US2776574A - Differential fluid pressure motors - Google Patents

Description

Jan. 8, 1957 w. E. O'SHEI 2,776,574

DIFFERENTIAL FLUID PRESSURE MOTORS Filed July 26, 1951 F/G l n 7 l LL 2/"' i \|-22 o o f [4 A 24 F G .2. r /3 T B r i B l Inventor IVY/1km fdmvm 05M. By @6 1: Ma

Attorneys United States Patent DIFFERENTIAL FLUID PRESSURE MOTORS William Edward OShei, London, England Application July 26, 1951, Serial No. 232,603 8 Claims. (Cl. 74-97 The present invention relates to differential fluid pressure motors, and more particularly to such motors for use in driving windscreen wipers, of the kind in which the automatic operation of the motor is controlled by an automatic valve mechanism comprising a kicker which is moved by the motor shaft through a lost motion connection and is associated with a spring whereby when it passes the deadcentre position the kicker is snapped over to move the control valve and reverse the direction of movement of the motor.

Some wiper motors are designed so that the wiper blade will be parked on the right-hand side of the motor, whilst in other cases the wiper motor is constructed so that the wiper blade will be parked on the left-hand side. In Patent 2,752,894, to Tomlin, issued July 3, 1956, there is shown a wiper motor construction which can be parked either on the right-hand side or left-hand side, at will, depending upon the adjustment of the manual control valve. For most satisfactory operation of such a motor, when the manual control valve is changed for parking from one side to the other, it is preferable to change the kicker so that the normal arc of movement will be shifted slightly in the opposite direction and thus allow the maximum arc of wiping and the full extent of over-travel to move the wiper blade to its parking position.

According to the invention, this adjustment is achieved, without changing the kicker, by making the position of that portion of the kicker which engages with the abutments on the rocker shaft, adjustable to either of two positions, depending upon whether the motor is to be parked at one end or the other of its arc of movement.

In order that the invention may be more clearly understood reference will now be made to the accompanying drawings in which:

Fig. 1 shows a side elevation of a suction motor accord- 1ng to the invention with the cover of the valve chamber removed,

Fig. 2 is a section through the kicker portion of the valve mechanism along the line A--A in Fig. 1 and on an enlarged scale,

Fig. 3 is a section along the line B-B in Fig.2.

Referring to the drawings, the motor shown is of the oscillating paddle type and is arranged for parking at either one end or the other of the motor chamber in accordance with the aforesaid Tomlin patent. The motor housing comprises a body portion 1 fitted with a cover portion 2 forming an arcuate piston chamber in which a vane or paddle type piston 4 secured to the rocker shaft 5 is adapted to oscillate in an arcuate manner about the axis of the shaft so as to rock the latter. The upper end of the paddle moves in known manner, in an auxiliary arcuate chamber (not shown) formed in the cover 2. One end of the rocker shaft 5 is adapted to be connected to drive a windscreen wiper arm (not shown) and the other end of the arm extends into a valve chamber 6 and is adapted to operate automatic valve mechanism for alternately connecting the source of suction to opposite sides of the paddle and thereby cause the latter to oscillate.

2,776,574 Patented Jan. 8, 1957 ice I The valve chamber is provided with a cover which has been omitted from the drawing in order to show the valve mechanism.

The valve mechanism comprises a semi-rotary valve adapted to move over a valve face provided with three ports, of which only one, 10 is shown in Fig. 1, the valve being moved with a snap-action by the movement of a kicker 11 which is moved by engaging with radial abutment surfaces formed at the end of the rocker shaft 5. The kicker 11 is associated with a stirrup 13 connected by a spring 14 to a pressure plate 15. The spring 14 serves the dual purpose of snapping over the kicker immediately it passes its dead-centre position whereby the kicker snaps over the valve 7 by engaging with one or other of the ears 7a thereof, and also of causing the pressure plate 15 to apply a light pressure to hold the valve 7 against the valve face. As so far described the valve mechanism is of conventional design and further description thereof and its mode of operation is unnecessary.

The motor illustrated in the drawing is adapted for parking the paddle at either one end or the other of the motor chamber, depending upon the position of the control valve 16. Details of the control valve and its mode of operation for selectively parking the paddle at either one end or the other of the motor housing are described in the Tomlin patent, referred to hereinabove. The paddle carries two sealing members 23, 24 at opposite sides thereof for respectively sealing off the cup-shaped valve seatings 21, 22 carried from the underside of the cover when the paddle is in one or other of its extreme limiting positions of movement.

In order to change the position of the kicker to shift the position of the arc of movement of the paddle depending upon the selected parking position (and without increasing or decreasing the actual arc movement), the normal V-shaped member of the kicker, which is adapted to engage with the radial abutment surfaces formed at the end of the rocker shaft 5 is made adjustable with respect to the actuating arm of the kicker. In the embodiment shown in the drawing, this is achieved by constructing the tubular portion 25 at the inner end of the actuating arm 11 of the kicker of slightly larger diameter than the diameter of the rocker shaft 5 and fitting therein a sleeve 26 with a closed end wall 27, this sleeve having an external diameter which frictionally fits the internal diameter of the tubular portion 25 and having an internal diameter to rotatably fit the end of the rocker shaft. This sleeve 26 carries within its bore the V-shaped member 28 of the kicker which is adapted to be moved by the radial abutment surfaces 29 of the rocker shaft formed by constructing the end portion 5a of the rocker shaft of semi-circular shape. The member 28 may be made integral with the sleeve 26, for example by die-casting, and the external surface of the sleeve is provided with a longitudinally extending ridge 3i) fitting within a recess 31 formed in the internal surface of the tubular portion 25 so as to permit limited angular adjustment between the sleeve 26 and the tubular portion 25. Projecting from the end wall 27 of the sleeve is a stud 32 which extends through a central aperture in the end wall of the tubular portion 25 and is riveted over to form a head 33. Between the end wall 27 and the end Wall of the tubular portion 25 is located a friction washer 34 so that the sleeve 26 and the tubular portion will be held, during normal operation of the motor, against relative movement. The head 33 is provided with a screw-driver slot 35 for enabling the sleeve 26 to be turned within the tubular portion 25 within the limits defined by the ridge and the groove 31.

