WO1997012124A1

WO1997012124A1 - Hydraulic machine having a gear ring which is divided radially into an inside inner part having the first internal toothing and an outside outer part having the second external toothing, which parts are rotatable relative to one another

Info

Publication number: WO1997012124A1
Application number: PCT/DK1996/000397
Authority: WO
Inventors: Gunnar Lyshøj HANSEN; Tom Tychsen; Hans Erik Larsen; Hans Christian Petersen
Original assignee: Danfoss A/S
Priority date: 1995-09-28
Filing date: 1996-09-19
Publication date: 1997-04-03
Also published as: AU6984296A; DE19536061C2; DE19536061A1

Abstract

A hydraulic machine is disclosed, having a gearwheel (1) which has a first external toothing (8), a gear ring (3, 5), which has a first internal toothing (9) having at least one tooth more than and meshing with the first external toothing (8), and a second external toothing (10), and a toothed rim (6), which has a second internal toothing (11) having at least one tooth more than and meshing with the second external toothing (10). In such a machine it is desirable to have a greater freedom of design. For that purpose, the gear ring (3, 5) is divided radially into an inside inner part (3) having the first internal toothing (9) and an outside outer part (5) having the second external toothing (10), which parts are rotatable relative to one another.

Description

Hydraulic machine having a gear ring which is divided radially into an inside inner part having the first internal toothing and an outside outer part having the second external toothing, which parts are rotatable relative to one another.

The invention relates to a hydraulic machine having a gearwheel which has a first external toothing, a gear ring, which has a first internal toothing having at least one tooth more than and meshing with the first external toothing, and a second external toothing, and a toothed rim, which has a second internal toothing having at least one tooth more than and meshing with the second external toothing.

Such a machine, which is also known as a ring piston machine (EP 0 038 482 A2) is operated as a motor by introducing pressurized fluid between one of the two pairs of external and internal toothings, commutation being required for supplying in the correct order the pressure spaces formed between the external and internal toothing. The gear ring consequently orbits around the gearwheel and by this movement causes the latter to rotate when the toothed rim is fixed. If the gearwheel is driven, this machine can be used also as a pump. Such machines have proved very successful as so- called slow-speed machines. They combine a relatively high torque with a low rotational speed.

Another machine without gearwheel and internal toothing on the gear ring is known from US 3 905 727. That machine operates according to the same principle, however. Here, the pressure pockets are defined by fins formed between the gearwheel and the gear ring. When the pressure pockets are appropriately supplied with fluid, the gear ring is caused to orbit, but cannot rotate. This movement is transmitted to the toothed rim which correspondingly rotates. In the construction of a machine as known from EP 0 038 482 A2, not only are there restrictions of a geometric nature, for example in respect of the eccentricity, but also restrictions of a kinematic kind. It is thus easy to see that the orbiting and rotary movements of gearwheel and gear ring on the one hand and of gear ring and toothed rim on the other hand, have to be matched to one another.

The problem underlying the invention is to have greater freedom in the design of the machine.

In a machine of the kind mentioned in the introduction, this problem is solved in that the gear ring is divided radially into an inside inner part having the first internal toothing and an outside outer part having the second external toothing, which parts are rotatable relative to one another.

The annular gear is therefore divided into two parts so that the rotary movements of inner part and outer part are able to take place independently of one another. For the rest, the gear ring behaves kine atically as one part, that is, in all directions other than the circumferential direction the two parts of the gear ring are movable only together. It has unexpectedly proved that despite this radial division of the gear ring, an orbiting movement leads to a rotary movement of toothed rim or gear ring, depending on which one of the two parts is fixedly held, when the tooth ratios are selected so that the external toothing always has at least one more tooth than the associated internal toothing. One advantage that can be obtained therefrom is reduction in the rotational speed with otherwise identical conditions. It is possible, as it were, to construct a motor with a built-in step-down gear system without having to provide additional installation space.

In a preferred construction, provision is made for a bearing to be arranged between the inner part and the outer part. Loading of the gear ring is effected substantially radially. The bearing then facilitates the relative movement between inner part and outer part.

The bearing is preferably in the form of a needle roller bearing. Such a bearing is capable of absorbing the forces that occur.

