefore, the front diaphragm 4 disposed on the back side of the front diaphragm 4 is not twisted as the front diaphragm 4 rotates, and a decrease in durability caused by being assembled in a twisted state can be prevented. In addition, the above-mentioned engaging part 1
5a has the rod portion 17a of the push rod 17 passed through the hole 15b, so that the large diameter portion 17b of the push rod 17 is connected to the large diameter portion 10 of the hub 10.
It is also possible to prevent the situation from escaping from c.

Further, in this embodiment, the stopper 11 is fitted onto the outer circumferential end of the reaction disk hub 10 and rotated 90 degrees to be attached to the hub 10. That is, Figures 3 and 4
As shown in the figure, a pair of notches 10d are formed by cutting out the upper and lower positions of the distal end of the hub 10, and a pair of engaging parts 10e are formed between both notches 10d. An engagement groove 10f with which the stopper 11 engages is formed on the outer periphery. On the other hand, the stopper 11 is ring-shaped as a whole, and has an inner circumferential portion that passes through the pair of engaging portions 10e of the hub 10 when the distal end of the hub 10 is inserted therein. A pair of notches 1
1a, and an engaging portion 11b that is positioned within the engaging groove 10f of the engaging portion 10e when the stopper 11 is rotated 90 degrees from that state.

In order to maintain the engagement state between the engagement groove 10f and the engagement portion 11b, a notch 11c is formed on the outer periphery of the stopper 11, and the notch 11c is expanded into the shaft hole of the valve body 6 along its axial direction. The protruded bulge 6
b, thereby preventing the stopper 11 from rotating relative to the valve body 6, and the hub 10 is inserted through the valve body 6 and the hub 10 in the radial direction thereof, as shown in FIG. Valve body 6 is controlled by key member 20.
This prevents it from rotating against the This key member 20 is connected to the hub 10 in the same way as a conventionally known key member.
The valve plunger 21 is provided to prevent the valve plunger 21 that is slidably fitted into the small diameter portion 10a of the valve mechanism 7 from falling out.
is connected at its end to an input shaft 22 that is linked to a brake pedal (not shown), and its tip is opposed to the end surface of the reaction disk 18.

Next, the aforementioned chamber A was communicated with an intake manifold (not shown) via the negative pressure introduction pipe 23 attached to the front shell 1, and this chamber A was bored in the large diameter portion 10c of the reaction disk hub 10. It is constantly communicated with the chamber C via the through hole 24, a first passage 25 formed in the center body 12, and a lateral hole 26 communicating with the passage 25. Furthermore, when the brake booster is not in operation, these chambers A and C are connected to a hole 27 formed in the rear power piston 13, a passage 28 formed in the valve body 6, and a gap between the valve body and the valve seat of the valve mechanism 7. and communicates with the chamber D via a radial passage 29 formed in the valve body 6, and a passage 3 formed in the valve body 6.
It also communicates with the chamber B via a second passage 31 formed in the center body 12 and the center body 12 . In this state, negative pressure is introduced into each of the chambers A, B, C, and D, making them equal pressures, and there is no pressure difference between the front and back of each diaphragm 4, 5, so that the pressure is reduced by the return spring 32. and is held in the non-operating position shown.

As understood from the above-mentioned structure of passage relations,
In this embodiment, the first
Since it is necessary to connect the passage 25 and the second passage 31 to the passage 28 and the passage 30 of the valve body 6 while maintaining airtightness separately, a sealing member is required to maintain airtightness between these passages, but in this embodiment, In order to simplify the configuration of this part and facilitate assembly, a part of the rear diaphragm 5 can be used as the sealing member. 5 is a front view showing the left end surface of the valve body 6, and FIG. 6 is a front view showing the inner peripheral part of the rear diaphragm 5 superimposed on the left end surface. A large-diameter annular groove 6c that collectively surrounds the outer periphery of the pair of passages 30 that communicate with the first passage 25 and the pair of second passages 31, and continuous with this annular groove 6c, Each of the above pair of passages 30
A small-diameter annular groove 6d is formed that surrounds only the groove.

Further, a passage 30 formed in the valve body 6
Enlarge the opening on the left end side of the engaging recess 6e.
At the same time, as shown in FIG.
The valve body 6 and the center body 12 can be positioned in the rotational direction by forming a protrusion and coupling them together. Note that the passage 28 on the side of the valve body 6 is provided at only one place because it is necessary to form a hole through which the key member 20 is passed in an axially symmetrical position, but the first passage 25 of the center body 12 that communicates with this passage is 2 in axially symmetrical position
This prevents any problem from occurring even if the center body 12 is deviated by 180 degrees in rotational direction when the valve body 6 and center body 12 are assembled.

On the other hand, as shown in FIG. 6, the inner peripheral bead portion of the rear diaphragm 5 has seal portions 5b, 5c that coincide with the annular grooves 6c, 6d, and therefore engages with the small diameter annular groove 6d. Sealing portion 5c that fits
has the protrusion 1 of the center body 12 inside it.
It has an engagement hole 5d into which the screw 2a is inserted. Further, as shown in FIG. 1, the inner circumference of the rear power piston 13 extends to the outer circumference of an annular protrusion 6f formed on the shaft portion of the left end surface of the valve body 6, through which the protrusion 12a of the center body 12 is inserted. It has a pair of holes and the hole 27 described above. A pair of holes 27 are also provided at axially symmetrical positions.

