JPH0147334B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a dual master cylinder to
A brake hydraulic pressure control device for a vehicle braking system, which has a brake hydraulic circuit configured into two independent systems, in particular a brake hydraulic pressure system that supplies hydraulic pressure lower than the front wheel brake hydraulic pressure as the rear wheel brake hydraulic pressure. This relates to a control device.

Conventionally, as shown in FIG.
Mutually independent first and second flow paths L ₁ and L ₂ extending from the output side of the dual master cylinder M are connected to the hydraulic operating parts of the rear wheel brakes Bf, Br' and Bf', Br, respectively. There are some types of In this type of braking system, during heavy braking, each rear wheel brake hydraulic pressure is automatically reduced at a fixed ratio to the front wheel brake hydraulic pressure of the same system, and the load on the rear wheels is reduced by tilting the vehicle forward. In order to obtain efficient braking even when the vehicle is in use, a common brake hydraulic control device C is provided between the first and second flow paths L ₁ and L ₂ on the way to the rear wheel brakes Br and Br'. is known, and its device C
A common housing is interposed in the middle of the first and second flow paths, a pair of left and right pressure receiving pistons are slid into cylinder holes in the housing, and the first and first and second input hydraulic chambers each communicating separately upstream of the second flow path,
Further, first and second output hydraulic chambers are formed on the outer end side, respectively, and communicate with the downstream side of both flow paths, and the pressure receiving area of each pressure receiving piston on the side of each output hydraulic chamber is adjusted to the side of each input hydraulic chamber. The pressure receiving area is larger than that of the pressure receiving area, and the adjacent input and output hydraulic chambers are communicated via a valve that opens at the outward sliding limit of each pressure receiving piston and closes when it slides inward. It has a configuration in which a common pressure regulating spring is compressed between the pistons.

By the way, in such a brake hydraulic control device, if the sliding parts of both the left and right pressure receiving pistons are worn out or damaged, and the first and second flow paths communicate with each other through the inside of the housing,
Naturally, the brake hydraulic circuit loses the function of two systems, so
In this state, if an oil leakage failure occurs somewhere in the brake hydraulic circuit, the entire brake hydraulic circuit becomes inoperable. Therefore, when the sliding part of one of the pressure receiving pistons becomes worn or damaged, this condition can be
It is desirable to quickly detect a failure in the system's hydraulic circuit and repair the failure before it causes wear or damage to the sliding portion of the remaining pressure-receiving piston.

The object of the present invention is to provide a simple and effective braking hydraulic control device that can meet such demands.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
As shown in the figure, it is configured in a tandem type. That is, in the cylinder hole 1a of the cylinder body 1,
A pair of front and rear first and second pistons 2 ₁ , 2 ₂ sliding thereon define first and second hydraulic chambers 3 ₁ , 3 ₂ independently of each other, and a rear second piston 2 ₂ is connected to a brake pedal P. are connected to each other, and when this brake pedal P is actuated, the first and second pistons 2
₁ and 2 ₂ pressurize the first and second hydraulic chambers 3 ₁ and 3 ₂ , respectively, and supply pressure oil to the first and second flow paths L ₁ and L ₂ . This pressure oil is guided to the front wheel brakes Bf, Bf' and the brake hydraulic control device C.

