DE3021893A1 - MAIN CYLINDER - Google Patents

Description

PATENT LAWYERS

WUESTHOFF-v. PECHMANN-BEHRENS-GOET2

professional representatives before the european patent office agrees pres l'office europeen des brevets

1A-53680

DR.-ING. PRANZ ¹ WUESTHOFF DR. PHIL. FREDA ~ mVtSrCROfS DIPL.-ING. GEKHAKD PULSE (19J2-I < > 7l) DIPU-CHEM. DK. E. BARON OF FECHMANN DR.-ING. DIETEK BEHKENS DIPL.-ING .; DIPU- ¹ TIKTSCa-INCRUPERT GOETZ

D-8000 MUNICH SCHWEIGERSTRASSE

phone: (089) ί6 20 j ι telegram »!: pkotectpatent telex: j 24 070 June 11, 1980

Patent application

Applicant!

LUCAS INDUSTRIES LIMITED

Great King Street,

Birmingham, West Midlands, UK

Title:

Master cylinder

030051/0882

DR-ING. PRANZ VUESTHOPP PATENT LAWYERS _{DR PHIL} . _PREDA ™ _ESTH of, (i ₉ z ₇ -i _9S 6)

WUESTHOFF - v. PECHMANN - BEHRENS - GOETZ dipu-ing. gerhard puls (1952-1971)

DIPL.-CHEM. DR. E. BARON PECHMANN PROFESSIONAL REPRESENTATIVES SEPORE THE EUROPEAN PATENT OFFICE DR.-ING. DIETER BEHRENS

MANDATAIRES AGREES PRES L'OPFICE EUROPEEN DES BREVETS DIPI.-ING .; DIPL.-VIRTSCH.-ING. RUPERT GOETZ

V.

D-8000 MUNICH 90

1A-53 680 SCHWEIGERSTRASSE 2

phone: (089) 66 20 ji telegram: protectpatent telex: ^ 24070

description

Master cylinder

The invention relates to a master cylinder for a vehicle brake system.

In view of the current world energy crisis, the automotive industry is forced to make the operation of road vehicles more economical. In many cases, component manufacturers are required to make components smaller and lighter without sacrificing safety and reliability. Each even small reduction in size and weight of a component is considered to be significant since a small saving on any component of a vehicle based on the vehicle as a whole a very significant reduction may result.

In known vehicle brake systems, a brake booster is between the brake pedal mechanism and a master cylinder arranged, which is attached to the front of the brake booster housing. The one from the main cylinder and the brake booster combined assembly has a

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takes up considerable space and must be arranged in the engine compartment of the vehicle, where there is a shortage of space. By doing An effort to reduce the space required for the master cylinder and the brake booster is the use a brake booster has been proposed, the construction of which is the arrangement of the rear end of the master cylinder in the brake booster. However, the position of the container on the main cylinder has the possible installation length of the master cylinder in the brake booster is limited. To overcome this limitation it is suggested been to change the arrangement of the container on the master cylinder. The location of the openings through which the container with the pressure chamber of the master cylinder is in communication, but is predetermined by the properties of the entire brake system and cannot be changed. In order to be able to maintain the position of the openings, channels along the Master cylinder needed to connect them to the container. In the construction proposed so far these channels formed as follows: In the housing of the master cylinder, an auxiliary chamber is formed, to their Connection with the bore in the housing two holes - one radial, the other at an acute angle to the main cylinder axis - be drilled to create the necessary openings. A third hole is at an angle drilled axially along the housing so that it intersects the container chamber and opens into the auxiliary chamber. The open end of the third hole and the open top of the chamber are then plugged. The formation of the passages, especially the oblique holes, is quite complicated.

From JP patent publication 53-115469 there is a master cylinder known, in which a communicating with its main bore opening with a container chamber through a longitudinal channel is connected which extends along the housing of the master cylinder, and through a radial channel that defines the longitudinal channel

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cuts and aligns with the opening. The longitudinal channel opens at an outer radial shoulder on the housing and is closed by a sealing member. The outer end of the radial channel is closed by a screw. This master cylinder is not intended for use in a brake booster, as it is attached to its rear End is provided with a mounting flange. Furthermore, a valve chamber is formed on the side of the housing, which with is connected to the longitudinal channel via a check valve and to the pressure chamber of the master cylinder.

According to the invention, a master cylinder is provided which has a Housing having an axial bore that is stepped to provide an internal shoulder near a rearward end of the housing To form a container chamber, a transverse opening in the housing that is between the shoulder and the container chamber opens into the bore, and a longitudinal channel which is at least approximately parallel to the axis of the Bore extending from the inner shoulder to the container chamber along the housing and intersecting the transverse opening, whereby the container chamber with the bore through the opening and the open end of the channel at the inner shoulder communicates.

