JPH0349087Y2 - - Google Patents

Description

[Detailed description of the invention] (1) Industrial application field The present invention provides a front part that is inserted into a cylinder hole of the cylinder body and defines a front hydraulic chamber between the front end wall and the cylinder body. a rear plunger inserted into the cylinder hole to define a rear hydraulic chamber between the plunger and the front plunger;
The present invention relates to a tandem type master cylinder including a front return spring that biases a front plunger in a backward direction and a rear return spring that biases a rear plunger in a backward direction.

(2) Conventional technology Generally speaking, tandem type master cylinders have
In order to regulate the distance between the front and rear plungers at the retraction limit of the rear plunger, a bolt with a head is screwed into one of the opposite ends of the plungers so as to protrude a certain length in the axial direction. A rear return spring is compressed between the spring retaining cylinder, which is penetrated by the spring holding cylinder and whose forward movement is restricted by the head, and the plunger, to which a bolt is screwed (for example,
58-16952).

(3) Problems to be solved by the invention However, in the conventional type, the front return spring was compressed between the front end wall of the cylinder hole and the front plunger. When the stopper means that restricts the retraction limit of the plunger is removed, the front return spring extends all at once to a free state, and its spring force causes the rear plunger, etc. to fall out of the cylinder hole, damaging its sliding surface and sealing member. There is a fear.

This invention was made in view of these points,
Even if the stopper means of the rear plunger is removed, the extension of the front return spring is restricted and the rear plunger is prevented from falling off due to the force of the spring, and each corresponding plunger can be moved without damaging the sliding surface of each plunger in any way. Another object of the present invention is to provide the tandem-type master cylinder, which allows small-scale assembly of the return spring and has good assemblability.

B. Structure of the invention (1) Means for solving the problems And in order to achieve this purpose, the present invention has the following features:
In the tandem master cylinder of the above type,
A front bolt with a head is screwed into the front end of the front plunger so as to protrude a certain length in the axial direction, and a front bolt with a head is screwed onto the rear end surface of the front plunger when the front bolt is screwed. A front tool engagement hole is provided in which a tool for preventing rotation of the front plunger is inserted, and the front tool engagement hole is penetrated by the shaft of the front bolt and its forward movement is restricted by the head thereof. A front return spring is compressed between the spring holding cylinder and the front plunger, and a rear bolt with a head is screwed into the front end of the rear plunger so as to protrude a certain length in the axial direction.
A rear tool engagement hole is formed in the rear end surface of the rear plunger, into which a tool is inserted to prevent rotation of the rear plunger when the rear bolt is screwed, and a rear tool engagement hole is formed in the rear end surface of the rear plunger. A rear return spring is compressed between the rear plunger and the rear spring holding cylinder which is penetrated and whose forward movement is restricted by its head, and a push rod capable of pushing the rear plunger is inserted into the rear tool engagement hole. It is characterized by what it did.

(2) Effect When each plunger is separated from the cylinder body, when screwing the bolts supporting each spring retaining cylinder into the front end of the corresponding plunger, insert a tool into the tool engagement hole at the rear end of the plunger. By fitting and preventing rotation, the bolt can be easily screwed in without damaging the sliding surface of the plunger.

Since the front plunger, front return spring, and front spring holding tube, as well as the rear plunger, rear return spring, and rear spring holding tube are each assembled using bolts, the assembly work can be carried out efficiently. Moreover, there is no risk that the return spring will be tilted during insertion into the cylinder body and the sealing member on the cylinder body side will be damaged.

In addition, even if the stopper means that restricts the backward limit of the rear plunger is removed for maintenance etc., the extension stroke of the front return spring is also restricted by the bolt via the corresponding spring retaining cylinder, just like the rear return spring. Therefore, it is possible to prevent the rear plunger and the like from falling off into the cylinder body due to the spring force.

Furthermore, the rear tool engagement hole opened in the rear end surface of the rear plunger is also used as an insertion hole for the push rod after the plunger is set into the cylinder body.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 1, M is a tandem type master cylinder for a two-system hydraulic brake of an automobile, and its cylinder body 1 has its rear end fixed to the front surface of a booster shell 2 of a negative pressure booster B supported by a vehicle body (not shown). be done.