The brake hydraulic control device C is configured symmetrically, and the housing 5 includes a pair of left and right cylinder holes 7 ₁ , 7 ₂ , and a hole located between the two cylinder holes 7 ₁ , 7 ₂ with a larger diameter. Diameter holes 8 ₁ and 8 ₂ are formed, and pressure receiving pistons 9 ₁ and 9 ₂ having the same diameter are slid into each cylinder hole 7 ₁ and 7 ₂ , respectively. Each pressure receiving piston 9 ₁ , 9 ₂ has a small cylinder hole 1 with the same diameter.
0 ₁ and 10 ₂ are formed, and valve moving pistons 11 ₁ and 11 ₂ whose back surfaces abut each other are slid into these small cylinder holes 10 ₁ and 10 ₂ , respectively. A common strong pressure regulating spring 12 is compressed between both the pressure receiving pistons 9 ₁ and 9 ₂ , and between both the valve moving pistons 11 ₁ and 11 ₂ , each piston 11 ₁ ,
11 ₂ shoulders 13 ₁ , 13 ₂ and small cylinder hole 10
₁ , 10 ₂ , the outer shoulder portions 14 ₁ , 14 ₂ and 15 ₁ ,
Washers 16 ₁ and 16 2 that can come into contact with 15 ₂ and 16 1 and 16 ₂ respectively
A relatively weak coiled positioning spring 17 is compressed through the coil.

First and second input hydraulic chambers 18 ₁ , 18 ₂ are connected to the outer ends of the valve moving pistons 11 ₁ , 11 ₂ in both small cylinder holes 10 ₁ , 10 ₂ , and both cylinder holes 7 ₁ , 7 ₂ includes pressure receiving pistons 9 ₁ , 9 ₂
The first and second output hydraulic chambers 19 ₁ ,
19 ₂ are respectively defined, and these first and second input hydraulic chambers 18 ₁ , 18 ₂ have inflow ports 20 ₁ ,
Upstream of the first and second flow paths L ₁ , L ₂ via 20 ₂ are also connected to the first and second output hydraulic chambers 19 ₁ , 1
9 ₂ has both flow paths via outflow ports 21 ₁ and 21 ₂
The downstream sides of L ₁ and L ₂ are connected so that they are always in communication with each other.

The end walls of the small cylinder holes 10 ₁ and 10 ₂ are provided between adjacent input and output hydraulic chambers 18 ₁ and 19 ₁ and between the adjacent input and output hydraulic chambers 18 1 and 18 ₂ , 1
Communication holes 22 ₁ , 22 ₂ are provided to communicate between the valve opening rods _{24 1} , ₂₄ , which project from the outer ends of the valves _{23 1 ,} 23 ₂ , respectively. ₂ can penetrate. Each valve 23 ₁ , 23 ₂ and valve moving piston 11 ₁ ,
Closing springs _{25 1 and} 25 ₂ are respectively compressed between the valves 11 and 11 2 , and normally the opening rods 24 ₁ and 24 ₂ of the valves 23 ₁ and 23 ₂ are connected to the end walls of the cylinder holes 7 ₁ and 7 ₂ . The valves 23 ₁ and 23 ₂ are held in the open position at the outward sliding limit of each pressure receiving piston 9 ₁ and 9. When the pressure receiving pistons 9 ₁ , 9 ₂ move inward and the end walls of the small cylinder holes 10 ₁ , 10 ₂ come into contact with the valves 23 ₁ , 23 ₂ , the communication holes 22 1 , 23 ₂ come into contact with each other.
22 ₂ is occluded.

Connectors 26 ₁ and 26 ₂ are attached to the inner ends of each valve 23 ₁ and 23 ₂ , respectively. The inner ends of these connectors 26 ₁ , 26 ₂ are connected to stoppers provided at the outer ends of the valve moving pistons 11 ₁ , 11 ₂ when the pistons 11 ₁ , 11 ₂ move inward by a predetermined distance l ₂ . 27 ₁ and 27 ₂ . This distance l ₂ is equal to the distance between the valves 23 ₁ ,
The distance l 1 that the pressure receiving pistons 9 ₁ , 9 ₂ move from the valve opening position to the valve closing position of 23 ₂ is greater than the distance l ₁ and the washers 16 1 , ₁₆ with respect to this distance l ₁ and the small cylinder holes 10 ₁ , 10 ₂ . ₂ is smaller than the sum of the possible distance l and ₃ . Note that the distance l ₃ is such that the valve moving pistons 11 ₁ and 11 ₂ are connected to the small cylinder holes 10 ₁ and 1
0 ₂ , these pistons 11 ₁ , 1
1 ₂ Either one of the seal members 31 ₁ , 31 ₂ attached to the outer periphery is the corresponding small cylinder hole 10 ₁ or 1
0 ₂ .

