JPS592666B2 - Brake master cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to master cylinders for hydraulic brake systems, and in particular to so-called "quick-absorbing" or "quick-filling" master cylinders.

When a quick-filling master cylinder is activated, it first sends a large amount of fluid to the brake circuit, and as a result, the gap between the brake engaging members can be quickly absorbed and the brake applied force can be applied with just a slight movement of the brake pedal. Positioning the shoes or pads in contact with the brake drum or disc.

Generally, quick-fill master cylinders have stepped holes and
a piston with two heads of different diameters sliding through each portion of the stepped bore.

A larger volume chamber is formed in the bore between the heads of the two pistons, while a smaller volume chamber is formed in the bore in front of the smaller piston head, this chamber having an outlet leading to the brake circuit. .

When the brake pedal is depressed, the piston is forced forward along the bore, reducing the volume of the larger chamber and transferring brake fluid from there to the smaller volume chamber and further into the brake circuit, filling the gap between the brake engaging members. absorb.

Once the gap is absorbed, the increased pressure in the smaller volume chamber prevents further fluid from being pumped into it from the larger volume chamber, and instead, as the piston continues to move forward, fluid is forced into the larger volume chamber. from the master cylinder through a pressure-responsive valve system to the master cylinder glue server.

The movement of the piston compresses the fluid in the small volume chamber, and the pressure is transmitted to the brake cylinder to provide brake action.

A quick-fill master cylinder shortens master cylinder length and brake pedal travel, making a booster unnecessary in at least some applications.

In any brake circuit, the pedal travel required to achieve brake application should be the same regardless of the speed at which the pedal is depressed.

Additionally, the pressure chamber of the master cylinder must be able to "breathe", i.e., have some fluid communication with the reservoir under normal brake-off conditions, e.g. when the vehicle is parked.
It is necessary to allow for fluid and thermal expansion and contraction in the brake circuit due to changes in ambient temperature.

Furthermore, in the case of a quick-fill master cylinder, the pressure in the quick-fill chamber, i.e., the large volume chamber, is allowed to decay through a restricted passage connecting the chamber to the reservoir, so that brake application is dependent on the pressure in the chamber. It is preferable that there is no resistance and it does not give a strange feeling to the pedal.

The known quick-fill master cylinder may solve all the above-mentioned problems and therefore has all the disadvantages.

Representative prior art is the quick-fill master cylinders described in U.S. Pat. No. 4,086,770, U.S. Pat.

In the master cylinder described in the first specification above, the quick filling chamber is connected via a valve that is opened when the pressure in the small volume compression chamber reaches a certain height, and also during the return stroke of the piston. It communicates with the reservoir via a one-way valve provided to allow fluid flow back to the quick fill chamber.

Adjustment holes normally communicate the compression chamber with the reservoir for "breathing"
is possible.

This master cylinder has two drawbacks.

Firstly, during very fast actuation the pressure in the compression chamber can rise to a high pressure, ie the pressure required to open the valve, before pressure is transmitted to the brake itself.

As a result, fluid flows from the quick fill chamber to the server, the quick fill function is lost, and the pedal travel increases.

Second, even at slow operating speeds, the regulating hole is quickly brought into communication with the quick fill chamber, so that at slow operating speeds, fluid passes from the quick filling chamber to the server through the regulating hole; Again, no quick fill operation occurs and the pedal travel increases.

In the master cylinder described in U.S. Pat. No. 4,133,178, the quick fill chamber and brewing hole communicate with the reservoir through a common passageway that includes a valve and a restriction port.

In normal brake off condition, the piston acts on the valve stem,
By keeping the valve open, the compression chamber can breathe.

As the piston moves forward, the valve closes under the action of the spring, allowing the pressure in the quick-fill chamber to develop sufficiently to transfer fluid into the compression chamber.

In case of fast actuation, the valve will not close due to the rapid increase in pressure, but the restriction in the passage will ensure that fluid is delivered to the compression chamber.

However, this master cylinder still has drawbacks.

The pressure in the quick fill chamber cannot decay and therefore resistance is felt on the pedal, especially during slow actuation.

