JPS599967Y2 - Tandem type master cylinder - Google Patents

Description

[Detailed description of the invention] The present invention is a tandem-type master cylinder mainly used in two-system hydraulic brakes for automobiles, in particular, a pair of front and rear first and The independent first and second hydraulic chambers are defined by the second piston, and an oil tank is provided on the upper side of the cylinder body, offset to one side in the front and back direction, and the lower part of the inside of the oil tank is formed by a partition wall. , a first oil reservoir chamber located near the front end of one of the first and second pistons and a second oil reservoir chamber adjacent to the first oil reservoir chamber, and a bottom wall of the first oil reservoir chamber; A relief hole and a replenishment hole are provided for one of the hydraulic chambers adjacent to the first oil reservoir chamber, and a relief hole and a replenishment hole are provided on the upper side of the cylinder body and extend substantially horizontally from the bottom of the second oil reservoir chamber, and the other hydraulic chamber is provided with a relief hole and a replenishment hole. The present invention relates to a mask cylinder provided with an oil supply path that reaches a relief hole and a supply hole for the hydraulic chamber.

This tandem type mask cylinder is, for example,
As shown in Japanese Patent No. 34889, it is conventionally known, and it is advantageous in terms of cost compared to a two-tank type in that it uses only one oil tank, and the approximately horizontal oil supply path is connected to the second oil sump chamber. This has the advantage that almost all of the oil stored in the second oil sump chamber can be effectively used as hydraulic oil for the mask cylinder. However, since the air inside the fuel tank is difficult to be discharged to the oil tank side during refueling, there is a drawback that the refueling operation requires a lot of effort and time.

Furthermore, it is known that a tandem mask cylinder with one oil tank has an oil supply path extending from one oil reservoir chamber in the oil tank with an upward slope toward the oil reservoir chamber ( For example, see Utility Model Application Publication No. 56-13055), but in this type of oil supply path, the air can be discharged to the oil tank side more smoothly than in the conventional type described above, but air and oil enter and exit through a single oil supply path. Since it is carried out in Moreover, due to the slope of the oil supply passage, the inlet is placed at a high distance from the bottom of the oil sump chamber, so the volume of the oil sump chamber below the inlet becomes invalid, and its effective The disadvantage is that the volume is reduced.

As a countermeasure to this problem, it is conceivable to raise the bottom of the oil reservoir so that the bottom is at the entrance of the oil supply passage, but this would increase the height of the oil reservoir to a necessary level, which is useful for example in narrow automobile engines. When installing the master cylinder in the chamber, a problem arises in that the oil tank interferes with the bonnet.

This invention was proposed in view of these circumstances.
In a tandem type master cylinder in which the oil supply path extends approximately horizontally from the bottom of the second oil reservoir chamber of the oil tank, the oil can be smoothly supplied from the second oil reservoir chamber to the inside of the mask cylinder without losing any of its advantages. The purpose is to provide an effective structure that allows for

In order to achieve this object, the present invention is characterized in that an air discharge passage is provided on the upper side of the cylinder body, extending upwardly from the downstream end of the oil supply passage and reaching the oil tank.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a cylinder body having a cylinder hole 2, which is arranged substantially horizontally.

The cylinder hole 2 has a pair of first and second pistons 3 in the front and rear.
,,3.

are slid together, both pistons 3, 3 and the second piston 3
A first hydraulic chamber 4 at the rear and a second hydraulic chamber 4 at the front are independent from each other between the inner surface of the front end wall of the cylinder hole 2.

and those hydraulic chambers 4,4.

are individually connected to two brake hydraulic circuits of the automobile.

The intermediate portions of the first and second pistons 3, 3 are shaped to have a small diameter, and these small diameter portions 5, 5.

First and second supply oil chambers 6, 6 are defined between the cylinder hole 2 and the inner peripheral surface of the cylinder hole 2.

