JPWO2000036303A1 - Automotive vane vacuum pump - Google Patents

Abstract

(57) [Abstract] To provide a lightweight, low-cost vane-type vacuum pump for automobiles that does not experience abnormal friction between shafts, the present invention provides a pump for pumping fluid from the suction port to the discharge port, which includes a cylindrical housing having an inlet and an outlet, a rotor eccentrically housed within the housing, a shaft that drives the rotor, and vanes that rotate in sliding contact with the inner circumferential surface of the housing as the rotor rotates. The pump features a protrusion or groove on the outer periphery of the shaft, and the shaft and rotor are integrally secured by insert molding or the like. The rotor can be formed by aluminum die casting, plastic molding, or metal sintering. The protrusion or groove on the outer periphery of the shaft can be formed integrally during cold forging or sintering of the shaft, or by welding a sheet metal molded product to the outer periphery of the shaft. The housing and rotor can also be formed from the same material.

Description

DETAILED DESCRIPTION OF THE INVENTION Vane-type vacuum pump for automobiles TECHNICAL FIELD The present invention relates to an improvement in a vane-type vacuum pump for automobiles.

BACKGROUND ART Fig. 9 is a side cross-sectional view showing an example of a conventional automotive vane vacuum pump, and Fig. 10 is a cross-sectional view showing the spline connection between the rotor and shaft of the conventional automotive vane vacuum pump shown in Fig. 9. As shown in Figs. 9 and 10, the conventional automotive vane vacuum pump has an inlet 1 and an outlet 2, and a cylindrical housing 4 and a bracket 5 connected to each other with bolts 3 to form a sealed space. The bracket 5 rotatably supports a shaft 7 with a bearing 8, and the shaft 7 is provided with a rotor 9 that is eccentrically housed within the housing 4 and can rotate within the housing 4. The rotor 9 is provided with vanes 11 disposed in radially arranged vane grooves 10 as shown in Fig. 10. As the rotor 9 rotates, centrifugal force causes vanes 11 to protrude radially outward from the vane grooves 10, and the vanes 11 rotate together with the rotor 9 while their outer edges are in sliding contact with the inner peripheral surface of the housing 4. As the rotor 9 rotates, fluid is sucked in through the inlet 1 and discharged pressure-fed from the outlet 2.

The shaft 7 is provided with a coupling 13, which allows rotational force to be input from the vehicle side. The shaft 7 also has splines 14, which mesh with splines 15 on the rotor 9 to transmit torque.

In such an automotive vane vacuum pump, when torque is transmitted to the shaft 7 from the coupling 13, the rotor 9 rotates eccentrically within the housing 4. In response to this eccentric rotation, the vanes 11 on the rotor 9 tend to protrude radially outward due to centrifugal force, rotating while sliding on the inner circumferential surface of the housing 4, sucking in fluid through the suction port 1 and pumping it out through the discharge port 2.

In such automotive vane-type vacuum pumps, the shaft 7 and rotor 9 are fitted together via splines 14 and 15, forming a splined connection. However, splines 14 and 15 are expensive to process, resulting in high product prices. Furthermore, although the splined connection formed by splines 14 and 15 is lubricated with oil, abnormal wear can occur depending on the properties of the oil. Because splined connections are loose, precision is difficult to achieve. Furthermore, splined connections require strength against spline torque, necessitating the use of high-strength materials. Conventionally, iron-based sintered products were used for the rotor 9 and steel for the shaft 7, preventing product weight reduction. Furthermore, because the rotor 9 and housing 4 were made of materials with different thermal expansion coefficients, a large gap was required between the rotor and housing to accommodate the thermal expansion difference.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a vane-type vacuum pump for automobiles that is lightweight, does not suffer from abnormal wear between shafts, and can be manufactured at low cost.

DISCLOSURE OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a vane-type vacuum pump for automobiles, which pumps fluid from the suction port to the outlet, and which comprises a cylindrical housing having an inlet and an outlet, a rotor housed eccentrically within the housing, a shaft for driving the rotor to rotate, and vanes that rotate in sliding contact with the inner peripheral surface of the housing as the rotor rotates, and which is characterized in that the shaft has protrusions or grooves on the outer periphery and the shaft and rotor are fixed integrally.

The shaft may be integrally cast by insert molding during the casting of the rotor, the rotor may be formed by aluminum die casting, the rotor may be integrally molded by plastic molding, or the rotor may be formed by molding aluminum powder and then sintering it.

