BACKGROUND ART A vane pump is composed of parts, such as a cylinder, an eccentrically positioned rotor, front and rear covers and a vane, which are disposed in a casing containing a vacuum oil. Its operating principle is that the rotor rotates according to the rotation of a pulley at a pump side connected by a motor and a belt. When the rotor rotates, the vane inserted into a straight-type rotor groove of the rotor proceeds outward in the radial direction of the rotor by a centrifugal force so that they can rotate integrally with the rotor and as such the vanes rotate with their front ends being contacted to an inner wall of a pump chamber, they pump a fluid into an outlet port.

However, the vane pump is most problematic in that since the front and rear ends of the vane are contacted to the inner wall of the pump chamber and an inner face of the covers upon the rotation of the vanes, the vane is easily abraded and thus the exchange cycle of the

vane is shortened. Moreover, as the ends of the vanes disposed outward in the radial direction is contacted to the inner face of the pump chamber and is rotated, the vanes are early abraded. Thus, the life span of the vane pump is shortened and also an air gap is generated between the end of the vane and the inner face of the covers and the pump chamber, thereby reducing pump efficiency.

In addition, since solids in a fluid are often introduced into the pump chamber along with cobbles, sand, metal fragments, the inner face of the pump chamber and the end of the vane is badly abraded by the solids. This causes the degradation of the pump efficiency and increases the maintenance cost including a casing replacement cost.

DISCLOSURE OF INVENTION It is an object of the present invention to provide a vane pump which minimizes abrasion of vanes and an inner wall of a pump chamber and has a lengthened life span by adjusting an air gap between the vanes and the pump chamber by moving the central axial line of the pump chamber as much as an abrasion deviation upon the abrading of the inner wall of the pump chamber.

It is another object of the present invention to provide a vane pump which is improved in pumping ability by manufacturing a housing constituting the pump chamber separately from a casing and attaching an expansion member of a low elastic rubber on the inner

face of the pump chamber contacting the vanes.

The above object of the present invention can be achieved by a solution in which a separate housing is mounted on the circumference of a rotor in constructing a pump chamber, an expansion member made from a low elastic rubber is attached to the inner wall of the housing, and an inlet port and an outlet port of a fluid is formed on the circumferential face of the housing, as well as the pump chamber is constructed by the housing, cover and casing in assembling the cover and casing of the vane pump, and a compensating unit is provide for compensating an abrasion deviation upon abrading of the inner face of the expansion member.

The other object of the present invention can be achieved by a solution in which the pump chamber is formed in a sealed state by attaching liners on the front and rear faces of the rotor in order to prevent the abrasion of the front and rear faces of the vanes and the abrasion of the vanes can be prevented by making the rotor, liner and vanes rotate along with the rotor.

Preferably, the vane pump further includes an engaging unit for forming the pump chamber by locating the housing between the cover and the casing.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features, aspects, and advantages of preferred

embodiments of the present invention will be more fully described in the following detailed description, taken accompanying drawings. In the drawings: Fig. 1 is an exploded perspective view illustrating a vane pump according to a first preferred embodiment of the present invention; Fig. 2 is an enlarged exploded perspective view illustrating a rotor, vanes, a housing and an expansion member as illustrated in Fig. 1; Fig. 3 is a longitudinal sectional view of the vane pump as illustrated in Fig. 1; Fig. 4 is a longitudinal sectional view of a cover, a rotor and a casing according to the first embodiment of the present invention; Fig. 5 is an exploded perspective view illustrating a vane pump according to a second embodiment of the present invention; Fig. 6 is an enlarged perspective view illustrating a rotor, vanes and liners as illustrated in Fig. 5; Fig. 7 is a longitudinal sectional view of the vane pump according to the second embodiment of the present invention; Fig. 8 is a longitudinal sectional view of a cover, a rotor and a casing according to the second embodiment of the present invention; Fig. 9 is a perspective view illustrating one example of a unit for engaging the cover and casing of the vane pump according to the present invention and a unit for compensating an abrasion deviation by moving the axial line of the housing; and

Fig. 10 is a sectional view illustrating one example of compensating an abrasion deviation according to the first and second embodiments of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION Fig. 1 is an exploded perspective view illustrating a vane pump according to a first preferred embodiment of the present invention.

