WO2018198369A1

WO2018198369A1 - Vane pump

Info

Publication number: WO2018198369A1
Application number: PCT/JP2017/017073
Authority: WO
Inventors: 崇寛小倉
Original assignee: 株式会社ミクニ
Priority date: 2017-04-28
Filing date: 2017-04-28
Publication date: 2018-11-01
Also published as: CN110546383A; JPWO2018198369A1; DE112017007482T5

Abstract

In this vane pump, a cylindrical rotor (18) is arranged within an accommodation space (10) of a pump housing (2), a pair of pump chambers (20) are individually defined on the front and rear sides of the rotor (18), and the left and right sides of the outer circumferential surface of the rotor (18) are each made to face the inner circumferential surface of the accommodation space (10) with a minute gap therebetween. The rotor (18) is rotationally driven by a motor (3) and air is taken in and discharged as a result of a vane (21) on the outer circumference causing the capacity of each of the pump chambers (20) to change. The accommodation space (10) is formed to have a cross-sectional track shape in which the ends of a pair of semicircular arc surfaces A are connected by a pair of parallel surfaces B in a planar view.

Description

Vane pump

The present invention relates to a vane pump, and more specifically, a rotor is disposed in a housing space of a pump housing to define a pair of pump chambers, and a vane tip provided so as to be able to appear and retract on an outer peripheral surface as the rotor rotates. The present invention relates to a vane pump that sucks and discharges fluid by changing the volume of each pump chamber while sliding in contact with the inner peripheral surface of the housing space.

¡There are various types of vane pumps of this type with different defined conditions in the pump chamber. For example, in the vane pump described in FIG. 4 of Patent Document 1, both sides of the cam ring are closed by plates to define a cylindrical storage space, and a cylindrical rotor is arranged at an eccentric position inside the storage space. Yes. As a result, a single crescent-shaped pump chamber is defined in the accommodating space, and the volume of the pump chamber is changed by a vane with the rotation of the rotor to suck and discharge fluid.

The capacity of the vane pump (the amount of fluid discharged) depends on the volume change of the pump chamber. However, the increase in the storage space for the purpose of increasing the capacity directly leads to an increase in the size of the vane pump itself and, in turn, the ease of mounting on vehicles. Resulting in.

Therefore, for example, in the vane pump described in FIG. 2 of Patent Document 2, an elliptical accommodating space is defined in the cam ring, and a cylindrical rotor is disposed at the center of the ellipse inside the cam ring, so that both sides of the rotor are arranged. It defines a pair of crescent-shaped pump chambers. For this reason, as the rotor rotates, the vanes cause volume changes in the respective pump chambers, thereby achieving an increase in pump capacity without enlarging the accommodating space.

JP 2013-60841 A JP 2005-351117 A

As described above, the vane pump of Patent Document 2 can increase the pump capacity in the same occupied space as compared with that of Patent Document 1. However, as long as the configuration of Patent Document 2 is adopted, in order to achieve a further increase in the volume of the pump chamber, and hence an increase in the pump capacity, there is no choice but to enlarge the accommodating space.

The present invention was made in order to solve such problems, and the object of the present invention is to achieve further increase in pump capacity after suppressing enlargement and ensuring good mountability. The object is to provide a vane pump that can.

In order to achieve the above object, the vane pump of the present invention has a cylindrical rotor disposed in a housing space provided in a pump housing, and defines pump chambers on both sides of the rotor. Both ends of the outer peripheral surface of the rotor perpendicular to the installation direction are opposed to the inner peripheral surface of the accommodating space via a minute gap, respectively, and the tip of a vane provided so as to be able to appear and retract on the outer peripheral surface of the rotor as the rotor rotates is provided. In a vane pump that draws and discharges fluid by changing the volume of each pump chamber while sliding in contact with the inner peripheral surface of the storage space, the storage space connects the ends of a pair of semicircular arc surfaces with a pair of opposing surfaces The cross section is formed in a track shape.