Each front large diameter portion 7, of the first and second pistons 3, 32,
7, the first and second supply oil chambers 61 and 6 are connected to the first
and oil supply holes 8, 8 communicating with the second hydraulic chambers 4, 4.

An elastic seal cup 9, which opens and closes each oil supply hole 8, is provided on the front surface of each of the first and second pistons 3, 3.
, 9 are provided.

101 and 102 are the first and second hydraulic chambers 4, .
4 is a return spring for the first and second pistons 3, 3, which are compressed within the piston 4.

An oil tank R is provided above the cylinder body 1.

Is the oil tank R a little closer to the center of the cylinder body 1? It consists of a cylindrical auxiliary oil reservoir 11 integrally protruding from the upper side of the auxiliary oil reservoir 11, and a transparent main oil reservoir 12 made of Hewei resin whose lower end is fitted and connected to the outer periphery of the auxiliary oil reservoir 11. Reservoir 12 is auxiliary oil reservoir 11
A cylindrical filter 13 is installed in the upper oil reservoir 12 to filter the hydraulic oil, and an elastic cap 14 is fitted onto the open upper end of the cylindrical filter 13.

The auxiliary oil reservoir 11 is internally divided into a first oil reservoir chamber 11a at the rear and a second oil reservoir chamber 1lb at the front by a partition wall 15 that is integrated with the cylinder body 1, and both oil reservoir chambers 11a, 11 b both communicate with the main oil reservoir 12.

The first oil reservoir chamber 11a is disposed near the front end of the first piston 3, and has a seal on its bottom surface that is closed when the first piston 3 moves forward, but when the first piston 3 moves backward. The relief hole 16 of the first hydraulic chamber 4 is sometimes opened. A replenishment hole 17 is drilled to constantly communicate the first replenishment oil chamber 6 with the first oil reservoir chamber 11a.

On the other hand, the thick upper wall 1a of the cylinder body 1 continues in front of the auxiliary oil sump 11, and the second oil sump chamber 1l is attached to the upper wall 1a.
The second piston 3 from the bottom of b.

A substantially horizontal oil supply passage 18 extending near the front end of the oil supply passage 18 and a vertical cylindrical oil chamber 19 connected to the downstream end of the oil supply passage 18 are provided.

The second piston 3 is thereby closed during the forward movement of the .

The relief hole 16 of the second hydraulic chamber 4 is opened when the vehicle is retracted.

Then, a replenishment hole 17 that constantly communicates the second replenishment oil chamber 62 with the oil chamber 18 is bored.

A screw plug 20 is provided at the upper opening of the oil chamber 18, and the ceiling surface of the oil chamber 18 is defined by the lower end surface of the screw plug 20.

Further, an oil supply passage 19 is provided in the thick upper wall 1a of the cylinder body 1.
At the upper part of the oil chamber 18, an air discharge passage 21 is formed with an upward slope from the oil chamber 18 toward the second oil reservoir chamber 11b.

The upper edge of the lower opening of the air discharge passage 21 is located in a relationship that substantially contacts the ceiling surface of the oil chamber 18, thereby preventing air from being trapped in the oil chamber 18.

After assembling the mask cylinder, when hydraulic oil is injected into the auxiliary oil sump 11 and the main oil sump 12, the first oil sump chamber 11
The hydraulic oil in a is led into the first replenishment oil chamber 6 through the replenishment hole 17, while the hydraulic oil in the second oil reservoir chamber 11b is introduced into the oil supply path 1.
9 and its oil chamber 18 through the supply hole 172.
They are each guided into the replenishment oil chamber 62.

Is hydraulic oil introduced into the first replenishment oil chamber 6? As the temperature increases, internal air flows through the supply hole 17 to the first oil sump chamber 11.
a, and the inside of the first replenishment oil chamber 6 is filled with hydraulic oil.

The air in the first oil sump chamber 11a is discharged to the outside through the main oil sump 12.