In an especially preferred construction, either the gearwheel or the toothed rim is held so that it does not rotate; in the case of the gearwheel the outer part has a torque output arrangement and in the case of the toothed rim the inner part has a torque output arrangement. Using such a construction it is possible to achieve, for example, a torque split. The gear ring is used as an additional torque-generator; here, use is made of the fact that in the case of that part of the gear ring that meshes with the fixed part of the gearwheel or toothed rim, a rotary movement is caused by the orbiting movement and this rotary movement also, of course, has an orbiting movement superimposed on it. The torque output arrangement merely has to be capable of transmitting the rotary movement despite the orbiting movement.

The torque output arrangement is preferably in the form of a toothing which co-operates with a counter- toothing. Such a construction enables a torque to be delivered in the form of a rotary movement despite the superimposition of an orbiting movement of the gear ring.

The torque output arrangement preferably acts on the rotatable part of gearwheel and toothed rim. The rotary movement of the gear ring is therefore coupled back to the rotatable part. The two torque sources therefore come together again.

This is of great advantage in particular when the counter-toothing is in the form of a third external toothing having a larger diameter than the first external toothing. The larger is the construction of the external toothing, the larger can the teeth be made with correspondingly the same tooth spacing, and the more robust do these teeth become. They are therefore capable of absorbing a larger torque. If, for instance, in this construction the rotary movement and thus the torque of the gear ring is transmitted to the moved part, this can be effected with a larger torque. The output of the machine can be increased considerably. In addition, with the correspondingly larger diameter of the third external toothing, the lever on which the force acts is greater, so that by this measure alone a correspondingly higher torque is achieved.

The third external toothing and the gearwheel are advantageously arranged non-rotatably on a common shaft. In the case of a motor this shaft then forms the driven part from which the large torque made available can be taken.

It has proved advantageous for at least two pressure pocket arrangements to be formed between the individual external toothings and the internal toothings co- operating therewith, and for fluid under pressure to be supplied to each pressure pocket arrangement, in particular for fluid under pressure to be supplied to two pressure pocket arrangements simultaneously. Fluid under pressure, for example, hydraulic fluid, can be introduced not only between the gearwheel and the gear ring but also between the gear ring and the toothed rim or even into the third toothing. Corresponding commutation is required, of course. By superimposing the pressures in the individual pressure pocket arrangements, it is possible, for example, to set different speeds. With two different pressurizationε, it is possible, for example, to set at least three different speeds. A first speed is achieved when just one pressurization is selected. A second speed is achieved when both pressurizations are allowed to act in the same direction, their sum being used. A third speed is achieved when the difference in the pressurizations is used, that is, they are allowed to act in opposite directions. With an appropriate configuration of the tooth ratios, it is possible to set even a fourth speed if merely the second pressurization is allowed to be effective. When the machine is used as a motor for a wheel it is thus possible to integrate both an auxiliary gear and a drive gear into the motor, that is, as it were, to achieve different speeds.

The invention is described hereinafter with reference to preferred embodiments in conjunction with the drawings, in which:

Fig. 1 is a diagrammatic plan view and a diagrammatic sectional view of a first embodiment of a hydraulic machine, Fig. 2 is a diagrammatic plan view and a diagrammatic sectional view of a second embodiment of the machine,

Fig. 3 is a longitudinal section through a machine and

Fig. 4 is an exploded view of essential parts of the machine.

In the first embodiment of a hydraulic machine illustrated in Fig. 1, which is to operate as a motor, a gearwheel 1 is mounted non-rotatably on a shaft 2. The gearwheel 1 is arranged inside a gear ring which comprises an inner part 3 and an outer part 5 which are separated from one another by a needle roller bearing 4. Inner part 3 and outer part 5 are rotatable relative to one another but are otherwise only movable together. The gear ring 3, 5 is arranged in a toothed rim 6. Longitudinally behind the inner part there is arranged a further gearwheel 7 which is also non- rotatably secured on the shaft 2. This iε clearly recognizable from the sectional view in Fig. lb. In Fig. la this gearwheel 7 would not normally be visible. It is therefore drawn in using merely broken lines.