As another aspect, the distance between the pair of opposing surfaces is set to be narrower than the diameter of the rotor, and a pair of sealing surfaces having a circular arc shape corresponding to the outer peripheral surface of the rotor are formed on the inner peripheral surface of the accommodation space. In addition, it is preferable that the outer peripheral surfaces of the rotor face each other through a minute gap in the area of each seal surface (Claim 2).

As another aspect, it is preferable that at least end portions of the pair of seal surfaces of the storage space on the rotation direction side of the rotor are respectively formed with buffer surfaces having a circular arc shape having a center outside the storage space. Item 3).

As another aspect, when the vane sliding on the buffer surface is displaced in the protruding direction following the curvature of the buffer surface, the sliding force to the buffer surface is caused by the centrifugal force acting on the vane and the fluid pressure in the outer circumferential direction. It is preferable that the curvature of the buffer surface is set so that the acceleration is in the protruding direction where the contact can be maintained (claim 4).

According to the vane pump of the present invention, it is possible to achieve a further increase in pump capacity while suppressing an increase in size and ensuring good mountability.

It is a perspective view which shows the vacuum pump of embodiment. It is a disassembled perspective view which shows a vacuum pump. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1 showing a rotor and vanes in the accommodation space. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3, showing a connection portion between the rotor and the output shaft of the motor. It is the schematic diagram which compared the shape of planar view of accommodation space by 1st Embodiment and patent document 2. FIG. It is a schematic diagram which shows the shape of planar view of the accommodation space of 2nd Embodiment. It is a schematic diagram which shows the shape of planar view of the accommodation space of another example of 2nd Embodiment. It is the elements on larger scale of the X area | region in FIG. 6 which shows the separation | spacing of the vane which arises in 2nd Embodiment. It is the elements on larger scale corresponding to FIG. 8 which shows the periphery of the buffer surface of the accommodation space of 3rd Embodiment. It is the elements on larger scale corresponding to FIG. 8 which shows the periphery of the buffer surface of the accommodation space of another example of 3rd Embodiment.

Hereinafter, an embodiment in which the present invention is embodied in a vane type vacuum pump will be described.
1 is a perspective view showing the vacuum pump of the present embodiment, FIG. 2 is an exploded perspective view showing the vacuum pump, FIG. 3 is a sectional view taken along the line III-III of FIG. 1 showing the rotor and vanes in the accommodating space, and FIG. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG.

The vacuum pump 1 of this embodiment is mounted on a vehicle in order to generate a negative pressure to be supplied to the vehicle brake assist device. In each figure, the vacuum pump 1 is shown in a posture when installed in the vehicle, and in the following description, the vehicle is mainly used to represent front and rear, left and right, and up and down directions.

As a whole, the vacuum pump 1 has a pump housing 2 as a center, a motor 3 fixed to the lower side, and a silencer housing 4 fixed to the upper side.

The pump housing 2 is manufactured by aluminum die casting and has a cylindrical shape extending in the vertical direction. An inner peripheral wall 6 is formed so as to have a double inner / outer positional relationship with respect to the outer peripheral wall 5. A bottom wall 7 is integrally formed and closed at a lower portion of the inner peripheral wall 6, and an upper plate 8 is fixed to an upper opening portion of the inner peripheral wall 6 with screws 9, and these inner peripheral wall 6, bottom wall 7 and upper plate are fixed. A storage space 10 is defined by 8. The storage space 10 has a track shape in plan view, and the shape will be described in detail later because it is related to the gist of the present invention.

A motor 3 is fixed to the lower surface of the pump housing 2 with screws 12, and an output shaft 13 is disposed in the motor 3 along an axis L extending in the vertical direction. A pair of upper and lower bearings 14 (the upper side is shown in FIG. 4). ) Is rotatably supported. A boss portion 15 projects upward from the upper portion of the motor 3 with the output shaft 13 as a center, and a cylindrical tube portion 16 projects downward from the lower surface of the bottom wall 7 of the pump housing 2. Yes. The cylinder portion 16 is fitted on the boss portion 15 with an O-ring 17 interposed therebetween, whereby the pump housing 2 and the motor 3 are positioned on the axis L.