Furthermore, the protrusions or grooves on the outer periphery of the shaft may be integrally formed during cold forging of the shaft, or the protrusions or grooves on the outer periphery of the shaft may be integrally formed during manufacture by sintering the shaft.

Furthermore, the projections on the shaft may be formed by welding a ferrous metal sheet to the outer periphery of the shaft, or the housing and rotor may be formed from the same material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side cross-sectional view showing an embodiment of a vane type vacuum pump for an automobile according to the present invention.

FIG. 2 is a cross-sectional view taken along line A-A in FIG.

FIG. 3 is a side view showing a second embodiment of the shaft of an automotive vane vacuum pump according to the present invention.

FIG. 4 is a cross-sectional view taken along line B-B in FIG.

FIG. 5 is a side view showing a third embodiment of the shaft of a vane type vacuum pump for a railcar according to the present invention.

FIG. 6 is a cross-sectional view taken along line CC of FIG.

FIG. 7 is a side view showing a fourth embodiment of the shaft of an automotive vane vacuum pump according to the present invention.

FIG. 8 is a cross-sectional view taken along line D-D in FIG.

FIG. 9 is a side cross-sectional view of a conventional vane type vacuum pump for an automobile.

FIG. 10 is a cross-sectional view showing the spline connection between the rotor and the shaft of the conventional automotive vane vacuum pump shown in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION In order to explain the present invention in more detail, an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, the same components as those in the conventional example will be designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a side cross-sectional view showing one embodiment of an automotive vane vacuum pump according to the present invention, and FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, showing the connection between the rotor and the shaft.

The automotive vane vacuum pump of the present invention has an overall structure similar to that of the automotive vane vacuum pump shown in Figures 9 and 10, with an inlet 1 and an outlet 2. A sealed space is formed by a cylindrical housing 4 and a bracket 5, which are connected to each other by bolts 3. The bracket 5 rotatably supports a shaft 21 via bearings 8, and the shaft 21 is fitted with a rotor 24, which is eccentrically housed within the housing 4 and rotatable within the housing 4. The rotor 24 is fitted with vanes 11, which are disposed in radially arranged vane grooves 10. As the rotor 24 rotates, centrifugal force causes the vanes 11 to protrude radially outward from the vane grooves 10, causing them to rotate together with the rotor 24 while their outer edges slide against the inner circumferential surface of the housing 4. Fluid is drawn in through the inlet 1 and discharged through the outlet 2 by the rotation of the rotor 24.

The shaft 21 is provided with a coupling 13, which allows rotational force to be input from the vehicle side.

According to this invention, instead of the splines 14 and 15 shown in Figures 9 and 10, the shaft 21 has two axially extending, radially protruding fin-like projections 23 at radially opposed positions on the shaft portion of the shaft body 22 corresponding to the entire axial length of the housing 4, and the rotor 24 has two axial grooves 25 that fit into the two fin-like projections 23, allowing torque to be transmitted via these fin-like projections 23 and axial grooves 25. The number of fin-like projections 23 may be one or more, and their axial length may be any number, as long as sufficient torque transmission and ease of manufacturing are ensured.

The fin-like projections 23 shown in Figures 1 and 2 can be formed integrally with the shaft body 22 during cold forging of the shaft 21, or can be formed during sintering if the shaft 21 is a sintered material. Alternatively, they can be formed by welding an iron-based sheet metal product to the round bar-shaped shaft body 22. It is preferable to use a sheet metal product with, for example, one flat end and the other curved end bent along the surface of the shaft body 22.

The rotor 24 is formed and attached integrally to the shaft 21 by integral casting or molding. This configuration eliminates the gap of the spline connection used in the past, and eliminates backlash between the shaft body 22 of the shaft 21 and the rotor 24. The shaft can also be integrally cast by insert molding when the rotor is cast.

The rotor may be integrally molded by aluminum die casting or plastic molding, or may be formed by molding aluminum powder and then sintering it.

In such an automotive vane vacuum pump, when torque is transmitted to the shaft 21 from the coupling 13, the rotor 24 rotates at an eccentric position within the housing 4. In response to this eccentric rotation, the vanes 11 on the rotor 24 tend to protrude radially outward from the rotor 24 due to centrifugal force, and rotate while sliding on the inner circumferential surface of the housing 4, sucking in fluid through the suction port 1 and pumping it out through the discharge port 2.

The automotive vane vacuum pump of the present invention makes it easy to ensure that the torque transmission area of the fin-shaped projections 23 on the shaft body 22 is large enough to transmit large torque. This allows the rotor to be made of low-strength aluminum alloys and plastic materials, which have not been used in the past, and reduces product weight. Furthermore, if the housing 4 and rotor 24 are made of the same material, there is no difference in thermal expansion.

