WO2001092731A1

WO2001092731A1 - Hydraulic motor

Info

Publication number: WO2001092731A1
Application number: PCT/NO2001/000228
Authority: WO
Inventors: Petter Sigmund Hansen
Original assignee: Petter Sigmund Hansen
Priority date: 2000-06-02
Filing date: 2001-06-01
Publication date: 2001-12-06
Also published as: NO20002854L; NO20002854D0; AU2001264424A1

Abstract

A hydraulic motor for stepped rotating motion of an outgoing shaft (8), which motor comprises a substantially circular cylindrical stator housing (2) with covers (1) mounted on each side of the housing's open sides and a rotor (3) rotatably mounted in the stator housing (2), which stator housing (2) has two ports (4, 5) for admission and discharge respectively of pressurized hydraulic fluid for rotating operation of the rotor (3) and which rotor (3) is further provided with, connected to or prepared for connection with an outgoing shaft (8). The motor is characterized in that the rotor (3) is circular cylindrical in shape with substantially flat end surfaces over the whole or parts of the rotor's (3) diameter and that along the rotor's (3) circular peripheral surface there are provided two or more recesses (20) for placing spring-loaded sealing rollers (7) which sealingly abut against the area between the stator's (2) internal circular peripheral surface (12) and the rotor's (3) external circular peripheral surface, and where the stator housing's (2) internal peripheral surface (12) over a part of the stator housing's (2) circumference is substantially circular cylindrical in shape with a diameter D1 and that the stator housing's (2) internal peripheral surface (12) over the remainder of the stator housing's (2) internal circumference is substantially circular cylindrical in shape with a diameter D2 and where the stator housing's (2) ports (4, 5) for admission and discharge of hydraulic fluid are provided at transmit ions between the diameters D1 and D2, and that D2 is larger than D1.

Description

Hydraulic motor

The present invention relates to a hydraulic motor, especially for stepped rotating motion of an outgoing shaft. The hydraulic motor includes a stator housing and a rotor rotatably mounted in the stator housing, which stator housing has two ports for admission and discharge respectively of pressurised hydraulic fluid for rotating operation of the rotor. The two ports are also preferably connected to a change-over valve, thus enabling pressurised hydraulic fluid to be supplied to each of the two ports, and where the port to which pressurised fluid is not supplied via the change-over valve is connected to a sump or hydraulic circuit for discharge of hydraulic fluid expelled from the motor. Thus according to the present invention the rotor in the hydraulic motor can rotate in both directions of rotation about its axis of rotation, with stepped rotating motion in both directions. The stepped rotating motion may also be controlled by the amount of hydraulic fluid supplied. The hydraulic motor according to the present invention can act as a hydraulic step motor with variable length of rotation or length of stroke and the motor can thereby be used in a great many different applications where it is desirable to achieve a stepped rotating motion within a limited and controlled length of rotation, or in applications where only a limited amount of pressurised hydraulic fluid is available for rotation of the motor.

The hydraulic motor according to the present invention, moreover, is particularly suitable for use in connection with the pivotable wheels on a jack- trolley, where the jack-trolley's hydraulic circuit for raising and lowering the jack-trolley's platform or forks can also be used to provide a pressurised hydraulic fluid for operation of the hydraulic motor according to the present invention. When the hydraulic motor is disposed in this manner in connection with the wheels on such a jack-trolley, these wheels can be given a rotating motion over the whole or a part of a revolution, or a multiple of rotation cycles to help to move the jack-trolley, e.g., over door sills, small obstacles or a particularly high friction surface.

The hydraulic motor in the present invention, however, may also be used in a great many other contexts, particularly in connection with trolleys and various kinds of tool-carrying units which can move on wheels or rollers, such as, e.g., different kinds of movable chassis, which are moved by manual power without a driving force on the wheels or rollers. It is a well-known fact that problems can arise when such vehicles have to negotiate obstacles such as, e.g. door sills, rough patches on the ground or surface with a generally high friction level. In such cases the user has to pull or push the vehicle, and if it is heavily loaded, or the load is raised to a considerable distance above the ground, this is not only heavy, but may also be potentially dangerous since the load can shift and fall off the vehicle.

