US2664074A - Suction motor - Google Patents

Description

w. EQO'SHEI SUCTION MOTOR Dec. 29, 1953 Filed Nov. 8. 1950 A ttorneyl Patented Dec. 29, 1953 SUCTION MOTOR William Edward OShei, London, England Application November 8, 1950, Serial No. 194,611

Claims priority, application Great Britain November 8, 1949 4 Claims. (Cl. 121-164) The present invention relates to suction motors, particularly for use in actuating windscreen wipers.

Such motors generally comprise a piston or paddle which is reciprocated back and forth in the motor housing by the application of suction alternately to opposite sides of the piston or paddle, by means of an automatic over-centre valve mechanism. For the purpose of controlling the operation of such motors a manual control valve is provided which, in the running position, connects the automatic valve to the source of suction, whereby the valve automatically applies suction alternately to opposite sides of the motor to cause it to operate, and in the stop position disconnects the source of suction from the automatic valve and connects it to one side only of the motor housing, whereby the piston or paddle is moved towards that side and is held stationary in a parking position at the ex treme limit of its movement in that direction. The provision of this manual'valve gives rise to the possibility of leakage and also necessitates a tortuous path through which the suction is applied to the motor housing, thereby resulting in a loss of power.

An object of the present invention is to provide a suction motor of which the starting and stopping is controlled by a member which is movable at will into or out of the path 01" movement of the automatic valve or its actuating mechanism whereby, when in the stop position, this member prevents the automatic valve from snapping over and the motor therefore stops.

Another object of the invention is to provide a suction motor which can be parked at either end of its travel, in either of which parking positions the source of suction will be shut on from the piston or paddle by valve means, the suction acting on said valve means to retain the piston or paddle in its parked position.

In conventional suction windscreen wiper motors, the automatic valve mechanism comprises a semi-rotary valve which is moved back and forth with a lost motion action by means of a kicker which is moved with an over-centre motion against the action of a spring. As soon as this kicker is moved by the motor shaft past a dead centre position, the spring snaps the kicker forwards to reverse the position of the semi-rotary valve.

In the preferred arrangement according to theinvention, the control member for starting and stopping the motor is moved into the path of the kicker when it is desired to stop the motor, and thus prevents the kicker from snapping over to reverse the position of the valve. Thus, the suction remains applied to one side or the pieton or paddle and the motor comes to a stop with the piston or paddle at one of the extreme limits of its movement. With the arrangement described, the motor will stop at either one end or other, depending upon its direction of movement at the time when the control member is moved into the path of the kicker, but by suitable design of the kicker or by provision of guards the motor may be so constructed that the control member can only be moved into the path of the kicker when the piston or paddle is moving in one particular direction, thus ensuring that the motor will always stop at the same end. In order that the suction will not continuously be applied to the paddle or piston when the motor is stopped or parked, the piston or paddle ma carry a shut-on valve member which engages with a seating in the motor housing when the piston or paddle is in its extreme limiting position. Preferably, this sealing off arrangement is provided at both limiting positions of the piston or paddle; thus, for example, in the case of a paddle type motor, the cover of the motor housing may carry two cup seatings, adapted to co-operate with two closure valve members respectively carried by opposite sides of the paddle. Thus, by simply interchanging or altering the adiustment or position of the kicker-or guards, the motor may be arranged to park at will at either one or other of its end positions.

In order that the invention may be more clearly understood, an embodiment thereof will now be described with reference to the accompanying drawing, in which- Fig. 1 shows a side view of a suction motor of the oscillating paddle type according to the invention, partly in section and with the cover of the valve chamber removed.

Fig. 1A is a view showing the elongated aperture in the cover plate.

Fig. 2 shows a section along the line AA in Fig. 1.

Referring to the drawings, the motor comprises a casing I having an arouate chamber therein within which a paddle 2 is adapted to rock about a rocket shaft 3, the casing I being closed by a cover 4 formed with an auxiliary arcuate cham bar 5 within which the upper end of the paddle moves. One end of the shaft 3 is adapted to be connected to drive a windscreen wiper arm (not U shown) and the other end of the shaft extends into a valve chamber and is adapted to operate valve mechanism for alternately connecting a source oi suction to opposite sides of the paddle and thereby cause the latter to oscillate. This valve mechanism comprises a semi-rotary valve 1 movable over a' valve face provided with three ports 8, 9 and H), the valve being shifted with a snap action by the over-centre movement of av kicker H which is moved by engaging with the radial surfaces 12 formed at the end of the rocker shaft. The kicker H is associated with a stirrup l 3 connected by a spring M to a pressure plate I5. The spring it serves the dual purpose of snapping over the kicker immediately it passes its deadcentre position, whereby the kicker snaps over the valve l by engaging with one or other of theears 5a thereof, and also of causing the pressure plate to apply a light pressure to hold the valve l against the valve face. The valve chamber is closed by a cover plate I5. As so far described the motor is of conventional and well-known'design and further description thereof and the mode of operation of the valve mechanism is unnecessary.