The housing 5 includes both pressure receiving pistons 9 ₁ and 9 ₂
It is composed of a pair of left and right housing halves 5 ₁ and 5 ₂ that are separably joined between the sliding parts of the cylinder holes 7 ₁ and 7 ₂ , that is, between the two cylinder holes 7 1 and 7 2 .
₁ and 5 ₂ are bolts 3 via connecting flanges 6 ₁ and 6 ₂
2 and a nut 33. A small hole 28 communicating with the outside is provided at the joint between these housing halves 5 ₁ and 5 ₂ , and a one-way seal member 29 is attached to an annular seal housing 34 formed inside this joint. This seal member 29 has a one-way flow function that prevents dust and the like from entering from the outside, but allows hydraulic oil to flow from the inside into the small hole 28 .

In addition, in Fig. 2, 30 ₁ and 30 ₂ are pressure receiving pistons 9.
This is a sealing member attached to the sliding portion of each cylinder hole 7 ₁ , 7 ₂ on the outer periphery of the cylinder hole 7 1 _, 9 ₂ .

As shown in FIG. 3, the master cylinder M is equipped with an oil tank R for storing hydraulic oil.
It consists of a cylindrical auxiliary oil reservoir 35 integrally protruding adjacent to the hydraulic chamber ₃₂ , and a transparent synthetic resin main oil reservoir 36 whose lower end is fitted and connected to the outer periphery of the auxiliary oil reservoir 35, The main oil sump 36 has a larger volume than the auxiliary oil sump 35, and a cylindrical filter 37 for filtering hydraulic oil is installed in the main oil sump 36, and an elastic cap 38 is fitted into the open upper end of the cylindrical filter 37. Installed by.

The auxiliary oil reservoir 35 is internally partitioned into a first oil reservoir chamber 35a and a second oil reservoir chamber 35b by a partition wall 39 that is integrated with the cylinder body 1, and both oil reservoir chambers 35a, 35b.
both communicate with the main oil sump 36. The second oil reservoir chamber 35b is arranged near the front end of the second piston ₂₂ ,
A relief hole 40 ₂ and a supply hole 41 ₂ for the second hydraulic chamber 3 ₂ are bored in the bottom surface thereof.

On the other hand, the cylinder body 1 is located in front of the auxiliary oil reservoir 35.
A thick upper wall 1b continues, and on the upper wall 1b,
A cylindrical oil chamber 42 disposed near the front end of the first piston ₂₁ and an oil passage 43 communicating it with the first oil reservoir chamber 35a are provided, and the bottom surface of the oil passage 42 is provided with a first oil pressure chamber 3. A relief hole 40 ₁ and a replenishment hole 41 ₁ are drilled for ₁ .

The main oil reservoir 36 is provided with an oil level detection device A that is activated when the oil level F of the hydraulic oil stored therein drops below a specified level L. This device A includes a switch cylinder 47 that protrudes from the lower surface of the cap 38 and plunges deeply into the main oil reservoir 36, and a switch cylinder 47 that
a magnetically sensitive reed switch 48 housed in the interior and installed at the specified level L; and a switch cylinder 47.
An annular float 50 is fitted around the outer periphery of the reed switch 48 so as to be freely raised and lowered, and a magnet 49 that can close the reed switch 48 is embedded inside the annular float 50.
An alarm device (not shown) such as a lamp, which is activated when the door is closed, is connected through a lead wire 51.
Further, a stopper 52 is provided at the lower end of the switch cylinder 47 to prevent the float 50 from descending below near the specified level L.