An auxiliary oil reservoir 3 is integrally provided on the upper side of the cylinder body 1, and a main oil reservoir 4 is connected thereto. The main oil reservoir 4 has a cap 5 at its upper end, and is equipped with a known oil level sensor 6 supported by the cap 5 inside.

The inside of the auxiliary oil reservoir 3 is divided into first and second oil reservoirs 8 ₁ and 8 ₂ by the partition wall 7, and these oil reservoirs 8 ₁ and 8 ₂
are each supplied with hydraulic oil from the main oil reservoir 4.

The first and second oil reservoirs 8 ₁ and 8 ₂ each have a through hole 9
₁ , 9 ₂ to the cylinder hole 10 of the cylinder body 1
will be communicated with. The cylinder hole 10 includes a first hole 10a with a closed front end, a second hole 10b having a larger diameter than the first hole 10a and continuous to the rear end, a third hole 10c having a larger diameter than the second hole 10b and continuous to the rear end, and a fourth hole 10d which has a larger diameter than the third hole 10c, is connected to the rear end, and has an open rear end.

In FIGS. 1 and 5, a front partition collar 12 ₁ is provided at the step between the second hole 10b and the third hole 10c.
The sleeve 13 that abuts the rear surface of this collar 12 ₁ is fitted over the third hole 10c and the fourth hole 10d, and the rear bulkhead collar 12 ₂ that abuts the rear end of this sleeve 13 and this collar 12 ₂ The bearing 14 that contacts the rear surface is fitted into the fourth hole 10d, and an annular retaining screw 15 that presses the rear surface of the bearing 14 is screwed from the rear end of the fourth hole 10d.

The sleeve 13 defines, by its outer peripheral surface, a front annular oil chamber 11 ₁ connected to the front through hole 9 ₁ as a third hole 10c, and a rear annular oil chamber 11 ₂ connected to the through hole 9 ₂ as a third hole 10c. It is defined in four holes 10d.

The sleeve 13 has a pair of front and rear plungers 16 ₁ ,
16 ₂ is slid, and a front hydraulic chamber 17 ₁ is defined between the front plunger 16 ₁ and the front end wall of the first hole 10a,
Rear hydraulic chamber 17 ₂ between both plungers 16 ₁ and 16 ₂
is defined. These hydraulic chambers 17 ₁ , 17 ₂ are located at the front and rear output ports 18 ₁ , 18 ₂ of the cylinder body 1 .
It is communicated with each of the two brake hydraulic circuits via.

A front bolt 32 ₁ is attached to the front end of the front plunger 16 ₁ as _described later.
A front tool engagement hole 40 ₁ having a transverse regular hexagonal shape is recessed into which a tool (not shown) is inserted to prevent rotation of the plunger 32 ₁ when screwing the plunger 32 1 .
Further, a similar rear tool engagement hole 40 ₂ is provided in the rear end surface of the rear plunger 16 ₂ (third,
(See Figure 4). Therefore, when each plunger 16 ₁ , 16 ₂ is separated from the cylinder body 1 , the tip of a tool (not shown), which has a regular hexagonal cross section, can be simply inserted into each tool engagement hole 40 ₁ , 40 ₂ . , rotation of the cylinder body 1 can be prevented without difficulty.

The rear end of the rear plunger 16 ₂ passes through the rear bulkhead collar 12 ₂ and the bearing 14 and connects to the cylinder body 1.
It extends rearward of the booster shell 2, further penetrates the front wall of the booster shell 2, and receives the tip of the output rod 19 of the negative pressure booster B in the tool engagement hole ₄₀₂ of the front machine part.

In order to prevent negative pressure inside the booster shell ₂ from leaking from the through hole 20 of the booster shell 2 through which the rear plunger 16 2 passes, a sealing member 21 whose lip is brought into close contact with the outer peripheral surface of the rear plunger 16 ₂ is installed in the cylinder body 1 . and the booster shell 2.

In order to communicate between the rear hydraulic chamber 17 ₂ and the rear output port 18 ₂ , the sleeve 13 is provided with an axial groove 23 running on its inner circumference, a lateral hole 24 , and an annular groove 25 running on its outer circumference.

