AU678726B2 - Hydraulic motor assembly - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT *a.

*S a a S. a a *a S Name of Applicant: Address of Applicant: Actual Inventor: FRANK SEGHEZZI 144 Shepperton Road Victoria Park W.A. 6100 FRANK SEGHEZZI Address for Service: Griffith Hack, Patent and Trade Mark Attorneys, 6th Floor, 256 Adelaide Terrace, Perth, Western Australia, 6000.

Standard Complete Specification for the invention entitled: HYDRAULIC MOTOR ASSEMBLY Details of Associated Provisional Applications: PN0089 filed on 15 December 1994 Details of Parent Application for Divisional Applications: The following is a full description of this invention, including the best method of performing it known to me:- 2 HYDRAULIC MOTOR ASSEMBLY The present invention relates to an hydraulic motor assembly in which the output shaft is effectively mechanically isolated from the source of motive power.

There are many applications where it may be desirable to have the output shaft of a motor mechanically isolated from the source of motive power so that jamming of the output shaft does not stall the power source. Thus, for example, it may r be advantageous in an electric wheelchair, or other electric 10 vehicle, to mechanically isolate the wheels from the electric V motor so that if a wheel becomes jammed or overloaded, the electric motor does not burn out.

e r rp The present invention was developed with a view to providing a mechanical assembly designed to isolate the output shaft 15 from the source of motive power.

According to the present invention there is provided an hydraulic motor assembly comprising: a hydraulic pump; a power transmission for coupling a source of motive power to said hydraulic pump, said power transmission having a reduction gear box connected directly to an acceleration gear box, an output shaft of said acceleration gear box being operatively coupled to a drive shaft of said hydraulic pump; and, a hydraulic motor supplied with pressurised hydraulic fluid from said hydraulic pump and having an output shaft driven by a plurality -f fluid-driven rotatable blades wherein said hydraulic motor output shaft is effectively mechanically isolated from the source of motive power.

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3 Preferably the source of motive power is an electric motor connected directly to an input shaft of said reduction gear box.

Preferably the hydraulic motor assembly further comprises a hydraulic pressure valve operatively connected between the hydraulic pump and the hydraulic motor for controlling the flow of hydraulic fluid to the motor and thereby regulating the speed of the hydraulic motor output shaft.

Typically said reduction gear box of the power transmission 10 comprises a plurality of worm gears and worm wheels arranged .o to provide a high reduction ratio between the input shaft and an output shaft of the reduction gear box. Typically said acceleration gear box of the power transmission comprises a plurality of sprocket wheels and sprocket chains arranged to provide a high acceleration ratio between the output shaft of the reduction gear box and the output shaft of the acceleration gear box.

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Preferably said hydraulic pump is a double stage fluid power pump comprising a spiral vane pump output stage.

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4 In order to facilitate a better understanding of the nature of the invention a preferred embodiment of the hydraulic motor assembly will now be described in detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a partial cut-away view of a preferred embodiment of the hydraulic motor assembly; Figure 2 is a section view through a preferred embodiment of a hydraulic pressure valve employed with the assembly of 10 Figure 1; and, 0* eeo Figure 3 is a partial cut-away view of a power transmission S" for a power generation assembly.

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The hydraulic motor assembly 10 illustrated in Figure 1 15 comprises a hydraulic pump 12, a power transmission 14 for 15 coupling an electric motor (not shown) to the hydraulic pump 00 00 12 and a hydraulic motor 16 supplied with pressurised hydraulic fluid from the hydraulic pump 12. The power transmission 14 comprises a reduction gear box 18 connected directly to an acceleration gear box 20, an output shaft 22 of the acceleration gear box 20 being operatively coupled to a drive shaft 24 of the hydraulic pump 12. The hydraulic motor 16 has an output shaft 26 driven by a pair of rotor blades 28 driven by pressurised fluid from the hydraulic pump 12. With this arrangement it will be seen that the output shaft 26 of motor 16 is effectively mechanically isolated from the electric motor (not shown) conrected to the power transmission 14.

The reduction gear box 18 is a compound worm and worm wheel gear box having an adaptation flange 30 provided on an input shaft 32 of the power transmission. A worm gear provided on input shaft 32 meshes with a worm wheel provided on a second AL. perpendicular gear shaft 34. A second worm gear provided on 5 gear shaft 34 meshes with a worm wheel (not visible) on a third gear shaft 36, which is the output shaft of the reduction gear box 18. The worm gears and worm wheels are arranged in the reduction gear box 18 to provide a high reduction ratio between the input shaft 32 and output shaft 36. The reduction gear box 18 is fixed to the acceleration gear box 20 by means of fasteners 38.