With this construction only two holes have to be drilled to form the necessary passages, one radially and the other axially so as to avoid drilling oblique holes.

The connection between the container chamber and the bore is via the open end of the channel on the inner shoulder advantageous as it allows the supply of fluid or brake fluid to the bore behind the sealing member of the master cylinder piston enables. This is necessary to lubricate the sealing member and to protect it from damage when sliding over the Muzzle to protect the opening.

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The invention can be of particular advantage when applied to tandem master cylinders that are comparatively are long.

A tandem master cylinder usually has a main part or housing with a non-through axial bore, a first piston which is slidable in the bore and divides it into front and rear pressure chambers, Openings for connecting the pressure chambers with associated container chambers, one between the first piston and the Spring acting at the end of the bore, which biases the first piston backwards, one that can be displaced in the bore second piston that telescopes with the first piston Coupling is connected, which limits the axial separating movement of the piston, one arranged between the pistons and they are urging apart a spring and an actuating rod extending through the open end of the bore penetrates.

If the operating rod is, for example, by a pedal mechanism or a brake booster is pushed inwards, the pistons are moved forward so that the connection between the pressure and the container chambers interrupted and brake fluid in the pressure chambers below Pressure is set, the pressure being passed on to the associated brake circuits via two Aualaßöffnungen, the are connected to the associated pressure chambers.

In a tandem master cylinder according to the invention, the rear pressure chamber is with the associated container chamber connected via the longitudinal channel penetrating the housing, with a refill chamber for a sealing member of the second piston to the container chamber via the open end of the channel on the inner shoulder of the housing in Connection.

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Starting with the same goal, namely to achieve low weight and small dimensions, a tandem master cylinder according to a preferred embodiment of the invention also have the following characteristics:

I) The second piston is barrel-shaped on the outside, which enables a reduction in size of the piston and thus of the entire master cylinder in the axial direction.

II) The first piston is hollow and open at its front end, and that between the piston and the end wall of the bore Acting spring is partially accommodated in the piston, which increases the weight and the axial length of the master cylinder let it decrease further.

III) The telescopic coupling between the two pistons is instead, as usual, formed by a solid pin and a sleeve of two tubular components, so that one Weight saving is achieved.

IV) The operating rod is sealed against the housing with a sealing member that is received in the bore and instead of a spring washer · of a component is held, which is attached to the end of the housing; this enables a reduction in length.

Combined by these features of the preferred embodiment With the basic features of the invention, a master cylinder of lighter weight and smaller axial length than conventional tandem master cylinders.

Embodiments of the invention are explained in more detail below with reference to schematic drawings. It shows:

1 shows an axial section through a first tandem master cylinder according to the invention,

Fig. 2 is a similar view of a second embodiment of the invention and

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^ & ager saw a section through, a front one End section of the master cylinder housing according to FIG. 2.

The master cylinder shown in Fig. 1 is for a Dual-circuit brake system and has a housing 1 with a stepped, non-continuous axial bore 2, which is divided into two cylinders 3 and 4 by an inclined shoulder 5 and near the rear, open end of the housing 1 additionally has an inner shoulder 6. In the rear cylinder 3, a piston 7 is displaceable, which is a Sealing member 8 carries and is fixedly or integrally connected to an actuating rod 9 through the rear end of the housing 1 penetrates.

In the front cylinder 4, another piston 10 is displaceable bar, which has an operating function at its front end fulfilling sealing member 11 and two at its rear end Sealing members 12 carries. The piston 10 is supported by an acting between it and the closed end of the bore 2 Spring 13 is biased backwards and has a protrusion 14 that stops its forward movement by bumping into it bounded by the end wall. The end piece of the piston 10 is connected to the front end piece des.Kolbens 7 by coupling members 15 connected, which allow a certain axial movement of the pistons 7 and 10 with respect to each other. The pistons 7 and 10 are biased away from each other by a spring 16.

The housing 1 of the master cylinder contains two container chambers 17 and 18 associated with the cylinders 3 and 4, respectively. The container or container chamber 18 stands with the pressure chamber formed between the piston 10 and the inner end of the bore 2 through an opening 19 in connection, also branch of the container or the container chamber 18 with the cylinder 4 between the sealing members 11 and 12 by a further one formed in a component 20

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Opening connected. The component 20 also forms a stop, which limits the movement of the piston 10 to the rear .