When an appropriate amount of hydraulic oil is stored in the main oil reservoir 36 and the oil level F is higher than the specified level L, the float 50 floating on the oil level F is activated by the reed switch as shown by the solid line. 48, the reed switch 48 is not affected by the magnetic force of the magnet 49 of the float 50 and remains open. Therefore, an alarm (not shown) connected to the lead wire 51 is not activated.

However, if an oil leakage failure occurs in the hydraulic circuit of the first hydraulic chamber 3 ₁ system, that is, in the first flow path L ₁ , then the main oil sump 36 and the first oil sump 35
Although the hydraulic oil in the oil reservoir chamber 35a is depleted, the hydraulic oil remains in the second oil reservoir chamber 35b of the auxiliary oil reservoir 35. Therefore, during braking operation, the pressure in the second hydraulic chamber ₃₂ is increased. The hydraulic circuit of the system, that is, the second flow path L ₂
can operate normally.

In this case, when the oil level F of the main oil reservoir 36 drops to the specified level L, the float 50 descends along the switch tube 47 to the chain line position, and the magnet 49
approaches the reed switch 48 and closes it, so that 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 50 is received by the stopper 52 and held near the specified level L, so that the closed state of the reed switch 48, that is, the alarm state can be maintained.

If the hydraulic circuit of the system of the second hydraulic chamber ₃₂ fails, the same effect as described above will occur, except that hydraulic oil remains in the first oil reservoir chamber 35a of the auxiliary oil reservoir 35.

Next, to explain the operation of the brake hydraulic control device C of the present invention, when the master cylinder M is not in operation, both the left and right pressure receiving pistons 9 ₁ and 9 ₂ are connected to the pressure regulating spring 1
2 and the positioning spring 17 to the outward sliding limit shown in the figure, the valves 23 ₁ and 23 ₂ are open, respectively, and a gap between the first and second input and output hydraulic chambers 18 ₁ and 19 ₁ is opened. and 18 ₂ and 19 ₂ are in communication with each other. Therefore, when the brake pedal P is operated here, the output hydraulic pressure of the master cylinder M is transmitted downstream of the first and second flow paths L ₁ and L ₂ , and the front and rear wheel brakes Bf, Bf' and Br are , Br′ operate simultaneously.

Then, as the output oil pressure of the master cylinder M increases, the first and second input and output oil pressure chambers 18 ₁ , 19 ₁
The pressure inside the pressure receiving pistons 9 ₁ , 19 ₂ also rises, but when the pressure reaches a certain value, the difference in the pressure receiving areas between the inner and outer ends of the pressure receiving pistons 9 ₁ , 9 _{2 increases} .
The differential hydraulic pressure acting on the pressure regulating _{spring 12} and the positioning spring 17 becomes larger than the set load of the pressure regulating spring 12 and the positioning spring 17, and the pressure receiving pistons ₉₁ and ₉₂ slide inward while compressing the pressure regulating spring 12 and the positioning spring 17, respectively. move. On the other hand, at this time, each valve moving piston 11 ₁ , 11 ₂
Since approximately equal oil pressure is applied to the outer ends of the pistons 11 ₁ and 11 2 , these pistons 11 1 and 11 ₂ do not move, and the springs 25 ₁ and ₂ close each valve 23 ₁ and 23 2 .
5 ₂ to keep the valve opening rods 24 ₁ , 24 ₂ in contact with the end walls of the cylinder holes 7 ₁ , 7 ₂ . Therefore, when each pressure receiving piston 9 ₁ , 9 ₂ moves inward by a distance l ₁ , the valves 23 ₁ , 2
3 ₂ closes the communicating holes 22 ₁ and 22 ₂ . During this period, the braking oil pressure for the rear wheels does not increase.

When the output hydraulic pressure of the master cylinder M further increases, the pressure within the input hydraulic chambers 18 ₁ and 18 ₂ increases, pushing each pressure receiving piston 9 ₁ and 9 ₂ outward.
Therefore, the valves 23 ₁ , 23 ₂ open again, increasing the pressure in the output hydraulic chambers 19 ₁ , 19 ₂ . When this pressure reaches a certain value, the pressure receiving piston 9 ₁ ,
9 ₂ is activated again, the communication holes 22 ₁ and 22 ₂ are closed, and the increase in pressure is stopped. By repeating these actions, the braking oil pressure for each rear wheel gradually increases.

