JP6916273B2 - Vane pump - Google Patents

Description

The present invention relates to a vane pump.

There are various types of vane pumps of this type that have different pump chambers. For example, in the vane pump described in FIG. 4 of Patent Document 1, both side surfaces of the cam ring are closed by plates to define a cylindrical accommodation space, and a cylindrical rotor is arranged at an eccentric position inside the accommodation space. There is. Hereinafter, this form is referred to as a non-equilibrium type. In such a non-equilibrium type vane pump, a single crescent-shaped pump chamber is defined in the accommodation space, and the volume of the pump chamber is changed by the vane as the rotor rotates to suck and discharge the fluid. There is.

The capacity of the vane pump (fluid discharge amount) depends on the change in the volume of the pump chamber, but increasing the size of the accommodation space for the purpose of increasing the capacity directly leads to the increase in the size of the vane pump itself and the deterioration of its mountability 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 arranged at the center of the ellipse inside the cam ring to form a cylindrical rotor on both sides of the rotor. It defines a pair of crescent-shaped pump chambers. Hereinafter, this type is referred to as an equilibrium type. In such a balanced type vane pump, the vane causes a volume change in each pump chamber as the rotor rotates, whereby the pump capacity is increased without increasing the accommodation space so much.

Japanese Unexamined Patent Publication No. 2013-60841 Japanese Unexamined Patent Publication No. 2005-351117

While the accommodation space of the non-equilibrium type vane pump of Patent Document 1 has a cylindrical shape, the accommodation space of the balanced type vane pump of Patent Document 2 has an elliptical tubular shape, so that the rotor can be accommodated through a minute gap. The curvature of the portion facing the outer peripheral surface is large. As a result, in the balanced vane pump, there is a large difference in curvature between the rotor and the accommodation space, so the seal lengths at the two locations that partition the pair of pump chambers on both sides of the rotor are very short, so to speak, line contact. It's just that.

A non-equilibrium vane pump having a single seal can adjust the minute gap when the rotor is assembled into the accommodation space, whereas a balanced vane pump with two seals can accommodate. Two minute gaps are naturally determined by the inner dimension of the space in the minor axis direction and the outer diameter of the rotor. For this reason, when assembling the rotor into the accommodation space, it is necessary to carefully adjust so that even minute gaps are formed at the two sealing points, and the assembling work is very complicated and productivity is poor. There was a problem.

Further, the two minute gaps formed by the inner dimension of the accommodation space in the minor axis direction and the outer diameter of the rotor are preferably made as small as possible in order to improve the pump efficiency, but the accommodation space and the rotor There is a dimensional change due to thermal expansion and contraction of each of the above, and there is a limit to reducing the minute gap. Therefore, there is a problem that the pump efficiency is lowered because it is necessary to provide a certain amount of gaps between the two minute gaps.

Further, in the equilibrium type vane pump, the seal lengths at the two locations are very short, so if the respective minute gaps are set to be large, the pump efficiency will decrease due to fluid leakage. On the contrary, when the minute gap is set small, if the adjustment at the time of assembly is insufficient, the minute gap on one side becomes too small, and the durability of the vane pump is lowered due to the sudden wear of the rotor. As a result, pump efficiency and durability became a trade-off relationship, and it was not possible to achieve both at a high level.

The present invention has been made to solve such a problem, and the purpose of the present invention is to adjust the minute gap at the time of assembly while achieving both pump efficiency and durability at a high level. The purpose is to provide a vane pump that can be easily implemented and can improve productivity.

In order to achieve the above object, in the vane pump of the present invention, a cylindrical rotor is arranged in the accommodation space provided in the pump housing, pump chambers are defined on both sides of the rotor, and the pump chambers are parallel to each other. Both sides of the outer peripheral surface of the rotor orthogonal to the installation direction are opposed to each other on the inner peripheral surface of the accommodation space via a minute gap, and the tip of a vane provided so as to appear and disappear on the outer peripheral surface of the rotor as the rotor rotates is accommodated. In a vane pump that sucks and discharges fluid by changing the volume of each pump chamber while sliding on the inner peripheral surface of the space, the inner peripheral surface of the accommodation space is a pair of arcuate cross-sections corresponding to the outer peripheral surface of the rotor. A sealing surface is formed, and the outer peripheral surfaces of the rotor face each other through a minute gap in the region of each sealing surface, and each sealing surface is located in a region biased toward the discharge side of each pump chamber in the parallel direction of the pump chambers. is formed, the accommodation space is, the arrangement direction of the pump chamber and a length axis, semi-elliptic to a direction orthogonal to the arrangement direction name to the short axis and the elliptical or track-like, which is 2 minutes minor axis as a boundary Jo areas, inner dimensions that compared to the outer diameter of the rotor passing through the center of rotation of the minor-axis direction of the rotor is set shorter Rutotomoni, opposite to each other from the minor axis direction of the center toward the suction side of each pump chamber The shape is offset in the direction, and each sealing surface is opposite to each other from the center in the minor axis direction toward the suction side of the pump chamber, which defines the area of the accommodation space divided into two in the major axis direction. By offsetting in the direction, the pump chamber is formed in a region biased toward the discharge side (claim 1).