From the shoulder 6 inwardly to the container chamber 17 extends a channel 21, which by drilling a hole has been formed parallel to the axis of the housing 1. The channel 21 and thus the container chamber 17 is with the between the pistons 7 and 10 formed pressure chamber connected by an opening 22 by a radially bored and finished hole is formed. The channel 21 is through with the cylinder 3 behind the piston seal 8 a gap between a slightly recessed portion of the shoulder 6 and one in the example shown Component 23 formed by an intermediate disk and connected by holes 24 in piston 7. The component 23 prevents the end of the channel 21 from being closed by a sealing member 25, which the end of the main- Seals cylinder and is supported on its outside by a component 26 which is in the bore 2 with a Spring ring 27 is attached. A hole 28 in component 23 ensures adequate lubrication of sealing member 25.

The operation is as follows: The master cylinder is attached to the front of a brake booster so that the section of the master cylinder in the brake booster housing arranged behind the outer flange of the housing 1 is recorded. When the brakes are to be operated, the brake booster pushes the operating rod 9 forward, the pistons 7 and 10 being moved along the cylinders 3 and 4 until the connection between the Pressure chambers and the container chambers 17 and 18 interrupted at the openings 22 and 19 by the sealing members 8 and 11 is. With further forward movement of the pistons 7 and 10, the pressure chambers are then used to actuate the brakes put under pressure. It is necessary that the containers or container chambers 17 and 18 with the cylinders 3 and 4

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behind the sealing members 8 and 11 are in communication to ensure that the latter is adequately lubricated and when sliding back over the mouths of openings 19 and 22 not be damaged.

When using the master cylinder described above, a considerable portion of the same can be used in the brake booster and achieve a significant saving in space. The passages that the container chamber 17 connect to the cylinder 3 are provided in a simple and expedient manner that the Requires drilling only two holes, one radial and the other parallel to the axis.

The master cylinder shown in Figs. 2 and 3 has a integral main part or housing 51 with a discontinuous one axial bore 52, a container 53 »which is divided into two chambers 55 and 56 by an inner partition 54 is, and a pad 57 for attaching the main cylinder to a brake booster, vehicle body part or other component. The bore 52 is through a cup-shaped piston 60 in a front and a rear Pressure chamber 58 and 59 divided. The open end of the piston 60 faces the closed front end of the bore 52, and the piston 60 is pretensioned to the rear by a spring 61 which is partially accommodated in its interior space, The piston 60 carries at its front and rear ends annular sealing members 62 and 63 »between those of the Piston 60 and the - bore wall an annular space is formed, which is connected to the container chamber 55 via an opening 64 is in communication. The front sealing member 62 is held in place by a ring 65 which is held on the piston 60 by four tabs which are cut into the ring 65 and into a circumferential groove in the piston 60 have been bent into it. The rear sealing member 63 is attached to the piston 60 by an external flange on a sleeve 66 held, the front end of which is received on a shoulder of the piston 60.

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In the open end of the bore 52 penetrates a substantially hollow actuating rod 67, which one with her has a fixed or one-piece piston 68 displaceable in the bore 52. The piston 68 is from small axial extension and for this reason barrel-shaped designed to eliminate any risk of the piston 68 jamming in the bore 52. The operating rod 67 has an axial projection 70 integral with it with a conical head piece and a neck of reduced diameter. On the protrusion 70 is a sealing member holder 71 arranged, which holds a sealing member 72 in position on the actuating rod 67 in front of the piston 68, as well as a tubular component 73 · bent out of the component 73 Tabs engage on the back of the head piece of the projection 70 to the component 73 on the actuating rod 67 hold on. The front end of the component 73 is received in the sleeve 66 and has an outer one Flange, which abuts an inner flange of the sleeve 66, to the axial separating movement of the pistons 60 and 68 to limit. A helical spring 74 is clamped between the outer flange of the sleeve 66 and the sealing member holder 71. In a bore widening of the housing 51, in the example shown, an intermediate disk is formed Component 75 received, which rests against an inner shoulder 76 and limits the rearward movement of the piston 68. In the bore extension sealing members 77 are also arranged between the housing 51 and the Seal the actuating rod 67 and hold it in place by a component 78, which is designed as a sleeve in the example shown are, which is slipped onto the end of the housing 51 and held in position by tabs coming out of it are bent out and into a circumferential groove in the housing 51 intervention.

The container chamber 55 is connected to the front pressure chamber 58 somewhat in front of the sealing member 62 via an opening 79 in connection.

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The other container chamber 56 is connected to the rear pressure chamber 59 via an opening 80 and a longitudinal one Channel 81 connected. The channel 81 opens at the radial shoulder 76 between the bore 52 and its bore widening, the space between the sealing member 72 and the piston 68 via the piston 68 penetrating holes, a refill chamber 82 and holes in the component 75 with the Channel 81 is connected.

According to FIG. 3, for connecting the pressure chambers 58 and 59 outlet openings 83 and 84 are provided on associated brake circuits. The outlet opening 84 is inclined with respect to the axial direction so as to be accessible from the outside of the wall to be to which the splash 57 is attached.

