JPH0424265B2 - - Google Patents

Description

Detailed Description of the Invention A. Object of the Invention (1) Industrial Field of Application The present invention relates to a tandem master cylinder, particularly a cylinder body provided with first and second oil reservoirs, and a cylinder hole in the cylinder body. a front plunger that is slid together to define a front hydraulic chamber between the front end wall thereof; and a rear plunger that is slidably engaged with the cylinder hole so as to define a rear hydraulic chamber between the front plunger and the front plunger; , a front return spring that biases the front plunger in the backward direction; a rear return spring that biases the rear plunger in the backward direction; and a front part that is attached to the cylinder body and brings the lip into close contact with the outer peripheral surface of the front plunger. It consists of a one-way seal member and a rear one-way seal member that is attached to the cylinder body and brings the lip into close contact with the outer periphery of the rear plunger. A front relief port communicating between the first oil sump and the front hydraulic chamber is bored immediately after the member, and a first relief port is bored in the rear plunger immediately after the rear one-way seal member when it is at the normal retraction limit. This invention relates to an improvement of a master cylinder having a relief port that communicates between two oil reservoirs and a rear hydraulic chamber.

(2) Prior Art This type of tandem master cylinder is disclosed in Japanese Patent Application Laid-Open No. 16952/1983, for example.
Already known.

(3) Problems to be Solved by the Invention In the conventional tandem type master cylinder, no consideration is given to the abnormal retraction of the front plunger rearward from the normal retraction position. That is, in the event that the rear return spring becomes fatigued or damaged, the front plunger may move back significantly due to the force of the front return spring until it comes into contact with the front end of the rear plunger. , the front plunger slips out rearward from the front one-way seal member. If this happens, the next time the front plunger is rapidly advanced to generate hydraulic pressure in the front hydraulic chamber,
When the plunger passes through the front one-way seal member again, there is a risk that the lip may be damaged by the leading edge or the seal member may be separated from the cylinder body.

An object of the present invention is to provide the tandem-type master cylinder that can prevent such inconveniences.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a means for reversing the front plunger even when the front plunger is abnormally retracted beyond the normal retraction limit until it collides with the rear plunger. In order to prevent the plunger from slipping out from the front one-way seal member, the length of the front plunger's forward protrusion from the front one-way seal member when both the front and rear plungers are at their normal retraction limits is determined in the same state. It is characterized by being set longer than the mutual spacing between both plungers.

(2) Effect According to the above configuration, even if the front plunger abnormally retreats from the normal retreat position until it comes into contact with the front end of the rear plunger, the front plunger will not come off from the front one-way seal member. Therefore, the front one-way seal member can always maintain proper close contact with the front plunger.

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

In Figures 1 to 3, M is 2 of the car.
This is a tandem type master cylinder for a systematic hydraulic brake, and the rear end of the cylinder body 1 is fixed to the front surface of a booster shell 2 of a negative pressure booster B supported by a vehicle body (not shown).

An auxiliary oil reservoir 3 is integrally connected to 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 have through holes 9 ₁ and 8 2 , respectively.
It communicates with the cylinder hole 10 of the cylinder body 1 via 9 ₂ . 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, and a front partition wall collar 12 ₁ is provided at the step between the second hole 10b and the third hole 10c. The sleeve 13 that contacts the rear surface of the collar ₁₂₁ is fitted into the third hole 10c and the fourth hole 10c.
The rear partition collar 12 2 that is fitted over the hole 10 d and abuts the rear end of this sleeve ₁₃ and the bearing bush 14 that abuts the rear surface of this collar 12 ₂ are fitted into the fourth hole 10 d, and the bearing bush 1
An annular retaining screw 15 that presses the rear surface of 4 is located in the fourth hole 1.
It is screwed on from the rear end of 0d.

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,
A rear hydraulic pressure 17 ₂ is defined between both plungers 16 ₁ , 16 ₂ . These hydraulic chambers 17 ₁ and 17 ₂ are communicated with two brake hydraulic circuits via front and rear output ports 18 ₁ and 18 ₂ of the cylinder body 1, respectively.

The rear end of the rear plunger 16 ₂ extends to the rear of the cylinder body 1 through the rear bulkhead collar 12 ₂ and the bearing bush 14 , and further extends to the rear of the cylinder body 1 .
It passes through the front wall of and connects with the output rod 19 of the negative pressure booster B.