Referring to Fig. 1, the vane pump 100 mainly includes a casing 10, a rotor 20, a housing 30, an expansion member 40, a cover 50 and an engaging unit 60 for fixing the housing 30 between the casing 10 and the cover 50, and a housing position compensating unit 70 for adjusting the pivotal position of the housing 30. The casing 10 is equipped therein with a motor (not shown) which operates by a power supply.

Fig. 2 is an enlarged exploded perspective view illustrating a rotor 20, vanes 22, a housing 22 and an expansion member 40 of the vane pump 100 according to the first embodiment of the present invention.

Referring to Fig. 2, cruciform rotor grooves 21 are formed on the front face of the rotor 20, and the vanes 22 are inserted into the cruciform rotor grooves 21. The vanes 22 are freely movable while sliding inward and outward in the radial direction along the rotor grooves 21. In the drawings, reference numeral 23 is a guide face which guides the vanes 22 to move in the inward and outward direction of the rotor 20.

The vanes 22 are of a platy body form having a thickness similar

to the diameter of the cruciform rotor grooves 21 of the rotor 20. The vanes 22 each are independently inserted into the rotor grooves 21. If the vanes 22 rotate along with the rotation of the rotor 20, the fluid introduced through an inlet port 31 is pumped to an outlet port 32. The vanes 22 have a shaft 22a attached thereto in parallel with a centerline C 1 of a rotor shaft 20a and a space portion 22c provided between a platy body 22b and the shaft 22a. Reference numeral 24 is a tube type bearing having a predetermined length. The bearing is inserted between the vane 22 and the shaft 22a. The width of the platy body 22b is the same as the length of the rotor.

In a first embodiment of the present invention, as shown in Fig. 3, the rotor 20 is provided with pressure plates 50a and 10a each having a smaller inner diameter than the rotor 20 and a larger outer diameter than the housing 30 on an inner wall of the cover 50 and casing 10 constituting a pump chamber P.

The pressure plates 50a and 10a forms the pump chamber by pressurizing the peripheral portion of the housing 30 and expansion member 40, and the front and rear faces of the vanes 22 are contacted to parts of the pressure plate 50a. In this case, the front end of the vanes 22 is effective for preventing abrasion caused by a contact to the inner face of the expansion member 40 made from a low elastic rubber to be described later.

In a second embodiment of the present invention, as shown in

Figs. 5 to 7, the front and rear faces of the rotor 20 respectively engage with disc type liners 25a and 25b by a bolt. The front and rear disc type liners 25a and 25b are effective for preventing the abrasion of the front and rear faces of the vanes 22 by a contact to the front and rear faces of the vanes 22 inserted into the rotor grooves 21.

Additionally, the two liners 25a and 25b have stepped portions 25c and 25d formed along the circumferential face of the outline of the surfaces having a similar outer diameter and facing each other, with openings 27a and 27b being formed on the center.

As shown in Fig. 5, when the cover 50 to be described later is assembled in the casing 10, the opening 27a of the front side liner 25a is penetrated by an induction pipe 52 for inducing and supporting the vanes 22 so as to be rotated while forming a constant track upon the rotation of the vanes 22. As shown in Fig. 7, the rear side opening 27b is engaged to the circumferential face of a reinforcing shaft 20b between the rotor 20 and a rotor shaft 20a. The two liners are also engaged and assembled to engagement holes formed at the front and rear faces of the rotor 20.

As shown in Fig. 2, the housing 30 is constructed by separating a portion constituting the pump chamber P (refer to Fig. 10) from the casing 10, unlike a conventional vane pump in which the pump chamber P is integrally formed with the casing 10. The housing 30 is roughly formed in a ring shape and has the pump chamber P formed

therein. And on the circumferential face, there are mounted an inlet port 31 for introducing a fluid and an outlet port 32 for discharging the fluid.