Additionally, there is a significant loss in pedal travel due to the piston movement required to close the valve.

The method described in US Pat. No. 4,208,881 attempts to avoid these drawbacks.

The valve stem was removed and a small hole passage was created in the valve seat member to allow the valve to be bypassed.

The presence of the restriction passage means that the compression chamber is still breathable and also allows the pressure in the quick fill chamber to decay under static pressure conditions.

However, in order to have a sufficient flow restriction effect, the passages must be very narrow and are easily clogged by dirt particles.

This drawback cannot be avoided by making the passage larger.

This is because in the case of slow actuation, the fluid from the quick fill chamber will flow through the passage into the reservoir and no quick fill operation will take place.The invention aims to reduce the disadvantages of known quick fill master cylinders. a piston having a main body having a stepped hole and opposite ends slidable within respective portions of the stepped hole and defining a compression chamber of small capacity and a quick filling chamber of large capacity; a hole provided in the main body and opening into the quick filling chamber; an adjustment hole provided in the main body and communicating with the compression chamber; a reservoir connected to the hole and the adjustment hole; a valve device for controlling communication between the hole and the adjustment hole, the valve device including a pressure responsive valve configured to open when the pressure in the quick filling chamber reaches a predetermined height; , a one-way valve for allowing fluid to freely flow in the direction from the reservoir to the quick-fill chamber, and forming a bypass restriction passage that bypasses the pressure-responsive valve, the master cylinder for a quick-fill type brake, The pressure-responsive valve includes a valve member and a seat having cooperating opposing surfaces, the opposing surfaces opening the pressure-responsive valve to allow fluid to flow substantially between the opposing surfaces and against the opposing surfaces. master cylinders which are movable apart from each other when the flow is caused to flow in parallel directions, and which are further adapted to form the bypass restriction passage between the opposing surfaces when the pressure responsive valve is closed; ,
According to the first invention of the present application, each of the opposing surfaces is a substantially flat surface that extends in parallel to each other over substantially the entire area where the valve member and the seat face each other, and has no lateral grooves. According to the second aspect of the present application, there is provided a master cylinder in which the bypass restriction passage is formed by the flat surfaces being held with a narrow gap between them when the pressure responsive valve is closed; According to the invention, one of said opposing surfaces is provided with a groove extending along a substantially helical path, such that said groove forms said bypass restriction passage when said pressure responsive valve is closed. A master cylinder is provided.

In master cylinders of these configurations, debris particles that become trapped between the opposing surfaces forming the restriction passage are washed away by pressurized fluid flowing into the reservoir at a velocity sufficient to lift the valve member off its seat during brake application. Ru.

In the first invention of the present application, the facing surfaces of the valve member and the seat forming the bypass restriction passage extend in parallel to each other over substantially the entire range of the area where the valve member and the seat face each other, and have a lateral groove. Since the bypass is a substantially flat surface, the bypass restriction passage formed has a very wide width in the direction along the opposite surface, so that the bypass restriction passage is completely blocked by solid waste particles. You won't be disappointed.

In one embodiment of the first invention, the pressure responsive valve is adapted to cooperate with the bottom of a cup-shaped seat member housed within and sealed against the boss on the body of the master cylinder. It is formed by a molded plastic valve member having a generally flat end face.

The valve member has an aperture within which captures and retains a ball which cooperates with an annular seat provided on the valve member to form a one-way valve.

The restriction passage is formed by three short legs on the flat end surface of the valve member, these legs keeping the flat end surface of the valve member from the surface of the cup-shaped seat member with a slight clearance of about 0.1M. I support it.

When the valve member is lifted from this seat, a flow of fluid scrubs the surface to remove trapped particles.

The restricted passage is therefore automatically cleaned.

During normal driving, many brake applications occur at low speeds, and if dirt becomes trapped between the valve member and its valve seat and prevents them from closing properly, automatic cleaning of the restriction passage may not be possible. High-speed braking will be required.

As a result, while applying at least the second or fifth brake,
Usually from the quick filling chamber to the server via a restricted passage.
The higher velocity of the fluid provides a different pedal feel and pedal stroke than normally experienced by the driver.