The output shaft 13 of the motor 3 protrudes upward from the shaft hole 15 a of the boss portion 15, and the upper portion is positioned in the accommodating space 10 through the cylindrical portion 16 of the pump housing 2 and the shaft hole 7 a of the bottom wall 7. Specifically, the upper portion of the output shaft 13 is located at the track center (both centered in the front-rear and left-right directions) of the accommodation space 10 in plan view.

A cylindrical rotor 18 centering on the axis L is disposed in the accommodation space 10. A shaft hole 18 a is drilled along the axis L from below, and the upper part of the output shaft 13 is inserted into the rotor 18. ing. The relative rotation between the output shaft 13 and the rotor 18 is restricted by a rotation-preventing member 19 disposed in the shaft hole 18a, and the motor 18 causes the rotor 18 to move in a predetermined direction (counterclockwise in plan view indicated by an arrow in FIG. 3). Around).

The lower surface of the rotor 18 is opposed to the bottom wall 7 of the accommodating space 10 via a minute gap, and the upper surface of the rotor 18 is opposed to the upper plate 8 via a minute gap. As a result, pump chambers 20 each having a crescent shape in plan view are defined on both front and rear sides of the rotor 18 in the accommodation space 10.

A vane groove 18b is provided in six equally divided portions on the outer peripheral surface of the rotor 18 over the entire vertical width of the rotor 18, and a plate-like vane 21 is centered around the axis L in each vane groove 18b. It is arranged to be able to appear and retract in the inside and outside direction. The vertical width of each vane 21 is substantially the same as the vertical width of the rotor 18, and the tip (outer peripheral end) is inclined with respect to the base end (inner peripheral end) in the rotational direction of the rotor 18.

As will be described below, the rotor 18 and the vane 21 are slidably contacted with each other in the housing space 10 during the operation of the vacuum pump 1, so that the rotor 18 and the vane 21 are made of self-lubricating carbon. Yes.

A silencer housing 4 is fixed to the upper surface of the pump housing 2 with screws 22, and an expansion chamber and a resonance chamber are formed in the silencer housing 4 to relieve pulsation of air discharged from the vacuum pump 1, although not shown. Has been.

As shown in FIG. 3, a connector 24 for supplying power to the motor 3 and a nipple 25 connected to a brake assist device via a pneumatic hose (not shown) are provided on the front side of the outer peripheral wall 5 of the pump housing 2. Yes. A pair of suction ports 26 are recessed in the lower surface of the upper plate 8, and each suction port 26 opens into the pump chamber 20 (shown in phantom lines in FIG. 3). One suction port 26 communicates with the nipple 25 via a first suction passage 27 formed in the pump housing 2 and is an annular first recess that is recessed on the lower surface of the upper plate 8 so as to surround the accommodation space 10. 2 communicates with the other suction port 26 via the suction path 28.
In addition, discharge ports (not shown) are opened in each pump chamber 20, and these discharge ports communicate with the outside from the discharge path 29 via the expansion chamber and the resonance chamber in the silencer housing 4.

Therefore, when the rotor 18 is rotationally driven in the accommodation space 10 by the motor 3, each vane 21 gradually changes the volume of the pump chamber 20 partitioned into a plurality while the tip end is in sliding contact with the inner peripheral surface of the accommodation space 10. . As a result, air from the brake assist device is sucked into one pump chamber 20 from one suction port 26 via the pneumatic hose, nipple 25 and first suction path 27, and the other via the second suction path 28. The suction port 26 is sucked into the other pump chamber 20.

