US 2345213 A
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March 28, 1944. w osHg I 2,345,213
FLUID PRESSURE MOTOR SYSTEM Filed April 5, 1943 A 770 N5 rs.
Patented Mar. 28, 1944 I OFFICE FLUID PRESSURE Mo'roR SYSTEM William Edward OSheLLondon, England Application April 5, 1943, Serial No. 481,842- In Great Britain March 31, 1942 J 2 Claims.
The present invention relates to motors oper ated by difierential fluid pressure such as are used for operating windscreen wipers.
Motors are known which are operated by suction, for example from the suction generated by the intake manifold of an internal. combustion engine of an automobile, but difficulties are xperienced with such motors in that under some operating conditions of the engine the suction drops so thatthe wiper motor slows down and even stops. To overcome this drawback a suction reservoir is sometimes connected in the conduit leading from the intake "manifold to the suction motor, which enables the wiper to run for a short period of time even if the suction generated by the intake manifold falls below that which is necessary for operating the motor.
' Motors are also known which'are operated b compressed fluid, such as compressed air. 1
The present invention consists in operating a differential fluid pressure motor both by suction and'compressed air, either simultaneously or alternatively. A feature of the invention consists in a motor which is operated by differential fluid pressure wherein suction is applied to one side of the piston 01' paddle, whilst compressed air is applied to the opposite side of the piston or paddle. In this way increased power can be obtained from the motor or the same power can be obtained from a smaller motor. The operation of the motor by the combined action of suction and compressed air enables lower air pressures to be used for the same power output, thus resulting in lower pressure differences between the compressed air pressure and atmospheric pressure and reducing difliculties in preventing air leaks by means of glands or the like.
From another aspect the invention consists in a differential fluid pressure motor which is oper able either by suction or fluid pressure and which is adapted for connection to a source of suction and to a source of fluid pressure, and wherein control means are provided which normally shut oil the supply of compressed fluid to the motor whilst it is operated under the action of the suction and which automatically operate to feed compressed fluid to the motor when the degree of suction applied to the motor falls below the value which is necessary for satisfactory motor operation. By means of this arrangement the motor can be normally operated from the source of suction and when it begins to slow down or tend to stop due to a change in the operating conditions in the internal combustion engine, a supply of compressed air is automatically fed to the motor to keep it operating.
Suitable forms of motors for carrying out this invention which will operate either on compressed air or suction or both simultaneously are described in the specification of my copending application Serial No. 481,843 filed April 5, 1943. One method of arranging the motor on an automobile vehicle in accordance with this'inven- 'tion'is illustrated, by way of example, in the accompanying drawing; The suction lead 2 of the motor (which is of the kind described in my aforesaid application) is connected to the intake manifold 3 whilst the compressed air lead 4 is connected through a control valve 5 to a source of compressed air '5. The valve 5 normally shuts off the motor from the source of compressed air. The conduit 4 or the valve chamber is provided with a check valve 1 or equivalent means so as to enable venting to take place whilst compressed air is not supplied to the motor, but which closes automatically to seal the vent'when compressed air is fed to the motor. In normal operation, the
suction generated in the intake manifold 3 oper ates the motor .111 the normal way, the motor being vented through the check valve I, but upon a fall in the degree'of suctionin the intake manifold 3, the valve 5 controlling the supplyof compressed air-to the motor is automatically opened to drive the motor by compressed air. This may be effected by a suction operated valve or switch connected with the intake manifold which operates to open the compressed air control valve when the degree of suction in the intake manifold fallsbelow a certain predetermined Value.
In the example shown a suction operated switch is shown which comprises a cylinder 8 in which slides a piston 9 which is urged against the action of the suction by a spring l0. As the suction falls the spring moves the piston 9 towards the end of its cylinder where it operates to close the spring contacts I I to complete a circuit through a relay winding l2. The relay moves the'valve 5 to the position in which the passage 1 3 therein connects the source of compressed air 6 to the conduit 4. When the suction again increases, the piston 9 opens the contacts II and the valve 5 is restored to the position shown in the drawing by the spring [4.
When operating with compressed air the exhaust from the motor may discharge into the intake manifold or, alternatively, as shown in the drawing, the operation of the relay I2 may also close the conduit 2 leading from the motor to the intake manifold and open itto an exhaust aperture !5 through the valve passage l6.
On the suction again reaching the degree necessary for successfully operating the motor, the suction actuated valve is again operated to cut oil the supply of compressed air so that the motor continues to operate on suction only.
The starting and stopping of the motor may be effected by means of a manual control valve l8. By arranging the valve either as shown in the air passage between the check valve 1 and the motor or alternatively in the exhaust passage of the motor (that is in the conduit 2 or a motor passage leading thereto) the one valve can be used for controlling the motor when it is being operated either by suction or compressed air. i
a The compressed air in all modifications of this invention may be supplied by a pump l1 driven from the vehicle engine which may charge the air reservoir 6. The pump may be automatically suction to operate both the motor and a pump,
the compressed air stored whilst there is ample suction being used to drive the motor when the suction falls.
In cases where the pressure is generated by a device whichcrea-tes a suction when compressing the air, the motor may be connected at one side to the compression side of the device and at the other side to the suction side of the device, so as to be operated by the combined action of suction and compressed air.
Although particular embodiments of the invention have been described, it will be understood that various modifications may be made therein without departing from the spirit of the invention. For example, motors other than the particular type described in the specification of my aforesaid copending application can be used for carrying out the invention. Further the valve 5 may be controlled mechanically from a suction operated device instead of electrically as shown in the drawing. Also the check valve 1 may be dispensed withand the valve 5 be provided with an additional" passage for connecting the conduit 4 to the atmosphere when the valve 5 is in the position shown in the drawing.
1. A fluid pressure motor system for motor vehicles, comprising a fluid motor operable both by suction and compressed air, means for supplying the motor with operating suction, means for su pplying the motor with operating compressed air, a control valve normally rendering the suction supply means operative and the compressed air supply means inoperative and operable to reverse the order of the two supply means whereby the motor will operate by compressed air, a solenoid operable for actuating said valve to so reverse the order, and a suction responsive switch in circuit with the solenoid and maintaining the circuit open in the presence of a predetermined degree of suction and closing the circuit to operate the solenoid when the suction fallsbelow such degree whereby a uniform speed of operation is provided for the motor.
2. A fluid pressure motor system for motor vehicles, comprising a fluid motor operable both by suction and compressed air, means for supplying the motor with operating suction, means for supplying the motor with operating compressed air, a control means operating; normally to shut off the means for supplying the compressed air while the motor is operating on suction, said control means being movable from its normal position to shut off the suction supply means and to open the compressed air supply means to the motor to operate the latter on such higher pressure, and means for so moving the control means including an electric device in circuit with a suction responsive switch, the latter being responsive to a predetermined variation in the supplied operating suction whereby the latter will be instantaneously disrupted and the compressed air supply means immediately connected to the motor for maintaining the operation of the latter substantially uniform.
WILLIAM EDWARD OSHEI.