The output shaft 36 of reduction gear box 18 forms the input shaft of the acceleration gear box 20, which is fitted with a large sprocket wheel 40. Sprocket wheel 40 is coupled to a sprocket wheel on a second sprocket shaft 42, which is in turn coupled to a sprocket wheel on a third sprocket shaft 44. Each of the sprocket wheels is coupled to another sprocket wheel by means of a sprocket chain. A sprocket chain 46 connecting the sprocket wheels on the second and third shafts 42, 44 respectively is shown in broken outline, however all of the other sprocket chains have been omitted from the drawing for clarity. The second and third sprocket shafts 42, 44 are fixed, with the corresponding sprocket wheels adapted to rotate freely thereon.

r sc r o a o A fourth sprocket shaft 48 is rotatably mounted within the acceleration gear box 20 and is provided with two sprocket wheels spaced apart and keyed to the shaft 48. The larger sprocket wheel on shaft 48 is coupled to a smaller sprocket wheel rotatably mounted on the third shaft 44, which is in turn coupled to a sprocket 50 keyed to the output shaft 22 of the acceleration gear box 20. Needle roller bearings are provided for rotatably mounting the sprockets on the second and third sprocket shafts 42, 44, and suitable thrust bearings are provided for rotatably mounting the fourth sprocket shaft 48 and the output shaft 22 within the housing of the acceleration gear box 20.The sprocket wheels of acceleration gear box 20 are arranged to provide a high acceleration ratio between the output shaft 36 of the R- 35 reduction gear box 18 and the output shaft 22 of the IVT -w ;§V0T 1 6 acceleration gear box 20. A sprocket chain (not shown) couples an output sprocket 52 on the output shaft 22 to a smaller sprocket 56 on the drive shaft 24 of the hydraulic pump 12.

In the illustrated embodiment, the gear ratio between the input shaft 32 and the output shaft 22 of the power transmission is equal to 1:1.445. Hence, if the electric motor drives the input shaft at 3,600rpm, the output shaft 22 will rotate at approximately 5,200rpm.

A bell housing 54 houses the output sprocket 52 keyed to output shaft 22 of the power transmission 14, as well as the e• esprocket chain and the sprocket 56 keyed to drive shaft 24 of "the hydraulic pump 12. The hydraulic pump 12, power oeog transmission 14 and hydraulic motor 16 are all mounted on the 15 bell housing 54 to form a single assembly.

The hydraulic pump 12 is a double stage fluid power pump that supplies the fluid required to drive the hydraulic motor 16.

The double stage hydraulic pump is designed to reduce back pressure. Hydraulic fluid from a reservoir is supplied to 20 the first stage of the hydraulic pump 12 via pump inlet A short length of hydraulic hose (not shown) connects the S"outlet 62 of the first stage of the hydraulic pump 12 to the inlet 64 of the second output 66. The second output 66 is a spiral vane pump which pumps the hydraulic fluid via an outlet 68 through a hydraulic hose (not shown) to a hydraulic pressure valve 70 illustrated in Figure 2.

Pressure valve 70 provides constant fluid flow and is activated by movement of a rack 72 which rotates pinion 74 which is keyed to the main regulator pressure shaft 76. The movement of rack 72 also activates an ignition switch for the electric motor (not shown) connected to the input shaft 32 of the power transmission 14. Hence actuation of the rack 72 automatically activates the power source for the hydraulic 7 motor assembly. Pressure valve 70 has two input ports (not visible), one of which is connected to the outlet 68 of the hydraulic pump, and the other of which is a pressure relief port. Output port 78 of the pressure valve 70 is connected to a pair of injectors (not visible) provided in connection with the hydraulic motor 16. Pressure valve 70 is used to control the flow of hydraulic fluid to the motor 16 and thereby to regulate the speed of the hydraulic motor output shaft 26. The controlled fluid outlet of the pressure valve also relieves back pressure from the hydraulic motor 16.

