GB1565969A

GB1565969A - Sliding-vane type hydraulic rotary machine

Info

Publication number: GB1565969A
Application number: GB42940/76A
Authority: GB
Original assignee: IHI Corp
Current assignee: IHI Corp
Priority date: 1975-10-15
Filing date: 1976-10-15
Publication date: 1980-04-23
Also published as: NO763487L; NO147925C; NO147925B; AU1840976A; DE2646635B2; BR7605178A; IN147059B; AU507076B2; JPS5248109A; DE2646635C3; JPS5520074B2; DE2646635A1

Description

(54) SLIDING-VANE TYPE HYDRAULIC ROTARY MACHINE (71) We, ISHIKAWAJIMA-HARIMA JUKOGYO KABUSHIKI KAISHA, a Company organised under the laws of Japan, of No. 2-1, 2-chome, Ote-machi, Chiyoda-ku, Tokyo-to, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to sliding-vane type hydraulic rotary machines, which can operate as pumps or motors.

Known vane-type hydraulic rotary machines have a stator with a cam track for vanes, and a rotor rotatably disposed within the cam track which also constitutes a rotor chamber wall and provided with radially slidable vanes. The inlet and outlet zones are defined between the rotor and the cam track and used as the low and high pressure working chambers or high and low pressure working chambers, respectively, depending upon whether the machine is used as a pump or motor.

In these hydraulic machines, the vanes contact the cam track as cam followers so as to provide suitable seals between the inlet and outlet zones in communication with the inlet or suction and outlet or discharge ports, respectively. Therefore the vanes must be fully extended outwardly between the sealed sections; that is, between the major- and minor-axis surfaces, and must be pressed against the cam track under a suitable force, whereby the complete rotary cycle may be attained.

Centrifugal force holds the vanes outwardly against the cam track. However, various operating conditions and forces prevent the vanes from functioning as the free cam followers, and causes them to be retracted away from the cam track. The above described adverse conditions are caused by mechanical viscosity, friction, contact pressure between the vanes and the cam track, contact pressure between the vanes and the rotor, and other adverse pressures such as the pressures acting on both the outer and inner ends of the vanes.

It is an object of the present invention to provide a vane type hydraulic rotary machine in which a good seal between the vane and the cam track is attained.

According to the present invention, a sliding vane type hydraulic rotary machine includes a rotor having a plurality of slots each slot slidably housing a vane, and passages formed in the rotor, one extending between the rotor peripheral surface on the trailing side of each vane and the inner end of the slot containing the same vane, and in which there is adjacent the outer edge of the leading side of each vane a projection extending in the direction of rotation and each vane has a generally axially extending channel arranged to put the underside of the projection into communication with a chamber at the inner end of the respective slot when the vane is in a radially inward position in its slot.

Thus when the part of the rotor chamber behind the vane is at outlet pressure in the case of a pump, and the vane is being moved inwardly by the action of the cam track, the pressure behind the vane acts on the inner end of the vane to urge the vane against the cam track.

When the high pressure chamber is in front of the vane there is a net radial force on the vane at the projection due to the outlet pressure which is radially outward and also acts to hold the vane against the cam track.

The vane changes from being in front of a high pressure chamber to being behind a high pressure chamber at the minor axis of the elliptical cam track when the vane is moved inwards in its slot, and it is preferably arranged that at that part of the cycle an area within the slot in communication with the underside of the projection is also in communication with the chamber at the inner end of the vane to maintain good contact against the cam surface.

When the vane is crossing the inlet and the outlet ports the pressures on either side of it are the same, but at those times it is not performing any pumping or motor action so that the maintenance of a good seal is unimportant.

The invention may be carried into practice in various ways and one embodiment will be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a side view, partly in section, of a vane type hydraulic rotary machine in accordance with the present invention Figure 2 is a sectional view taken along the line II--II of Figure 1; Figure 3 is a front view of a vane in contact with the major-axis surface of the cam track; Figure 4 is a fragmentary view thereof, on an enlarged scale; Figure 5 is a front view of a vane in contact with the minor-axis surface of the cam track; and Figure 6 is a fragmentary view thereof, on the enlarged scale.

As shown in Figures 1 and 2, a slidingvane type hydraulic rotary machine in accordance with the present invention has an outer casing assembly consisting of a rear cover 2 and a front cover 3 with a cam ring I located between them. The cam ring 1 is provided with a substantially elliptical cam track 4 with minor-axis surface 5 and majoraxis surfaces 6.

A rotor 7 which is disposed within the cam track 4 is keyed or splined to a shaft 8 which in turn is driven by a rotor (not shown). Two diametrically opposed operating chambers 9 and 10 are defined by the major axis surfaces 6 of the cam track 4, the rotor 7, and the rear and front covers 2 and 3.

A plurality of radial slots 11 are provided around the peripheral surface of the rotor 7, and a vane 12 is slidably fitted into each slot 11.