A stopper ring 28 having one cut 27 is attached to the outer peripheral groove 26 of the rear plunger ₁₆₂ (see FIG. 2). This stopper ring 28 includes one or more protrusions 28a that protrude outward from the outer peripheral surface of the rear plunger ₁₆₂ .
is engaged with the axial groove 23 of the sleeve 13. The rear end of the axial groove 23 is closed by a stopper wall 29 that is integral with the sleeve 13, and when the projection 28a comes into contact with the stopper wall 29, a predetermined retreat limit of the rear plunger ₁₆₂ is regulated.

A rear return spring 3 is provided on the front end surface of the rear plunger 16 ₂ to bias the plunger 16 ₂ in the backward direction.
A bottomed spring holding hole 31 ₂ for receiving 0 ₂ is provided. Further, a headed rear bolt 32 ₂ that projects a certain length in the axial direction from the end wall of the spring holding hole 31 ₂ is screwed onto the rear plunger 16 ₂ .

This rear bolt ₃₂₂ has a hat-shaped rear spring holding cylinder ₃₃₂ that supports the front end of the rear return _{spring 302} .
is fitted in a slidable _manner , and the extension limit of the rear return spring ₃₀₂ is regulated by the rear spring retaining tube 332 coming into contact with the head _322a of the rear bolt ₃₂₂ . .

In the illustrated example, the head _322a of the rear bolt ₃₂₂ protrudes from the front end surface of the rear plunger ₁₆₂ , but even when the rear plunger ₁₆₂ is fully stroked forward, the head _322a does not extend beyond the front plunger 162. 16 ₁ so as to be received in a front tool engagement hole 40 ₁ opened at the rear end surface (see FIG. 3).

A radial groove 34 ₂ connected to the rear annular oil chamber 11 ₂ is formed in the rear bulkhead collar 12 2 , and a rear one-way seal member 35 ₂ allows oil to flow from this groove 34 ₂ to the axial groove 23 of the sleeve ₁₃ . is attached to the rear end of the sleeve 13 with its lip in close contact with the outer peripheral surface of the rear plunger ₁₆₂ .

Also, at the rear end of the sleeve 13 is a retainer 36 ₂ that holds the front end of the rear one-way seal member 35 _{2 .}
and a spacer 37 ₂ inserted between the rear one-way seal member 35 ₂ and the rear bulkhead collar 12 ₂ .

The rear plunger 16 ₂ is provided with a rear relief port 38 ₂ that communicates between the radial groove 34 2 and the spring retaining hole 31 ₂ immediately after the rear one-way seal member 35 ₂ when the rear plunger 16 ₂ is at a predetermined retraction limit. Ru.

Further, a sealing member 39 ₂ is attached to the bearing 14 to bring the lip into close contact with the outer peripheral surface of the rear plunger 16 ₂ .

On the other hand, the front end of the front plunger 16 ₁ extends through the front partition wall collar 12 ₁ to the first hole 10a, and the front plunger 16 ₁ is attached to the front end surface thereof.
A bottomed spring holding hole 31 ₁ is provided for receiving a front return spring 30 ₁ that biases the front part in the backward direction. Also,
A front bolt 32 ₁ with a head that protrudes in the axial direction by a certain length from the end wall of the spring holding hole 31 ₁ is screwed onto the front plunger 16 ₁ .

This front bolt 32 ₁ has a hat-shaped front spring holding cylinder 33 ₁ that supports the front end of the front return spring 30 ₁ .
is slidably fitted, and the extension limit of the front return spring 30 ₁ is regulated by the front spring holding cylinder 33 ₁ coming into contact with the head 32 _1a of the front bolt 32 ₁ . It's summery.

A predetermined retreat limit of the front plunger 16 ₁ is regulated by contacting the rear spring holding cylinder 33 ₂ . In this case, in order to hold the rear spring holding cylinder 33 ₂ in contact with the head 32 _2a of the rear bolt 32 ₂ ,
The set load of the front return spring 30 ₁ is set to be weaker than that of the rear return spring 30 ₂ , and a gap s is provided between the front spring holding cylinder 33 ₁ and the head 32 _1a of the front bolt 32 ₁ . .