On the other hand, in the second replenishment oil chamber 6, as the hydraulic oil is introduced, internal air is discharged into the oil chamber 18 through the replenishment hole 17, and the second replenishment oil chamber 6 is filled with the hydraulic oil.

Furthermore, in the oil chamber 18, air is separated from the hydraulic oil that has flowed into the oil chamber 18, so the separated air is passed through the air exhaust passage 21 along with the discharged air from the second oil supply chamber 6 to the second oil sump chamber 1L. b, and is then discharged to the outside via the main oil sump 12.

First and second hydraulic chambers 41,4.

Press the brake pedal (not shown) to release the air inside the
and each relief hole 16 when the second pistons 3, 3 are pushed forward. , 16 or each piston 3, , 3.

When the brake pedal is released, the air is discharged to the outside through the air bleed hole of each wheel cylinder, while when the brake pedal is released, the return spring 10. ,10.

Due to the elastic force of the pistons 3, 32 move backward, and the first and second hydraulic chambers 4, 4 accordingly.

When the internal pressure is reduced to below atmospheric pressure, the seal cup 9
The outer peripheries of 1.92 mm are the first and second hydraulic chambers 4, respectively.
,4.

Since it narrows toward the side and leaves a gap between it and the inner circumferential surface of the cylinder hole 2, hydraulic oil that does not contain air flows from each oil supply chamber 6, 6 through the oil supply hole 8, 8 into each hydraulic chamber 4, 42. By repeating the depression and release operations of the brake pedal, the air in both hydraulic chambers 41 and 42 is discharged, and the interior thereof is filled with hydraulic oil.

After the air venting operation described above, the air vent hole in the wheel cylinder is closed.

During braking, when the first and second pistons 3, 32 are pushed forward by depressing the brake pedal, the relief holes 16. , 16 are the respective pistons 3, , 3.

The hydraulic pressure generated in each hydraulic chamber 4, 4 is transmitted to the corresponding brake hydraulic circuit, and each brake can be operated.

Also, first and second pistons 31,3.

When retracting, the first and second hydraulic chambers 41 and 42 are replenished with hydraulic oil in the same manner as described above.
.

From oil supply hole 8,8.

through the relief holes 16. , 16.

The oil can then be returned to the first and second oil reservoir chambers 11a, 1lb, respectively.

As mentioned above? Before installing the plug 20, check for clogging in the oil chamber 18, the relief hole 16 and the supply hole 17, and check the second piston 3.
The retracted position of the vehicle can be confirmed.

The other relief hole 16 and supply hole 17 can be inspected from the first oil reservoir chamber 11a by removing the cap 14 and filter 13.

Note that 22 is a blind plug provided during processing of the oil supply passage 19.

The main oil reservoir 12 has an oil level detection device A that is activated when the oil level F of the hydraulic oil stored there falls below a specified level L.
will be provided.

The device A is provided protrudingly from the lower surface of the cap 14, and the main oil reservoir 1
2, a magnetically sensitive reed switch 24 housed within the switch tube 23 and installed at the specified level L, and fitted on the outer periphery of the switch tube 24 so as to be movable up and down; It is composed of an annular float 26 with a magnet 25 embedded therein that can close the reed switch 24, and an alarm (not shown) such as a lamp that is activated when the reed switch 24 is closed is connected to the node wire 27. connected via.

Further, a stopper 28 is provided at the lower end of the switch tube 23 to prevent the float 26 from falling below the vicinity of the specified level L.

When an appropriate amount of hydraulic oil is stored in the main oil reservoir 12 and the oil level F is higher than the specified level L, the float 26 floating on the oil level F is activated by the reed switch as shown by the solid line. Since the reed switch 24 is far away upward from the float 24, the reed switch 24 is not affected by the magnetic force of the magnet 25 of the float 26 and remains open.

Therefore, an alarm (not shown) connected to the lead wire 27 does not operate.