In such situations it is desirable that the wheels or rollers on which the vehicle is moved can be supplied with a rotating force which gives a rotary motion and helps to negotiate the obstacle. This rotating motion, however, need not be continuous and indeed in many cases it will not be desirable for the rotating motion to be of too long duration, since this could result in the vehicle reaching a high speed which in turn makes it unmanageable, once more giving rise to the risk of instability and related problems of shifting of the load.

A great many such vehicles are also provided with a hydraulic system, e.g. in order to raise or lower the load from the vehicle. In such cases it is obvious that the hydraulic system which already exists should be employed to also generate a rotary motion in one or more of the wheels or rollers on the vehicle.

In order to be able to use an existing hydraulic circuit normally employed for raising and lowering the load to generate rotating motion in one or more of the wheels, the principal requirement is a hydraulic rotary motor and a changeover valve in the existing hydraulic circuit which permits hydraulic fluid, preferably pressurised hydraulic fluid, to be supplied to the hydraulic motor when required.

In most hydraulic circuits associated with such vehicles where the load is raised and lowered hydraulically, some kind of pump is included in the hydraulic circuit, such as, e.g., on a jack-trolley where the hydraulic pump is connected to a relatively long arm which is also used to steer and pull or push the jack-trolley. In such a case the obvious solution will be to mount a changeover valve in the hydraulic circuit, thus enabling the pump to be employed for providing pressurised hydraulic fluid which is supplied to the hydraulic motor for generating rotary motion on one or more of the wheels, without affecting the raising/lowering mechanism. Another obvious measure will be to mount an additional change-over valve which can reverse the flow of pressurised hydraulic fluid to/from the hydraulic motor, thus permitting it to rotate in the opposite direction. Alternatively, an accumulator may be provided in connection with a hydraulic circuit of this kind, thus permitting the pump to be used to increase the pressure in the accumulator, and subsequently supply pressurised hydraulic fluid from the accumulator by means of a manually operable valve, thus avoiding the necessity of pumping while the load has to be raised/lowered after the wheels have to be supplied with a rotating motion.

In order to overcome the above-mentioned problem related to different vehicles where it is desirable to have drive on one or more of the wheels, amongst the solutions known in the prior art are various kinds of electromotors which are connected via a shaft or flange connection with one or more of the wheels. An electric motor of this kind, however, has to be supplied with electric power, for which purpose the use of battery operation for the electric motor is an obvious solution. Moreover, it will be natural to employ chargeable batteries, thereby introducing a not inconsiderable maintenance aspect in connection with the motor, battery and control which is both expensive, time-consuming and otherwise demanding of resources. In a great many cases, moreover, an electromotor will have too low torque to enable it to initiate a rotary motion in one of the wheels in order to also be capable of moving, e.g. a jack-trolley with a load over a door sill or the like. The use of an electromotor and battery also creates obvious problems with regard to space.

On the basis of the above-mentioned problems and previously known solutions, the object of the present invention is to provide a hydraulic motor for stepped rotating motion of an outgoing shaft, which motor can be used to generate a rotating motion in a wheel, or a roller in connection with, e.g. a jack-trolley or other kind of trolley or carriage.

The above-mentioned objects are met with a hydraulic motor according to the present invention, as indicated in the introduction to the following claim 1, with characterising features as indicated in the characterising part of the following claim 1. Further embodiments of the motor are specified in the following dependent patent claims.