With the arrangements described, by rotating the sleeve 26 within the tubular portion 25 to either one or other of its limiting positions, the position of the arc of movement of the kicker 11 relative to the rocker shaft may be shifted to either of two positions which are respectively designed to produce the desired movement of the paddle within the motor housing depending upon the selected parking position.

The adjustment may be effected by turning the head 33 after removing the cover of the valve chamber or alternatively the cover may be provided with an aperture through which a screw-driver may be inserted to engage in the slot 35. In this latter case it is referable to provide a second aperture in the cover through which a rod may be inserted to prevent the kicker from moving whilst the sleeve is being turned within the tubular portion 25 against the resistance of the friction washer 34.

Whilst particular embodiments have been described it will be understood that various modifications may be made without departing from the scope of the invention. For example the invention may also be applied to motors in which the piston or two interconnected pistons move in a rectilinear path.

I claim:

1. For a differential fluid pressure motor, a valve mechanism comprising a rocker shaft and a kicker associated therewith, an abutment member on said kicker, said rocker shaft having abutment surfaces arranged to engage co-operating abutment surfaces on the abutment member to move said kicker with lost-motion through a dead-centre position between two limit positions, an overcentre spring acting on said kicker to snap said kicker to the limit position approached by the kicker as it moves over the dead-centre position, said abutment member being angularly adjustable to either of two predetermined positions relative to the kicker.

2. Mechanism as claimed in claim 1, including means frictionally restraining rotation of said abutment member relative to said kicker.

3. For a differential fluid pressure motor, a valve mechanism comprising a rocker shaft and a kicker carried thereby, a sleeve carried by the kicker and rotatably adjustable relative thereto, said sleeve having abutment surfaces thereon arranged to be engaged by cooperating abutment surfaces on said rocker shaft to move said kicker with lost-motion through a dead-centre position between two limit positions, an over-centre spring acting on the kicker to snap said kicker to the limit position approached by said kicker as it moves over the deadcentre position, and stop means limiting the rotational adjustment of said sleeve to movement between two predetermined positions of adjustment, said stop means comprising a protuberance on one of the two co-operating elements constituted by the sleeve and of the kicker, said protuberance being movable Within a recess in the other element.

4. For a differential fluid pressure motor, a valve mechanism comprising a rocker shaft and a kicker carried thereby, a sleeve carried by the kicker and enclosing said rocker shaft, said rocker shaft having abutment surfaces arranged to engage cooperating abutment surfaces on said sleeve to move said sleeve and said kicker with lostmotion through a dead-centre position between two limit positions, an over-centre spring acting on said kicker to snap said kicker to the limit position approached by said kicker as it moves over the dead-centre position, a frictional member between said sleeve and said kicker,

means holding together said sleeve and said kicker for rotational movement relative to each other with the friction member clamped therebetween and arranged to restrain said rotational movement, and stop means limiting said rotational movement to movement between two predetermined positions of adjustment, said stop means comprising a protuberance on one of the two cooperating elements constituted by the sleeve and the kicker, said protuberance being movable within a recess in the other element.

5. Mechanism as claimed in claim 4, wherein the means for holding together said sleeve and said kicker comprises a boss on said sleeve projecting through an aperture in said kicker, said boss being riveted over and being shaped to receive the end of a turning implement.

6. A valve mechanism for a differential fluid pressure motor, comprising a rocker shaft and a kicker associated therewith, said rocker shaft having abutment surfaces arranged to engage cooperating abutment surfaces on the kicker to move said kicker with lost-motion through a dead-centre position between two limit positions, an over-centre spring acting on said kicker to snap said kicker to the limit position approached by said kicker as it moves over the dead-centre position, and means for changing the position of the abutment surfaces on the kicker without changing the angle between the said abutment surfaces, whereby the position of the arc of movement of the rocker shaft may be changed relative to the dead-centre position of the kicker.

7. For actuating the valve mechanism of a differential fluid pressure motor, a kicker having a boss portion and an arm portion projecting therefrom, a sleeve rotatably adjustable within limits within said boss, and abutment surfaces within said sleeve, a friction member between said sleeve and the boss, means holding together said sleeve and said boss for rotational movement relative to each other with the friction member clamped therebetween, and stop means limiting said rotational movement to movement between two predetermined positions of adjustment.

8. A kicker as claimed in claim 7, wherein said stop means comprises a protuberance on one of the two cooperating elements constituted by the sleeve and the boss, said protuberance being movable within a recess in the other element.

References Cited in the file of this patent UNITED STATES PATENTS 224,964 Stephenson Feb. 24, 1880 993,570 Webster May 30, 1911 1,395,604 Skinner Nov. 1, 1921 1,492,878 Eklundh May 6, 1924 1,499,139 Arnc'd et al June 24, 1924 1,566,075 Cotton Dec. 15, 1925 1,978,634 Hueber Oct. 30, 1934 2,075,959 Previti Apr. 6, 1937 2,148,473 Joy Feb. 28, 1939 2,177,052 Blough Oct. 24, 1939 2,523,992 Hess Sept. 26, 1950 FOREIGN PATENTS 107,854 Great Britain 1917 697,976 France Nov. 5, 1930

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