JPH084372Y2 - Two-system hydraulic braking system for automobiles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Purpose of the Invention (1) Field of Industrial Application The present invention relates to a two-system hydraulic braking system for an automobile, and in particular, a tandem type having independent first and second output ports. A housing of the rear wheel braking hydraulic pressure control device is connected to one side of the master cylinder, and first and second pressure receiving pistons aligned coaxially are slid into the housing, and the first and second pressure receiving pistons are arranged on the inner end side of the pressure receiving pistons. First and second input hydraulic chambers that communicate with the first and second output ports, respectively, and first and second output hydraulic chambers that communicate with the left and right rear wheel brakes, respectively, are formed on the outer ends of the pressure receiving pistons. Set the pressure receiving area on each output hydraulic chamber side to be larger than that on each input hydraulic chamber side, open between each adjacent input and output hydraulic chambers with the outer sliding limit of each pressure receiving piston, and slide inward. Both receivers communicate with each other through a valve that sometimes closes. And it provided under compression the pressure-adjusting spring between the piston and the housing, to a cavity ゝ improvement that provided a discharge hole which opens to the outside between the two pressure-receiving pistons.

(2) Conventional technology Such a two-system hydraulic braking device is disclosed in, for example, Japanese Patent Publication No. 2-25.
It is already known as disclosed in Japanese Patent No. 825. According to such a two-system hydraulic braking device, when the sliding portion of one pressure receiving piston in the rear wheel braking hydraulic control device is worn or damaged, the operation in one hydraulic circuit to which the pressure receiving piston belongs is actuated. It is possible to know the wear and damage of the sliding portion by discharging the oil to the outside from the discharge hole provided in the housing and detecting the abnormal lowering of the stored oil surface in the oil sump of the master cylinder.

(3) Problem to be Solved by the Invention By the way, when the sliding portion is worn or damaged, the leak speed of the working oil from the discharge hole of the housing is extremely slow. It will take a long time to detect.

The present invention has been made in view of the above circumstances, and provides the two-system hydraulic braking device that enables the leakage of hydraulic oil from the housing of the rear wheel braking hydraulic control device to be known as early as possible. The purpose is to

B. Configuration of the Invention (1) Means for Solving the Problem In order to achieve the above-mentioned object, the present invention installs a transparent oil drain sump which is empty in the normal time in the vicinity of the master cylinder. A drainage hole of the housing is connected to the oil sump.

(2) Operation In the above configuration, when hydraulic oil leaks from the discharge hole of the housing, the oil is sent to the drain oil sump. This oil sump is set near the master cylinder and has translucency, so if you look at the oil sump when checking the master cylinder, you can see through even the slight amount of oil that has accumulated inside it. As a result, wear and damage of the sliding portion of the pressure receiving piston can be known at an early stage.

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

In FIG. 1, a tandem type master cylinder 2 driven by an output rod 1a is mounted on the front surface of a known negative pressure type booster 1 mounted on the front surface of a dashboard that divides the engine room and the vehicle compartment of an automobile.

The master cylinder 2 is provided with first and second connection bosses 3 ₁ and 3 ₂ arranged on the left side surface thereof in front and rear, and a rear wheel braking hydraulic control device 6 is attached to these. The rear wheel braking hydraulic control device 6 includes a third and a fourth connecting bosses 3 ₃ arranged in front and rear on the upper surface thereof.
3 and ₄ , 5th and 6th connection bosses lined up on the left side
3 ₅ and 3 ₆ , hydraulic pipes 5 ₁ and 5 ₂ respectively connected to the right and left front wheel brakes Bfr and Bfl are connected to the 3rd and 4th connecting bosses 3 ₃ and 3 ₄ , respectively, and 5th and left and right rear wheel brake Brl, hydraulic conduits 5 ₃ contiguous respectively to Brr, 5 ₄ are respectively connected to the sixth connection boss 3 _5, 3 _6.