Of course, it is preferable to avoid changes in pedal characteristics while driving.

This disadvantage can be avoided if one or both of the opposing surfaces defining the restricted passageway between them are provided with a member of elastic material.

When the two components of a pressure-responsive valve are pressed together to form a control passage, the elasticity forces dirt particles between the contact surfaces into the elastic material, ensuring that the components join together to form a restriction passage. be able to.

However, if the components are subsequently opened apart again, for example during high-speed braking, the self-cleaning function is not lost, since the dirt particles can be washed away.

Since the hermetic joint between the components is not disturbed by dirt trapped between them, the pedal travel remains constant at all pedal depression speeds.

Generally speaking, it is not sufficient to provide a restricted passageway by forming a direct transverse groove in one of the opposing surfaces.

In order for the restriction function to be sufficient, the cross-section of the groove must be small, in which case the groove will be easily blocked by solid dirt particles, and it is also difficult to form such an accurate and narrow groove. The costs will be high.

However, according to the master cylinder of the second invention of the present application, the groove can be used as a restriction passage without the above-mentioned drawbacks.

That is, in the second invention, since the bypass restriction passage is formed by providing a groove extending along a spiral path on one of the opposing surfaces, the bypass restriction passage is formed by providing a groove extending along a spiral path, rather than a straight lateral groove. can be made longer.

If the bypass restriction passage is long and spiral, the same flow resistance can be provided even if the cross-sectional area is relatively larger than that of a short, straight bypass restriction passage.

Therefore, solid waste particles are less likely to clog.

The helical groove desirably has at least approximately one revolution.

If the master cylinder includes a member of resilient material as described above, the helical groove can be formed in this member by a molding process.

For a better understanding of the invention, the invention will now be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 designates a master cylinder body, which is provided with a stepped bore consisting of a small diameter section 2 and a large diameter section 3 separated by a shoulder.

The piston 4 accommodated in the bore carries at its front end a sealing member 5 sliding in the bore part 2 and at its rear end carrying a sealing member 6 sliding in the bore part 3. .

A compression chamber 7 with a small volume is formed in front of the piston in the hole 2, and a quick filling chamber 8 with a large volume is formed around the piston 4 between the sealing members 5 and 6.

The body 1 has an integral boss 9, the interior of which communicates via a bore 10 with the quick-fill chamber 8 and via an adjustment bore 11 with the compression chamber 7 when the piston is in the normal brake-off position shown. is connected to.

A reservoir 13 is connected to the outer end of the boss 9 by a sealing member 12.

A valve assembly is located within the boss 9 and is retained there by a circlip 14.

The valve assembly includes a cup-shaped seat member 15 whose periphery is sealed to the boss 9 by a sealing member 16, the seat member including a central hole 17 in its bottom wall and a recess in the lower surface of the bottom wall. 10 and 11 are formed into a passage connecting them to the central hole 17.

A cap 18 with an end wall (hole) is located on the seat member 15 and supports one end of a spring 19, the other end of which acts on the valve member 20.

The valve member 20, made of plastic material, has a hole in which a ball 21 is captured and held by a transverse pin 22.

A longitudinal groove is formed in the hole to facilitate the flow of fluid passing beside the ball 21.

The ball is compressed by the valve member 20 under the action of pressure developed by the flow of fluid from the master cylinder chamber to the server.
cooperates with the upper end of the valve member 20 to form a one-way valve for controlling fluid flow through the aperture of the valve member 20.

The ball 21 is sufficiently flow sensitive that it can be pushed into the closed position at any operating speed;
It also moves easily downward to allow fluid to flow from the reservoir to the master cylinder.

The bottom surface of the valve member 20 is flat and has three short legs 23.
have.

The legs 23 are spaced apart from their periphery and define a restricted passageway 24 by holding the flat bottom surface of the valve member 20 with a small clearance, typically about 0.1 m, from the top surface of the bottom wall of the seat member 15. The holes 10 and 11 communicate with the reservoir 13 via this passage.