In each pump chamber 20, air is transferred from the suction port 26 side to the discharge port side by the vane 21, and flows into the silencer housing 4 through the discharge path 29 from each discharge port. Air pulsation is relaxed in the process of flowing through the expansion chamber and the resonance chamber, and then air is discharged to the outside.

An annular space 30 is formed between the inner peripheral wall 6 and the outer peripheral wall 5 of the pump housing 2, and the annular space 30 communicates with the outside through slits 31 formed on both front and rear sides of the outer peripheral wall 5. ing. Although not shown, an engine cooling fan is disposed in front of the vacuum pump 1, and a part of the cooling air is sent to the vacuum pump 1. The cooling air flows into the annular space 30 from the front slit 31 and branches to the left and right, flows through both the left and right sides of the inner peripheral wall 6, joins, and is discharged from the rear slit 31 to the outside. Due to the circulation of the cooling air, the temperature rise of the vacuum pump 1 is suppressed.

On the other hand, mounting flanges 33 having buffer members 32 are integrally formed on both the left and right sides of the pump housing 2, and the vacuum pump 1 is fixed to the vehicle body via these mounting flanges 33.

By the way, as described in [Problems to be Solved by the Invention], in the vane pump of Patent Document 2 in which the pump chambers are defined on both sides of the rotor as in the present embodiment, the accommodation space is required to further increase the pump capacity. However, there is a problem that the mountability of the vane pump itself deteriorates due to the enlargement of the vane pump itself.

In view of the above problems, the present inventor has focused on the shape of the accommodation space. The accommodation space of the vane pump of Patent Document 2 is elliptical in plan view. Specifically, it has a shape expressed by the following equation (1) on the X-axis and Y-axis planes.
X ² / A ² + Y ² / B ² = 1 …… (1)
Here, A / B is the ratio of the major axis to the minor axis of the ellipse.
The shape setting of the accommodation space is intended to suppress the change in acceleration in the protruding direction of the vane as much as possible.

That is, during the operation of the vane pump, each vane receives centrifugal force and air pressure in the outer peripheral direction (air pressure acting on the base end-air pressure acting on the tip end, which corresponds to the fluid pressure of the present invention). is recieving. Each of the vanes is urged in the outer circumferential direction by these forces, and repeatedly moves in and out in the vane groove following the shape of the inner circumferential surface while the tip is in sliding contact with the inner circumferential surface of the accommodation space.

FIG. 5 is a schematic diagram comparing the shape of the accommodation space 10 in plan view between the first embodiment (solid line) and Patent Document 2 (virtual line).
For example, the vane 21 when entering the one pump chamber 20 via the point a is displaced in the protruding direction, and the acceleration change in the protruding direction at this time depends on the shape of the inner peripheral surface of the accommodating space 10. . When the change in acceleration is rapid, the tip of the vane 21 is separated from the inner peripheral surface in spite of the centrifugal force and the air pressure described above, and the pump efficiency is reduced due to air leakage. Therefore, the shape giving priority to suppressing the acceleration change in the protruding direction of the vane 21 as much as possible is the accommodating space (indicated by 10 ′ in FIG. 5) of Patent Document 2.

However, as long as the sliding contact of the vane 21 with respect to the inner peripheral surface can be maintained, it is not always necessary to adopt the shape of the accommodation space 10 ′ of Patent Document 2, and it is possible to adopt a shape that further contributes to an increase in the volume of the pump chamber 20. It is. Under this point of view, the accommodation space 10 of the present embodiment is set, and its shape will be sequentially described below as first to third embodiments.

[First Embodiment]
As indicated by a solid line in FIG. 5, the accommodation space 10 of the vacuum pump 1 of the present embodiment has a track shape in plan view. In the present invention, a shape in which the ends of a pair of semicircles having a constant radius Rp are connected by a pair of straight lines is defined as a track shape.