On the other hand, since the output hydraulic pressure of the master cylinder M directly acts on the front wheel brakes Bf, Bf', the front wheel braking hydraulic pressure increases rapidly as the output hydraulic pressure of the master cylinder M increases. In this way, when braking is applied strongly, the front wheel brakes Bf and Bf′ are applied more strongly to the front wheel on the side where the vehicle body leans forward and the downward load increases.
Rear brake for the rear wheel on the side where the load is reduced
Since Br and Br' are operated weakly, efficient braking can be performed without causing skids in each wheel.

Next, it is assumed that there is an oil leakage failure in one of the systems of the brake hydraulic circuit, for example, the second flow path _L2 , and the brake hydraulic pressure is no longer applied to the hydraulically operating part of the rear wheel brake Br'. At this time, when the brake pedal P is operated, the output hydraulic pressure of the master cylinder M is transferred to the first flow path.
L ₁ only, the first input hydraulic pressure chamber 18 ₁
However, the pressure within the second input hydraulic pressure chamber 18 ₂ does not increase. Therefore, both the valve moving pistons 11 ₁ and 11 ₂ move to the right in the figure,
The washer 16 ₁ is the inner shoulder part 14 ₁ of the small cylinder hole 10 ₁
engage with. And valve moving piston 11 ₁
moves the pressure receiving piston 9 ₁ inward. When the valve moving piston 11 ₁ moves a predetermined distance l ₂ , the stopper 27 ₁ at its outer end engages with the inner end of the connector 26 ₁ and moves the valve 23 ₁ inwardly.
Since the distance l ₂ is smaller than l ₁ +l ₃ , the valve 23 ₁ is separated from the end wall of the small cylinder hole 10 ₁ during this period and maintains its open state. In this way, the valve moving piston 11 ₁ , the pressure receiving piston 9 ₁ , and the valve 23 ₁ move inward to a position where the inner end of the pressure receiving piston 9 ₁ abuts the inner end of the other pressure receiving piston 9 ₂ .

When the pressure receiving pistons 9 ₁ and 9 ₂ are in contact with each other, the valve moving piston 11 ₁ is pressed inward by the hydraulic pressure in the first input hydraulic pressure chamber 18 ₁ .
Washer 16 ₁ is inside shoulder _{14 1} of small cylinder hole 10 1
The stopper 27 ₁ of the valve moving piston 11 ₁ remains engaged with the inner end of the connector 26 ₁ . Therefore, at this time, the valve 23 ₁ opens the communication hole 22 ₁ . As a result, the output hydraulic pressure of the master cylinder M is directly transmitted to the first output hydraulic chamber ₁₉₁ , the front and rear wheel brakes Bf' and Br of the system of the first flow path _L1 operate with the same strength, and the brakes of other systems operate with the same strength. This compensates for the lack of braking power due to the inoperation of the brake. That is, this brake hydraulic control device C is provided with a bypass function.

Of course, at the time of this failure, the oil level F in the oil tank R drops abnormally as described above, and an alarm is issued by the operation of the oil level detection device A.

In addition, if either the left or right pressure receiving piston 9
Seal member 30 ₁ , 3 attached to the outer periphery of ₁ , 9 ₂
0 ₂ or wear of the seal members 31 ₁ , 31 ₂ attached to the outer periphery of the valve moving pistons 11 ₁ , 11 ₂ ,
If the hydraulic oil leaks from the input hydraulic chambers 18 ₁ , 18 ₂ into the large diameter holes 8 ₁ , 8 ₂ due to damage, the hydraulic oil will flow out through the one-way seal member 29 and the small holes 28 . , an oil leak failure occurs in one of the flow paths L ₁ and L ₂ , and the oil level in the oil tank R similarly drops abnormally, and an alarm is issued by the operation of the oil level detection device A.