Referring particularly to Figures 3 to 6, the outer or upper end of a vane 12 terminates in a projection 13 extending in the direction of rotation of the rotor 7, and the upper edge 14 of the projection 13 circumferentially between the leading and rear ends of the projection can be held in contact with the cam track 4 so that the operating chamber 9 or 10 is divided by the vanes projecting into it into a plurality of pressure chambers. An axially-extending groove 15 extends along the leading face of the vane 12.When the edge 14 of the vane 12 contacts the minor-axis surface 5 of the cam track 4 so that the vane 12 is moved into the slot 11, the groove 15 provides hydraulic communication between a chamber 16 constituted by a recess below the mouth 18 of the slot 11, and an inner chamber 17 formed in the rotor 7 below the inner end of the vane 12 as best shown in Figure 5. When the vane is retracted into the slot 11 as shown in Figure 5, the projection 13 on the vane closes the mouth of the slot 11.

The rotor 7 also has a communication passage 19 drilled through the rotor 7 from each chamber 17 to the rotor surface on the trailing side of the vane 12 and slot so that the space behind the vane 12 communicates with the inner chamber 17.

Referring again to Figures 1 and 2, an inlet duct 20 in the rear cover 2 communicates with inlet ports 21 and 22 while duct 23 in the front cover 3 communicates with outlet or discharge ports 24 and 25. A space defined between two adjacent vanes 12 each in axial alignment with one of the inlet and discharge ports constitutes a working chamber 9 or 10.

The pressure acting on the outer and inner ends of a vane 12 are in equilibrium when the vane 12 is in axial alignment with an inlet or outlet port because the pressure in the inlet or outlet port is transmitted through the communication passage 19 to the inner chamber 17. Therefore the vane 12 is forced to extend out of the slot 11 against the cam track 4 only by the centrifugal force on the vane.

Figures 3 and 4 shows a vane in position dividing the adjacent portion of an operating chamber 9 or 10 into sub-working inlet or outlet chambers in axial alignment with one of the inlet or outlet ports 21 and 22 or 24 and 25. The edge 14 of the vane 12 is forced against the major-axis surface 6 of the cam track under a contact force equal to: P(a-b) where P=pressure of working liquid at outlet port if the machine is working as a pump, a=area of the lower surface of the projection 13, and b=area of the upper surface thereof forward of the contact edge 14.

When a vane 12 is in contact with the minor-axis surface 5 of the cam track 4, it is forced into the slot 11 as shown in Figure 5 so that the projection 13 of the vane 12 closes the mouth 18 of the slot 11, and the chamber 16 is in communication with the high pressure at the outlet port behind the vane through the communication passage 19, the inner chamber 17, and the groove 15.

As a result, the edge 14 is pressed against the minor-axis surface 5 under a contact force (Pxa) (See Figure 6). The two expressions assume that the pressure at the inlet port is negligible.

In another embodiment of the invention, instead of having the mouth 18, the opening of the slot 11 may diverge outwardly in such a way that when the vane 12 is retracted as shown in Figure 5, it may close the diverging opening.

It will be seen that when a vane 12 is traversing an inlet or outlet port, it is only urged outwards against the cam track by centrifugal force, but that does not matter because at those times the vane is not performing any pumping or motor action.

When the vane is moving over the minor axis surface 5, the outlet pressure from the outlet 24 or 25 just left acts as described above to hold the vane against the cam track, and that continues until the passage 19 reaches the central or low point of the minor axis surface 5 when the inlet to the passage 19 closes.

During operation as a pump, after a vane has left an inlet passage 21 or 22, outlet pressure begins to build up in the working chamber 9 or 10 under the pumping action of the rotating vane, and that pressure is also used to hold the vane against the cam track as described above.

Thus whenever a vane is being used to define one end of the outlet pressure chamber, the outlet pressure is being used to hold the vane against the cam track and establish a good seal. There is some flexibility in design in determining the radial dimension of the projection 13 which determines the precise moment at which the passage in advance of the vane is cut-off from the space 16, and of course it can also be a matter of design whether that is at the same time as the groove 15 comes into communication with the inner chamber 17, and hence with the passage behind the vane.

As described above, according to the present invention, the vanes 12 are forced into contact with the major- and minor-axis surfaces of the cam track 4 under a controllable pressure, but they are forced into contact with the cam track surfaces other than the major- and minor-axis surfaces under centrifugal force and inertia only. Therefore, as compared with the conventional vane-type hydraulic rotary machines of the type in which the whole or part of the working pressure is normally transmitted to the lower ends of the vanes during operation, a considerably higher pressure can be obtained. In the conventional rotary machines in which the grooves or passages are formed in the side plates so as to transmit the working pressure to the ends of the vanes, correct timing is very critical and difficult to achieve.