As shown in FIGS. 2 and 4, in the cylinder hole 10a of the cylinder body 10 of the master cylinder 2, first and second hydraulic chambers 11 ₁ and 11 ₂ independent from each other are defined in the front and rear directions.
A pair of front and rear pistons 12 ₁ and 12 ₂ are slidably fitted.
The pistons 12 ₁ and 12 ₂ return springs 15 ₁ and 15 ₂ are biased in the backward direction, respectively, and the rear piston 12 ₂ is connected to the output rod 1a of the booster 1.

Further, the first and second connection bosses 3 ₁ and 3 ₂ are integrally provided on the left side surface of the cylinder body 10, and the first output boss 3 ₁ that communicates with the first hydraulic chamber 11 ₁ is connected to the first connection boss 3 _1. A port 13 _{1 and a} second output port 12 ₂ communicating with the second hydraulic chamber 11 ₂ are formed in the second connecting boss 3 ₂ .

Further, a cylindrical auxiliary oil reservoir 16 protruding from the upper surface of the cylinder body 10 is integrally formed at the front portion thereof. The auxiliary oil sump 16 is divided into first and second oil sump chambers 18 ₁ and 18 ₂ by a partition 17 that is integral with the cylinder body 10. The first oil reservoir chamber 18 ₁ is disposed near the front end portion of the front piston 12 _1, a relief port 19 ₁ and the supply port 20 ₁ for the first hydraulic chamber 11 ₁ is bored in the bottom wall thereof It

On the other hand, an oil passage 21 extending rearward from the second oil reservoir chamber 18 ₂ is formed on the upper wall of the cylinder body 10, and a relief port 19 ₂ for the second hydraulic chamber 11 ₂ is formed on the bottom wall of the oil passage 21. and supply port 20 ₂ is bored.

On the outer circumference of the auxiliary oil sump 16, a larger capacity than both oil sump chambers 18
A main oil sump 22 made of translucent synthetic resin, which communicates with ₁ and 18 ₂ , is fitted and connected. The main oil sump 22 is provided with a filter 23 for filtering hydraulic oil, and an oil level detection device 24 that operates when the level of the hydraulic oil storage level drops below a prescribed level L. This oil level detection device 24 is provided on a lower surface of a cap 25 of the main oil sump 22 and has a switch cylinder 26 that protrudes deeply into the main oil sump 22, and is housed in the switch cylinder 26 to have the specified level L position. The reed switch 27 and the annular float 29, which is fitted to the outer periphery of the switch cylinder 26 so as to be able to move up and down and has the magnet 28 embedded in the inner peripheral surface thereof. When the float 29 descends to the specified level L, The reed switch 27 is adapted to close in response to the magnetism of the magnet 28. This reed switch 27 has
An alarm device 30 such as a lamp that operates when it is closed is connected.

As shown in FIG. 3 and FIG. 4, the rear wheel braking hydraulic control device 6 includes a cylinder portion 32 parallel to the cylinder body 10.
And a housing 31 including a pair of front and rear ears 33 ₁ and 33 ₂ protruding from the lower surface of the cylinder portion 32.
The third and fourth connection bosses 3 ₃ and 3 ₄ are integrally formed on the upper surface of 32, and the fifth and sixth connection bosses 3 ₅ and 3 ₆ are integrally formed on the left side surface.

Both ears 33 _1, 33 _2, union bolts passing through them
By 34 and 34, they are oil-tightly fixed to the first and second connection bosses 3 ₁ and 3 ₂ , respectively.

Each ear portion 33 _1, 33 _2, the seating surface for the union bolt 34 head, a plurality of pin holes arranged at irregular intervals along its periphery
55 is provided in one of these pin holes 55, and the detent pin 56 that abuts against the head side surface of the union bolt 34 is provided in any one of these pin holes 55.
Is driven. This prevents the union bolt 34 from loosening.