In FIG. 5, A indicates a semicircular region (semicircular arc surface A described below), B indicates a straight region (parallel surface B described below), a point including the linear region B, and a constant radius Rp. The point having the semicircular region A is a track-like feature. Since the accommodation space 10 has a width in the vertical direction, the accommodation space 10 of this embodiment is formed by connecting the ends of a pair of front and rear semicircular arc surfaces A with a pair of left and right parallel surfaces B (opposing surfaces). It can be expressed as a cross-sectional track shape.

The cylindrical rotor 18 disposed in the accommodating space 10 defines a crescent-shaped pump chamber 20 corresponding to the front and rear semicircular arc surfaces A, and both left and right sides of the outer peripheral surface of the rotor 18. (Both sides perpendicular to the direction in which the pump chambers 20 are arranged in parallel) are opposed to the left and right parallel planes B through minute gaps, and the front and rear pump chambers 20 are partitioned through these minute gaps.

Of course, also in this track-shaped accommodation space 10, the tip of the vane 21 always keeps sliding in contact with the inner peripheral surface of the accommodation space 10 due to the centrifugal force and air pressure acting on the vane 21. For this reason, air leakage is reliably prevented, and pump efficiency comparable to that of the elliptical accommodation space 10 ′ of Patent Document 2 is obtained.

In this embodiment, the radius Rp of the pair of semicircular arc surfaces forming the track shape is made to coincide with the radius Rr of the rotor 18 (Rp = Rr). However, the radius Rp of the pair of semicircular arc surfaces does not necessarily have to be the same, and different radii (one Rp> Rr> the other Rp) are included in the track shape of the present invention.

For the accommodation space 10 of this embodiment, the accommodation space 10 ′ of Patent Document 2 expressed by the above formula (1) is elliptical. The main difference from the track shape is that there is no straight region, and there is no region with a constant radius Rp like the track shape, and the radius is not determined based on the equation (1). Due to this difference, the volume of the pump chamber 20 of this embodiment is increased compared to the pump chamber of Patent Document 2 by an amount corresponding to the four regions C in FIG.

Hereinafter, the pump chamber 20 secured by the track-like and elliptical containing spaces 10, 10 'after setting the long axis L1 and the short axis L2 of the containing spaces 10, 10' that affect the space occupied by the vacuum pump to be the same. Compare the volumes.

In the case where both the track-like and

elliptical accommodation spaces

10, 10 ′ are formed with the major axis L1 = 51 mm and the minor axis L2 = 40 mm, the total area of the pair of pump chambers in the elliptical accommodation space 10 ′ is 292 mm ² . In the track-shaped accommodation space 10, the total area of the pair of pump chambers 20 is 382 mm ² and an increase of about 31% can be achieved. As a result, the volume of the pump chamber 20 increases accordingly, so that according to the present embodiment, the vacuum pump 1 can be prevented from being enlarged and a good pumpability can be ensured. An increase in capacity can be achieved.

By the way, as explained based on FIG. 5, the outer peripheral surface of the cylindrical rotor 18 is locally opposed to the pair of parallel surfaces B forming the accommodation space 10 at two points on the left and right sides. It is. For this reason, the seal length in the front-rear direction (region where the minute gap is formed) partitioning the front and rear pump chambers 20 is very short, that is, only line contact.

Since the aluminum pump housing 2 in which the accommodation space 10 is defined and the carbon rotor 18 are greatly different in linear expansion coefficient, the inner circumferential surface of the accommodation space 10 and the outer circumferential surface of the rotor 18 are different. Even if the gap is adjusted to be small, the gap increases at high temperatures. As a result, coupled with the short seal length described above, there is a concern that pump efficiency may be reduced due to air leakage particularly at high temperatures.
Therefore, a second embodiment in which a measure for extending the seal length is added based on the configuration of the present embodiment (track-shaped accommodation space 10) will be described below.