However, according to the present invention, the pressure in the working chamber can be directly transmitted to the ends of the vanes so that ideal timing can be attained. Unlike the conventional rotary machines, it is not necessary to provide special means for reducing the pressure so that high efficiency can be attained and the manufacturing cost can be reduced. In addition, in the present invention, the sliding contact pressure can be suitably reduced without the use of any special means so that the contact pressure may be reduced accordingly. Therefore the choice of materials is not so limited; high pressure and high speeds of revolution can be attained; and a longer life can be expected for the unit, thus providing a vane pump or motor offering both technical and economic advantages.

The dimensions of the passages 15 and 19 can be designed to produce such pressure losses as are found to be desirable.

WHAT WE CLAIM IS: 1. A sliding vane type hydraulic rotary machine including a rotor having a plurality of slots, each slot slidably housing a vane, and passages formed in the rotor, one extending between the rotor peripheral surface on the trailing side of each vane and the inner end of the slot containing the same vane, and in which there is adjacent the outer edge of the leading side of each vane a projection extending in the direction of rotation, and each vane has a generally axially extending channel arranged to put the underside of the projection into communication with a chamber at the inner end of the respective slot when the vane is in a radially inward position in its slot.

2. A rotary machine gs claimed in Claim 1 including a generally elliptical rotor chamber with a peripheral wall consituted by a cam track co-operating with the vanes.

3. A rotary machine as claimed in either of the preceding claims in which each vane has a part circumferentially between the leading end of the projection and the rear end of the projection, which contacts the chamber wall.

4. A rotary machine as claimed in any preceding claim in which the underside of the projection is in communication with the rotor chamber when the vane is in a radially outward position, and that communication is broken as the vane moves inwards.

5. A rotary machine as claimed in any preceding claim in which the axial channel

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. In another embodiment of the invention, instead of having the mouth 18, the opening of the slot 11 may diverge outwardly in such a way that when the vane 12 is retracted as shown in Figure 5, it may close the diverging opening. It will be seen that when a vane 12 is traversing an inlet or outlet port, it is only urged outwards against the cam track by centrifugal force, but that does not matter because at those times the vane is not performing any pumping or motor action. When the vane is moving over the minor axis surface 5, the outlet pressure from the outlet 24 or 25 just left acts as described above to hold the vane against the cam track, and that continues until the passage 19 reaches the central or low point of the minor axis surface 5 when the inlet to the passage 19 closes. During operation as a pump, after a vane has left an inlet passage 21 or 22, outlet pressure begins to build up in the working chamber 9 or 10 under the pumping action of the rotating vane, and that pressure is also used to hold the vane against the cam track as described above. Thus whenever a vane is being used to define one end of the outlet pressure chamber, the outlet pressure is being used to hold the vane against the cam track and establish a good seal. There is some flexibility in design in determining the radial dimension of the projection 13 which determines the precise moment at which the passage in advance of the vane is cut-off from the space 16, and of course it can also be a matter of design whether that is at the same time as the groove 15 comes into communication with the inner chamber 17, and hence with the passage behind the vane. As described above, according to the present invention, the vanes 12 are forced into contact with the major- and minor-axis surfaces of the cam track 4 under a controllable pressure, but they are forced into contact with the cam track surfaces other than the major- and minor-axis surfaces under centrifugal force and inertia only. Therefore, as compared with the conventional vane-type hydraulic rotary machines of the type in which the whole or part of the working pressure is normally transmitted to the lower ends of the vanes during operation, a considerably higher pressure can be obtained. In the conventional rotary machines in which the grooves or passages are formed in the side plates so as to transmit the working pressure to the ends of the vanes, correct timing is very critical and difficult to achieve. However, according to the present invention, the pressure in the working chamber can be directly transmitted to the ends of the vanes so that ideal timing can be attained. Unlike the conventional rotary machines, it is not necessary to provide special means for reducing the pressure so that high efficiency can be attained and the manufacturing cost can be reduced. In addition, in the present invention, the sliding contact pressure can be suitably reduced without the use of any special means so that the contact pressure may be reduced accordingly. Therefore the choice of materials is not so limited; high pressure and high speeds of revolution can be attained; and a longer life can be expected for the unit, thus providing a vane pump or motor offering both technical and economic advantages. The dimensions of the passages 15 and 19 can be designed to produce such pressure losses as are found to be desirable. WHAT WE CLAIM IS:

1. A sliding vane type hydraulic rotary machine including a rotor having a plurality of slots, each slot slidably housing a vane, and passages formed in the rotor, one extending between the rotor peripheral surface on the trailing side of each vane and the inner end of the slot containing the same vane, and in which there is adjacent the outer edge of the leading side of each vane a projection extending in the direction of rotation, and each vane has a generally axially extending channel arranged to put the underside of the projection into communication with a chamber at the inner end of the respective slot when the vane is in a radially inward position in its slot.

connects the chamber at the inner end of the respective slot with a chamber in the rotor beneath the projection on the vane.

6. A sliding vane type hydraulic rotary machine constructed and arranged substantially as herein specifically described with reference to the accompanying drawings.