Each union bolt 34 has a corresponding first and second connection boss.
T-shaped oil passage 35 communicating with the output ports 13 ₁ and 13 ₂ of 3 ₁ and 3 _2.
And an annular groove 36, also in the ears 33 _1, 33 _2, first communicates a corresponding annular groove 36 in the cylinder bore 32a of the cylinder portion 32
The first and second inflow ports 37 ₁ and 37 ₂ are drilled.

The cylinder hole 32a of the cylinder part 32 is open at one end, and the open end is closed by a screw plug 38. First and second pressure receiving piston 39 ₁ of the same diameter to one another in the cylinder bore 32a,
39 ₂ is slidably fitted through the seal members 60 ₁ and 60 ₂ .

Small cylinder holes 40 ₁ and 40 ₂ having the same diameter are formed in the pressure receiving pistons 39 ₁ and 39 ₂ , respectively.
Valve moving pistons 41 ₁ and 41 ₂ whose backs are in contact with each other are fitted to 40 ₁ and 40 ₂ via slidable members 61 ₁ and 61 _{2 so} as to be slidable. A common pressure adjusting spring 43 is contracted between the pressure receiving pistons 39 ₁ and 39 ₂ via spacers 42 ₁ and 42 ₂ . Each of the spacers 42 ₁ and 42 ₂ has a flange portion 42 a that is sandwiched between the pressure receiving pistons 39 ₁ and 39 ₂ and the pressure adjusting spring 43 at its outer end, and faces the outer end surface of each flange portion 42 a. The shoulders 41a on the outer circumference of the valve moving pistons 41 ₁ and 41 _2.
Are formed respectively.

In both small cylinder holes 40 ₁ and 40 ₂ , the valve moving piston 41
The first and second input hydraulic chambers 44 ₁ , 44 _{2 are formed} by the outer ends of ₁ , 41 ₂ , respectively.
However, both pressure receiving pistons 3 are attached to both ends of the cylinder hole 32a.
Due to the outer ends of 9 ₁ and 39 ₂ , the first and second output hydraulic chambers 45 ₁ and 45 ₂
Respectively, and the pressure receiving area on the output hydraulic chamber 45 ₁ , 45 ₂ side of each pressure receiving piston 39 ₁ , 39 ₂ is the input hydraulic chamber 4
4 _1, which is larger than the pressure receiving area of 44 ₂ side.

_On the end walls of the small cylinder holes 40 ₁ and 40 ₂ are formed valve holes 47 ₁ and 47 ₂ which communicate between the adjacent input and output hydraulic chambers 44 ₁ 45 _{1 and} between 44 ₂ and 45 ₂ , respectively. These valve holes 47 ₁ and 47 ₂ are provided at the outer ends of the valves 48 ₁ and 48 ₂ , respectively, so as to project from the valve opening rods 49 ₁ and 49 _{2 respectively.}
Can be penetrated.

Valve springs 50 ₁ and 50 ₂ are respectively provided between the valves 48 ₁ and 48 ₂ and the valve moving pistons 41 ₁ and 41 ₂ in a contracted manner, and normally the valve opening rods 49 _{1 of the} valves 48 ₁ and 48 ₂ are opened. , 49 ₂ abuts the respective end wall and the inner end of the screw plug 38 of the cylinder bore 32a, holds the valve 48 _1, 48 ₂ in the open position in the pressure-receiving pistons 39 _1, 39 ₂ of the outer sliding limit It is supposed to do. And each pressure receiving piston
39 _1, 39 ₂ is moved inward, the valve 48 _1, 48 ₂ into the small cylinder hole 40 _1, 40 ₂ of the end wall is seated, the valve hole 47 _1, 47 ₂ are closed.