[Second Embodiment]
FIG. 6 is a schematic diagram showing the shape of the accommodation space 10 of the second embodiment in plan view.
The shape of the accommodation space 10 of this embodiment is the same as that of the first embodiment, and the same is true in that the pair of front and rear semicircular arc surfaces A are set to the same radius Rp. However, in this embodiment, the radius Rp of the semicircular arc surface A is set slightly smaller than the radius Rr of the rotor 18. For this reason, the interval between the pair of parallel surfaces B connecting the ends of the semicircular arc A is set slightly narrower than the diameter of the rotor 18. As a result, a seal surface D having an arc cross section corresponding to the outer peripheral surface of the rotor 18 is formed in the region of each parallel surface B, and the outer peripheral surface of the rotor 18 has a minute gap in the entire region of the seal surface D. Are opposed to each other.

In other words, in this embodiment, a very long region corresponding to the seal surface D is secured as the seal length in the front-rear direction that partitions the front and rear pump chambers 20, and against the line contact of the first embodiment. In other words, it can be expressed as surface contact. Therefore, when the air leaks, it is necessary to pass through a long path (seal length) with a minute gap, so even if the gap increases due to the temperature rise of the vacuum pump 1, it is the same as that of the first embodiment. In comparison, the amount of air leakage can be significantly reduced.

Therefore, according to the present embodiment, it is possible to prevent a decrease in pump efficiency due to leakage at a high temperature, and in combination with an increase in pump capacity due to the adoption of the track-shaped accommodation space 10, the performance of the vacuum pump is greatly increased. Can be improved.

In addition, an advantageous feature against such an air leak is that a pump equivalent to that of the first embodiment can be obtained even if the gap between the inner peripheral surface of the accommodating space 10 and the outer peripheral surface of the rotor 18 is set to be slightly larger. It means that efficiency can be achieved. For this reason, the assembly of the vacuum pump 1 can be facilitated and the productivity can be improved, and the rapid wear of the rotor 18 that occurs when the gap is too small can be avoided, and the durability of the vacuum pump 1 can be improved. Another advantage is also obtained.

By the way, as the radius Rp of the semicircular arc surface A is greatly reduced as compared with the radius Rr of the rotor 18 (as the distance between the parallel surfaces B is greatly reduced as compared with the diameter of the rotor 18), the longitudinal length of the seal surface D is increased. When the front-rear length exceeds the front-rear length of the parallel surface B, the parallel surface B is replaced with the seal surface D. The present invention includes such setting of the seal surface D, and will be described below as another example of the second embodiment.

FIG. 7 is a schematic diagram showing the shape of the accommodation space 10 of another example of the second embodiment in plan view.
As shown in the drawing, in this alternative example, there are no parallel surfaces B on both front and rear sides of the seal surface D, and both front and rear ends of the seal surface D are directly connected to the end of the semicircular arc surface A. In another example configured in this manner, a longer seal length than that of the second embodiment is ensured. Therefore, the amount of air leakage at a high temperature can be further reduced, and a decrease in pump efficiency can be more reliably prevented.

On the other hand, when the seal surface D is formed on the inner peripheral surface of the accommodation space 10 as in the second embodiment and another example, the acceleration in the direction in which the vanes 21 protrude and retract with the rotation of the rotor 18 is discontinuous. Some adverse effects occur.
That is, as described with reference to FIG. 5, when the acceleration change in the protruding direction of the vane 21 is abrupt, the tip of the vane 21 is instantaneously separated from the inner peripheral surface of the accommodation space 10, and the pump leaks due to air leakage. Efficiency will decrease. Moreover, since abnormal noise may be generated due to the instantaneous separation of the vanes 21, it is desirable to suppress the acceleration change of the vanes 21.

However, in the second embodiment and another example, the undulation is discontinuous at the location of the seal surface D formed on the inner peripheral surface of the accommodation space 10, and the change in acceleration in the protruding direction of the vane 21 is necessarily discontinuous. become.
FIG. 8 is a partially enlarged view of a region X in FIG. 6 showing the separation of the vanes 21 generated in the second embodiment. When the vane 21 shifts from the seal surface D to the parallel surface B with the rotation of the rotor 18 (point b in FIG. 8), the acceleration in the protruding direction of the vane 21 increases rapidly. May cause an instantaneous leak (twice per rotation of the rotor).

