DE1902673A1 - Medium-pressure servomotor, especially for vehicles - Google Patents

Description

AUTOMOTIVE PRODUCTS COMPANY LIMITED, Tachbrook Road, Leamington Spa, Warwickshire, England

For this filing, the priority is taken from the UK Patent application No. 3264/68 dated January 22, 1968 claimed

Pressure medium-operated servo motor, in particular for vehicles

The invention relates to fluid operated servomotors with a housing, the interior of which by a movable dividing component, such as a membrane or a piston, is divided into two chambers, wherein Both chambers when the servomotor is out of operation with a supply source for pressure medium, for example air, of relatively low pressure are connected, wherein the supply of a pressure medium of relatively higher pressure after Chamber on one side »^ e :? mobile divisional

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components is controlled by a valve device which is held by the movable partition component so that that it moves with it, and the actuation of the valve by a pedal or another, by one Operator operated control device is controlled.

It is the object of the invention to improve the design of the valve device in a pressure medium-actuated Provide servo motor of the above type.

In a pressure medium-operated servomotor with a housing which is divided by a movable dividing component into a first and a second chamber, the first of which is in constant communication with a supply source for the pressure medium of relatively low pressure, and with a valve device which is controlled by the movable Dividing component is carried and moves with this in order to selectively connect the second chamber with the first chamber or with a second supply source for a pressure medium of relatively higher pressure, according to the invention, the valve device is composed of a valve caromer, which at one end by a movable niand is closed, in which there is at least one recess that establishes a connection with the supply source for pressure medium of relatively higher pressure, from a valve seat in the valve chamber passages, which open into the valve chamber on opposite sides of the valve seat and this valve chamber jew eeil to connect with the first and second chamber, from an operable by an operator control device which moves the movable V / and, from a first valve closure component, which cooperates with the valve seat in the valve chamber, from a second valve closure component, which with the recess in the movable wall cooperates, as well as a thrust device which connects these valve closure components with one another, the arrangement being such that when the ^{servomotor is not L} -activated, the second valve closure component dl ". Off-isp ^ r = - '! ;;;

909837/0899 BAD ORfGiNAL

closes in the movable wall and the first valve closure member is lifted from its seat so that the first and second chambers are interconnected and by the movement of the movable wall by means of the control device operated by the operator, the first valve closure component is moved on the valve seat to separate the second chamber from the first chamber, with further movement of the from the operator actuated control device a relative movement between the movable wall and the second valve closure member caused to pressure medium from the supply source of higher pressure after the valve chamber and after the second chamber allow in the servomotor housing, and cause a differential pressure on the movable partition member and the operation of the servomotor.

The invention will now be described in more detail with reference to the drawings showing them as examples, namely shows

Pig. 1 shows a longitudinal section through an embodiment a pressure fluid operated servo motor according to the invention,

Pig. Figure 2 is a section, on a larger scale than that of the Pig. 1, through the valve device, those in the fluid-actuated servo motor according to Pig. 1 is included,

Pig. 3 a section, similar to the Pig. 2, by a modified valve device, while

Fig. 4 is a section similar to part of the Pig. 1, by means of which a drag force according to that of the operator operated control device, -proportional to that by the servomotor exerted thrust, can be transmitted to give the operator the opportunity

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to give emotional determination of the degree of thrust exerted.

The pressure-medium-operated servomotor shown in FIG. 1 is of the so-called vacuum-dependent type and is used to provide an auxiliary force in a hydraulic brake system of a vehicle, the servomotor im Use is arranged so that it actuates the piston of a pressure medium master cylinder. However, the invention is not based on fluid operated servomotors are limited for this purpose.

According to FIG. 1, the servomotor has a housing 10 made up of two curved shells 11 and 12 which are thus assembled are that they form a substantially cylindrical housing, the interior of the housing in two separate chambers

13 and H is divided by a flexible membrane 15, which is formed by clamping a peripheral edge portion of the membrane is attached between overlapping parts of the two shells 11 and 12. The chamber 13 is in the following referred to as the first or vacuum chamber, while the chamber

14 is hereinafter referred to as the second or working chamber. The housing 10 has an opening 16 to the vacuum chamber 13 with a vacuum source (not shown), e.g.

the exhaust manifold / the vehicle engine, to connect, wherein the diaphragm 15 is spring-loaded by a helical spring in the vacuum chamber 13 to the diaphragm in the direction to bias on the working chamber 14.