The central port 9 leads directly through a passage [1 in the cover A to a'nipple it by means of which the motor can be connected to a source of suction, such as the intake manifold of an internal combustion engine. The outer ports 3 and Hi connect respectively through passages l9 and 2!! in the cover 4 the motor chamber at opposite sides of the paddle. The passages l9 and 2G terminate respectively within cup-shaped valve seatings El and 22 carried from the underside of the cover. Carried on opposite sides of the paddle 2 are two sealing members 23, 24, which may comprise fle zible or pad-like members which are adapted to fit overthe valve-seatings 2!, 22, respectively when the paddle is in either one or the other of its extreme limiting positions of movement. The edges of the cupsil, 22 are inclined, as shown in order that the sealingmembers may fit flat against the valve seatings. When a sealing member is fitting against its associated valve seating and suction is app ied thereto, the sealing member is sucked against the valve seating, thereby holding the paddle in its limiting position while sealing off the suction from the motor chamber in order that suction will not be continuously acting on the paddle packings whilst the motor is parked. By the provi ion of sealing members on both sides of the paddle and the provision of two valve seatings 2 l, 22 at opposite limiting positions of movement of the paddle, the latter may be parked at either end of its travel, at will, simply maintaining the suction on that end of the motor at which the paddle is to be parked instead of allowing the automatic valve 1 to change over the suction connection to the opposite side of the paddle.

This is achieved by providing a stop member 25 which can be moved into the'path of'move men-t of the kicker i! to prevent'thelatter from moving sufficiently, after passing its dead-centre position to change over the valve '5. The kicker is arranged to reach its dead-centre position when a sealing member closely approaches its associated valve seating, so that by arresting the kicker after only a small angular movement under the action of the spring it beyond the dead-centre position, the valve '5 is not shifted whilst the paddle continues to move, under the action of the suction which is still applied to the same side of the paddle, until the sealing member closes over the valve seating and the paddle is stopped in a parking position. To start the motor the stop member 25 is withdrawn out of the path of movement of the kicker ll, whereupon the spring ll will move the kicker and cause it to move the valve I, whereby the suction connections are interchanged and the paddle will move away from the position in which it was parked. The valve 1 will then continue to be automatically reversed and the motor will continue to operate until the stop member is again moved into the path of movement of the kicker.

In theembodiment illustrated in the drawing, the.-.stop member 25 comprises a rod slidable in a bushing 26 carried at one end of a plate 21 secured. over. an elongated aperture 28 in the cover plate IS. The outer end of the rod 25 is fitted witha knob 29. The kicker H carries an arcuate guard plate 30 which moves opposite the end of the rod 25 when the latter is withdrawn. By reason of the guard plate 39, the stop member is prevented from being moved inwards to its st0p" position when the kicker is in its right-hand position (referring to Fig. 1); it can only be moved into the path of movement of the kicker when the latter is in its left-hand position, and when moved into this position the inner end of the rod engages with the right-hand end of the guard plate shortly after the kicker has again been moved clockwise over its dead-centre position, thereby arresting the kicker and preventing it from shifting the valve 7. The paddle is thus held in its parked position at the left-hand side of the chamber.

If it be desired that the motor should stop with its paddle at the right-hand end of the chamber, it is only necessary to reverse the position of the plate 2'! so that the stop member is positioned to the left of the centre line of the motor; the stop member can then only be moved inwards when the kicker is' in its right-hand position.

With the arrangement described the conventional manual valve with its restricted passages is eliminated, thus enabling the motor to operate with full power.

A further advantage of the arrangement according to the invention is that the stop member may be remotely controlled in a very simple manner, either mechanically, for example, by a Bowden cable or electrically by means of a magnet or solenoid which actuates the control member and is energised from a remote point.