Connectors 51 ₁ and 51 ₂ are integrally connected to the inner ends of the valves 48 ₁ and 48 ₂ , respectively. The inner ends of these connectors 51 ₁ , 51 ₂ are stoppers 52 provided on the outer ends of the pistons 41 ₁ , 41 ₂ when the valve moving pistons 41 ₁ , 41 ₂ move inward by a predetermined distance l _2. It is designed to engage with ₁ and 52 ₂ . This distance l ₂ is larger than the distance l ₁ over which the pressure receiving pistons 39 ₁ , 39 ₂ move from the valve opening position of the valves 48 ₁ , 48 _{2 to} the valve closing position, and larger than this distance l ₁ , and this distance l ₁ When,
Valve moving pistons 41 ₁ and 41 ₂ from the neutral position to spacer 42
It is set to be smaller than the sum of the distance l _{3 of 1} and 42 ₂ moving to the position where it abuts the flange 42a. That is the _{l 1 <l 2 <l 1} + l 3.

A drain hole 53 is provided in a side wall of an intermediate portion of the housing 31, which accommodates the pressure adjusting spring 43, and a discharge pipe connected to the oil drain hole 53.
62 is fixed to the housing 31.

On the other hand, as clearly shown in FIG. 5, an empty oil sump 63 made of a translucent synthetic resin is installed near the master cylinder 2 in the normal state, and in the illustrated example, it is integrally formed on one side of the main oil sump 22. It is formed.
An introduction pipe 64 is formed integrally with the oil sump 63, and the introduction pipe 64 and the discharge pipe 62 are connected via a tube 65. The oil sump 63 has a cap 63a at the top.

Referring again to FIG. 3, the first and second input hydraulic chambers 44 ₁ , 4
4 ₂ includes the first and second inflow ports 37 ₁ and 37 ₂ and the first and second outflow ports 46 ₁ and 46 ₂ formed in the third and fourth connection bosses 3 ₃ and 3 _4. Are known to each other. The first inflow port 37 ₁ and the first outflow port 46 ₁ and the second inflow port 37 ₂ and the second outflow port 46 ₂ are coaxially arranged so that they can be drilled by the same drilling tool. And the third and fourth
The connection bosses 3 ₃ and 3 ₄ have first and second outflow ports 46 ₁ and 46 _{2 respectively.}
The conduits 5 ₁ and 5 ₂ communicating with the right and left front wheel brakes Bfr and Bfl are connected by flare bolts 57 and 57, respectively.

In addition, the first and second output hydraulic chambers 45 ₁ and 45 ₂ have the above-mentioned fifth
And sixth connecting boss 3 _5, 3 ₆ the third and fourth outlet ports 46 ₃ are formed in, 46 ₄ lead. And the fifth and sixth connection bosses
3 ₅ and 3 ₆ have conduits 5 ₃ and 5 _{4 connecting} the third and fourth outflow ports 46 ₃ and 46 ₄ to the left and right rear wheel brakes Brl and Brr, respectively.
Are connected by flare bolts 58, 58, respectively.

Next, the operation of this embodiment will be described. When the master cylinder 2 is not in operation, both the first and second pressure receiving pistons 39 ₁ and 39 ₂ in the rear wheel braking hydraulic control device 6 are both pressure adjusting springs.
The set load of 43 is pressed to the outer sliding limit shown in FIG. 3, the valves 48 ₁ and 48 ₂ are open, respectively, and the first and second input / output hydraulic chambers 44 ₁ and 45 _{1 are connected to} each other. 44 _2, 45 ₂ between the in each communicating state.

If you operate the booster 1 and drive the master cylinder 2 with its output rod 1a, both front and rear pistons 12
_The hydraulic pressure generated in the first and second hydraulic chambers 11 ₁ and 11 ₂ by the forward movement of ₁ and 12 ₂ is output from the first and second output ports 13 ₁ and 13 ₂ , and the first and second inflow ports 37 ₁ , 37 ₂ and input to the first and second input hydraulic chambers 44 ₁ , 44 ₂ of the rear wheel braking hydraulic control device 6, respectively.