A preferred embodiment of the hydraulic motor according to the present invention is further specified in the attached drawings, in which: figure 1 illustrates in cross section from in front a hydraulic motor assembled with drive gear and wheels; figure 2 illustrates in cross section from the side in section B-B in figure 1 the hydraulic motor according to the present invention; figures 3, 4 and 5 illustrate the operating sequence when using the motor as illustrated in figures 1 and 2. Figure 1 illustrates an embodiment of a hydraulic motor for stepped rotating motion, according to the present invention, assembled on each side with a drive device and wheels. The drive device and the wheels in the embodiment illustrated in the figure are particularly suitable for use in connection with a jack-trolley or the like. The hydraulic motor consists substantially of a circular cylindrical stator housing 2 and a cover 1, which is mounted on each side of the housing's open sides and which is connected to the stator housing 2 via bolt connections 10. The hydraulic motor further comprises a circular cylindrical rotor 3, and as illustrated particularly in figure 2, along the rotor's circular external peripheral surface are provided six recesses 20 where a spring 19 is mounted in the bottom of the recess 20, and at the opening of each of the recesses 20 there is mounted a circular cylindrical sealing roller 7. The number of sealing rollers 7 may, of course, be varied and a greater number of sealing rollers 7 will generally result in lower radial forces on the rotor 3, which in turn leads to lower bearing pressure in the support bearings 11, 15 for the rotor 3 or the rotor's shaft 8.

As illustrated particularly in figure 1, the rotor 3 is designed with a centrally located opening for mounting a shaft 8. As illustrated in figure 1 in the illustrated embodiment, however, this shaft 8, like the rotor 3, is designed with a radial through-going opening for mounting a fixing screw 17 which keeps the rotor 3 and the shaft 8 at a constant distance apart. Furthermore, as illustrated in figure 1, the shaft 8 in the said embodiment is further connected with the wheels via coupling devices on each side of the motor. In the illustrated embodiment, therefore, the shaft 8 is through-going through the motor's rotor 3.

As illustrated in figure 2, the stator housing 2 is also designed with the ports 4 and 5 which preferably extend radially on the circular cylindrical stator housing 2. The ports 4, 5 may be employed as an outlet or inlet respectively in order thereby to reverse the motor's direction of rotation. As further illustrated in figure 1, the width of the circular cylindrical stator housing 2, the circular cylindrical rotor 3 and the circular cylindrical sealing rollers 7 is substantially the same, thus enabling the covers 1 to be sealingly mounted on each side of the housing 2. The covers 1 are also provided with central openings for passing through the shaft 8, and as illustrated in figure 1 the covers 1 in the preferred embodiment are provided with bearings 11 on each side of the rotor, which bearings 11 provide steering and bearing support for the rotating shaft 8 which in turn is connected to the rotor 2. Furthermore, in the opening for passing through the shaft 8, a sealing ring, such as, e.g. an O-ring 13, is mounted in the covers 1 in order to prevent the motor from leaking or sweating oil to the environment.

Figure 1 also illustrates that the stator housing 2 is designed with a number of openings 6 along its peripheral external part of the material of the stator housing 2, which openings 6 are preferably threaded in such a manner that the bolts 10 with their threads can be used to pull the covers 1 into sealing connection on each side of the stator housing 2. In an alternative embodiment, use may be made here of through-going bolts with nuts on the outside of the opposite cover 1.

The stator housing 2 also has an internal peripheral surface 12 which is substantially circular cylindrical in shape over a part of the stator housing's 2 circumference, with a diameter Dl, and that over the remainder of the stator housing's 2 internal peripheral surface 12, the stator housing's 2 internal peripheral surface 12 is substantially circular cylindrical in shape with a diameter D2. As illustrated in figure 2, D2 is larger than Dl. The diameter of the circular cylindrical rotor 3, moreover, is substantially the same as the diameter D 1 in the stator housing minus the necessary tolerances to enable the rotor to rotate in the stator housing 3 in an easy and lubricating manner. This means that the sealing rollers 7 will be pushed substantially all the way into the recess 20 in the rotor's peripheral surface when the sealing rollers 7 are located against the internal peripheral surface 12 in the stator housing 2 where the diameter is Dl.

