JPS584660A - Master cylinder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION In particular, the present invention relates to a quick-absorption or quick-fill master cylinder in which a piston is adapted to moveably cooperate with a housing having a receiving bore therein. The piston and housing cooperate to substantially define a pair of variable volume chambers that expand or contract simultaneously in response to movement of the piston within the bore. One of the pair of variable volume chambers communicates with the brake system. A channel communicates the pair of variable volume chambers. The piston is moved by input from the driver to contract the pair of variable volume chambers and communicate pressurized fluid from one variable volume chamber to the brake system. At the same time, pressurized fluid is communicated from the other of the pair of variable volume chambers to one variable volume chamber via the flow path.

As a result, a greater volume of pressurized fluid is communicated from the master cylinder to the brake system than the volume reduction of one of the variable volume chambers.

Accordingly, the present invention provides a housing having an aperture therein, a pair of chambers of a possible volume disposed movably within a portion of the aperture, cooperating sealingly with the housing and retaining a fluid. a limiting piston, a device cooperating with the piston to contract one of the pair of variable volume chambers when the piston moves relative to the housing, and communicating the pair of variable volume chambers; a passageway device for communicating pressurized fluid from the one variable volume chamber to the other of the pair of variable volume chambers when the piston moves relative to the housing to contract the pair of variable volume chambers; It concerns the master cylinder that contains the.

Rapid-filling master cylinders are already known which have a housing with a stepped bore in the interior. In this known master cylinder, the stepped hole has a small diameter part and a large diameter part which cooperate with each other to form a step in the aperture. A stepped piston is movably housed within the small diameter and large diameter portions of the bore. The stepped piston is housed within a small diameter portion of the first hole and sealingly cooperates with the housing to communicate with the brake system.
a small diameter section substantially delimiting a variable volume chamber. The master cylinder also has a second variable volume chamber movably disposed within the small diameter portion of the bore to sealingly partition the first variable volume chamber into a pair of variable volume compartments communicating with a pair of independent brake systems. Contains a piston. A larger diameter portion of the stepped piston is received within the larger diameter portion of the bore and cooperates sealingly with the housing.

The large diameter portion of the piston cooperates with the housing and the small diameter portion of the piston to substantially limit the second variable volume chamber. A flow path communicates the first and second variable volume chambers. The first stepped piston moves in response to operator input to move the first and second stepped pistons.
The variable volume chambers of the chambers are simultaneously deflated to communicate pressurized fluid from the second chamber to the first chamber. Pressurized fluid is communicated from the first variable volume chamber to the brake system to effect brake application. Therefore, a larger volume of pressurized fluid is supplied to the brake system than the amount by which the volume of the first variable volume chamber decreases. m, a check valve is disposed in the passage to allow fluid to flow only from the second variable volume chamber to the first variable volume chamber; Additionally, the master 7 cylinder includes a valving arrangement that evacuates pressurized fluid from the second chamber upon the occurrence of a predetermined condition terminating the first phase of brake application. Thus, during the second phase of brake application, the driver is only resisted by the pressurized fluid in the first chamber.

In the above-mentioned known master cylinder, the housing is
It must be of sufficient size to form the large diameter portion of the stepped hole. Further, the small diameter portion and the large diameter portion of the stepped hole must be substantially concentric.

If the small diameter portion and large diameter portion of the hole are eccentric, the stepped piston may become stuck within the stepped hole. For this reason, when machining the stepped hole in the housing during manufacture of the master cylinder, it is necessary to use a tool setting with a cylindrical size for forming the stepped hole. The stepped piston must also be substantially concentric to prevent sticking within the stepped bore. For this reason, when manufacturing stepped pistons, it is necessary to use rod-shaped blanks that have an outer diameter smaller than (or equal to) the large diameter part of the piston. A significant portion will be removed to form the reduced diameter section of the stepped piston.

The invention provides that a portion of the hole has a constant diameter, a device cooperating with the piston is arranged substantially immovably within the portion of the hole, and an annular ring surrounding the piston. By providing a master cylinder having the above-mentioned structure, comprising a partition member, the partition member working sealingly with the notousing and the piston to limit the one variable volume ridge. , which eliminates the drawbacks of conventionally known master cylinders.

A major advantage of the present invention is that the housing need only be of sufficient size to form a hole of constant diameter. Also, since the holes have a constant diameter, there are no problems with the concentricity of the holes. Holes of constant diameter can be easily and inexpensively formed during the manufacture of the master cylinder. Refreshingly, the piston is not stepped to cooperate with the stepped hole, so when manufacturing the piston,
There is no need to scrape off a large amount of bar-shaped rough material.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In FIGS. 1 and 2, the braking device has a brake pedal 1o pivoted by a pin 12. In FIGS. Brake pedal 10 is operatively connected to master cylinder 14 by input rod 16 . Guide W1B and 20
connects the master 7 cylinder 14 to a pair of independent brakes 22
and 24, respectively. When the brake pedal is rotated clockwise by the driver, input lot 16
is moved into the master cylinder to generate fluid pressure. The generated fluid pressure communicates via conduits 18 and 20 to brakes 22 and 24, respectively, for braking application.