In the above embodiment, the valve moving pistons 11 ₁ and 11 ₂ are constructed as separate bodies, but they may be constructed as one piece as long as there is no problem with machining accuracy.

As described above, according to the present invention, the housing that accommodates the pair of left and right pressure receiving pistons is composed of a pair of housing halves that are separably joined at the middle of each sliding portion of both pressure receiving pistons, and these housing halves are separably joined. A small hole that communicates the inside and outside of the joint is provided at the joint of the body, and a one-way seal member is installed inside the joint to allow hydraulic fluid to flow from the inside to the small hole. The sealing function of the parts prevents external dust from entering the housing through the small holes, but in the unlikely event that the sliding part of either the left or right pressure receiving piston becomes worn or damaged. , the hydraulic oil leaking from the worn or damaged parts can be allowed to flow out through the one-way seal member and the small holes, resulting in an abnormal drop in the oil level in the master cylinder's oil tank.
This failure condition can be detected, and the sliding part of the other pressure-receiving piston may also be worn out or damaged, causing the braking hydraulic circuit to fail.
Both systems can be repaired before they become inoperable.

Furthermore, only one one-way sealing member installed inside the joint of both housing halves is sufficient for both pressure-receiving pistons, which has advantages such as a simple structure and easy installation.

[Brief explanation of drawings]

Fig. 1 is a two-system hydraulic circuit diagram of an automobile braking system, Fig. 2 is a longitudinal cross-sectional plan view of essential parts showing an embodiment of the device of the present invention, and Fig. 3 is an enlarged view of the dual-system master cylinder in Fig. 2. It is a longitudinal side view of the main part. Bf, Bf'...Front wheel brake, Br, Br'...Rear wheel brake, C...Brake hydraulic control device, _L1 , _L2 ...
...First and second flow paths, M...Dual master cylinder, 5...Housing, 5 ₁ ...Left housing half, ₅₂ ...Right housing half, ₇₁ , ₇₂ ...Cylinder holes , 9 ₁ , 9 ₂ ... pressure receiving piston, 12 ...
Pressure regulating spring, 18 ₁ , 18 ₂ ... first and second input hydraulic chambers, 19 ₁ , 19 ₂ ... first and second output hydraulic chambers, 2
3 ₁ , 23 ₂ ... valve, 28 ... small hole, 29 ...
One-way seal member.

Claims (1)

[Claims] 1. A braking system for a vehicle in which the output hydraulic pressure of a dual master cylinder is separately supplied to the hydraulic operating parts of a pair of left and right rear wheel brakes through first and second flow paths. A common housing is inserted in the middle of the path, and a pair of left and right pressure receiving pistons are slid into the cylinder holes in the housing.
First and second input hydraulic chambers are connected to the inner ends of these pressure receiving pistons, respectively, upstream of the first and second flow paths, and first and second input hydraulic chambers are connected to the outer ends of the pressure receiving pistons, respectively, and are connected to the downstream of both flow paths. In addition to forming first and second output hydraulic chambers that communicate with each other, the pressure receiving area of each output hydraulic chamber side of each pressure receiving piston is made larger than the pressure receiving area of each input hydraulic chamber side, and the pressure receiving area between each adjacent input and output hydraulic chambers is are communicated through a valve that opens at the outward sliding limit of each of the pressure receiving pistons and closes at the time of inward sliding, and a common pressure regulating spring is compressed between both the pressure receiving pistons, The housing is composed of a pair of housing halves that are separably joined at the middle of each sliding portion of the pressure receiving pistons, and a small hole is provided in the joint of these housing halves to communicate the inside and outside of the joint. A brake hydraulic control device for a vehicle brake system, characterized in that a one-way seal member is installed inside the section to allow hydraulic oil to flow from the inside to the small hole.