The operation of the master cylinder is the same as that of known tandem master cylinders. When the operating rod 67 is pushed forward, the piston 68 moves forward so that the sealing member 72 closes the opening 80, and the piston 60 is moved forward so that the sealing member 62 blocks the opening 79. By further As the pistons 60 and 68 move forward, the brake fluid in the pressure chambers 58 and 59 is pressurized. This pressure is passed on via the outlet openings 83 and 84 to the wheel brake cylinders for actuating the brakes. During the compression process in the pressure chamber 59, the component 73 slides in telescoping the sleeve 66 into it. The connection between the channel 81 and the refill chamber 82 behind the sealing member 72 is prevented the creation of a negative pressure behind the piston 68, which counteracts its forward movement.

The very compact design and the low weight of the main cylinder result from the combination of several Features which include the formation of the longitudinal channel 81 that connects the container chamber 56 with the pressure chamber 59 and the refill chamber 82 for the sealing member 72

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connects the use of a hollow piston 60 which houses the spring 61, the use of a component 78 in the form of an outer ring for holding the sealing members 77f in place and the formation of a very short, barrel-shaped Piston 68 on the actuating rod 67.

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Claims (5)

DIU-ING. FRJlNZ "WUESTHOR" PATENT LAWYERS. _{DR pHIL} . _PREDA ™ _ESTHOFP WUESTHOFF - v. PECHMANN - BEHRENS - GOETZ dipping, gerhard puls DIPL.-CHEM. DR. E. BARBER OF PECHMANN PROFESSIONAL REPRESENTATIVES BEFORE THE EUROPEAN PATENT OFFICE DR.-ING. DIETER BEHRENS MANDATAIRES AGREED PRES l'OFFICE EUROPtEN DES BREVETS DIPL.-ING .; DIPL.-VIRTSCH.-ING. RUPERT GOETZ D-8000 MUNICH 90 1A-53 680 SCHWEIGERSTRASSE 2 ————— ~ phone: (089) 66 20 ji telegram: protectpatent telex: j 24070 Claims Master cylinder with a housing (1; 51) with a bore (2; 52), a container chamber (17; 56), a transverse opening (22; 80) in the housing (1; 51) which is spaced to the rear from the container chamber (17; 56) opens into the bore (2; 52), and a channel (21; 81) which extends along the housing (1; 51) and the transverse Opening (22; 80) and the container chamber (17; 56) connects to one another, characterized in that that the bore (2; 52) is stepped to form a shoulder (6; 76) near the rear end of the housing (1; 51), the opening (22; 80) is arranged between the shoulder (6; 76) and the container chamber (17; 56) and the channel (21; 81) extends at least approximately parallel to the bore axis from the shoulder (6; 76) to the container chamber (17; 56), whereby the container chamber (17; 56) with the bore (2; 52) both via the opening (22; 80) and via the open End of the channel (21; 81). the inner shoulder (6; 76) is in communication. 2. Master cylinder according to claim 1, wherein the open rear The end of the bore (2; 52) is closed by a sealing member (25; 77), characterized in that that a component (23; 75) between the shoulder (6; 76) and the sealing member (25; 77) is arranged around the sealing member (25; 77) to be kept at a sufficient distance from the shoulder (6; 76), whereby the sealing member (25; 77) is prevented from to close the open end of the channel (21; 81). 03 ^ 051/0882 - 2 - 53 680 3. Master cylinder according to claim 1 or 2, in which the bore (52) is divided into a front and a rear pressure chamber (58, 59) by a first piston (60) which can be displaced in it and which has a first and a second opening ( 79, 80) with associated container chambers (55 _t 56) are connected, wherein the second opening (80) communicating with the associated reservoir chamber (56) through the channel (81) in communication, in the bore (52), a second piston (68 ) is displaceable and a spring (61) between the first piston (60) and the end of the bore (52) acts and biases the first piston (60) backwards, characterized in that the first piston (60) is hollow and at its front end is open, the spring (61) is partly received in the piston (60) and the second piston (68) is of small axial extent and barrel-shaped. 4. Master cylinder according to claim 3 »in which the two pistons (60,68) are connected to one another by a telescopic coupling, which the axial separating movement of the pistons (60, 68), characterized in that the telescopic coupling has two tubular components (66, 73), which are connected to the associated piston (60, 68). 5. Master cylinder according to claim 3 or 4, wherein an actuating rod (67) is coupled to the second piston (68) and protrudes through the open end of the bore (52) and a sealing member (77) seals the open end of the bore (52) around the actuating rod (67), thereby characterized in that the sealing member (77) in the bore (52) from one to the end of the housing (51) attached component (78) is held. 030051/0882