JPH0513663Y2 - - Google Patents

Description

[Detailed Description of the Invention] a. Field of Industrial Application The present invention relates to a master cylinder used in various brake devices and the like.

b. Prior Art As a conventional tandem master cylinder, there is one shown in FIG. 3, for example. This master cylinder 51 has a cylinder body 52 with an open end, and a primary piston 5 inside the cylinder body 52.
3 and a secondary piston 54 are slidably disposed via piston guides 55 and 56, and the opening of the cylinder body 52 is closed with a screwed cap 57. A first pressure chamber 59 is formed inside the cylinder body 52 by the primary piston 53 and the sleeve 58, and a second pressure chamber 60 is formed by the secondary piston 54 and the inner wall surface of the cylinder body 52.
are formed, and spring mechanisms 61 and 62 are formed in the first pressure chamber 59 and the second pressure chamber 60, respectively.
is installed.

A pressure relief groove 6 is provided in the side wall of the sleeve 58.
3 is formed, and the relief groove 63 acts when the brake operation is released. That is, when the brake pedal is suddenly released, the spring mechanism 61 causes the primary piston 53 to rapidly move to the left. At this time, a vacuum is generated in the sleeve 58 and prevents the primary piston 53 from moving to the right. However, when the hydraulic fluid in the reservoir 64 flows into the sleeve 58 through the relief groove 63, the vacuum is released. At the same time, the primary piston 53 can move smoothly to the right. Note that the piston guides 55 and 56 and the sleeve 58 are fixedly arranged by annular seal members 65 and 66.

In such a master cylinder 51, when the primary piston 53 and the secondary piston 54 are pushed into the first pressure chamber 59 and the second pressure chamber 60, respectively, the working fluid in the pressure chambers 59, 60 is discharged to the outlet ports 67, 68. It is constructed so that it is fed under pressure to a brake system (not shown).

c. Problems to be solved by the invention As mentioned above, in the conventional master cylinder 51, the opening of the cylinder body 52 is closed using the screw-type cap 57 to prevent the internal components from slipping out. Therefore, during new assembly or periodic inspection (rubber and seals of the master cylinder are required to be replaced during vehicle inspection), tighten the cap 57 with a normal tool such as a box wrench and screw it onto the cylinder body 52. Therefore, there is a risk that the cap 57 may be screwed in with more torque than necessary, especially during periodic inspections in which the cap 57 is tightened with a torque other than the specified torque.

When the cap 57 is screwed in with a torque higher than the set value, since the piston guides 55, 56 and the sleeve 58 are made of resin, not only the part A, which serves as a stopper, but also the parts B and C are pressed by the cap 57, and the fourth It is deformed as shown in FIGS. That is, in the A section, the left side of the piston guide 56 is deformed, and in the B section, the piston guide 56 is deformed.
6 and the sleeve 58 are pressed against each other and deformed, and furthermore, the relief groove 63 of the sleeve 58 is deformed at the C portion. As the piston guides 55, 56 and sleeve 58 deform, the axial lengths of these components become shorter, the loss stroke (meaning play in the master cylinder) increases, and the primary piston 53 and secondary piston 54 Since the cylinder moves to the left position, there is a drawback that the function and feeling of the master cylinder 51 are deteriorated.

Furthermore, since the sealing member 65 also deforms in the B section, the sliding resistance to the secondary piston 54 increases and the sealing performance deteriorates, which may impede the function of the master cylinder 51. In addition, the relief groove 63 in the C section
The narrow space makes it difficult to bleed air, making it impossible to release the vacuum, resulting in a lack of product reliability.

The present invention has been made in view of these circumstances, and its purpose is to provide a master cylinder that can eliminate the above-mentioned drawbacks.

d Means for solving the problem In order to solve the problem of the above-mentioned conventional technology,
In the present invention, in a master cylinder in which a cap is screwed onto the open end of the cylinder body and the cap closes the opening of the cylinder body, a part of the screw tightening portion of the cylinder body and the cap is connected. Each cylinder is provided with a stepped portion, and when the cap is excessively tightened, the stepped portions are engaged with each other to prevent the cap from moving toward the cylinder body.

e Effect In the master cylinder according to the present invention, when the cap is excessively tightened with a normal tool, the stepped portions provided on the cylinder body and the screw tightening part of the cap engage with each other, so that the cap is directed toward the cylinder body. The cap no longer destroys the components within the cylinder body, which could not previously be moved.