The housing 30 has an expansion member 40 made of a low elastic rubber inserted and attached to the inner face. A flange 41 extending and projecting in the axial direction is formed on both peripheral portions of the expansion member 40 and performs a sealing action by an expansion force upon assembling of the cover 50 and casing 10. And at least one hole 42 is prepared on the flange 41 of the expansion member 40 and forms a space which is formed by the stepped portions 25c and 25d of the front and rear liners 25a and 25b when the front and rear liners 25a and 25b are coupled to the rotor 20.

The expansion member 40 is attached to the inner face of the housing 30 excepting the passages of the inlet port 31 and outlet port 32 attached to the housing 30. The inner face of the expansion member 40 is a space where an actual pump chamber P is formed. In the first embodiment, as shown in Figs. 3 and 4, the pump chamber P is formed, being sealed by the pressure plates 10a and 50a of the cover 50 and casing 10, the outer surface of the rotor 20 and the inner surface of the expansion member 40.

Therefore, the rotor 20 is located so that it is spaced part at the same interval along the inner diameter of the expansion member 40 and the vanes 22 passes through the interval. Moreover, as shown in Fig. 7,

an anti-collision pin 25 extending inward in the radial direction of the rotor is further provided so that the other vanes may not interfere between the locomotor rods of the two symmetric vanes 22 when the vanes slid along the rotor grooves 21 during the rotation. Also, it is arranged so that the rotary traces of the vanes are not overlapped.

In the second embodiment of the present invention, as shown in Figs. 7 and 8, the pump chamber P is formed by the liners, the inner face of the expansion member and the outer diameter of the rotor 20.

The vanes 22 pass through the interval between the inner diameter of the expansion member 40 and the rotor 20 while being rotated.

The rotor 20 is freely rotatable as it receives a power from the motor installed in the casing 10 and thus is rotatably supported on a bearing 12 mounted on a shaft hole 11.

As shown in Figs. 1,3 and 4, the above-mentioned cover 50 acts to protect the housing 30 located in the casing 10, the vanes 22, expansion member 40 and liners assembled in the housing 30, and forms the sealed pump chamber P. On the outer circumferential face of the cover 50 are prepared engaging flaps 51 being spaced apart at an approximately 120° interval and having an engaging hole 5 Ia. On the inner face of the cover 50, a vane induction pipe 52 is inserted into a shaft hole 50b and is rotatably supported by a bearing 54. Unexplained reference numeral 55 is an E-shaped ring which supports the axis of the induction pipe 52 so as not to be separated from the shaft hole 50b.

The induction pipe 52 prevents the abrasion of the outer diameter of the shaft and the inner surface 52a of the induction pipe 52 and reduces noise by the rolling operation of the tube type bearing 24 inserted into the inner surface 52a when the vanes 22 rotates by the rotor 20. And the central axial line C2 of the rotor shaft is eccentric to the central axial line C 1 of the induction pipe 52.

Therefore, when the vanes 22 rotates, the central axial line Cl of the rotor shaft and the central axial line C2 of the induction pipe 52 becomes eccentric and thus the free end of the vanes 22 carries out rotary motion on an elliptical-shaped rotary track. When the vanes 22 rotates while forming an elliptical rotary track, the front end of the vanes 22 are rotated upon slightly pressing the surface of the expansion member 40, thereby improving the pumping ability of a fluid.

Moreover, if the size of the inner diameter 52a of the induction pipe 52 is increased, the stroke width of the vanes 22 becomes larger, and if the diameter is decreased, the stroke width becomes smaller.

Thus, the width of a stroke moving inward and outward in the radial direction of the rotor 20 is adjustable by the inner diameter 52a of the induction pipe 52. That is, the pressure of the free end of the vanes 22 applied on the surface of the expansion member 40 by a centrifugal force is adjustable according to a size of the inner surface 52a of the induction pip 52. Thus, even if the expansion member 40 or the vanes 22 are not replaced, the stroke width of the vanes 22 can be extended

by replacing the induction pipe 52 whose size of the inner surface 52a is large. This increases the pressure applied on the expansion member 40 to thus improve the pumping ability of a fluid.