Master cylinder 14 includes a housing 26 with a split recess 28 . The flexible diaphragm 30 and the camp 32 cooperate to close the dividing recess 28. The cap 32 includes a pair of holes 34 that vent the top side of the diaphragm 30 to atmospheric pressure. Thus, diaphragm 30 and cap 32 cooperate with housing 26 to form a segmented reservoir 36 that stores fluid at substantially atmospheric pressure.

Reservoir 36 is connected to hole 3 through openings 40, 42, 44 and 46.
It is connected to 8. A valve arrangement 48 is housed within opening 46 . The valve arrangement 48 includes an annular flap valve element 50 that responds to a fluid pressure differential across the aperture 38.
Fluid can only flow towards. Valve device 4
8 also includes a spring-loaded relief valve element 52 which responds to a predetermined fluid pressure level within bore 38 by
Fluid can only flow through the holes 38.

A first piston 54 is connected to the input rod 16 and a second piston 54 is connected to the input rod 16.
The piston 56 is housed in the hole 38 together with the piston 56 . 1st
Piston 54 cooperates with second piston 56 to substantially define a first variable volume chamber 58 therebetween. Similarly, the second piston 56 cooperates with the end wall 6o of the bore 38 to substantially limit the second variable volume chamber 62. 1st room 58
communicates with brake 22 via conduit 18. Similarly,
Second chamber 62 communicates with brake 24 via conduit 20 . The first return spring 64 urges the first piston 54 to the right and engages the retaining ring 66, causing the piston 54 to engage the retaining ring 66.
Limit the non-braking position of The seventy-first piston 54 supports a spring cage that includes a stem 68 with a head 70. The spring cage also includes an annular cup-shaped spring seat 7 movably supported on the stem 68.
Contains 2. A first return spring 64 extends between the spring seat 72 and a block retainer 74 seated at a periphery 76 on the first piston 54 to engage the spring seat 72 with the second piston 56. . The spring seat 72 engages the head 70 and connects the first and second
Limiting the relative unbraked position of pistons 54 and 56.

A second return spring 78 is attached to the end wall 60 of the housing 26.
and the second piston 56, and urges the second piston rearward (to the right in the figure). Since the spring rate and/or preload of spring 64 is greater than the spring rate and/or preload of spring 78, spring seat 72 normally engages head 70 to limit the unbraked position of second piston 56.

The first piston 54 includes a pair of axially spaced apart, radially extending second lands 80 and 82 with a fourth land defining an annular recess 84 therebetween.

2nd 80 supports a block-shaped resilient lip 7-rule 86 having a pair of radially spaced apart lips 88 and 90 extending in a direction toward chamber 58. The radially outer lip 88 sealingly engages the housing 26 while the radially inner lip 90 sealingly engages the first piston 54.

Land 82 supports an annular resilient seal 92 that sealingly engages miusing 26 . Annular partition member 94
surrounds the first piston 54 within the recess 84 . The septum member 94 includes a pair of radially outwardly facing annular recesses 96 and 98. A retaining member 100 is threaded into the bore 102 of the housing 26 and includes a cylindrical protrusion 104 extending radially inwardly into the bore 38 . The protrusion 104 is located in the recess 9
6 to substantially immovably secure the septum member 94 within the bore 38 . Annular elastic seal member 106
has an annular bead 1a7 fitted into another recess 98. Seal member 106 sealingly cooperates with first piston 54 and housing 26 to divide recess 84 into a pair of variable volume compartments 108 and 110.

Compartment 110 communicates with reservoir 36 through opening 46, while compartment 108 communicates with the reservoir through a notch 112 extending across the threads of retaining member 100.

The recess 84 of the first piston 54 has a large diameter portion 114 and a small diameter portion 116 separated by an annular notch 118 . A hole 120 extends in the axial direction through the land 80 and large diameter portion 114 of the first piston 54 . Hole 120 communicates with lip seal 86 at its left end;
It leads to the notch 118. The large diameter portion 114 of the first piston 54 also includes a plurality of axially extending grooves 122 leading to the notches 118, the grooves tapering such that their cross-sectional area increases as they approach the notches 118. ing.