The front bulkhead collar 12 ₁ has a front annular oil chamber 11 ₁ .
A radial groove 34 ₁ connected to the front hydraulic chamber 17 ₁ is provided, and a front one-way seal member 35 ₁ that allows oil to flow only from this groove 34 ₁ to the front hydraulic chamber 17 1 connects the lip to the front plunger 16 ₁ . It is attached to the second hole 10b in close contact with the outer peripheral surface of.

A retainer 36 ₁ that holds the front end of the front one-way seal member 35 ₁ and a spacer 37 ₁ that is inserted between the seal member 35 1 _and the front partition collar 12 ₁ are attached to the second hole 10b. be done.

The front plunger 16 ₁ has a radial groove 34 ₁ and a spring retaining hole 3 when it is at a predetermined retraction limit.
A front relief port 38 ₁ communicating between 1 ₁ and 1 1 is bored.

Further, a sealing member 39 ₁ is attached to the front end of the sleeve 13 to bring the lip into close contact with the outer peripheral surface of the front plunger 16 ₁ .

Here, when the front and rear plungers 16 ₁ and 16 ₂ respectively occupy predetermined retreat positions, the forward protrusion length ₁ from the front one-way seal member 35 ₁ of the front plunger 16 ₁ and both plungers 16 ₁ and 16 If the interval between ₂ is ₂ , then ₁ > ₂ is set. If this is done, the rear return spring ₃₀₂ may be damaged, and the temporary front plunger ₁₆₁
Even if the front plunger 16 1 abnormally retreats until it comes into contact with the front end of the rear plunger 16 ₂ , the front plunger 16 ₁ can be prevented from slipping out rearward from the front one-way seal member 35 ₁ .

The front and rear spring holding tubes 33 ₁ , 33 ₂ have their outer circumferential surfaces facing the inner circumferential surfaces of the openings of the corresponding spring holding holes 31 ₁ , 31 ₂ , respectively, and also have their outer circumferential surfaces facing the corresponding return springs 30 ₁ , 30 _{2 .} It is adapted to the inner peripheral surface of.

Next, the operation of this embodiment will be explained.

Now, when the negative pressure booster B is operated to advance the push rod 19, the plungers 16 ₁ and 16 ₂ are pushed forward while compressing the corresponding return springs 30 ₁ and 30 _2, respectively. And the relief port 3 of the front plunger 16 ₁
8 ₁ moves to the front of the front one-way seal member 35 ₁ , hydraulic pressure is generated in the front hydraulic chamber 17 ₁ according to the forward force of the front plunger 16 ₁ , and the relief port 38 ₂ of the rear plunger 16 ₂ When the rear one-way seal member 35 ₂ moves forward, hydraulic pressure is generated in the rear hydraulic chamber 17 ₂ in response to the forward force of the rear plunger 16 ₂ .

The hydraulic pressure generated in the front and rear hydraulic chambers 17 ₁ , 17 ₂ is transferred to the corresponding output ports 18 ₁ , 18 _{2 .}
It is possible to simultaneously operate two hydraulic brake systems and apply braking to a car.

When the negative pressure booster B is returned to the inoperative state in order to release the brake, each plunger 16 ₁ , 16 ₂ is returned to a predetermined retraction limit by the repulsive force of the corresponding return spring 30 ₁ , 30 ₂ , but after that, If the pressure in each hydraulic chamber 17 ₁ , 17 ₂ is reduced during the retraction process, the lips of the corresponding one-way seal members 35 ₁ , 35 ₂ will bend toward the hydraulic chambers 17 ₁ , 17 ₂ due to the pressure difference between the front and rear, so that Hydraulic oil in the oil reservoir 8 ₁ flows into the front hydraulic chamber 1 through the through hole 9 ₁ , the front annular oil chamber 11 ₁ , the radial groove 34 ₁ and the inside of the lip of the front one-way seal member 35 ₁ .
7 ₁ and the hydraulic oil in the second oil reservoir 8 ₂ is supplied to the through hole 9 ₂ , the rear annular oil chamber 11 ₂ , the radial groove 34 ₂ , the inner side of the lip of the rear one-way seal member 35 ₂ and the axial groove. 23 and is supplied to the rear hydraulic chamber ₁₇₂ .