At normal operating speeds, as the piston 4 moves forward from the position shown, the seat member 1 resists the force of the spring 19.
Since the pressure is not high enough to open the pressure-responsive valve by lifting the valve member 20 from 5, the volume of the quick fill chamber 8 decreases and the flow passes through the side of the sealing member 5 into the compression chamber 7. Sent.

When the pressure in chamber 7 increases to prevent fluid delivery to this chamber, valve 20 opens to allow fluid to flow from the quick fill chamber to reservoir 13.

During quick actuation by the driver pressing the pedal, the small aperture 17 in the seat member 15 prevents the rapid opening of the valve 20 so that sufficient fluid is removed from the chamber 8 before it can migrate to the compression chamber for a quick fill actuation. This prevents escape to the reservoir 13.

Quick fill operation is also obtained at slow actuation speeds.

The restriction passage 24 formed between the opposing surfaces of the seat member 15 and the valve member 20 provides sufficient resistance to flow, and the sealing member 5
This is because the necessary pressure is generated in the quick fill chamber 8 to force the fluid through the side of the quick fill chamber 7 into the compression chamber 7.

At the same time, the passage 24 allows the pressure in the quick fill chamber 8 to decay, so that this pressure does not resist brake application and does not produce any strange feel on the brake pedal.

Furthermore, passage 24 allows the brake circuit to "breathe" through adjustment hole 11 during periods when the master cylinder is not in use.

When the piston moves on the return stroke, the ball 2 of the one-way valve
1 is moved to the position shown, allowing fluid to return to the quick fill chamber 8.

From the above it can be seen that quick fill actuation is achieved independent of actuation speed, thus resulting in approximately uniform pedal travel under all conditions.

Additionally, when the valve member is open, such as at normal operating speeds, pressurized fluid flowing through the valve from the quick-fill chamber cleans deposits on the surfaces of the valve member and seat member forming the restriction passageway 24. The advantage is that automatic cleaning of this channel 24 for washing is achieved.

The master cylinder shown in FIGS. 2-4 includes a body 51 having a stepped bore consisting of a smaller diameter portion 52 and a larger diameter portion 53 separated by a shoulder.

A piston 54 received in the bore has a front end sealing member 55 sliding within the bore portion 52 and a rear end sealing member 56 sliding within the bore portion 53 .

A compression chamber 57 with a small volume is formed in the bore part 52 in front of the piston 54, and a quick fill chamber 58 with a larger volume is formed around the piston by a sealing member 55.5.
It is formed between 6.

The body 51 has an integral boss 59, the interior of which communicates with the quick fill chamber 58 through a hole 60 and with the compression chamber 57 through an adjustment hole 61 when the piston is in the normal brake-off position shown. is connected to.

A reservoir 63 is connected to the outer end of the boss 59 via a sealing member 62.
are connected.

The boss 59 forms a valve chamber, the bottom wall of which has a central spigot 80 through which the passages 60 and 61 open into the valve interior through a common hole 81.

An inner circumferential groove 82 provided in the boss forms an inwardly directed shoulder 83 which serves to retain the pre-assembled valve unit within the valve chamber.

The valve unit includes a valve structure.

The valve structure is held within an annular metal cage 84;
The cage 84 has a bottom wall located at the bottom of the valve chamber surrounding the spigot 80 and an outwardly extending tongue piece 85 that abuts and joins with the shoulder 83 to hold the unit within the boss 59. side walls and inwardly directed top flanges 86.
It has

The valve structure comprises an annular sealing member 87 of resilient material, e.g. rubber, located at the bottom of the cage, an outer flange 89 for cooperating with the sealing member 87 and an inner valve seat 9 at its upper end.
a valve member 88 which is generally tubular with 0; a ball 91 captured and retained in the valve member by a recess 92 and which cooperates with the seat 90 to form a one-way valve; a flange 86 of the cage;
89 and the valve member to urge the flange 89 into sealing connection with the sealing member 87.

As more clearly shown in FIGS. 2 and 3, the sealing member 87 has an upwardly and inwardly sloping lip 94 on its inner periphery for sealing around the spigot 80. As best shown in FIGS.