On account of the spring force in the spring 19, those of the sealing rollers 7 which are located in the area where the diameter of the stator housing's internal peripheral surface is D2 will be moved in the recess 20 in the rotor's peripheral surface towards the internal peripheral surface 12 in the stator housing 2 with diameter D2. The sealing rollers 7 form a substantially sealing relationship between the stator 2 and the rotor 3 in this area and the opening which is formed between the stator's internal peripheral surface 12 and the rotor's external peripheral surface in the area where the stator housing's 2 internal diameter is D2 is thereby divided into different chambers between the following sealing rollers 7.

The inlet and outlet ports 4, 5 are further provided in the stator housing 2 at the transition between the diameter D 1 and the diameter D2 in the stator housing's 2 internal peripheral surface 12. In the area of the inlet and outlet 4, 5, moreover, a cut-out 21 is provided parallel with the stator housing's 2 internal peripheral surface 12, in order to permit a technically satisfactory efflux or influx of hydraulic fluid from the ports 4, 5 into the space between the stator housing 2 and the rotor 3 where the stator housing's internal diameter is D2. Furthermore, figures 3, 4 and 5 illustrate a sequence showing how the hydraulic motor as illustrated in figures 1 and 2 operates on being supplied with pressurised hydraulic fluid in the port 4. As illustrated in figure 3, the pressurised hydraulic fluid flows in through the port 4, filling the space between the internal peripheral surface 12 in the stator housing 2 and the external peripheral surface on the rotor 3 between the sealing roller 7a and the sealing roller 7f, with pressurised hydraulic fluid from the port 4. The rotor 3 will thereby be given a rotating motion in the direction illustrated by the arrow A, and the rotating motion achieved in the rotor 3 will be dependent on how much pressurised hydraulic fluid is fed through the port 4. In figure 4 a situation is also indicated where the sealing roller 7a has almost passed the curved section 21 inside the port 4, and where the area between the stator housing's internal peripheral surface 12 and the rotor's external peripheral surface, between the sealing roller 7a and 7b is gradually filled with hydraulic pressurised fluid via the port 4. The pressurised fluid between the sealing roller 7a and 7f is forced on together with the rotary motion of the rotor 3, and as illustrated in the figure the hydraulic fluid will also fill the recess 20 under each of the sealing rollers.

Finally, in figure 5 the sequential position is illustrated where the sealing roller 7a has passed the cut-out 21 and the pressurised hydraulic fluid gradually fills the space between the stator housing's internal peripheral surface 12 and the external peripheral surface of the rotor 3 between the sealing rollers 7a and 7b. This results in a further continued rotating motion of the rotor in the direction of rotation marked by the arrow A.

In figures 3, 4 and 5 it is only the active, driving hydraulic fluid which is illustrated by shading inside the area between the inside of the stator housing 2 and the external peripheral surface of the rotor 3. The inactive hydraulic fluid located between the remaining sealing rollers in figure 3 is forced out through the outlet port 5. As further illustrated in figure 3, the remaining hydraulic fluid between the sealing rollers 7c, 7d, 7e and also between 7e and 7f will be forced out through the port 5 as the rotor 3 rotates in the direction of rotation A.

If it is desirable to alter the direction of rotation for the rotor 3, the previously mentioned change-over valve which is connected to the ports 4 and 5 is employed, thus causing the pressurised hydraulic fluid to be supplied to the port 5 instead of 4, where the port 4 is further connected to a sump or additional receiving hydraulic circuit.

As illustrated in the figures, the rotation speed and torque can be varied by varying the different dimensions in the hydraulic motor, and variation of the amount of pressurised hydraulic fluid supplied will further be able to determine the extent to which the rotor rotates.