In such a configuration, the connecting portion between the passage 30 and the second passage 31 is sealed by the seal portion 5c of the rear diaphragm 5, and the connecting portion between the first passage 25 and the passage 27 is sealed by the rear diaphragm 5. The seal members 34 provided on the seal portions 5b and 5c of the hub 10 and the small diameter portion 10a of the hub 10 provide a seal.

However, in the present invention, the key member 20
A required gap δ is always formed between the end face of the push rod 17 and the valve body 6, and a retaining ring 33 prevents the key member 20 from slipping out from the valve body 6. 7 and 8 show the key member 20 and the retaining ring 33. The key member 20 is a fork that is inserted through the valve body 6 and the hub 10 and engages with the reduced diameter portion of the valve plunger 21. The valve body 6 includes a shaped engaging portion 20a, a bent portion 20b bent from the engaging portion 20a into a crank shape, and an arcuate portion 20c extending along the circumferential direction of the valve body 6 from both sides of the bent portion. . On the other hand, the retaining ring 33 includes a C-shaped main body 33a molded from spring steel and a retaining portion 33b at the tip of the main body.
and an engaging portion 33c extending from the main body portion 33a in the axial direction of the valve body 6.
As shown in Fig. 8, this retaining ring 3
3 is fitted onto the outer periphery of the valve body 6, and is connected to the arc portion 20 of the valve body 6 and the key member 20.
c, and prevents the key member 20 from falling off from the valve body 6 by the stopper portion 33b. Also, at this time, the engaging portion 33
c engages in an engagement groove (not shown) formed on the end surface of the valve body 6, thereby preventing the retaining ring 33 from rotating relative to the valve body 6.

In the above configuration, when the valve mechanism 7 is operated via the input shaft 22, atmospheric pressure is introduced into the chambers B and D, similar to the operation of a conventionally known tandem brake booster, and the valve body 6 and center body 1
The second class is moved forward and transmits thrust to the push rod 17. In the intermediate load range of the brake booster, the valve plunger 12 is located at a flow path switching position where the chambers B and D are communicated with the atmosphere or with the chamber A.
The depression force applied to the brake pedal 1 is not continuously transmitted to the key member 20.

On the other hand, when the brake booster is fully loaded, the valve plunger 21 is stopped from advancing by the key member 20, and the valve plunger 21
The pedal force applied to the key member 20 is continuously transmitted to the key member 20. In this case, conventionally, the key member 20 was supported by the valve body 6 made of synthetic resin, so that if the valve body 6 was made thinner, a clutch would occur.

However, in the present invention, the stopper 11 is located at a position rearward of the key member 20.
The hub 10 is connected to the valve body 6 so that it does not come out forward, and a gap δ is formed between the valve body 6 and the key member 20 so that the valve body 6 and the key member 20 do not come into contact with each other at all times. Therefore, the forward force due to the pedal force is transmitted from the valve plunger 21 to the valve body 6 via the key member 20, the hub 10, and the stopper 11.

Therefore, in the present invention, the wall thickness of the valve body 6 on the front side of the stopper 11, which is the transmitting portion of the forward force, is made sufficiently large compared to the wall thickness of the valve body 6 on the front side of the key member 20. As a result, even if the valve body is made thinner and lighter, the occurrence of cracks can be effectively prevented.

As described above, according to the present invention, it is possible to expect the effect that cracks will not occur even if the valve body is made smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, in which a key member 2
2, 3, 5, and 6, except for the 0 part, Figure 2 is a sectional view taken along the - line in Figure 1, and Figure 3 is a sectional view along the 4 is a perspective view showing the right end of the reaction disk 10, and FIG. 5 shows the left end surface of the valve body 6 in FIG. 1. The front view shown in Figure 6 is the valve body 6.
7 is a front view showing the engagement relationship between the key member 20 and the retaining ring 33, and FIG. 8 is a front view taken along the line - in FIG. 7. FIG. 6... Valve body, 7... Valve mechanism, 10...
Hub, 11... Stopper, 13... Rear power piston, 15... Front power piston, 17
...Push rod, 20...Key member, 21...
...Valve plunger, 22...Input shaft, δ...Gap.

Claims (1)

[Scope of Claim for Utility Model Registration] A valve body with a built-in valve mechanism that controls the opening and closing of a pressure fluid flow path according to the forward and backward movement of an input shaft;
a hub disposed on the distal end surface of the valve body and having its base fitted within the valve body; a valve plunger of the valve mechanism that is slidably fitted within the hub and interlocks with the input shaft; A key member that is inserted through the valve body and hub and engages with the valve plunger, a push rod whose end is fitted into the hub, and a front that operates in response to fluid pressure from the valve mechanism and transmits thrust to the push rod. In a tandem brake booster comprising a power piston and a rear power piston, the hub is connected to the valve body at a position rearward of the key member so as not to be pulled out forward from the valve body, and the push rod side end surface of the valve body and the key member is connected. A gap is formed between the valve body and the push rod side end surface of the key member to prevent them from coming into contact with each other, and when the input shaft is further advanced with the brake booster fully loaded, its forward force is A tandem type brake booster characterized in that transmission is transmitted to a valve body via the valve plunger, key member, and hub.