In the above-described construction of the first embodiment according to the present invention, in the construction of the pump chamber P, the inner wall of the pump chamber P contacting the vanes 22 is formed from the expansion member 40, thereby minimizing the rate of abrasion caused by the contacting. In this embodiment, an example is exemplified in which the pressure plate 50a formed on the casing 10 and cover 50 are tightly adhered to both peripheral portions of the expansion member 40 and housing 30 in order to seal the pump chamber P.

In the second embodiment of the present invention, in the construction of the pump chamber P, the inner wall of the pump chamber P contacting the vanes 22 is formed from the expansion member 40, thereby minimizing the abrasion of the free end of the vanes 22. At the same time, both peripheral portions of the expansion member 40 are pressurized by the liners 25a and 25b so that the vanes 22 rotates with the rotor 20 with the front and rear faces being contacted to the surface of the liners, thereby preventing the abrasion of the front and rear surfaces of the vanes 22.

In Figs. 1,3, 5, 7 and 9, reference numeral 60 is a unit for engaging the housing 30 surrounding the components constituting the

pump chamber P between the cover 50 and the casing 10. As one example of the engaging unit, as shown in Fig. 9, a tension bolt 61 extending to opposite ends and having a thread formed on the surface is inserted into engaging holes 51 a and 13 of engaging flaps 51 and 10b of the cover 50 and casing 10 and thus the projected thread is engaged with a nut, thereby assembling the cover 50 and the casing 10.

Reference numeral 70 is a unit for recovering or compensating a pumping ability due to abrasion upon the abrasion of the expansion member 40. As one example of the compensating unit, a plurality of bolts 70a are engaged to the center of the tension bolt 61 so that the end of the bolts 70a can be pressurized inward in the radial direction on the circumferential face of the housing 30. It is possible to uniformly compensate the interval between the rotor 20 and the expansion member 40 by moving the central axial line of the housing 30 by clamping or loosening the bolt 70a.

An example of assembling the vane pump 100 according to the present invention will be explained.

In the example of assembling according to the first embodiment, when the rotor shaft 20a of the rotor 20 is inserted into the shaft hole 11 of the casing 10, the rotor 20 is freely rotated on the rotation of the motor. As shown in Figs. 1,2, 5 and 6, in the rotor grooves 21, the vanes 22 engaging with the tube type bearing 24 are inserted into the shafts 22a of the vanes 22 and then the shafts 22a are gathered to be

adjacent to each other.

After arranging the housing 30 including the expansion member 40 on the circumference of the rotor 20, the cover 50 is put on the housing 30 so that the front face of the housing 30 can be covered. At this time, the cover 50 is assembled so that the tube type bearing 24 can be inserted into the inner diameter of the induction pipe 52, and is firmly fixed by engaging the bolt penetrating each flange by a nut using a tension bolt.

At this time, as the surface of the pressure plate 50a formed on the inner wall of the cover 50 and casing 10 pressurizes the flange portion of the expansion member 40 and thus the front and rear faces of the vanes 22 are contacted to parts of the surface of the pressure plate 50a, an sealed pump chamber P is constructed on the inner face of the expansion member 40. Simultaneously, a sludge storage space is prepared which leads to a hole 42 formed on the flange 41 of the expansion member 40.

In the example of assembling according to the second embodiment, firstly, the circumferential face of the reinforcing shaft 20c is penetrated at the rear side of the rotor 20, whereby the rear side liner 25b is engaged and attached to the rear face of the rotor 20 by a bolt and is inserted into the shaft hole 11 of the casing 10. As described above, as shown in Figs. 1,2, 5 and 6, in the rotor grooves 21, the vanes 22 engaging with the tube type bearing 24 are inserted into the

shafts 22a of the vanes 22 and then the shafts 22a are gathered to be adjacent to each other.

And the housing 30 attached with the expansion member 40 is arranged around the rotor 20 and the front liner 25a is engaged to the front face of the rotor 20 by a bolt. This makes the flange 41 portion of the expansion member 40 to be pressurized by the front side liner and makes the front and rear faces of the vanes 22 to be contacted to the surface of the liners, thereby rotating the liners 25a and 25b along with the rotor 20. In Fig. 5, reference numeral 52b is a space portion formed so as not to interfere in the rotation of the front face liner.