Although not shown, the same phenomenon occurs when the vane 21 moves from the seal surface D to the semicircular arc surface A in another example. For this reason, the second embodiment and the other examples can suppress the leakage at a higher temperature than the first embodiment by increasing the seal length, but the instantaneous leakage synchronized with the rotation of the rotor 18 occurs and the merit is reduced by half. There is a concern.
Therefore, a third embodiment and another example in which measures for suppressing instantaneous leaks are added based on the configuration of the present embodiment and another example (track-shaped accommodation space 10 + seal surface D) will be described below.

[Third Embodiment]
FIG. 9 is a partially enlarged view corresponding to FIG. 8 showing the periphery of the buffer surface of the accommodation space 10 of the third embodiment.
As described above, in the second embodiment, when the vane 21 moves from the seal surface D to the parallel surface B, the acceleration in the protruding direction of the vane 21 increases rapidly. These are two places (indicated by point b in FIGS. 6 and 7) corresponding to the ends on the rotational direction side (the traveling direction side of the vane 21).

Therefore, in the present embodiment, the buffer surface E is formed at each connection point (point b) between the end of each seal surface D on the rotor rotation direction side and the end of the parallel surface B. These buffer surfaces E have a circular arc shape with a radius Rb having a center p outside the accommodating space 10, and the seal surface D and the parallel surface B are connected via the buffer surface E. The buffer surface E is curved in the direction opposite to the curved shape of the semicircular arc surface A and the seal surface D (concave when viewed from inside the accommodating space 10) (convex when viewed from inside the accommodating space 10). is doing.

Therefore, during the operation of the vacuum pump 1, the vane 21 moves from the seal surface D to the parallel surface B through the buffer surface E as the rotor 18 rotates. Then, the vane 21 gently increases the acceleration in the protruding direction following the curvature of the buffer surface E by sliding the tip to the buffer surface E. As a result, the rapid increase in acceleration in the protruding direction that occurs when the seal surface D directly shifts to the parallel surface B at the point b in FIG. 6 is suppressed, and the tip of the vane 21 is the inner peripheral surface of the accommodation space 10. Since the sliding contact is maintained without being separated, instantaneous air leakage is avoided.

Therefore, according to the present embodiment, it is possible to suppress the instantaneous leak synchronized with the rotation of the rotor 18 while suppressing the leakage at a high temperature by increasing the seal length of the second embodiment. A decrease in pump efficiency can be prevented more reliably. In addition, abnormal noise caused by the separation of the vanes 21 can be suppressed.

The radius Rb of the buffer surface E having such an action is set so as to satisfy the following requirements.
As described above, the acceleration in the protruding direction of the vane 21 in sliding contact with the buffer surface E depends on the curvature determined by the radius Rb of the buffer surface E. On the other hand, the vane 21 that is in sliding contact with the buffer surface E receives a centrifugal force about the axis L, and receives an air pressure in the outer peripheral direction and is biased toward the outer peripheral side. When the vane 21 is displaced in the projecting direction at an acceleration exceeding the urging force, the sliding contact with the buffer surface E cannot be maintained and the tip is separated.

Therefore, the curvature of the buffer surface E and the radius Rb are determined so that the vane 21 receiving the biasing force is displaced in the protruding direction at an acceleration slightly smaller than the maximum acceleration at which the sliding contact with the buffer surface E can be maintained. It has been. By setting the radius Rb of the buffer surface E as described above, the effect related to the instantaneous air leakage can be obtained with certainty.