With regard to the assembly of the stator housing 2 and the covers 1, as indicated in figure 2 dowel pins 18 are also mounted along the peripheral surface on each side of the stator housing 2 which has corresponding recesses or holes in the covers 1. This will make it possible to orientate the covers 1 in relation to the stator housing 2 when assembling the motor, according to generally known principles for assembly of mechanical components.

The above-mentioned embodiment, which is illustrated in figures 1-5, is preferred since it provides a compact motor consisting of a small number of parts, while satisfying the needs which have to be met and the requirements imposed on a hydraulic motor which must be capable of stepped driving of wheels in connection with a trolley or other kind of supporting chassis.

The above-mentioned motor which is illustrated in the attached figures should only be regarded as one embodiment of the invention and the variations and adaptations which are obvious to a person skilled in the art should also be considered to fall within the protection which is set forth in the following patent claims.

Claims

PATENT CLAIMS

1. A hydraulic motor for stepped rotating motion of an outgoing shaft (8), which motor comprises a substantially circular cylindrical stator housing (2) with covers (1) mounted on each side of the housing's open sides and a rotor (3) rotatably mounted in the stator housing (2), which stator housing (2) has two ports (4, 5) for admission and discharge respectively of pressurised hydraulic fluid for rotating operation of the rotor (3) and which rotor (3) is further provided with, connected to or prepared for connection with an outgoing shaft (8), characterized in that the rotor (3) is circular cylindrical in shape with substantially flat end surfaces over the whole or parts of the rotor's (3) diameter and that along the rotor's (3) circular peripheral surface there are provided two or more recesses (20) for placing spring-loaded sealing rollers (7) which sealingly abut against the area between the stator's (2) internal circular peripheral surface (12) and the rotor's (3) external circular peripheral surface, and where the stator housing's (2) internal peripheral surface (12) over a part of the stator housing's (2) circumference is substantially circular cylindrical in shape with a diameter Dl and that the stator housing's (2) internal peripheral surface (12) over the remainder of the stator housing's (2) internal circumference is substantially circular cylindrical in shape with a diameter D2 and where the stator housing's (2) ports (4, 5) for admission and discharge of hydraulic fluid are provided at transitions between the diameters Dl and D2, and that D2 is larger than Dl.

2. A hydraulic motor according to claim 1, characterized in that at the ports (4, 5) in the stator housing (2) for admission and discharge of hydraulic fluid there is provided a curved cut-out (21) parallel with the stator housing's (2) internal peripheral surface (12).

3. A hydraulic motor according to claims 1-2, characterized in that the rotor (3) is provided with a completely or partly through-going opening around the rotor's (3) axis or rotation for placing an outgoing shaft (8) from the hydraulic motor.

4. A hydraulic motor according to claim 3, characterized in that the outgoing shaft (8) is connected to the rotor (3) by a radial screw connection (17).

5. A hydraulic motor according to any of the claims 1-4, characterized in that the sealing rollers (7) are circular cylindrical in shape.

6. A hydraulic motor according to claim 5, characterized in that the width of the sealing rollers (7) is substantially the same as the width of the rotor (3) and substantially the same as the internal width of the circular cylindrical space in the stator housing (2).

7. A hydraulic motor according to claim 6, characterized in that in the recesses (20) in the rotor (3) under the sealing rollers (7) there are mounted one or more spring bodies (19) which push the sealing rollers (7) out of the recess (20) towards the stator housing's (2) internal peripheral surface (12).

8. A hydraulic motor according to one or more of the claims 1-7, characterized in that the outgoing shaft (8) is provided with a boss for placing in the stator housing (2).

9. A hydraulic motor according to claim 8, characterized in that the boss's external peripheral surface abuts against one or more bearings (11) in the passage in the stator housing's (2) cover (1).

10. A hydraulic motor according to any of the claims 1-9, characterized in that the ports (4, 5) for admission and discharge of hydraulic fluid are coimected to a change-over valve which alternately connects the ports (4, 5) with a supply of pressurised hydraulic fluid and a receiving sump or hydraulic circuit respectively.