The gear wheel 1 has a first external toothing 8, which meshes with a first internal toothing 9 of the inner part 3. The outer part 5 has a second external toothing 10 which meshes with a second internal toothing 11 in the toothed rim 6. The outer part 5 has, as clear from Fig. lb, a third internal toothing 13 which meshes with a third external toothing 12 on the gearwheel 7. A first pressure pocket arrangement 14 is formed between the first external toothing 8 and the first internal toothing 9, a second pressure pocket arrangement 15 is formed between the second external toothing 10 and the second internal toothing 11, and a third pressure pocket arrangement 16 is formed between the third external toothing 12 and the third internal toothing 13. The teeth of the toothings 12 , 13 are here illustrated merely diagrammatically. An orbit- type toothing, for example, can be used to advantage here.

The toothed rim 6 is mounted non-rotatably in a housing, not illustrated. When oil under pressure is now supplied to the first pressure pocket arrangement 14 with appropriate commutation, individual pressure pockets will enlarge and other pressure pockets will reduce correspondingly. By this means first of all the inner part will be displaced in an orbiting movement relative to the gearwheel 1. The outer part 5 is constrained to follow this orbiting movement, but it does not have to rotate to the same extent as the inner part 3. On the contrary, rotation of the outer part 5 is determined by the engagement between the second external toothing 10 and the second internal toothing 11. The rotary movement of the outer part 5 then extends by way of the third internal toothing 13 to the third external toothing 12 of the second gearwheel 7 and starts to turn the latter. The third external toothing 12, together with the third internal toothing 13, forms a torque output arrangement. The torque output arrangement has a relatively large diameter and thus a relatively large lever arm. As a consequence, on the one hand the teeth can be made relatively large, and therefore robust and, secondly, with the same forces the large lever arm creates a larger torque than is the case with the first toothing. The machine can therefore be operated with relatively large moments without risk of damage to individual elements.

Because of the tooth ratios in the individual toothings, the speed at which the shaft 2 is to rotate can be relatively freely selected. Since inner part 3 and outer part 5 are freely rotatable relative to one another, even relatively large reduction ratios can be obtained, that is, the machine can run very slowly.

One is not restricted to supplying the fluid under pressure only to the first pressure pocket arrangement 14. It can also be supplied to the second pressure pocket arrangement 15 or even to the third pressure pocket arrangement 16. In each case a different rotary speed will be achieved. It is also possible to supply two of the three pressure pocket arrangements with fluid under pressure. When the fluid under pressure is injected into both pressure pocket arrangements in the same direction, that is, so that the rotating speeds are added together, a speed increase can be achieved. When the fluid under pressure is injected in opposite directions, only the difference of the speeds will be obtained.

With appropriate dimensioning, the first toothed coupling can be kept virtually free from torque. Forces are then applied just by the fluid under pressure such that they displace the gear ring more or less exclusively radially. The main driving power is then transmitted by way of the second gearwheel 7 to the shaft 2.

Fig. 2 shows a similar construction, in which corresponding elements are provided with primed reference numerals. The illustration in Fig. 2a is a view along the line A-A of Fig. 2b.

Unlike the tooth form in Fig. 1, the tooth form used in Fig. 2 is of involute construction. The gearwheel 7' has a much larger diameter.

In the construction shown in Fig. 1, the first toothed coupling has 6-7 teeth, the second toothed coupling 15-

16 teeth and the third toothed coupling 10-11 teeth. In the construction shown in Fig. 2 the first toothed coupling again has 6-7 teeth, the second toothed coupling has 50-52 teeth and the third toothed coupling has 38-40 teeth. Other tooth differentials are possible provided that they cause the orbiting movement of the gear ring 3, 5 and 3', 5'.

Fig. 3 shows a motor which has one of the sets of gearwheels 20 illustrated in Fig. 1 or 2 and with which the shaft 2 is driven. For commutation purposes the motor has a distributor valve 21 which rotates synchronously with the inner part 3 of the gear ring. Channels in a distributor plate 22 are in that case supplied alternately with pressure depending on which pressure pockets of the pressure pocket arrangement 14 are to be filled. Synchronization of the movement between the distributor valve 21 and the inner part 3 is effected by means of pins 23 which engage in openings or apertures 17 in the distributor valve. Since the inner part 3 must both rotate and also orbit in relation to the distributor valve 21, the apertures