At this time, if excess hydraulic oil is supplied to each hydraulic chamber 17 ₁ , 17 ₂ , the excess amount is supplied to each hydraulic chamber 16 ₁ , 17 2 .
When the oil pump 16 ₂ returns to the backward limit, the oil is discharged from the respective relief ports 38 ₁ and 38 ₂ to the oil reservoirs 8 ₁ and 8 ₂ .

By the way, the projection 28a of the stopper ring 28 attached to the rear plunger ₁₆₂
When the plunger 6 ₂ moves forward, it only moves the axial groove 23 of the sleeve 13 forward, and does not prevent the plunger 16 ₂ from moving forward.

Further, the front and rear spring holding cylinders 33 ₁ and 33 ₂ are adapted to fit the inner peripheral surfaces of the corresponding return springs 30 ₁ and 30 ₂ inside the openings of the corresponding spring holding holes 31 ₁ and 31 ₂ , respectively. Therefore, these return springs 30 ₁ ,
30 ₂ is the spring holding cylinder 33 ₁ , 33 ₂ when compressed.
Since the plunger 16 ₁ , 1 is prevented from buckling by
The plungers 16 _{1 ,} 1 do not protrude toward the front end surface of the plungers 16 ₁ and 1 due to their protrusion.
_6.2 reduction in the forward stroke can be prevented.

When the rear plunger ₁₆₂ is retracted, it comes into contact with the stopper wall 29 of the sleeve 13 and the plunger 1
6 Regulates the retreat limit of ₂ . In this way, the limit of retraction of the rear plunger 16 ₂ is regulated within the cylinder hole 10, so that it is possible to shorten the cylinder body 1 and the bearing 1 cylinder so as to expose the rear end of the rear plunger 16 ₂ . .

On the other hand, the front spring holding cylinder 33 ₁ and the front bolt 32 ₁
Since a gap s is provided between the front return spring 30 ₁ and the head 32 _1a of the front spring holding cylinder 33,
The front plunger 16 ₁ can be reliably held at the abutment position with the rear spring holding cylinder 33 ₂ , that is, at the retracted limit, without being interfered with by the front bolt 32 ₁ .

In this way, when both plungers 16 ₁ and 16 ₂ are at their respective retraction limits, when the retaining screw 15 is removed for maintenance etc., the front return spring 30
₁ extends and pushes the front plunger 16 ₁ , the rear plunger 16 ₂ and the sleeve 13 rearward,
The extension of the front return spring ₃₀₁ is caused by the extension of the front return spring 301.
Due to the contact with the head 32 _1a of the front bolt 32 ₁ , the stroke is limited to a small enough to close the gap s, so the spring force causes the sleeve ₁ to
The third grade will not be thrown out of the cylinder hole 10. Therefore, the sleeve 13 and the rear plunger 1
6 ₂ and front plunger 16 ₁ etc. into the cylinder hole 10
It can be pulled out quietly.

To assemble such a tandem type master cylinder M, first, the front bolt 32 ₁ inserted through the front spring holding cylinder 33 ₁ and the front return spring 30 ₁ is screwed onto the front end of the front plunger 16 ₁ . By doing so,
A small assembly of the front plunger 16 ₁ and the return spring 30 ₁ is constituted, and at this time, in order to fix the front plunger 16 ₁ , a tool (not shown) is inserted into the front tool engagement hole 40 ₁ opened at the rear end surface. The tip portion having a regular hexagonal cross section is inserted. Further, a small assembly is constructed in the same manner for the rear plunger ₁₆₂ side. Next, after attaching the stopper ring 28 to the rear plunger ₁₆₂ , both of the subassemblies are inserted into the sleeve 13, and this sleeve 13 is inserted into the front,
It is inserted into the cylinder body 1 together with the rear collars 12 ₁ , 12 ₂ and the bearing 14, and finally the cap screw 15 is screwed.

When assembled in this way, the front and rear plungers 16
Do not damage the sliding surfaces of ₁ and 16 ₂ with a tool, or damage the seal members 35 ₁ and 35 with return springs 30 ₁ and 30 _2.
There is no risk of damaging ₂ , 39 ₁ , 39 ₂ ,
Moreover, the work can be divided and carried out efficiently.