As another embodiment, the outer peripheral surface of the rotor is inscribed on the inner peripheral surface of the accommodating space on the suction side of each pump chamber so that each sealed surface discharges from the center in the long axis direction of the accommodating space. It is preferably formed in a region biased toward the side (claim 2 ).

As another aspect, a cushioning surface having an arcuate cross section having a center outside the accommodating space is formed at the boundary between each sealing surface and the region corresponding to the discharge side of each pump chamber on the inner peripheral surface of the accommodating space. (Claim 3 ).

According to the vane pump of the present invention, each sealing surface is formed in a region biased toward the discharge side of each pump chamber in the parallel direction of the pump chambers. For this reason, the inner peripheral surface of the accommodation space has undulations discontinuous at the boundary between the region corresponding to the discharge side of each pump chamber and each seal surface, but is located on each seal surface and the suction side of each pump chamber. At the boundary with the corresponding region, the undulations are gently continuous, or the undulations are slightly discontinuous, but compared to the discontinuity of the undulations on the inner peripheral surface that occurs on the discharge side of the pump chamber on the opposite side. If you do, it will be mild.

During the operation of the vane pump, in the process of the vane shifting from the discharge side of one of the pump chambers to the seal surface, the vanes momentarily separate from the seal surface due to the discontinuity of undulations, but each seal surface and the rotor Momentary leakage of fluid is prevented by the minute gap between the outer peripheral surface of the fluid. Further, in the process of the vane moving from the sealing surface to the suction side of the other pump chamber after that, the undulations are gently continuous or only a slight discontinuity, so that the vanes are prevented from separating and the moment of fluid. Leakage is also prevented.

Further, in the present invention, since the outer peripheral surfaces of the rotor face each other with each other through a minute gap in the entire region of each sealing surface, the sealing length separating both pump chambers is very long. As a result, the amount of steady fluid leakage through the microgap is reduced, and good pump efficiency is maintained even if the microgap is set slightly larger. Therefore, the fine gap is adjusted when the vane pump is assembled. Becomes easier. Further, even if the adjustment is insufficient and the minute gap on one side becomes slightly smaller, sudden wear of the rotor can be avoided.
As described above, in the present invention, it is possible to improve the productivity by making it possible to easily adjust the minute gap at the time of assembly while achieving both pump efficiency and durability at a high level.

It is a perspective view which shows the vacuum pump of an embodiment. It is an exploded perspective view which shows the vacuum pump. FIG. 3 is a sectional view taken along line III-III of FIG. 1 showing a rotor and a vane in the accommodation space. FIG. 3 is a sectional view taken along line IV-IV of FIG. 3 showing a connection portion between the rotor and the output shaft of the motor. It is a schematic diagram which shows the shape of the accommodation space of 1st Embodiment in a plan view. It is a partially enlarged view of the X region in FIG. 5 which shows the separation of vanes generated in 1st Embodiment. It is a partially enlarged view corresponding to FIG. 6 which shows the periphery of the cushioning surface of the accommodation space of 2nd Embodiment. It is a schematic diagram which shows the shape of the accommodation space of 3rd Embodiment in a plan view. It is a schematic diagram which shows the shape of the accommodation space in a plan view corresponding to another example of 1st Embodiment in which the formation area of a seal surface was changed.

Hereinafter, an embodiment in which the vane pump of the present invention is embodied in a vane type vacuum pump will be described.
FIG. 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 line III-III of FIG. 1 showing a rotor and a vane in the accommodation space, and FIG. FIG. 3 is a sectional view taken along line IV-IV of FIG. 3 showing a connection portion between the rotor and the output shaft of the motor.