On its upper surface, the sealing member 87 has on its upper surface a shallow (fK1W11) helical groove 95 extending almost 360 degrees around the axis of the sealing member, the groove forming an inner and an outer periphery at each end. and communicate with the reservoir 63 via the hole 81 and the valve chamber, respectively.

The upper surface portions 96 of the sealing member radially inside and outside the groove are chamfered as shown in FIG. 3 to ensure a good sealing connection with the flange 89 of the valve member 88.

A series of notches 97 are distributed around the outer circumference of the sealing member,
It serves to prevent undue deflection of the radially inner portion of the seal when the seal is pressed toward the cage 84.

From the above description, it can be seen that the valve unit can be pre-assembled and the boss 59 is inserted until the tongue 85 fits behind the shoulder 83.
It will be appreciated that it can be accurately attached to the body of the master cylinder by inserting it into the body of the master cylinder.

The operation of the master cylinder is essentially the same as described in connection with FIG.

When the brake pedal is pressed down, the piston 54 moves forward, and as the volume of the chamber 58 decreases, fluid is transferred from this chamber to the chamber 57 to absorb gaps in the brake circuit.

After the gap has been absorbed, pressure increases in chamber 58 and valve member 88 is lifted against the force of spring 93, allowing fluid to flow from quick fill chamber 58 into reservoir 63.

Any remaining pressure in the quick fill chamber when the valve member 88 rejoins the sealing member 87 is allowed to decay through the restricted passageway formed by the helical groove 95.

This restricted passage also allows the compression chamber 57 to "breathe" through the clearance hole 61 without the use of a brake.

During the return stroke of the piston, the ball 91 of the one-way valve
is separated from the valve seat 90 to allow fluid to flow freely from the reservoir into the quick fill chamber.

When the valve closes, any dirt particles may be trapped in the sealing member 87.
and valve member 88, there is no adverse effect on the operation of the master cylinder.

The elasticity of the material of the sealing member forces such particles inward from the surface of the sealing member, so that an effective seal will still be obtained.

Therefore, when the next brake application is at a low speed, the restriction passage defined by the helical groove still ensures that sufficient fluid is delivered to chamber 57 for a quick fill operation, and that all fluid is delivered to chamber 58. There is no risk of passing through to the Karari server, thereby avoiding an increase in pedal travel.

Many variations to the embodiments described above are possible and can be easily envisioned by those skilled in the art.

For example, in the master cylinder of FIG. 2, the groove need not be formed in the sealing member, but can instead be provided in the valve member.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a part of a master cylinder according to an embodiment of the first invention of the present application, and FIG.
3 is a cross-sectional view of a master cylinder according to an embodiment of the invention, in which the cross section of the elastic sealing member is taken along the line X-X in FIG. 3, FIG. 3 is a plan view of the elastic sealing member, and FIG. 4 is a cross-sectional view of the elastic sealing member. FIG. 1.51: Master cylinder body, 2.3°52.5
3: Step hole parts, 4, 54: Piston, 7.57: Compression chamber, 8.58: Quick filling chamber, 10.60: Hole, IL
61: Adjustment hole, 15° 87: Seat, 20.88: Valve member.

Claims (1)

