US3125003A

US3125003A - Diaphragm plate construction

Info

Publication number: US3125003A
Authority: US
Priority date: 1961-03-16
Publication date: 1964-03-17
Anticipated expiration: 1981-03-17
Also published as: US3053235A; DE1293028B; DE1228931B; GB1011732A; GB964289A; FR1317767A

Description

H. M. HOEKSTRA Filed March 16. 1961 JZrc-s. 5.

' INVENTOR. l/[RMJN M l/MKSTM A T TORIJEY V United States Patent The present invention relates as indicated to a novel diaphragm plate construction and more particularly to a diaphragm plate construction for a fluid pressure servomotor wherein novel means are provided for retaining the control valve mechanism in the diaphragm plate.

An object of the present invention is the provision of a simplified construction of a diaphragm plate for a fluid pressure motor in which internal parts are retained in position by a radially extending pin that is held in place by means of the power diaphragm.

A further object of the present invention is the provision of a new and improved diaphragm plate construction for a fluid pressure servomotor in which the diaphragm plate has an axially extending valve chamber which opens outwardly at one side of the diaphragm plate and into which the various valve elements are placed-this structure further including a retainer member for the valve elements which is slid into a radial opening in the diaphragm plate to project into the valve elements and hold them in position, and the retainer member being adapted to be held in position by an annular power diaphragm which is snapped over the retainer member.

The invention resides in certain constructions and combinations and arrangements of parts; and further objects and advantages of the invention will become apparent to those skilled in the art to which the invention relates from the following description of the preferred embodiment described with reference to the accompanying drawings forming a part of this specification, and in which:

FIGURE 1 is a cross sectional view of fluid pressure servomotor embodying principles of the present invention;

FIGURE 2. is a fragmentary cross sectional view through a portion of the diaphragm plate seen in FIG- URE l; and

FIGURE 3 is a plan view of a key or stop member shown in FIGURE 1.

The shell or housing of the servomotor shown in the drawings is formed by means of a cup-shaped front housing section and a rear cover section 12 which is slid into the open end of the front section and suitably held in place to provide an enclosure for its axially extending internal chamber. The internal chamber of the servomotor is divided into front and rear

opposing power chambers

14 and 16 respectively by means of a diaphragm 18the radially outer portion of which is suitably clamped between the housing sections, and the radially inner portion of which is sealingly affixed to a diaphragm plate 20. 'In the preferred embodiment shown in the drawing, the diaphragm plate 20 is made in one integral plastic piece having a rearwardly extending cylindrically formed boss 22 which projects out through an opening in the rear cover plate 12 for the purpose of providing a sliding vacuum type seal with respect to the cover plate 12. The sliding vacuum seal may be formed in any suitable manner, and as shown in the drawing, is formed by a U-packing 24 that is seated up against a stamped shoulder 26 in the cover plate 12. The U-packing 24 is held in place by means of an annular spaldite washer 28-which in turn is held in place by means of an annular metal ring 30 having interference fit with respect to the sidewalls of the stamped cylindrical section 32 of the cover plate 12. A corrugated rubber boot 34 is suitably lice afiixed between the outer end of the cylinder boss 22 and the outer end of the stamped cylindrical section 32 of the cover plate 12 to provide a suitable dirt seal for the sliding sealing outer surfaces of the cylinder boss 22.

The diaphragm plate 20 is further provided with a radially extending integral flange 36 for the purpose of supporting the center section of the diaphragm 18; and inasmuch as the diaphragm shown is of the curtain type, the periphery of the integral flange 36 is turned forwardly as at 3 8 so that the diaphragm 18 will lay up against the periphery of the turned portion 38 in the manner customary for curtain diaphragm structures. The radially inner portion of the diaphragm 18 has a central opening 40 therethrough of a diameter which will slip or pass over the annular boss 22. The diaphragm plate 20 is of course thickened at the juncture of the cylindrical boss 22 and the integral flange 36; and a suitable diaphragm receiving groove 42 is provided in this thickened portion adjacent the rear surface of the integral flange 36 to provide a seat into which the diaphragm 18 may be snapped. The diaphragm 18 may be provided with rubber bumpers 44, and a thickened annular portion 46, as explained in the Maxwell L. Cripe application Serial No. 75,596; so that once the diaphragm is seated in position in the groove 42, a vacuum type seal will automatically be provided between the diaphragm l8 and the diaphragm plate 20.