Whilst a particular embodiment has been described, it will be understood that various modifications may be made without departing from the scope of the invention. Thus, for example, the cover plate 16 may carry two stop members in the two positionswhich the member 25 may alternatively be arranged so that the motor may be parked either on one side or the other, at will, and without having to make any adjustment or alteration to the motor. These two stop members may be actuated through a rocking lever so that the side on which the motor parks will be determined by the direction in which the lever is rocked. Further, instead of moving the stop member into the path of movement of the kicker, it is suiiicient if it is arranged to frictionally engage the kicker with sufficient friction that the spring l4 cannot move the kicker until the stop member is moved out of frictional engagement therewith. In a further modification, the valve may be stopped in its dead-centre position, whereby suction may be cut off from both sid of the piston or paddle.

I claim:

1. A suction motor having a chamber, a piston movable therein, a rocker shaft oscillated by said piston, a suction line, a valve controlling the connection of said chamber at opposite sides of said piston to said suction line, valve actuating member operated by the movement of said shaft with an over-centre snap-action to reverse the position of the valve and thereby alternately to reverse the direction of movement of said'piston, a stop member movable into the path of movement of said valve actuating member to prevent the valve actuating member from snapping over the valve to reverse the direction of movement of the piston, and thereby cause the motor to stop, means for preventing the stop member from being moved into the path of movement of the valve actuating member except when the valve is in a position corresponding to one particular direction of movement of the piston, and means for changing the cooperative relationship between the stop member and said preventive means to select the valve position in which the stop member may be operated, thereby selecting the limiting position in which the piston will be parked when the motor is stopped.

2. A suction motor having a chamber, a piston movable therein, a rocker shaft oscillated by said piston, a suction line, a valve controlling the connection of said chamber at opposite sides of said piston to said suction line, a valve-actuating kicker driven by the movement of said shaft through a lost motion connection, a spring acting on said kicker and serving to move said kicker with an over-centre snap-action in one direction when the piston approaches one of its extreme limiting positions of movement and to move the kicker in the other direction when the piston approaches its other extreme limiting position of movement, means interconnecting the kicker valve to reverse the position of the valve when the kicker snaps over-centre under the action of the spring, thereby alternately to reverse the direction of movement of said piston, and a stop member movable into the path of movement of said kicker and at a position such that it will stop the movement of the kicker shortly after the kicker has moved beyond its dead centre position and is being advanced by the spring but before the kicker has moved the valve to reverse the valve connections.

3. A suction motor having a chamber, a piston movable therein, a rocker shaft oscillated by against which two sealing members carried at opposite sides of the piston respectively engage when the piston is in one or other of its extreme limiting positions of movement, a valve-actuating kicker driven by the movement of said shaft through a lost motion connection, a spring acting on said kicker and serving to move said kicker with an over-centre snap-action in one direction when the piston approaches one of its extreme limiting positions of movement and to move the kicker in the other direction when the piston approaches its other extreme limiting position of movement, means interconnecting the kicker with the valve to reverse thepositionof the valve when the kicker snaps over-centre under the action of the spring, thereby alternately to reverse the direction of movement of said piston, and a stop member movable into the path of movement of said kicker and at a position such that it will stop the movement or/ the kicker shortly after the kicker has moved beyond its dead centre position and is being advanced by the spring but before the kicker has moved the valve to reverse the valve connections.

4. A suction motor having a chamber, a, piston movable therein, a rocker shaft oscillated by said piston, a suction line, a valve controlling the connection of said chamber at opposite sides of said piston to said suction line, a valve-actuating member driven by the movement of said shaft with an over-centre snap-action to reverse the position of the valve and thereby alternately to reverse the direction of movement of said piston, a stop member movable into the path of movement of said valve-actuating member, and means for changing the cooperative relationship between the stop member and the valve-actuating member for selecting the limiting position in which the piston will be parked when the stop member is moved into the path of movement of the valve-actuating member.

WILLIAM EDWARD OSHEI.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,602,270 Kern Oct. 5, 1926 1,717,700 Lippert June 18, 1929 1,853,758 Brumm Apr. 12, 1932 1,921,846 Sparks Aug. 8, 1933 2,260,852 Buchmann Oct. 28, 1941 2,354,189 Bell July 25, 1944 2,590,475 Stoltenberg Mar. 25, 1952 FOREIGN PATENTS Number Country Date 697,976 France Nov. 5, 1930 352,265 Great Britain July 9, 1931

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