C. Effect of the invention As described above, according to the invention, a front bolt with a head is screwed into the front end of the rear plunger so as to protrude a certain length in the axial direction, and the front bolt is screwed onto the rear end face of the front plunger. is provided with a front tool engagement hole into which a tool for preventing rotation of the front plunger is inserted when the front bolt is screwed, and is penetrated by the shaft of the front bolt. At the same time, a front return spring is compressed between the front spring holding cylinder and the front plunger whose forward movement is restricted by the head, and a rear bolt with a head is installed in the front end of the rear plunger in the axial direction. At the same time, the rear plunger has a rear tool engagement hole in which a tool is inserted to prevent rotation of the rear plunger when screwing the rear bolt. A rear return spring is compressed between the rear plunger and the rear spring retaining cylinder, which is penetrated by the shaft of the rear bolt and whose forward movement is restricted by the head thereof, and pushes the rear plunger. Since the push rod that can be used is inserted into the rear tool engagement hole, the front plunger and front return spring subassembly, and the rear plunger and rear return spring subassembly are damaged by using a tool on the sliding surfaces of each plunger. Moreover, when these assemblies are inserted into the cylinder body, the return spring can be maintained in a proper position, thereby preventing damage to the sealing member. Moreover, when the stopper means of the rear plunger is removed, the front spring holding cylinder and the front bolt work together to limit the amount of extension of the front return spring, thereby preventing the rear plunger etc. from falling off or being damaged by the spring. It is extremely easy to maintain.
Furthermore, since the rear tool engaging hole opened in the rear end face of the rear plunger also serves as the insertion hole for the push rod, the structure is that much simpler.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional side view of a master cylinder, and FIGS. 2, 3, and 4 are sectional views taken along lines -, -, and - of FIG. 1. , FIG. 5 is an exploded perspective view of the main part of FIG. 1. M... Tandem type master cylinder, 1... Cylinder body, 10... Cylinder hole, 16 ₁ , 16 ₂ ...
...Front, rear plunger, 17 ₁ , 17 ₂ ... Front, rear hydraulic chamber, 19 ... Push rod, 30 ₁ , 3
0 ₂ ... front, rear return spring, 32 ₁ , 32 ₂ ... front,
Rear bolt, 32 _1a , 32 _2a ...Head, 33 ₁ , 3
3 ₂ ... Front and rear spring holding tubes, 40 ₁ , 40 ₂ ...
Front and rear tool engagement holes.

Claims (1)

[Scope of utility model registration request] A front plunger 16 1 that is inserted into the cylinder hole 10 of the cylinder body ₁ and defines a front hydraulic chamber 17 ₁ between the cylinder body 1 and the front end wall thereof;
Between this front plunger 16 ₁ and the rear hydraulic chamber 1
a rear plunger 16 ₂ inserted into the cylinder hole 10 so as to define a diameter of 7 ₂ ; and a front return spring 30 ₁ that biases the front plunger 16 ₁ in the backward direction.
and a rear return spring ₃₀₂ that urges the rear plunger ₁₆₂ in the backward direction.A front bolt ₃₂₁ with a head is fixed in the axial direction at the front end of the front plunger 161 _. The front plunger 16 ₁ is screwed with a protruding length, and a tool is fitted to the rear end surface of the front plunger 16 1 to prevent rotation of the front plunger 16 ₁ when the front bolt 32 ₁ is screwed. A front spring holding cylinder 33 ₁ is provided with a front tool engagement hole 40 ₁ into which the front tool is inserted, is penetrated by the shaft of the front bolt 32 1, and whose forward movement is restricted by its head 32 _{1a .} A front return spring ₃₀₁ is compressed between the front plunger ₁₆₁ , and a headed rear bolt 3 is installed at the front end of the rear plunger ₁₆₂ .
The rear plunger 16 ₂ is screwed onto the rear end surface of the rear plunger 16 ₂ so as to project a certain length in _the axial direction.
A rear tool engagement hole 40 ₂ into which a tool is inserted to prevent the rotation of the rear bolt 32 ₂ is provided _.
A rear return spring 30 ₂ is compressed between the rear plunger 16 ₂ and the rear spring retaining cylinder 33 ₂ which is penetrated by the shaft portion of the cylinder and whose forward movement is restricted by its head 32 _{2 a} . A tandem type master cylinder characterized in that a push rod 19 that can be pushed is inserted into the rear tool engagement hole ₄₀₂ .