17 are correspondingly enlarged. The distributor valve 21 is also mounted on the shaft 2. The distributor plate 22 serves as intermediate member between the distributor valve 21 and the orbiting assembly comprising gearwheel 1 and inner part 3. A piston 24 serves on one side as a seal against the distributor valve 21 and on the other side is in connection with a motor connection 30. Furthermore, a balancing piston 15 is provided, which is in connection on one side with a motor connection 40 and on the other side acts against the piston 24. The essential construction of such a distributor valve 21 with pistons 24, 25 which are stationary in relation to the axle and are therefore secured in the housing against turning in a manner not illustrated, is known from DE-AS 22 20 350 or DE 30 29 997 C2.

The essential parts of the motor are illustrated in an exploded view in Fig. 4 by way of clarification.

In Fig. 3 two further plates 26, 28 can be seen, between which the gearwheel assembly 20 and the distributor valve 21 with its pistons 24, 25 are arranged. The shaft 2 is mounted by way of a bearing 27 in the housing 18 and securely held there by means of a nut 19 which acts on the inner ring of the bearing. The other plate 28 iε also secured in the housing, for which purpose an end cover 29 can be used.

Hydraulic pressure is able to build up only between the two plates 26, 28. The resultant forces are absorbed by the shaft 2. Axial forces on the housing cannot be caused by the hydraulic fluid. Conversely, neither are external forces able to affect the internal balance of forces since the parts between the two plates 26, 28 will follow all axial movements. Since all inner moving parts are secured on the continuous shaft, and at the same time it is possible to give the shaft 2 very large dimensions, the εhaft 2 is able to absorb even radial forces up to a certain magnitude. Beyond the hydraulic components, the pressure in the housing itself is tank pressure. Hydraulic fluid which leaks from the hydraulic components can be used for lubricating the outer part 5 of the gear ring or even for lubricating the bearing 27.

Such a construction is a very compact and space-saving combination of an orbiting motor and a step-down gear. The pressure in the motor can be allowed to rise considerably, for example, by a factor of 2 or 3 and the speed can be allowed to reduce by this factor at the same time, so that with the same power the torque can be dramatically increased.

Because the shaft is continuous, there is the further advantage that mounting of different forms of brakes on the continuous axle is very easy.

Claims

Patent Claims

1. Hydraulic machine having a gearwheel which has a first external toothing, a gear ring, which has a first internal toothing having at least one tooth more than and meshing with the first external toothing, and a second external toothing, and a toothed rim, which has a second internal toothing having at least one tooth more than and meshing with the second external toothing, characterized in that the gear ring (3, 5) is divided radially into an inside inner part (3) having the first internal toothing (9) and an outside outer part (5) having the second external toothing (10) , which parts are rotatable relative to one another.

2. Machine according to claim 1, characterized in that a bearing (4) is arranged between the inner part (3) and the outer part (5) .

3. Machine according to claim 2, characterized in that the bearing (4) iε in the form of a needle roller bearing.

4. Machine according to one of claimε 1 to 3, characterized in that either the gearwheel (1) or the toothed rim (6) is held so that it does not rotate, wherein in the case of the gearwheel (1) the outer part

(5) has a torque output arrangement (13) and in the case of the toothed rim (6) the inner part (3) has a torque output arrangement (13) .

5. Machine according to claim 4, characterized in that the torque output arrangement (13) is in the form of a toothing which co-operates with a counter-toothing (12).

6. Machine according to claim 4 or 5, characterized in that the torque output arrangement acts on the rotatable part of gearwheel (1) and toothed rim (6) .

7. Machine according to claim 6, characterized in that the counter-toothing (12) is in the form of a third external toothing having a larger diameter than the first external toothing (8) .

8. Machine according to claim 7, characterized in that the third external toothing (12) and the gearwheel (1) are arranged non-rotatably on a common shaft (2) .

9. Machine according to one of claims 1 to 8, characterized in that at least two presεure pocket arrangements (14, 15, 16) are formed between the individual external toothings (8, 10, 12) and the internal toothings (9, 11, 13) co-operating therewith, and fluid under presεure is arranged to be supplied to each pressure pocket arrangement.

10. Machine according to claim 9, characterized in that fluid under pressure is arranged to be supplied to two pressure pocket arrangements simultaneously.