f. Embodiments Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

1 and 2 show an embodiment of the present invention. In the figures, 1 is a tandem master cylinder, and this master cylinder 1 is interlocked with a brake pedal via a brake actuator (not shown). When the pedal is pressed, the force is converted into hydraulic pressure and sent to each wheel cylinder. The master cylinder 1 has a cylinder body 2 with one end open, and an opening 3 is closed by a cap 4 screwed onto the cylinder body 2. First and second replenishment ports 5 and 6 are formed on the outer surface of the cylinder body 2, and a reservoir 7 is attached at a location corresponding to these replenishment ports 5 and 6. The bottom of the reservoir 7 has through holes 8 and 9.
are drilled, and the through holes 8 and 9 serve as supply ports 5 and 9, respectively.
It is connected to 6.

Ring-shaped piston guides 10, 11 and a sleeve 12 are arranged inside the cylinder body 2 and cap 4, and a primary piston 13 and a secondary piston 14 are inserted into these piston guides 10, 11 and sleeve 12, respectively. has been done. Both pistons 13 and 14 are disposed to be slidable in the axial direction and are guided and supported by piston guides 10 and 11 and sleeve 12. Further, the primary piston 13 and the secondary piston 14 have a recess opening at the tip, and small holes 15 and 16 are formed in the peripheral wall forming the recess, respectively. The piston guides 10 and 11 are provided with vertical holes 17 and 18 in the radial direction, and one end of these vertical holes 17 and 18 is connected to the pistons 13 and 14.
The other end is communicated with a replenishment liquid passage 19 or a second replenishment port 6 formed between the inner wall surface of the cap 4 and the outer periphery of the sleeve 12.

Furthermore, inside the cylinder body 2, a first pressure chamber 20 is formed by the primary piston 13 and the inner wall surface of the sleeve 12, and a second pressure chamber 20 is formed by the secondary piston 14 and the inner wall surface of the cylinder body 2. A chamber 21 is formed, and a first pressure chamber 20
Spring mechanisms 22 and 23 are disposed in the second pressure chamber 21, respectively, for returning the primary piston 13 and the secondary piston 14 to their original positions. Therefore, the first pressure chamber 20
In the non-operating state of the master cylinder 1 shown in the figure, the small hole of the primary piston 13, the vertical hole 17 of the piston guide 10, the replenishment fluid passage 19, and the first
It communicates with a reservoir 7 via a supply port 5. Further, in the same state, the second pressure chamber 21 is connected to the small hole 16 of the secondary piston 14 and the piston guide 11.
It communicates with the reservoir 7 through the vertical hole 18 and the second supply port 6 . In addition, the piston guide 10,
11 and the sleeve 12 are positioned and fixed by annular seal members 24 and 25 provided on both sides.

The cap 4 has a substantially U-shaped cross section with an engaging portion 26 having a polygonal outer peripheral surface and a tightening portion 27 having a large diameter, and allows a tightening tool such as a box wrench to be engaged with the engaging portion 26. It is screwed into the opening 3 of the cylinder body 2 by tightening with the screws. Therefore, the components inside the cylinder body 2 are prevented from coming out of the master cylinder 1 by the cap 4. For this reason, the tightening portion 27 of the cap 4 is formed with a male threaded portion 28, and the tightening portion 29 provided on the inner circumferential wall of the cylinder body 2 is screwed into the male threaded portion 28 of the cap 4. A female threaded portion 30 is formed. Further, as shown in FIG. 2, stepped portions 31 and 32 are formed in a portion of the tightening portion 27 of the cap 4 and the tightening portion 29 of the cylinder body 2 at corresponding positions, respectively. , 32 are adapted to engage with each other when the cap 4 is excessively tightened. On the other hand, an insertion hole 33 through which the primary piston 13 is inserted is bored in the center of the cap 4.

In FIG. 1, reference numeral 34 is a pressure relief groove formed in the side wall of the sleeve 12 located on the piston guide 10 side, and one end of this relief groove 34 opens toward the sealing member 25 side, and the other end opens to the replenishment liquid. Passage 1
It is connected to 9. The relief groove 34 is formed in a tapered shape in which the opening area is smaller on the inside of the sleeve 12 and larger on the outside.As a result, when the brake is activated, the hydraulic pressure inside the sleeve 12 increases, and the sealing member 25 closes the sleeve 12. The corners of the seal member 25 do not bite into the escape groove 34 even when pressed against the end of the seal member 25 and the left side wall of the piston guide 10. Further, reference numerals 35 and 36 are outlet ports provided on the inner wall surface of the cylinder body 2, and the first and second pressure chambers 20, 21 are connected to a brake system (not shown) through these outlet ports 35, 36 (for example, wheel cylinder).