The servomotor shown in the drawing is of the type which is intended to be used for the power actuation of a conventional master cylinder of an automotive hydraulic braking system; so that the front end of the shell 10 is adapted to be bolted directly to the rear end of the master cylinder in a manner providing a vacuum tight seal. The diaphragm plate 20 is provided with an axially extending opening 48 which extends from the front surface of the diaphragm plate 20 through the cylindrical boss 22; and the front end of the opening 48 is enlarged as at 50 to receive the headed end 52 of a push rod 54 which abuts and drives the hydraulic piston of the master cylinder, not shown.

In the fluid pressure motor construction shown in the drawing, vacuum is continually supplied to the front opposing power chamber ]l4 through a tubular check valve structure 56; and the diaphragm plate 20 is caused to be biased into the position shown in the drawing by the piston return spring 58 whenever vacuum is also admitted to the rear opposing power chamber 16. A block of elastomeric material 60 is provided between the headed end 52 of the push rod 54 and the bottom of the enlarged section so of the axially extending opening 48, for the purpose of resiliently transmitting force from the diaphragm plate 2!} to the push rod 54, as is explained more fully in the above referred to Maxwell L. Cripe application.

The structure so far described will have utility in various types of fluid pressure motors. Power output of the fluid pressure motor is of course regulated by controlling the pressure in the rear opposing power chamber 16; and inasmuch as the motor shown in the drawing is a servo.- motor, the control valve structure is mounted in, and carried by the diaphragm plate 20. In the servomotor construction shown in the drawing, the control valve structure is very conveniently and simply constructed by a. plurality of stacked elements which are installed upon the control rod 62and after which, the assembly is completed by inserting the assembled stacked elements into the rear end of the central opening 48 in the cylindrical boss 22.

The elements which are assembled upon the push rod 62 generally comprise a control member 64 having a rearwardly facing annular atmospheric valve seat 66 thereon for sealing abutment with a flexible annular rubber poppet member 68. The annular rubber poppet member 68 is suitably stifiened by an annular metal washer '70 about which the rubber is molded, and the poppet member 68 further includes an integral flexible diaphragm portion 72 having a radial outer periphery which is suitably thickened for sealing engagement with the sidewalls of the axial opening 48 in the cylindrical boss 22. The rubber poppet member 68 is biased up against the atmospheric valve seat 66 by a coil spring 76 that is interpositioned between the rod 62 and a flanged tube 78 which is fitted into the inside of the annular poppet member 68 in abutment with its stiffening washer '70. The valve structure is caused to assume the normal servomotor deactuating position shown in the drawing by a. valve return spring 30 which is interpositioned between the push rod 62 and a sealing washer 82 which biases the outer thickened portion 74 of the poppet diaphragm 72 into sealing engagement with the sidewalls of the opening 46. A suitable shoulder 84 is provided on the push rod 62 for receiving a spring retainer 86 against which the valve return spring 80 is positioned.

The opening 48 through the diaphragm plate 20 is provided with a plurality of gradually increasing diameter sections proceeding from its smallest portion adjacent the reaction disc 60 to the rear opened end of the cylindrical boss 22 so that all of the parts which are assembled upon the push rod 62 can he slid into position. The previously enumerated valve parts will be assembled on the push rod 62 in generally the reverse order given above; and after the control member 64 is placed over the ball end of the push rod 62, it is suitably stacked in position as at 88. The vacuum valve seat 90 for the control valve structure is provided by a. shoulder formed by increasing the diameter 48 at a position generally opposite to the assembled position of atmospheric valve seat 66; so that a small annular control pressure area exists between the two valve seats 66 and 90. This control pressure area 92 extends around the control member 64 and is communicated to the rear opposing power chamber 16 by means of the control passage 94. The outer periphery of the poppet member 68 is of course adapted to seat against the vacuum valve seat 90; and the central opening 48 is further enlarged at a point rearwardly of the vacuum valve seat 90 to provide a suitable shoulder 96 against which the outer thickened portion '74 of the poppet member can be biased to assure a vacuum type seal with respect to the sidewalls of the opening 48. Vacuum is continually communicated to the annular area between the shoulders 90 and 96 and radially outwardly of poppet member 68 by means of the vacuum passage 98 which is cast in the diaphragm plate 20 to at all times communicate with the front opposing power chamber 14.