[Claims] 1. A main body 1 having a stepped hole, and each portion 2 of the stepped hole.
, 3, and defines a compression chamber 7 with a small capacity and a quick filling chamber 8 with a large capacity, and a piston 4 provided in the main body and opening into the quick filling chamber. an adjustment hole 11 provided in the main body and communicating with the compression chamber, and the hole and adjustment hole 10.
．． 11 and a valve device for controlling communication between the reservoir and said hole and regulating hole 10.11, said valve device being configured such that the pressure in the quick fill chamber reaches a predetermined height. a bypass restriction that bypasses the pressure responsive valve, including a pressure responsive valve configured to open when A quick-fill brake master cylinder having a passageway, the pressure responsive valve comprising a valve member 20 having cooperating opposing surfaces.
and a seat 15, the opposing surfaces being moved away from each other when the pressure responsive valve is opened to allow fluid to flow between the opposing surfaces in a direction substantially parallel to the opposing surfaces. in a master cylinder wherein the bypass restriction passage is formed between the opposed surfaces when the pressure responsive valve is closed; substantially flat surfaces extending parallel to each other over substantially the entire extent of opposing regions and having no transverse grooves, the flat surfaces narrowing between each other when the pressure-responsive valve is closed; A master cylinder that is held with a gap to form the bypass restriction passage. 2. In the master cylinder according to claim 1, each of the opposing surfaces is annular, and the seat 15 has a center portion of the annular surface of the seat with respect to the hole and the adjustment hole 10°11. A master cylinder featuring a continuous sliding mechanism. 3. In the master cylinder according to claim 2, the valve member 20 has a shaft hole opening in the center of its annular surface, and the one-way valve has an annular hole in the shaft hole. A master cylinder comprising a notebook and a member 21 accommodated in the shaft hole and capable of cooperating with the annular seat. 44-'j The master cylinder according to claim 1, 2, or 3, wherein one of the opposing surfaces is formed of a member of an elastic material. 5. A piston having a main body 51 having a stepped hole, and both ends slidable within respective portions 52 and 53 of the stepped hole, and defining a compression chamber 57 with a small capacity and a quick filling chamber 58 with a large capacity. 54, a hole 60 provided in the main body and opening into the quick filling chamber, an adjustment hole 61 provided in the main body and communicating with the compression chamber, and the hole and adjustment hole 60.61. and a valve device for controlling communication between the reservoir and the holes and regulating holes 60, 61, the valve device controlling the pressure in the filling chamber to a predetermined height. a bypass restriction that bypasses the pressure responsive valve, including a pressure responsive valve configured to open when A quick-fill type brake master cylinder having a passageway, the pressure-responsive valve includes a valve member 88 and a seat 87 having opposing surfaces that move IW relative to each other; the opposing surfaces are movable away from each other when opened to allow fluid to flow between the opposing surfaces in a direction substantially parallel to the opposing surfaces; and when the pressure responsive valve is closed, the opposing surfaces a groove 95 extending along a substantially helical path in the master cylinder between which the bypass restriction passage is formed;
is provided on one of said opposing surfaces, said groove 95 being adapted to define said bypass restriction passage when said pressure responsive valve is closed. 6. In the master cylinder according to claim 5, each of the opposing surfaces is annular, and the seat 87 is connected to the hole and the adjustment hole 60° 61 at the center of the annular surface of the seat. A master cylinder that is characterized by its ability to communicate. 7. In the master cylinder according to claim 6, the valve member 88 has a shaft hole opened at the center of its annular surface, and the one-way valve has an annular seat in the shaft hole. A master cylinder comprising: a member 91 accommodated in the shaft hole and capable of cooperating with the annular seat. 8. The master cylinder according to claim 5, 6, or 7, wherein one of the opposing surfaces is formed of a member of an elastic material. 9. In the master cylinder according to claim 8, the elastic material member constitutes the annular sheet 87, and the main body has a shaft hole 81 connected to the hole and the adjustment holes 60, 61. a master cylinder having a protrusion 80 with the member of resilient material extending around and sealingly joining the protrusion; 10 In the master cylinder according to claim 8 or 9, the groove 95 is formed of the material 87 made of rational material.
〇11 In the master cylinder according to any one of claims 5 to 10, the valve member 88 and the seat 87 of the pressure responsive valve are are housed within a cage 84 and the opposing surfaces are pressed into contact with each other by a spring 93 inserted between the valve member and the cage, thereby causing the valve member, the seat, the spring and the cage to contact each other. and a master cylinder which are assembled together and inserted as a unit into a valve chamber 82 provided in the main body 51. 12 In the master cylinder according to claim 11, the cage 84 is provided with an abutting surface 8 in the valve chamber 82.
The master cylinder is provided with an elastic protrusion 85 adapted to engage with the rear surface of the valve chamber 3, and the unit is inserted and held in place within the valve chamber by the elastic protrusion.