In the master cylinder 1 having the above configuration, when pressure is applied to the primary piston 13 by stepping on the brake pedal, the primary piston 13 and the secondary piston 1 are
4 is pushed to the left in FIG.
5 and 16 is blocked by a sealing member 25. When this liquid passage is blocked, the first
The hydraulic fluid in the second pressure chambers 20, 21 is forced to be sent to the brake system from the delivery ports 35, 36. Moreover, when the brake pedal is released and released, the primary piston 13 and the secondary piston 14
is moved to the right by the biasing force of the spring mechanisms 22 and 23, and returns to the original position shown in FIG.
Along with this, the small holes 1 of both pistons 13 and 14
5, 16 and the vertical hole 1 of the piston guide 10, 11
7 and 18 are in communication with each other, and the hydraulic fluid is supplied from the reservoir 7 to the through holes 8 and 9, the replenishment ports 5 and 6, and the replenishment fluid passage 19.
, and is replenished into the first pressure chamber 20 and the second pressure chamber 21 through the vertical holes 17 and 18 and the small holes 15 and 16.

According to the master cylinder 1 configured in this way, when the cap 4 is screwed into the opening 3 of the cylinder body 2 using a normal tightening tool, it is possible to overtighten the cap 4 with more torque than necessary. Even if the threaded portion 28 is screwed into the female threaded portion 30 of the cylinder body 2, the stepped portion 31 provided on the tightening portion 27 of the cap 4
is a stepped portion 32 provided in the tightening portion 29 of the cylinder body 2.
Since the caps 4 contact and engage with each other, the movement of the cap 4 is prevented and it stops at the engagement position, and the cap 4 is directed inward (to the left in the figure) of the cylinder body 2 and cannot be screwed in any further. It becomes impossible.

Although one embodiment of the present invention has been described above, the present invention is not limited to the embodiment described above. By forming a female thread on the inner peripheral surface of the cap 4, the cap 4 is attached to the cylinder body 2.
Needless to say, the present invention can be applied to a master cylinder screwed onto a master cylinder.

g. Effects of the invention As mentioned above, the master cylinder according to the invention has the following effects:
Steps are provided on the cylinder body and a part of the screw tightening part of the cap, and when the cap is over-tightened, the steps are engaged with each other to prevent the cap from moving toward the cylinder body. Especially in market service, the cap can be easily and securely attached to the cylinder body using ordinary tools without using special tightening tools that can be tightened with a certain torque, which improves the efficiency of assembly work. , can reduce work costs.
In addition, with the master cylinder of the present invention, even if the cap is tightened excessively, the components inside the cylinder body will not be destroyed by the screwed-in cap, so the efficiency and feeling of the master cylinder will be reduced. This does not occur, and the product is highly reliable.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, in which FIG. 1 is a sectional view of the master cylinder, and FIG. 2 is a partially enlarged sectional view of the cap 4 screwed onto the cylinder body. 3 to 6 show conventional examples, in which FIG. 3 is a sectional view of the master cylinder, FIG. 4 is an enlarged sectional view of section A in FIG. 3 in a deformed state, and FIG. 5 6 is an enlarged sectional view of section B in FIG. 3 in a deformed state, and FIG. 6 is an enlarged sectional view of section C in FIG. 3 in a deformed state. 1... Master cylinder, 2... Cylinder body,
3...Opening part, 4...Cap, 27...Cap tightening part, 28...Male thread part, 29...Cylinder body tightening part, 30...Female thread part, 31...Cap step Part, 32...Step part of the cylinder body.

Claims (1)

[Scope of utility model registration request] In a master cylinder in which a cap 4 is screwed onto the open end of the cylinder body 2 and the cap closes the opening of the cylinder body, a stepped portion is formed on a portion of the screw tightening portion of the cylinder body and the cap, respectively. 31 and 32, and when the cap is excessively tightened, the stepped portions engage with each other to prevent the cap from moving toward the cylinder body.