On the one hand, the hydraulic pressure input to the first and second input hydraulic chambers 44 ₁ and 44 ₂ passes straight through the input chambers 44 ₁ and 44 ₂ , and the first and second outflow ports 46 ₁ and 46 ₂ and the hydraulic conduit 5 _The signal is transmitted to the right and left front wheel brakes Bfr, Bfl via ₁ and 5 ₂ to operate them. On the other hand, on the other hand, the valve holes 47 ₁ , 47 ₂ , the first and second output hydraulic chambers
45 ₁ , 45 ₂ , the third and fourth outflow ports 46 ₃ , 46 ₄ and the hydraulic conduits 5 ₃ , 5 ₄ are sequentially transmitted to the left and right rear wheel brakes Brl, Brr to operate them.

Then, as the output hydraulic pressure of the master cylinder 2 increases,
The pressure in the first and second input / output hydraulic chambers 44 ₁ , 44 ₂ ; 45 ₁ , 45 ₂ also rises, but when the pressure reaches a certain value, the first and second pressure receiving pistons 39 ₁ , 39 ₂ The differential hydraulic pressure acting on each pressure receiving piston 39 ₁ , 39 ₂ becomes larger than the set load of the pressure adjusting spring 43 due to the difference in the pressure receiving area on the inside and the outside of the first and second pressure receiving pistons 39 ₁ , 39 ₂ . Each of the pressure adjusting springs 43 moves inward while being compressed, and when the moving distance reaches l ₁ , the valves 48 ₁ and 48 ₂ close the valve holes 47 ₁ and 47 ₂ . As a result, the hydraulic pressure in the output hydraulic chambers 45 ₁ and 45 ₂ , that is, the rear wheel brakes Brl and Brr.
The increase of the braking hydraulic pressure of is stopped.

Further the output hydraulic pressure of the master cylinder 2 is increased, the pressure in the input hydraulic pressure chamber 44 _1, 44 in ₂ rises, the pressure receiving piston 39
Push ₁ , 39 ₂ outward. Therefore, the valves 48 ₁ , 48 ₂
Opens again and increases the pressure in the output hydraulic chambers 45 ₁ , 45 ₂ . It reaches a certain value the pressure, operating the first and second pressure receiving piston 39 _1, 39 ₂ again, the valve hole 47 _1, 47 ₂ is closed, is stopped increasing its pressure. By repeating such an operation, the braking oil pressure of each rear wheel is the output oil pressure of the master cylinder 2 reduced at a constant ratio.

On the other hand, since the output hydraulic pressure of the master cylinder 2 directly acts on the front wheel brakes Bfl and Bfr by passing through the input hydraulic chambers 44 ₁ and 44 ₂ , the braking hydraulic pressure of the front wheels increases as the output hydraulic pressure of the master cylinder 2 increases. Increase rapidly. In this way, when braking strongly, the brake Brl, Bfr is strongly applied to the front wheel on the side where the vehicle body leans forward and the downward load increases.
For the rear wheel where the load decreases, the brake Brf,
Since Brr is actuated weakly, efficient braking can be performed.

Then, one of the strains of the braking hydraulic circuit, for example a hydraulic circuit of the second output port 13 ₂ side by failure, and the braking hydraulic pressure to the left front wheel brake Bfl and the right rear wheel brake Brr no longer applied. If the booster 1 is operated at this time, only the output hydraulic pressure from the left and right first output ports 13 ₁ of the master cylinder 2 becomes effective.

Thus, according to the output hydraulic pressure from the first output port 13 ₁ , the pressure in the first input hydraulic chamber 44 ₁ rises, but the pressure in the second input hydraulic chamber 44 ₂ does not rise. Therefore, the valve moving pistons 41 ₁ and 41 ₂ are both rearward (to the right in FIG. 3).
To move the front valve moving piston 41 ₁ to the spacer 42 ₁
Abutting on the flange portion 42a of. Then, the valve moving piston 41 ₁ compresses the pressure adjusting spring 43 via the spacer 42 ₁ as the valve moving piston 41 ₁ moves.