The diaphragm 15 has a centrally located hub 18 which is attached to the diaphragm so that it moves with this. The. Hub 18 consists of a body section 19, which is arranged on the vacuum chamber side of the membrane, and a sleeve section 21, which on the working chamber side of the membrane is arranged. The sleeve section 21 of the hub extends axially through the working chamber 14 through and out of the housing 10 via a recess

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in the end wall of the working chamber, the sleeve in the Recess when moving the hub 'is displaceable with the membrane. A sealing member 23 is provided in order to be fluid-tight Ensure seal between the wall of the recess and the outer periphery of the sleeve part piece. The end of the sleeve section 21 which protrudes from the working chamber 14 is open and forms an air inlet. One Sealing cap or a flexible cover 24 is advantageously provided at this end of the sleeve bore, with at least a part of it consists of a wire mesh or some other perforated material to make an air filter form. The bore of the sleeve section 21 is the hub stepped at 25 to a bore portion 26 of larger Diameter at the outer end of the sleeve section and a bore section 27 of smaller diameter at the inner end to form the same. A central bore 28 in the body portion 19 of the hub, coaxial with the bore portions 26, 27, is at its' end, which is in the bore section 27, as shown at 29, opens, expanded. In the bore section 27, a flange 31 is displaceable on a plunger 32, one end of which is displaceable in the body bore 28, the flange having a sealing ring on its peripheral edge 33 carries, which produces a fluid-tight sliding connection with the wall of the bore section 27. The flange 31 thus forms a movable end wall for a valve chamber 30, which through the bore section 27 · and the Extension 29 of the body bore 28 is limited.

At its other end, the plunger -32 has a recess, around a ball end 34 on a push rod 35 take up and to hold against relative axial movement, the push rod 35 axially through the sleeve section 21 of the Hub runs through and via a corresponding connecting linkage (not shown) to the brake pedal of the vehicle can be connected. A spring 36 between a stop 37 on the push rod 35 and the gradation 25 in

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the bore of the sleeve section is effective, pushes the Push rod and with this the plunger 32 and the flange 31 in a retracted position, which corresponds to the de-energized state of the fluid-actuated servo motor corresponds.

Bores 38 (Fig. 2) in the flange 31, parallel to its axis, define passages for the flow of air from the outer end of the sleeve section 21 of the hub into the valve chamber 30. A bore 39 in the body section 19 of the hub connects the first or vacuum chamber 13 with the enlargement 29 of the body bore, while a bore 4-1 connects the second or working chamber 14 to the end of the bore section 27 in the vicinity of the enlargement 29. The inner edge of a shoulder 42 at the junction of the bore section 27 and the extension 29 forms a seat for a first valve 'closure component, which consists of an annular disc 43 made of natural or synthetic rubber, plastic or another suitable material and surrounds the plunger 32 , the inner periphery of the disc 43 sealing around the outer periphery of the plunger. The annular disk 43 is carried by a flat ring 44 and is attached to this, from which a plurality of rigid, axially extending rods 45 protrude, which run with play through the bores 38 and on a further ring 46 on the other On the side of the flange 31. A ring 47, which is located on the plunger 32 by a spring clip, forms a stop for the annular disk 43, limiting its movement along the plunger away from the flange 31. The disk 43 separates when it is in contact with the shoulder 42, the. Parts of the valve chamber 30 from one another, which are each connected to the vacuum chamber 13 and the working chamber 14.

The ring 46 carries on its flange 31 facing Side two spaced apart coaxial sealing rings 48 and 49, which can be O-rings and on the flange 31 each radially outside and radially inside the ring of

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Attack bores 38, the ring 46 and the sealing rings 48 and 49 in this v / eise a second valve closure component form in order to prevent the ingress of air into the valve chamber 30 via these bores. A helical compression spring 51, which their abutment on an annular bracket 52, which sits on the push rod 35, finds, presses the sealing rings 48 and 49 against the flange and via the rods 45 the washer 43 in the direction of ring 47.

A second push rod 53 with a head 54 which is fixed in the bore 28 of the hub 18 extends through an opening in the end wall of the vacuum chamber 13 and engages the piston of a liquid pressure master cylinder (not shown), which is coupled to actuating cylinders for actuating the vehicle brakes, a fluid seal 55 is provided in the opening.

When the brakes of the vehicle are not applied, the hydraulic servomotor is de-energized.