Furthermore, since no splines are used, processing costs can be reduced, there is no play due to gaps in the spline connection, and abnormal wear does not occur.

Figure 3 shows a second embodiment of another shaft 26 that can be used in an automotive vane vacuum pump according to the present invention, and Figure 4 shows a cross section taken along line B-B in Figure 3. This shaft 26 differs from the shaft 21 shown in Figures 1 and 2 in that it has three fin-like projections 23, but otherwise has the same structure. This shaft 26 can be formed integrally with the shaft body 22 and fin-like projections 23 by cold forging or sintering.

Figure 5 is a side view showing a third embodiment of the shaft of an automotive vane vacuum pump of the present invention, and Figure 6 is a cross-sectional view taken along line C-C in Figure 5. This shaft 28 comprises a round-bar-shaped shaft body 29 and two fin-like protrusions 30 extending radially outward from the shaft body 29. The fin-like protrusions 30 are formed from two sheet metal moldings 31, with semi-cylindrical portions 32 of the sheet metal moldings 31 joined to the shaft body 29 by welding 27. Two overlapping fin portions 33 extend from both ends of the semi-cylindrical portions 32 in opposite radial directions of the shaft body 29. The number of fin-like protrusions 30 is arbitrary.

Figure 7 is a side view showing a fourth embodiment of the shaft for an automotive vane vacuum pump of the present invention, and Figure 8 is a cross-sectional view taken along line D-D in Figure 7. This shaft 34 has grooves 36 extending axially formed on the surface of a round bar-shaped shaft body 35, with protrusions 37 provided between the grooves. This shaft 34 can be manufactured by cutting, cold forging, or sintering.

INDUSTRIAL APPLICABILITY As described above, the automotive vane vacuum pump of the present invention comprises a cylindrical housing having an inlet and an outlet, a rotor eccentrically housed within the housing, a shaft for driving the rotor to rotate, and vanes that rotate in sliding contact with the inner circumferential surface of the housing as the rotor rotates, and which pumps fluid from the inlet to the outlet. Since the shaft has projections or grooves on its outer periphery and the shaft and rotor are fixed together as a single unit, it is possible to provide an automotive vane vacuum pump that is lightweight, does not suffer from abnormal wear at the spline fitting portions, and can be processed at low costs.

───────────────────────────────────────────────────── Continued from the front page (72) Inventor: Takashi Kinoshita 2-6-2 Otemachi, Chiyoda-ku, Tokyo Corporation: Mitsubishi Electric Engineering Co., Ltd. (Note) This publication is based on the publication published internationally by the International Bureau of Patents (WIPO). The effect of the international publication of the Japanese patent application (Japanese utility model registration application) related to this publication arises pursuant to Article 184-10, Paragraph 1 of the Patent Act (Article 48-13, Paragraph 2 of the Utility Model Act) and is unrelated to this publication.

Claims (9)

[Claims] 1. A vane-type vacuum pump for automobiles that pumps fluid from the suction port to the discharge port, the pump having a cylindrical housing with an inlet and an outlet, a rotor eccentrically housed within the housing, a shaft that drives the rotor, and a vane that rotates in sliding contact with the inner periphery of the housing as the rotor rotates, characterized in that the shaft has a protrusion or groove on its outer periphery, and the shaft and rotor are fixed integrally. 2. The vane type vacuum pump for an automobile according to claim 1, wherein the shaft is integrally cast by insert molding when the rotor is cast. 3. The automotive vane vacuum pump according to claim 2, wherein the rotor is formed by aluminum die casting. 4. The vane type vacuum pump for an automobile according to claim 2, wherein the rotor is integrally molded by plastic molding. 5. The automotive vane vacuum pump according to claim 2, wherein the rotor is formed by molding aluminum powder and then sintering it. 6. An automotive vane vacuum pump according to any one of claims 1 to 5, wherein the projections or grooves on the outer periphery of the shaft are integrally formed during cold forging of the shaft. 7. An automotive vane vacuum pump according to any one of claims 1 to 5, characterized in that the projections or grooves on the outer periphery of the shaft are integrally formed when the shaft is manufactured by firing. 8. The vane-type vacuum pump for an automobile according to any one of claims 1 to 5, wherein the shaft protrusion is formed by welding an iron-based sheet metal product to the outer periphery of the shaft. 9. The automotive vane vacuum pump according to any one of claims 1 to 8, wherein the housing and the rotor are made of the same material.