Additionally, as described above, when the front and rear liners are coupled to the rotor 20, there is formed a sludge storage space leading to the hole formed on the flange 41 of the expansion member 40.

Afterwards, the cover 50 is assembled in the same manner as in the example of assembling of the first embodiment.

The operational examples according to the first and second embodiments of the present invention will be explained as below.

As shown in Fig. 9, in the vane pump 100 of the invention, when the motor rotates by a power supply, as the rotor 20 rotates along with the rotor shaft 20a, the vanes 22 inserted into the rotor grooves 21 start to be rotated. At this time, the vanes 22 proceed in the radial direction of the rotor 20 by a centrifugal force. However, as the tube type bearing 24 is caught on the inner surface of the induction pipe 52, the

proceeding of the vanes 22 is suppressed and then the vanes 22 rotates along the inner surface of the induction pipe 52 by the rolling operation of the bearing 24.

However, since the central axial line Cl of the rotor 20 and the central axial line C2 of the induction pipe 52 are eccentric, the free end of the vanes 22 performs a rotary motion along the elliptical-shaped rotary track.

Thus, the inner face of the expansion member 40 made from a low elastic rubber is slightly pressed down by the free end of the vanes 22 and then is rotated, thereby pumping a fluid introduced to the inlet port 31 into the outlet port 32.

If solids and sludge are introduced along with the fluid, the sludge is introduced into the sludge storage space as shown in Figs. 3 and 7 through the hole 42 formed on the flange 41 of the expansion member 40, is accumulated therein and performs sealing operation.

The vanes 22 according to the first embodiment rotate, partially being contacted to the pressure plate 50a formed on the surface of the cover 50 and casing 10. Nevertheless, although their front end is contacted to the inner face of the expansion member 40, the vanes 22 has a very low abrasion rate because of its relatively high degree of hardness. Therefore, the vane pump of the invention is excellent in abrasion resistance as compared to the conventional vane pump provided with a pump chamber and thus the life span of the vane pump

100 can be lengthened.

On the other hand, in the second embodiment, though the front and rear faces of the vanes are contacted to the liners by attaching the liners to the front and rear faces of the rotor 20, the rotor 20 and the liners rotates together and thus there occurs almost no abrasion on the front and rear faces of the vanes. And, as described above, even if the front end of the vanes rotates, being contacted to the inner face of the expansion member 40 by a centrifugal force, the vanes having a relatively large hardness has a very low abrasion rate.

However, in a case the inner face of the expansion member 40 is abraded with the passage of time, it is possible to compensate for a decrease in pump efficiency by moving the central axial line of the housing 30 differently from the central axial line Cl of the rotor 20.

In this way, in order to adjust an abrasion deviation by moving the housing 30, as shown in Fig. 10, the housing can be moved in a desired direction by clamping or loosening the compensating unit pressurizing the circumferential face of the housing 30, i. e. , the plurality of bolts 70a coupled approximately perpendicular to the tension bolt 61a. When the housing 30 is moved, the expansion member 40 is also moved and deviates from the central axial line of the rotor 20. As such, the vanes rotate with the front end being more tightly contacted to the surface of the expansion member, thereby recovering the pumping ability.

INDUSTRIAL APPLICABILITY As explained above, in the first embodiment of the vane pump 100 according to the present invention, the housing is separately formed for preventing abrasion of the front end of the vanes and the expansion member is attached in the housing. Thus, when the front end of the vanes is contacted by a low elastic expansion force of the expansion member, the contact pressure becomes more compact, thereby improving the pumping pressure.

In the second embodiment, it is possible to effectively prevent the abrasion of the front and rear faces and front end of the vanes and the inner wall of the pump chamber P. Also, although the pumping ability is degraded by abrasion, an allowance caused by the abrasion is compensated by the compensating unit without replacing parts, thereby recovering the pumping ability.