As a result, the pressing force is not applied by the pressure control spring 43 to the first pressure receiving piston 39 _1, the pressure receiving piston 39 ₁
Are moved inward or backward by the differential pressure from the inside and outside.

When the valve moving piston 41 ₁ moves backward by a predetermined distance l ₂ , the stopper 52 ₁ at its outer end engages with the inner end of the connector 251 ₁ and moves the valve 48 ₁ inward. Distance l ₂ is l ₁
Since it is set to be smaller than + l ₃ , the valve 48 ₁ is separated from the end wall of the small cylinder hole 40 ₁ during this period, and the valve open state is maintained.

Thus, in the valve moving piston 41 ₁ , the valve 48 ₁ , and the first pressure receiving piston 39 ₁ , the inner end of the spacer 42 ₁ is the other spacer.
42. Move inward to the position where it abuts the inner end of ₂ .

In the state where the valve moving piston 41 ₁ moves to the innermost side and the inner ends of the spacers 42 ₁ and 42 ₂ are in contact with each other, the first
The inner end of the pressure receiving piston 39 ₁ also has a flange portion of the spacer 42 ₁ .
Although it has moved to a position where it abuts against 42a, at this time, since the stopper 52 ₁ is engaged with the inner end of the connector 51 ₁ , the valve 48 ₁ continues to open the valve hole 47 ₁ . Therefore, the output hydraulic pressure from the first output port 13 ₁ of the master cylinder 2 is directly transmitted to the first output hydraulic pressure chamber 45 ₁ , and the first output port 13 ₁
The rear wheels of this system will be braked with the same strength as the front wheels. That is, when one of the systems fails, the rear wheel braking hydraulic control device 6 operates without reducing the braking hydraulic pressure of the rear wheels. Therefore, the rear wheel braking hydraulic control device 6 has a bypass function. It has been granted. In this case, when the oil level in the main oil sump 22 drops to the specified level L, an alarm is issued by the operation of the oil level detection device 24.

Also if ₁ the first and second pressure receiving piston 39, 39 ₂ of the seal member 60 _1, 60 ₂ of either one, or valve displacing piston 41 _1, 41 ₂ of the seal member 60 _1, 60 ₂ of one wear if damage, the input hydraulic pressure chamber 44 ₁ or 44 ₂ of the hydraulic oil is the wear, leak through the damaged portion to the discharge hole 53, and outlet pipe 62, the oil discharge reservoir 63 through tube 65 and inlet tube 64 Sent.

The drain oil sump 63 is formed integrally with the main oil sump 22 of the master cylinder 2 and has a light-transmitting property, so that when the master cylinder 2 is inspected, for example, when the amount of oil in the main oil sump 22 is checked,
By looking at the drainage sump 63, even a small amount of oil accumulated at the bottom can be seen through, and thus wear and damage of the seal member can be known at an early stage.

After repairing the worn and damaged parts, in order to drain the oil from the oil sump 63, the cap 63a is removed and the oil is sucked by an appropriate suction device inserted into the oil sump 63 from above, or the tube 65 is used.
Is removed from the outlet pipe 62, and the oil in the oil sump 63 is discharged to an appropriate container through the tube 65. In this way, it is possible to avoid the contamination of peripheral devices due to oil drainage.

Be returned then the master cylinder 2 so as to release the braking inoperative state, the input hydraulic pressure chamber 44 _1, 44 ₂ along with it since the reduced pressure, the front wheel brake Bfr, actuation of Bfr is released immediately.

On the other hand, if the pressure receiving pistons 39 ₁ and 39 ₂ are in the inward moving position and the valves 48 ₁ and 48 ₂ are closed at this time, the hydraulic pressure of the output hydraulic chambers 45 ₁ and 45 ₂ is the input hydraulic chamber 44 ₁ , 44 ₂ is relatively higher than the hydraulic pressure, but such input and output hydraulic chambers 44 ₁ , 45 ₁
Valve 48 _1, 48 ₂ by and between 44 _2, 45 the pressure difference between the _two is opened to open the valve hole 47 _1, 47 _2. As a result, the output hydraulic chambers 45 ₁ and 45 ₂ can also be depressurized to release the operation of the rear wheel brakes Brl and Brr.