On the other hand, the buffer surface E as described above can be applied to another example of the second embodiment, and a partially enlarged view thereof is shown in FIG.
As shown in this figure, another buffer surface E as in the third embodiment has an arcuate cross section having a center p outside the accommodation space 10, and the end of the seal surface D on the rotor rotation direction side and the semicircular arc surface A. It is formed in the connection location (point b) with the edge part. Since the operation of the buffer surface E is the same as that of the third embodiment, the description thereof will not be repeated. However, the increase in acceleration in the protruding direction of the vane 21 during sliding contact with the buffer surface E is moderated, and the rotor 18 Instantaneous leakage synchronized with the rotation of can be suppressed.

In the third embodiment and the other examples described above, the buffer surface E is formed based on the single center p and the radius Rb. However, the present invention is not limited to this. For example, the cross-sectional shape of the buffer surface E may be formed by combining a plurality of arcs having different centers and radii.
In the third embodiment and another example, the buffer surface E is formed at the end of each seal surface D on the rotor rotation direction side (point b in FIGS. 6 and 7). The buffer surface E may also be formed (indicated by point c in FIGS. 6 and 7).

This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the above embodiment, the present invention is applied to the vacuum pump 1 that sucks and discharges air as a fluid to generate a negative pressure, but the type of the vane pump is not limited to this. For example, the pump may be embodied as an air pump that operates by supplying discharged air to an actuator, or may be embodied as a pump that sucks and discharges liquid such as oil or fuel.

In the above embodiment, the pump housing 2 is made of aluminum die casting and the rotor 18 and the vane 21 are made of carbon. However, the material is not limited to these materials. Since the pump housing 2 may be made of a material having good heat conduction, it may be made of stainless steel or cast iron, for example. The rotor 18 and the vane 21 are not necessarily made of a material having self-lubricating properties. For example, the rotor 18 and the vane 21 may be made of aluminum on the premise of lubrication with oil, or limited to carbon even in the case of no lubrication. Alternatively, other self-lubricating materials such as resin may be used.

In the above embodiment, the outer peripheral wall 5, inner peripheral wall 6 and bottom wall 7 of the pump housing 2 are integrally formed. However, the present invention is not limited to this. For example, the inner peripheral wall 6 is a separate cam ring and the bottom wall 7 is separated. The lower plate of the member may be used, and these may be assembled to the pump housing 2.

1 Vacuum pump (vane pump)
2 Pump housing 10 Housing space 18 Rotor 20 Pump chamber 21 Vane A Semi-circular arc surface B Parallel surface (opposing surface)
D Seal surface E Buffer surface

Claims

A cylindrical rotor is disposed in a housing space provided in the pump housing to define pump chambers on both sides of the rotor, and both sides of the outer peripheral surface of the rotor perpendicular to the direction in which the pump chambers are arranged side by side. To the inner circumferential surface of the housing space through a minute gap, and the tip of a vane provided on the outer circumferential surface of the rotor as the rotor rotates is slid onto the inner circumferential surface of the housing space. In the vane pump that sucks and discharges the fluid by changing the volume of each pump chamber while making contact,
The vane pump is characterized in that the accommodation space is formed in a cross-sectional track shape formed by connecting ends of a pair of semicircular arc surfaces with a pair of opposing surfaces.
An interval between the pair of opposed surfaces is set narrower than a diameter of the rotor,
A pair of arc-shaped seal surfaces corresponding to the outer peripheral surface of the rotor is formed on the inner peripheral surface of the housing space, and the outer peripheral surface of the rotor is opposed to the seal space through the minute gap in the area of each seal surface. The vane pump according to claim 1, wherein the vane pump is provided.
The buffer surface having an arcuate cross-section having a center outside the storage space is formed at least at the end of the pair of seal surfaces of the storage space on the rotation direction side of the rotor. 2. The vane pump according to 2.
When the vane in sliding contact with the buffer surface is displaced in the projecting direction following the curvature of the buffer surface, the sliding contact with the buffer surface is caused by the centrifugal force acting on the vane and the fluid pressure in the outer circumferential direction. 4. The vane pump according to claim 3, wherein the curvature of the buffer surface is set so that the acceleration in the protruding direction is maintained.