However, if an oil leak failure were to occur in the hydraulic circuit of the first hydraulic chamber 41, the main oil sump 12 and the auxiliary oil sump 1
Even if the hydraulic oil in the first oil reservoir chamber 11a of the auxiliary oil reservoir 11 dries up, the hydraulic oil is stored in the second oil reservoir chamber 11b of the auxiliary oil reservoir 11. Therefore, during braking operation, both pistons 3, 3, the pressure in the second hydraulic chamber 4 can be increased and the hydraulic circuit of the system can be operated normally.

In this case, when the oil level F of the main oil reservoir 12 drops to the specified level L, the float 26 moves down along the switch tube 23 to the chain line position, and the magnet 25 moves toward the reed switch 24.
In order to close it, an alarm (not shown) is immediately activated to alert the driver of the vehicle to the abnormal drop in the oil level F.

Even if the oil level F further decreases, the float 26 is received by the stopper 28 and held near the specified level L, so that the closed state of the reed switch 24, that is, the alarm state can be maintained.

Second hydraulic chamber 4.

If the hydraulic circuit of the system breaks down, the same effect as described above will occur, except that hydraulic oil remains in the first oil reservoir chamber 11a of the auxiliary oil reservoir 11.

As described above, according to the present invention, in a tandem type master cylinder in which an oil supply passage extends substantially horizontally from the bottom of a second oil storage chamber of an oil tank, a downstream end of the oil supply passage is provided on the upper side of the cylinder body. Since an air discharge path is formed that extends upwardly from the section and reaches the oil tank, during refueling, the oil in the second oil reservoir chamber is supplied to the inside of the mask cylinder through the oil supply path, and the air inside the mask cylinder is Is it smoothly discharged to the oil tank through the discharge passage, and therefore inside the mask cylinder by the cooperation of the oil supply passage and the air discharge passage? Refueling can be performed smoothly without leaving any residual air, reducing refueling work time.

Moreover, by using a nearly horizontal oil supply path, the required effective volume can be secured in the second oil storage chamber without increasing the height of the oil tank more than necessary, which is the original goal of making the oil tank smaller. It doesn't take away any of the advantages.

[Brief explanation of drawings]

The drawing is a longitudinal sectional side view of a main part showing an embodiment of the mask cylinder of the present invention. R...Oil tank, 1...Cylinder body, 1
a...Upper side part, 2...Cylinder hole, 3
, 32...first and second pistons, 4, 42...
...1st, 2nd hydraulic chamber, 6, 62...1st
, second supply oil chamber, 11 a, 1l b...first and second oil storage chambers, 15...partition wall, 16,,16
2... Relief hole, 17, 17... Supply hole, 1... Oil supply path, 21... Air discharge path.

Claims (1)

[Claims for Utility Model Registration] In the cylinder hole 2 of the cylinder body 1 which is arranged approximately horizontally,
a pair of front and rear first and second pistons 3 slidingly engaged therewith;
, 32, the independent first and second hydraulic chambers 41, 4
. A single oil tank R is provided on the upper side of the cylinder main body 1 and shifted to one side in the front-rear direction, and the lower part of the inside of this oil tank R is provided with a partition wall so that the first and second pistons 3, 32 The first oil sump chamber 1 is located near one front end of the
1 a and a second oil reservoir chamber 11 b adjacent to the chamber, and a bottom wall of the first oil reservoir chamber 11 a is provided with a second oil reservoir chamber 11 b adjacent to the first oil reservoir chamber 11 a.
Relief hole 1 for one of the hydraulic chambers 41 adjacent to a
61 and a supply hole 17, and a relief hole 16 and a supply hole for the other hydraulic chamber 4 extending substantially horizontally from the bottom of the second oil reservoir chamber 11b on the upper side of the cylinder body 1. In a tandem type master cylinder provided with an oil supply passage 19 that reaches the hole 17, an air discharge passage 21 is provided on the upper side of the cylinder body 1 and extends at an upward slope from the downstream end of the oil supply passage 19 and reaches the oil tank R. A tandem type mask cylinder characterized by being provided with.