It will now be seen that atmospheric pressure continually communicates to the area inside of the flexible poppet member 68 from the right hand open end of the opening 48 in the cylindrical boss 22. In the position shown in the drawing, the atmospheric valve seat 66 sealingly abuts the poppet member 68; so that atmospheric pressure is isolated from the rear opposing power chamber 16 of the servomotor. It has further been explained that the valve spring 80 biases the push rod 62 rearwardly with sutficient force to hold the atmospheric valve seat 66 against the poppet member 68, and in turn hold the poppet member 68 away from the vacuum valve seat 96. In this condition of the control valve structure, vacuum from the front opposing power chamber 14 flows through passage 93 to the control area 22, and passage 94, to the rear opposing power chamber 16. When it is desired to actuate the servomotor, the push rod 62 is pushed forwardly to a point where the poppet member 68 abuts the vacuum valve seat 90 to isolate the vacuum submerged front opposing power chamber 14 from the rear opposing power chamber 16-after which time a slight further movement of the push rod 62 moves the atmospheric valve seat 66 out of engagement with the poppet member 68 to permit air pressure to flow past the atmospheric valve seat 66 and into the rear opposing power chamber 16. Pressure in the rear opposing power chamber 16 biases the diaphragm 20 firmly up against the flange 36 of the diaphragm plate 20 to assure positive sealing engagement therewith, and thereafter transmit force to the diaphragm plate to drive the push rod 54 forwardly into the master cylinder.

The forward end of the control member 64 has a close sliding fit in the small diameter section of the opening 48 and is normally held out of engagement with the elastomeric disc 60. After a differential pressure is established across the diaphragm 18 and force is applied to the push rod 54, a suflicient squeezing of the elastomeric disc 60 takes place to cause it to flow up against the front face of the control member 64 and provide a reaction which opposes the valve opening movement on the push rod 62. This functioning is generally described in considerable detail in the above referred to Maxwell L. Cripe application, and so will not now be further elaborated upon. After the desired braking effort is achieved, forward movement of the control rod 62 is stopped-following which the diaphragm plate 20 moves forward a slight additional amount to bring the poppet member 68 into engagement with the atmospheric valve seat 66, and thereby preventing further flow of air to power chamber 16.

When it is desired to reduce the force generated by the servomotor, the force applied to the control rod 62 is reduced; whereupon the pressure of the elastomeric disc 60 along with the force of the return spring tit) causes the control member 64 to bias the poppet member 68 out of engagement with the vacuum valve seat and so reduce the pressure in the rear opposing power chamber 16. Complete removal of force on the control rod 62 permits the valve parts to assume the position shown in the drawing, and a vacuum established in the rear opposing power chamber 16 of the same intensity as exists in the front opposing power chamber 14.

It will be seen that the servomotor construction so far described is the epitomy of simplicity. As has been previously explained, the entire assembly of the control valve structure is accomplished by stacking elements upon the push rod 62, and thereafter inserting the entire valve assembly into its receiving bore to automatically provide all of its necessary sealing, guiding and reaction producing engagements.

According to principles of the present invention, the diaphragm plate 20 is proportioned so that the rear surface of the radial flange 36 falls radially outwardly of the control member 64. A radially inwardly extending opening or slot 100 is cast between the bottom of the groove 42 and the surfaces of the control member 64; and an annular groove 102 is formed in the surface of the control member 64 to receive a stop pin or abutment member 104. The groove 102 in the control member 64 is provided with suflicient axial width to accommodate all necessary valve travel; and the forward face of the groove 102 is so positioned as to provide the desired valve return or release position wherein the front face of the control member 64 is out of engagement with the elastomeric disc 60, and the desired clearance provided between the vacuum valve seat and the poppet member 68. After the valve assembly has been installed upon the rod 62 and the assembly pushed into position, the pin 104 is inserted into the slot 100. The diaphragm 18 is thereafter snapped into its sealing position to automatically hold the stop pin 104 in its receiving opening 100. The pin 104 is of course provided with sufficient length so that its inner end extends into the groove 102 when its outer end is resiliently engaged by the thickened portion 46 of the diaphragm 13. It will thereby be seen that the entire assembly is accomplished by simply snapping the various parts together; and that the diaphragm 18 not only provides the function of affecting a seal between the

chambers

14 and 16, but retains the stop pin 1M in position to hold the entire assembly together.