As shown in FIG. 3, the partition wall member 94 consists of a pair of C-shaped members 124 having the same shape. Valley C-shaped member 1
24 has a radially extending groove 126 at one end and a radially extending tongue 128 at the other end. Both members 124 are thus locked together by the lug 126 and the tongue 128 and cooperate with each other to define a bore 130 for receiving the first piston 54.

When applying the brakes, the brake pedal 10 is rotated clockwise by the driver. Input from the driver is transmitted via the input 'η rad 6 to the first piston 54, displacing it to the left within the bore 38. During the initial phase of brake application, leftward movement of the first piston 54 from the non-braking position causes the compartment 110 to contract so that fluid flows from the compartment 110 through the hole 120 and into the lip seal 86.
and is transferred into the chamber 58. Fluid initially transferred to chamber 58 is returned to reservoir 36 via opening 44. Because the spring rate and/or preload of the first return spring 64 is greater than that of the second return spring 78, the first piston 54 and the second piston 56 simultaneously move to the left from the unbraked position. Accordingly, the upward groove seal 86 on the first piston 54 and the similar upward groove seal 1 on the second piston 56
32 are moved to the left across openings 44 and 40, respectively, to substantially simultaneously confine fluid within chambers 58 and 62;
Initiate the first phase of brake application. Continued leftward movement of first piston 54 then pressurizes the fluid within chamber 58 and compartment 110. The pressurized fluid in chamber 62 and the contraction of first return spring 64 cause second piston 56 to move further to the left to pressurize the fluid in chamber 62 .

During the first phase of brake application, continued leftward movement of first piston 54 displaces fluid from compartment 110 through bore 120 and lip seal 86 and into chamber 58 . Despite differences in seal friction and the spring rates of the two return springs, the fluid pressure levels in the two chambers 58 and 62 are substantially the same, so that the relative unbraked positions of the first and second pistons The amount of movement from the brakes 22 and 24 is determined by the rate of fluid absorption of the fluid pressure in the chambers 58 and 62 at the brakes 22 and 24.

The second phase of brake application is initiated when either of the following two conditions occur: One condition is when the fluid pressure in chamber 58, taking into account the fluid pressure in compartment 110 and the pressure drop caused by lip seal 86, exceeds the predetermined pressure required to open relief valve element 52. be.

When a predetermined pressure is developed within compartment 110, relief valve element 52 opens to communicate compartment 110 with reservoir 36.

Thereafter, operator input acting on first piston 54 is resisted only by the fluid pressure within chamber 58 and the predetermined fluid pressure within compartment 110. Accordingly, operator input can pressurize the fluid within chamber 58 to a higher level.

Another condition in which the second phase of brake application is initiated is when the first piston 54 has moved to the left to a position where the groove 122 moves below the seal member 106. Groove 122 communicates pressurized fluid from compartment 110 to compartment 108.
Decrease the fluid pressure within 10.

Because the compartment 108 communicates with the reservoir 36 through the notch 112, the fluid pressure within the compartment 110 will eventually drop to atmospheric pressure. The groove 122 is tapered in the axial direction,
And because the shallow end of the groove moves under seal member 106 first, fluid communication from compartment 110 to compartment ios is incremental and increases as a function of leftward movement of piston 54. Therefore, the driver does not substantially feel the ψ transition shock that can occur during the transition between the first and second phases of brake application. Previously, transition shocks occurred when the brake pedal was suddenly rotated clockwise rather than by gradually increasing driver input. This transition shock gives the driver a feeling that the brake system is malfunctioning, making him or her anxious.

Historically, transition shocks are undesirable because they interfere with the driver's ability to adjust inputs.

By allowing the second phase of brake application initiated by the opening of the relief valve element 52, the groove 12
The piston 54 can be moved sufficiently to the left to move the piston 2 under the seal member 106. Furthermore, during brake application, conditions may arise where compartment 110 is at atmospheric pressure, regardless of the state in which the second phase of brake application is initiated. In either case, the fluid pressure within the compartment 110 is maintained at a predetermined pressure or is gradually reduced from this pressure, thereby substantially preventing the occurrence of a transition shock between the first and second phases. It is.

As can be seen in FIG. 1, the first piston 54 is able to move a distance X to the left into the bore 38 from the unbraked position. Therefore, the hole 3 in which the piston 54 is movably accommodated
8 is limited to length Y. master cylinder 14
Even considering the taber or non-uniformity that may occur during the manufacturing of
The portion of hole 38 defined by length Y has a substantially constant diameter. Furthermore, the diameter of the small diameter section 1.16 of the piston 54 is sufficiently smaller than the diameter of the large diameter section 114 so that the seal member 106 does not sealingly engage the small diameter section 116. As a result, even after the notch 118 of the piston 54 moves to the left of the seal member 106, the fluid within the compartment 110 is not pressurized. For example, if brake application occurs with one conduit 18 or 20 broken,
The notch 118 of the piston 54 may move to the left of the seal member 106. In such a case, if the fluid in compartment 110 were pressurized after the first phase of brake application, the generation of this pressurized fluid would occur because the driver input would be resisted by the pressurized fluid. It is important to prevent this.