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 16 ₂ .
This stopper ring 28 is provided with one or more projections 28a that project outward from the outer peripheral surface of the rear plunger ₁₆₂ , and this projection 28a is connected to the sleeve 13.
is engaged with the axial groove 23 of. The rear end of the axial groove 23 is a stopper wall 2 integral with the sleeve 13.
9, and when the projection 28a comes into contact with this stopper wall 29, a predetermined retraction limit of the rear plunger ₁₆₂ is determined.

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 bolt 32 that protrudes in the axial direction by a certain length from the end wall of the spring holding hole 31 ₂ is screwed onto the rear plunger 16 ₂ , and this bolt 32 has a hat shape that supports the front end of the rear return spring 30 ₂ . A spring holding cylinder 33 is slidably connected within a certain stroke range.

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 immediately after the rear one-way seal member 35 2 when the rear plunger 16 ₂ is at a predetermined retraction limit. .

The bearing bush 14 also has a rear plunger 16.
Seal member 39 ₂ that brings the lip into close contact with the outer peripheral surface of ₂
is installed.

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. The predetermined retraction limit of the front plunger 16 ₁ is determined by the rear end coming into contact with the spring holding tube 33 in the extended position.

In this case, the set load of the front return spring 30 ₁ is set to be weaker than that of the rear return spring 30 ₂ so as to keep the spring holding cylinder 33 in a predetermined extended position.

The spring retaining hole 31 ₁ of the front plunger 16 ₁ is arranged so that the front return spring 31 ₁ can be reliably accommodated in its entirety when the plunger 16 ₁ moves forward until it abuts the front end wall of the first hole 10a. The diameter of the majority portion 31 _1a is enlarged. Such expansion may be stepped, as shown in FIG. 1, or tapered, as shown in FIG.

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

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 each occupy a predetermined retreat position, the forward protrusion length of the front plunger 16 ₁ from the front one-way seal member 35 ₁ is l ₁ , and both plungers 16 ₁ , 16 ₂ is set to l ₂ , then l ₁ > l ₂ is set.

Next, the operation of this embodiment will be explained.

Now, operate negative pressure booster B and increase its output rod 1.
9 is pushed forward, both plungers 16 ₁ and 16 ₂ are pressed by the corresponding return springs 30.
It moves forward while compressing _{1,30 2} . Then, when the relief port 38 ₁ of the front plunger 16 ₁ moves to the front of the front one-way seal member 35 ₁ , hydraulic pressure in the front hydraulic chamber 17 ₁ is generated in response to the forward force of the front plunger 16 ₁ . Also rear plunger 16 ₂
When the relief port 38 ₂ of the rear one-way seal member 35 ₂ moves to the front of the rear plunger 16 ₂
Hydraulic pressure is generated in the rear hydraulic chamber 172 in response to the forward force of the rear hydraulic chamber ₁₇₂ .

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 is supplied to the front hydraulic chamber 17 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 . Also, the hydraulic oil in the second oil reservoir ₈₂ is
Through hole 9 ₂ , rear annular oil chamber 11 ₂ , radial groove 34 ₂ ,
The rear hydraulic chamber 17 ₂ is supplied through the inner side of the lip of the rear one-way seal member 35 ₂ and through the axial groove 23 .

At this time, if excess hydraulic oil is supplied to each hydraulic chamber 17 ₁ , 17 ₂ , the excess amount will be absorbed by each relief port 38 ₁ , 38 ₂ when each plunger 16 ₁ , 16 ₂ returns to the retraction limit. The oil is discharged from the oil sump 8 ₁ and 8 ₂ side.

By the way, assuming that when the front and rear plungers 16 ₁ and 16 ₂ are retreating, the rear return spring 30 ₂ loses its original spring function due to fatigue or damage, the front plunger 16 ₁ will be moved as shown in FIG. As such, the force of the front return spring 30 ₁ causes the rear plunger 16 ₂
Retract until it touches the front end of the

In other words, the front plunger 16 ₁ will be moved back an extra distance l ₂ from the normal retraction limit, but the front plunger 16 ₁ will be further forward than the front one-way seal member 35 ₁ at the normal retraction limit. Since the front end protrudes by l ₁ which is greater than the distance l ₂ , even in the case of abnormal retraction as described above, the front plunger 16 ₁ will not come out of the front one-way seal member 35 ₁ to the rear, and the front The one-way seal member 35 ₁ can be maintained in proper close contact with the front plunger 16 ₁ .
Therefore, by moving the front plunger 16 ₁ forward again, hydraulic pressure can be reliably generated in the front hydraulic chamber 17 ₁ .