The push rod 35 is pushed into the retracted position by the spring 36, with the plunger 32 also is held in one position by the push rod 35, in which the washer 43, which forms the first locking component, is lifted from its seat, the O-rings: 48, 49, which form the second closure component, are placed on the adjacent surface of the flange 31 by the spring 51 will. When the first locking component is lifted off, the housing chambers 13 and 14 are mutually via the bores 39, 41 in the Have and open to the valve chamber 30, so that the membrane is held in the position shown in FIG. 1 by the spring 17 in which the volume of the working chamber 14 is a minimum is. The second closure component, which is seated, prevents air from entering the working chamber 14 via the bores 38.

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When the brake pedal is pressed to apply the brakes, the push rod 35 is against it Spring load moved into the hub. The plunger 32 thus moves, taking the locking components with it. While this movement the washer 43, which forms the first locking component, is placed on the shoulder 42, to separate the working chamber 14 from the vacuum chamber 13, and if it is so placed, another movement the rings 44 and 46 prevented, so that the plunger 32 is caused by a continued movement of the push rod 35 is to move relative to these rings, whereby the flange 31 is separated from the O-rings 48, 49 to the axial To release bores 38 so that air can get into the valve chamber 30 and into the working chamber 14. Feeding Air in the working chamber 14 leads to the generation of a differential pressure on the membrane 15, so that this membrane counteracts their Pederbelastung is deflected, the movement of the membrane a movement of the second push rod 53 in the usual Way caused to actuate the master cylinder and effect braking. When the brake pedal is released, then the push rod 35 and the plunger 32 are withdrawn by the peder 36 which acts on the push rod, wherein the peder 51 acts on the ring 46 to return the locking components to their original positions relative to the plunger, and wherein the retraction of the plunger moves the disc 43 away from the shoulder 42. In this way the air supply to the working chamber 14 is blocked, and A vacuum is restored in this chamber, which gives the membrane 15 the opportunity to return to its original position .

In the embodiment of the invention described above, slides the plunger 32 through the annular disk 43, which forms the first locking component. Around however, to avoid friction that can lead to undesirable deceleration, the first closure component,

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as shown in Fig. 3, have the shape of a membrane 56, which includes a relatively thick outer section which is attached to ring 44 and a thinner, flexible inner section has, the inner circumference of which is seated in an annular groove 58 in the plunger, so that this membrane is deflected, to allow movement of the plunger relative to the outer portion of the diaphragm. The second closure component could be a one piece casting including washer 46 and washers 48, 49, in natural or synthetic rubber, plastic or some other suitable material. Alternatively the second closure component could also have a disc 46 which is formed as a molding in plastic material, the O-rings of this second closure component respectively sit in concentric grooves in the corresponding face of the disc.

Means k, ur delivery of one are advantageous "Brake feel" provided to the driver via the brake pedal. This can be done, for example, by providing a spring device reached between the rod 35 of the valve device and the actuated by the membrane of the servomotor push rod 53 will.

Alternatively, the "feeling" can also be achieved by transmitting the thrust force from the membrane 15 to the push rod 53 a lever mechanism can be achieved, the reaction thrust to the tappet 32 and thus to the push rod 35. Thus, according to FIG. 4, the plunger 32 has an extension 32a, which extends from the hub 18 into the vacuum chamber 13, and radial levers 61 which at their outer ends with a attack resilient ring 62, which is supported by a plate 63 which sits on the hub 18, and on their inner ends with the plunger extension 32a are in operative connection, also grip between their ends on a cylindrical Edge 64 on a disc 65 that is attached to the push rod

ORIGINAL INSPECTED 90983770899

is attached. The spring which returns the diaphragm 15 to its original position, shown at 66, acts on the levers 61 at their outer ends. Ve'nn the pressure-operated servomotor by actuating the valve in action is set, then the thrust on the diaphragm 15 via the plate 63 and the resilient ring 62 on the outer ends of the lever 61 and thus transmitted via the disc 65 to the push rod 53, with a reaction force through the inner ends of the levers on the plunger 32 and the push rod 35 is exerted.

The levers 61 can be replaced by a cup spring washer, the essence of the arrangement, whether Lever or a Belleville spring washer are used, is that the lever device, which by the lever or is formed by the Belleville washer, on the subdivision component of the engine in a radially outer zone, the The ram in a radially inner zone and the thrust component that transfers the thrust from the servomotor to the master cylinder, attack in a radial intermediate zone.