Although the present invention has been illustrated and described with reference to preferred embodiments, the present invention is not limited thereto (many changes and modifications can be made without departing from the scope of the present invention). In □, the master cylinder is of a tandem type having two pistons, but the present invention is of course applicable to a mask-cylinder having a single piston.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a brake device showing a master series/recess according to the present invention, FIG. and an exploded perspective view of the partition wall member in FIG. 2. 14° Master cylinder, 26...]\Using, 3
6...Reservoir, 38...Hole, 48...Valve device J54,
56.-Piston, 58.62.-Chamber of variable volume, 80
, 82... Land, 84... Annular recess, 86... Elastic lip seal, 94... Partition member, 100... Holding member.
106...Elastic sealing member, 108, 110...Variable volume compartment, 112...Notch, 114...Large diameter portion, 1
16.-small diameter part, 118..cut, 120..hole, 1
22...Groove, 124, 126...C-shaped member.

Claims (1)

[Scope of Claims] 1. A housing having a hole therein, a pair of variable volumes movably mounted within a portion of the hole and energized in a sealing manner with the housing to retain fluid. a piston bounding a chamber, a device for excitation with said piston to entrain one of said pair of variable volume chambers when said piston moves relative to said housing; In communication, when the piston moves relative to the housing to fill the pair of variable volume chambers, pressurized fluid is transferred from the upper variable volume chamber to the pair of variable volume chambers. a passageway device communicating with the other chamber of the hole, wherein a device having a circular diameter of a diameter of one diaphragm and energizing the piston l is substantially located within a portion of the hole. an annular partition member fixedly disposed in the housing and surrounding the piston, the partition member sealingly engaging the housing and the piston to limit a variable volume chamber of the one of the pistons; A master cylinder that features terukoki. 2. The piston of claim 5, wherein the piston includes a pair of axially spaced lands defining four locations therebetween, and the partition member is housed within the recess. The master cylinder according to item 1. 3. The piston has an annular notch in the middle of the land, and has a large diameter portion between one of the lands and the notch and a small diameter portion between the other land and the notch. 3. The master cylinder according to claim 2, wherein the partition wall member is attached to the large diameter portion of the piston in a sealing manner. 4. The piston momentarily contacts the one land to provide a ring seal, and the lip seal extends toward the other variable volume chamber that seals FMJ with the housing and the piston, respectively. radially outer and radially inner lips, the piston having a radially extending hole communicating with the lip seal and communicating with the annular notch, the aperture defining the passageway device; 4. The master cylinder according to claim 3, characterized in that: 5. Claims characterized in that the piston is provided with a monument extending in the axial direction in the large diameter portion, the turning direction leads to the notch, and the cross-sectional area of the piston increases as it approaches the notch. The master cylinder described in item 3. 6. The partition member has a pair of members that cooperate with each other to form an annular body, and the annular body supports an annular elastic sealing member that sealingly cooperates with the piston and the housing. The master cylinder according to claim 1, characterized in that: 7. The master cylinder according to claim 6, wherein the partition member is comprised of a pair of C-shaped members having the same shape and provided with a device for locking each other to form the annular body. . 8. Claim 7, characterized in that the annular body and the elastic sealing member are provided with a device for fitting into each other.
Master cylinder as described in section. 9. The locking device comprises a radially extending tongue at one end of the C-shaped member and a radially extending groove at the opposite end of the C-shaped member; 8. A master cylinder according to claim 7, wherein the groove of the valley C-shaped member is adapted to receive the tongue of the other C-shaped member so as to lock together. 10. The fitting device is comprised of an annular recess provided in the annular body and facing outward in the upper radial direction, and an annular bead provided in the elastic sealing member, and the annular recess is arranged in contact with the annular bead. 9. The master cylinder according to claim 8, wherein the master cylinder is adapted to receive a cylinder. 11. the annular body having another radially outwardly facing annular recess, the housing supporting a retaining member having a protrusion extending radially inwardly into the bore of the nozzle; Claim 1, wherein the protrusion is housed within the other annular recess to aesthetically restrict axial movement of the annular body within the bore of the nozzle. A master cylinder according to item 6. 12. Claims characterized in that the housing and the holding member cooperate to form a flow path that communicates the hole in the housing with a reservoir storing fluid at atmospheric pressure. The master cylinder according to item 11.