C. Effect of the Invention As described above, according to the present invention, an empty light-transmitting oil sump is installed in the vicinity of the master cylinder in normal times, and this oil sump holds the housing of the rear wheel braking hydraulic control device. Since the drain hole is connected, you can see through the oil sump when you check the master cylinder, and simply check for oil in the oil sump.
Whether or not the hydraulic oil is leaking from the housing can be easily and quickly detected. Therefore, if hydraulic oil is leaking from the housing, the oil level in the oil sump of the master cylinder will be abnormally lowered. Previously, the situation of the leak can be detected early, so that the response such as repair can be taken early, and the leaked oil can be stored in the drain sump, so that the leaked oil can be stored. It is also effective in preventing stains on surrounding equipment.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a plan view of a two-system hydraulic braking system for an automobile, FIG. 2, FIG.
4 and 5 are lines II-II, III-III, and IV of FIG.
FIG. 7 is an enlarged cross-sectional view taken along line −IV and line VV. Bfl …… left front wheel brake, Bfr …… right front wheel brake, Brl
...... Left rear wheel brake, Brr …… Right rear wheel brake, 2 …… Master cylinder, 6 …… Rear wheel braking hydraulic control device,
13 ₁ , 13 ₂ …… First and second output ports, 31 …… Housing,
39 ₁ , 39 ₂ …… First and second pressure receiving pistons, 43 …… Pressure adjusting spring,
44 ₁ , 44 ₂ …… First and second input hydraulic chambers, 45 ₁ , 45 ₂ …… First and second output hydraulic chambers, 48 ₁ , 48 ₂ …… Valve, 53 …… Discharge hole, 62
…… Outlet pipe, 63 …… Oil sump, 64 …… Introduction pipe, 65 …… Tube

Claims (1)

[Scope of utility model registration request] _1. A tandem master cylinder (2) having first and second output ports (13 ₁ , 13 ₂ ) independent of each other.
The rear wheel braking hydraulic control device (6) housing (3
1) is connected to the housing (31), and first and second pressure receiving pistons (39 ₁ , 39 ₂ ) coaxially arranged are slid on each other,
On the inner end side of these pressure receiving pistons (39 ₁ , 39 ₂ ), the first
And the first and second input hydraulic chambers (44 ₁ , 44 ₂ ) communicating with the second output ports (13 ₁ , 13 ₂ ), respectively, and on the outer end side,
First and second output hydraulic chambers (45 ₁ , 45 ₂ ) communicating with the left and right rear wheel brakes (Brl, Brr) are formed, and each output hydraulic chamber (45 ₁ , 45 ₂ ) of each pressure receiving piston (39 ₁ , 39 ₂ ) is formed. The pressure receiving area on the ₁ , 45 ₂ ) side is set to be larger than that on the input hydraulic chamber (44 ₁ , 44 ₂ ) side, and the adjacent input and output hydraulic chambers (44 ₁ , 45 ₁ ; 44 ₂ , 4
5 ₂ ) communicate with each other through the valves (48 ₁ , 48 ₂ ) that open at the outer sliding limit of each pressure receiving piston (39 ₁ , 39 ₂ ) and close at the time of inward sliding. the piston (39 _1, 39 ₂₎ under compression of the pressure regulating spring (43) between said on the housing (31), discharge holes for releasing the space between both the pressure receiving piston (39 _1, 39 ₂₎ to the outside ( Five
In a two-system hydraulic braking system for automobiles provided with 3), a light-transmitting oil sump (63) that is empty in normal time is installed near the master cylinder (2), and this oil sump (63) The discharge hole (53) of the housing (31) is connected to
Two-system hydraulic braking system for automobiles.