C. Effects of the Invention As described above, according to the present invention, even if the front plunger is abnormally retreated beyond the normal retreat limit until it collides with the rear plunger, the front plunger is prevented from slipping out from the front one-way seal member. , the length of the front plunger's forward protrusion from the front one-way seal member when both the front and rear plungers are at their normal retraction limits is set to be longer than the mutual spacing between both plungers in the same state; Even if the front plunger backs up abnormally as described above, the front plunger can be reliably prevented from coming off the front one-way seal member, and the front one-way seal member and front Appropriate close contact with the plunger is always maintained, and as a result, when the front plunger moves forward again, the front one-way seal member is not damaged or removed from its fixed position, and hydraulic pressure is reliably supplied to the front hydraulic chamber. can be generated.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional side view of a tandem type master cylinder, and FIG.
3 is an exploded perspective view of the main parts, FIG. 4 is an explanatory diagram of operation, and FIG. 5 is a sectional view showing a partial modification of FIG. 1. M...tandem type master cylinder, 1... cylinder body, 8 ₁ , 8 ₂ ... first and second oil sump, 10...
... Cylinder hole, 16 ₁ , 16 ₂ ... Front, rear plunger, 17 ₁ , 17 ₂ ... Front, rear hydraulic chamber, 18 ₁ ,
18 ₂ ... front, rear output port, 30 ₁ , 30 ₂ ...
...Front and rear return springs, 35 ₁ , 35 ₂ ... Front and rear one-way seal members, 38 ₁ , 38 ₂ ... Front and rear relief ports.

Claims (1)

[Claims] 1 A cylinder body 1 equipped with first and second oil reservoirs 8 ₁ and 8 ₂ and a cylinder hole 10 of this cylinder body 1
A front hydraulic chamber 17 is inserted between the front end wall and the front end wall.
₁ , a rear plunger 16 ₂ that is slid into the cylinder hole ₁₀ so as to define a rear hydraulic chamber 17 ₂ between the front plunger 16 ₁ , and a front plunger 16 1 . A front return spring 30 ₁ that urges the rear plunger 16 ₁ in the backward direction, and a rear return spring 3 that urges the rear plunger 16 ₂ in the backward direction.
₀₂ , a front one-way seal member ₃₅₁ that is attached to the cylinder body 1 and brings the lip into close contact with the outer circumference of the front plunger ₁₆₁ , and a front one-way seal member 351 that is attached to the cylinder body 1 and makes the lip closely contact the outer circumference of the rear plunger ₁₆₂ . It consists of a rear one-way seal member 35 ₂ that is brought into close contact with each other,
The front plunger 16 ₁ has a front relief port 38 that communicates between the first oil reservoir 8 _{1 and the front hydraulic chamber 17 1} immediately after the front one-way seal member 35 ₁ when the front plunger 16 ₁ is at the normal retraction limit. ₁ , and the rear plunger 16 ₂ is provided with a rear portion that communicates between the second oil sump 8 ₂ and the rear hydraulic chamber 17 ₂ immediately after the rear one-way seal member 35 2 when the rear plunger 16 ₂ is at its normal retraction limit. In a tandem type master cylinder with a relief port ₃₈₂ , even if the front plunger ₁₆₁ is abnormally retreated beyond the normal retreat limit until the front plunger 161 collides with the rear plunger ₁₆₂ , the front plunger ₁₆₁ moves forward in one direction. The front plunger 16 with both the front and rear plungers 16 ₁ and 16 ₂ at their normal retraction limits so as not to slip out of the seal member 35 _1
1 , the forward protrusion length l ₁ from the front one-way seal member 35 ₁ is set longer than the mutual spacing l ₂ between both plungers 16 ₁ and 16 ₂ in the same state.
Tandem type master cylinder.