The invention also relates to modifications of the enclosed Claim 1 outlined embodiment and relates above all to all features of the invention that are disclosed individually - or in combination - throughout the description and drawing.

Claims

original inspected 909837/0899

Claims (12)

Claims ■, I .. ^{1 he} pressure medium actuated servo motor, especially for vehicles, with a housing which is divided by a movable dividing component into a first and a second chamber, the first of which is in constant communication with a fluid source of relatively low pressure, and valve means carried by the movable partition member and movable therewith for selectively connecting the second chamber to the first chamber or to a second source of pressurized medium of relatively higher pressure, characterized in that the valve means is composed of a valve chamber, which is closed at one end by a movable wall which has at least one recess which is connected to the pressure medium source of. relatively higher pressure is in communication, from a valve seat in the valve chamber, from passages that open into this valve chamber on opposite sides of the valve seat .. and connect the valve chamber with the first and second chamber, from a control device that can be operated by an operator, which moves the movable wall, from a first valve closure component which cooperates with the valve seat in the valve chamber, from a second valve closure component which cooperates with the recess in the movable wall, and from a 90983 77 0899 Thrust device which connects the valve closure components with one another, the arrangement being such that when the servomotor is not actuated, the second valve closure component closes the recess in the movable wall and the first valve closure component is lifted from its seat, so that the first and second Kamme'r are interconnected and by the movement of the movable wall by means of the control device operated by the operator, first the first valve closure component is pressed onto its seat in order to separate the second chamber γοη the first chamber, with a further movement of the caused by the operator-operated control device a relative movement between the movable wall and the second valve closure component to allow pressure medium from the source of higher pressure in the valve chamber and the second chamber in the servomotor, to generate a pressure difference on the movable partition component and the loading to initiate actuation of the servomotor. 2. Servomotor according to claim 1, characterized in that that the movable wall, which is the one and the other Valve chamber closes, is held by a plunger which extends through the valve chamber and in "a hole is guided from the other end of the Valve chamber extends forth. 3. Servomotor according to claim 2, characterized in that the first valve closure component has an annular shape Sealing component contains that the valve seat, with which it cooperates, formed by a shoulder in the valve chamber is, and that the annular sealing component is held by a ring which is axially movable relative to the plunger is and creates a sealing connection with the plunger at its inner edge. 909837/0899 4. Servomotor according to claim 3, characterized in that the sealing component engages slidably on the plunger. 5. Servomotor according to claim 3, characterized in that the sealing component is a flexible diaphragm component has, the inner edge of which sits in a groove in the plunger. 6. Servomotor according to claim 1, characterized in that that the second valve closure component has a ring which is located in the direction of the outside of the valve chamber Side of the movable wall is pressed by a spring, and that this ring carries sealing means attached to it Attack the side of the movable wall. 7. Servomotor according to claim 6, characterized in that the sealing means carried by the ring are two coaxial Have sealing rings which are arranged so that they are each radially inside and radially outside one Ring of recesses in the movable wall. 8. servomotor with a first valve closure component according to claim 3 to 5, and a second valve closure component according to claim 7, characterized in that the ring of one of the valve closure components is one Supports plurality of rods that extend with play through the recesses in the movable wall and on attack other valve closure member so that a displacement of a valve closure member relative to Plunger and in the direction of the movable wall a movement of the other valve closure component of the .mobile Wall away with it. 9. Servomotor according to claim 1 to 8, characterized in that that a device is provided which on the 909837/0899 operator operated control device a Reaction thrust proportional to that provided by the servo motor exerted thrust transfers. 10. Servomotor according to claim 9, characterized in that that on a lever device on which the dividing component acts in a radially outer zone and with a movable by the control device actuated by the operator control device in a radially inner plunger Zone is in operative connection, a round edge engages in a radial intermediate zone, which is driven by an output thrust component of the servo motor is held so that a thrust force generated on the subdivision component by pressure medium pressure difference in the Servomotor is exerted, transmitted to the output thrust member via the lifting device and a reaction thrust force by the lever device to act on the plunger is brought. 11. Servomotor according to claim 10, characterized gekennzeiohne t that the lever device has a plurality of radial levers. 12. Servomotor according to claim 10, characterized in that the lever device has a cup spring washer. 13- servomotor according to claim 11 or 12, characterized in that that a resilient seat is arranged between the partition member and the lever means. 909837/0899 Blank page