First and second hydraulic fluid injectors (not visible) are mounted on the housing of the hydraulic motor 16 and are adapted to inject hydraulic fluid into the space between the a outer periphery of the rotor blades 28 and the motor housing.

o e S" 15 rotor blades 28 are retained between three seal plates 80 and are keyed to a rotatable hub 82 forming part of the output shaft 26. Hydraulic fluid pumped under pressure into the hydraulic motor 16 is injected into vanes (not visible) on the rotor blades 28, causing it to rotate until the fluid 20 discharges through an outlet port (not shown) of ti., hydraulic motor 16 and returns to the hydraulic fluid reservoir.

oe o Figure 3 illustrates a power transmission 90 which may be used in a power generation assembly for generating electrical power for the electric motor used in as a source of motive power the hydraulic motor assembly 10 of Figure 1. The power transmission 90 is substantially the same as the power transmission 14 of the hydraulic motor assembly 10, and will not be described again in detail. A battery powered electric motor (not shown) is connected to an input shaft 92 of the power transmission 90, and a cog belt pulley 94 is keyed to the output shaft 96 of the power transmission 90. A dynamo or electric generator (not shown) is mounted to mounting bracket 98 and is coupled to the pulley 94 by means of a cog belt (not shown) 8 Now that a preferred embodiment of the hydraulic motor assembly according to the invention has been described in detail, numerous variations and modifications will suggest themselves to persons skilled in the mechanical arts, in addition to those already described, without departing from the basic inventive concepts. For example, the type of gearing and the particular gear ratios adopted in the power transmission may be varied depending on the particular application. All such variations and modifications are to be considered within the scope of the present invention, the nature of which of which is to be determined from the foregoing description and the appended claims.

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Claims (10)

1. An hydraulic motor assembly comprising: a hydraulic pump; a power transmission for coupling a source of motive power to said hydraulic pump, said power transmission having a reduction gear box connected directly to an acceleration gear box, an output shaft of said acceleration gear box being operatively coupled to a drive shaft of said hydraulic pump; and, 10 a hydraulic motor supplied with pressurised hydraulic fluid from said hydraulic pump and having an output S•shaft driven by a plurality of fluid-driven rotatable blades wherein said hydraulic motor output shaft is effectively mechanically isolated from the source of motive power.

2. An hydraulic motor assembly as defined in claim i, further comprising a hydraulic pressure valve operatively oo connected between the hydraulic pump and the hydraulic motor for controlling the flow of hydraulic fluid to the motor and thereby regulating the speed of the hydraulic motor output shaft.

3. An hydraulic motor assembly as defined in claim 1 or claim 2, wherein said reduction gear box of the power transmission comprises a plurality of worm gears and worm wheels arranged to provide a high reduction ratio between the input shaft and an output shaft of the reduction gear box.

4. An hydraulic motor assembly as defined in claim 3, wherein said acceleration gear box of the power transmission comprises a plurality of sprocket wheels and sprocket chains arranged to provide a high acceleration ratio between the 0 output shaft of the reduction gear box and the output shaft Ir I I 10 of the acceleration gear box.

An hydraulic motor assembly as defined in claim 1, wherein said hydraulic pump is a doucle stage fluid power pump comprising a spiral vane pump output stage.

6. An hydraulic motor assembly as defined in claim 2, wherein said hydraulic pressure valve has a rack operated pressure regulator shaft for regulating fluid flow from the hydraulic pump to the hydraulic motor. S7. An hydraulic motor assembly as defined in claim 2, 1" i0 wherein movement of said rack also activates an ignition switch for th. source of motive power.

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8. An hydraulic motor assembly as defined in any one of the preceding claims, wherein said hydraulic pump, power transmission and hydraulic motor are all mounted on a common housing to form a single assembly.

9. An hydraulic motor assembly as defined in any one e• of the preceding claims, wherein said source of motive power is an electric motor connected directly to an input shaft of said reduction gear box. o

10. An hydraulic motor assembly substantially as herein described with reference to and as illustrated in the accompanying drawings. Dated this 12th day of February 1997 FRANK SEGHEZZI By his Patent Attorneys GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia. ~n II I ude I- ABSTRACT An hydraulic motor assembly (10) includes a hydraulic pump a power transmission (14) for coupling a source of motive power to the hydraulic pump (12) and a hydraulic motor The power transmission (14) has a reduction gear box (18) connected directly to an acceleration gear box An output shaft (22) of the acceleration gear box (20) is operatively coupled to a drive shaft (24) of the hydraulic pump Hydraulic fluid under pressure is supplied from the pump (12) to the hydraulic motor (16) which has an output shaft (26) driven by a plurality of fluid-driven rotor blades The output shaft (26) of the hydraulic motcr is a* a effectively mechanically isolated from the source of motive S power. 0o a go a Irsrlb~"C-Y