It will be apparent that objects heretofore enumerated as well as others have been accomplished, and that there has been provided a fluid pressure motor construction of the type using a power diaphragm wherein the diaphragm, when snapped into sealing position, is used to retain internal parts in their assembled positions.

While the objects and advantages of the invention have been accomplished, I do not wish to be limited to the particular construction shown and described; it is my intention to cover hereby all novel adaptations, modifications and arrangements thereof which come within the practice of those skilled in the art to which the invention relates.

I claim:

1. In a fluid pressure motor: a housing having an axially extending chamber therein, a diaphragm plate in said chamber, said diaphragm plate having an internal chamber therein and a radially inwardly extending groove in its external surface, said diaphragm plate having a radially extending opening extending between said groove and its internal chamber, a pin positioned in said radially extending opening, and an annular diaphragm having a central opening with its radially inner portion surrounding its central opening snapped into said groove to retain said pin.

2. In a fluid pressure servomotor: a housing having an axially extending chamber therein, a diaphragm plate in said chamber, said diaphragm plate having an axially extending internal chamber therein and a radially inwardly extending groove in its external surface, said diaphragm plate having a radially extending opening extending between said groove and its internal chamber, an axially movable member in said internal chamber of said dia phragm plate, said axially movable member having a groove in its external surface opposite said radially extending opening of said diaphragm plate, a pin positioned in said radially extending opening and extending from the bottom of said groove in said diaphragm plate and into said groove of said axially movable member, and an annular diaphragm having a central opening with its radially inner portion surrounding its central opening snapped into said groove in said diaphragm plate to retain said pin and the radially outer portion of said annular diaphragm being sealed to said housing.

3. In a fluid pressure servomotor: a housing having an axially extending chamber therein, a diaphragm plate in said chamber, said diaphragm plate having an axially extending internal valve chamber therein and a radially inwardly extending groove in its external surface, said diaphragm plate having a radially extending opening extending between said groove and its internal'chamber, said axially extending valve chamber being enlarged at its outer end to form a valve seat shoulder, a flexible annular poppet member having a radially inner portion adapted to abut said shoulder and a radially outer portion sealed to the sidewall of said valve chamber, a control member in said valve chamber axially inwardly of said shoulder for abutment with said annular poppet member, said control member having a groove therein positioned generally opposite said radial opening, a stop member positioned in said radial opening and extending from said groove in the outer surface of said diaphragm plate into said groove of said control member, and an annular flexible diaphragm having a central opening, said diaphragm having a radially outer portion sealed to said housing and a radially inner portion surrounding its central opening slipped into said groove of said diaphragm plate to cover and hold said stop member in said radial opening.

4. In a fluid pressure servomotor and the like: a housing having an internal axially extending chamber therein; a movable wall in said chamber, said movable wall having a generally cylindrically shaped boss axially extending through one end of said housing, said boss having an axially extending internal valve chamber therein which is stepped down in at least two successive stages to provide an inner and an outer shoulder facing axially outwardly of said valve chamber, an annular ilexibie poppet member having an inner thickened portion for engaging said inner shoulder and an outer portion having an interference fit with the sidewalls of said valve chamber, and an intregal flexible portion interconnecting said inner and outer portions, a control member positioned axially inwardly of said poppet member and having an axially outwardly facing valve seat for engaging said poppet member radially inwardly of said inner shoulder and adapted for axial movement to sealingly engage said poppet member and disengage it from said inner shoulder, a control rod connected to said control member and projecting axially outwardly through said annular poppet member, means biasing said outer portion of said poppet member radially outwardly into sealing engagement with the sidewalls of said valve chamber and axially inwardly against said outer shoulder, and said movable wall having a low pressure source communicating with said valve chamber between said shoulders, a control passage communicating to the portion of said valve chamber inwardly of said inner shoulder, and a higher pressure source communicating to the outer end of said valve chamber, said movable wall having a generally radially extending opening communicating with said valve chamber opposite said control member, said control member having a recess therein opposite said radially extending opening, and an abutment pin positioned in said radially extending opening and extending into said recess to prevent withdrawal of said control member and to thereby hold the structure together.

References Cited in the file of this patent UNITED STATES PATENTS 2,411,458 Penrose Nov. 19, 1946 2,811,925 Crookston Nov. 5, 1957 2,834,184 Ingres May 13, 1958 2,949,892 Ayers Aug. 23, 1960 2,976,846 Stelzer Mar. 28, 1961