The vacuum pump 1 of the present embodiment is mounted on a vehicle, and has a function of generating a negative pressure by sucking and discharging air as a fluid and supplying it to a brake assist device of the vehicle. In each figure, the vacuum pump 1 is shown in the posture when it is installed in the vehicle, and in the following description, the vehicle is mainly used to represent the front-rear, left-right, and up-down directions.

As a whole, the vacuum pump 1 is configured such that the pump housing 2 is centered, the motor 3 is fixed on the lower side thereof, and the muffling housing 4 is fixed on the upper side thereof.

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

A motor 3 is fixed to the lower surface of the pump housing 2 by screws 12, and an output shaft 13 is arranged in the motor 3 along an axis L extending in the vertical direction, and a pair of upper and lower bearings 14 (the upper side is shown in FIG. 4). ) Is rotatably supported. A boss portion 15 is projected upward from the upper part of the motor 3 with the output shaft 13 as the center, and a cylindrical tubular portion 16 is projected downward from the lower surface of the bottom wall 7 of the pump housing 2. There is. The tubular portion 16 is fitted onto 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 projects upward from the shaft hole 15a of the boss portion 15, and the upper portion is positioned at the center in the accommodation space 10 through the inside of the cylinder portion 16 of the pump housing 2 and the shaft hole 7a of the bottom wall 7. ..

A cylindrical rotor 18 centered on the axis L is arranged in the accommodation space 10, and a shaft hole 18a is bored in the rotor 18 from below along the axis L, and the upper portion of the output shaft 13 is inserted. ing. The relative rotation between the output shaft 13 and the rotor 18 is regulated by the rotation stop member 19 arranged in the shaft hole 18a, and the rotor 18 is rotationally driven by the motor 3 in the counterclockwise direction shown by the arrow in FIG. It has become like.

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

Vane grooves 18b are recessed over the entire vertical width of the rotor 18 at six equally divided positions on the outer peripheral surface of the rotor 18, and plate-shaped vanes 21 are centered on the axis L in each vane groove 18b. It is arranged so that it can appear and disappear in the inward and outward directions. 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) of each vane 21 is tilted in the rotational direction of the rotor 18 with respect to its base end (inner peripheral end).

As described below, since the rotor 18 and the vane 21 slide in the accommodation space 10 without lubrication during the operation of the vacuum pump 1, the rotor 18 and the vane 21 are made of self-lubricating carbon. There is.

The sound deadening housing 4 is fixed to the upper surface of the pump housing 2 by screws 22, and although not shown, an expansion chamber and a resonance chamber for alleviating the pulsation of the air discharged from the vacuum pump 1 are formed in the sound deadening housing 4. Has been done.

As shown in FIG. 3, a connector 24 for supplying power to the motor 3 and a nipple 25 connected to the 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. There is. As shown by a virtual line in FIG. 3, a pair of suction ports 26 are recessed on the lower surface of the upper plate 8, and each suction port 26 is open in the pump chamber 20. 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 third recessed in the lower surface of the upper plate 8 so as to surround the accommodation space 10. 2 It communicates with the other suction port 26 via the suction path 28.

Further, 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 an expansion chamber and a resonance chamber in the muffling 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 divided into the plurality of compartments while sliding the tip of the rotor 18 against 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 through the pneumatic hose and nipple 25 and the first suction passage 27, and the other through the second suction passage 28. It is sucked into the other pump chamber 20 from the suction port 26 of the above.

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 muffling housing 4 from each discharge port via the discharge path 29. The pulsation of air is relaxed in the process of flowing through the expansion chamber and the resonance chamber, and then the 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 arranged 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 slit 31 on the front side, branches to the left and right, circulates on both the left and right sides of the inner peripheral wall 6, merges, and is discharged to the outside from the slit 31 on the rear side. The flow of the cooling air suppresses the temperature rise of the vacuum pump 1.

On the other hand, mounting flanges 33 provided with cushioning 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 balanced vane pump of Patent Document 2 in which a pair of pump chambers are defined on both sides of the rotor as in the vacuum pump 1 of the present embodiment, there are two. There is a problem that the adjustment of the minute gap at the seal portion is complicated and the pump efficiency and durability cannot be achieved at the same time.

In view of the above defects, the present inventor has focused on the fact that all the defects are caused by the short seal length at the two locations. That is, if the seal length is long, it is possible to prevent a decrease in pump efficiency due to air leakage even if the minute gap between the inner peripheral surface of the accommodation space 10 and the outer peripheral surface of the rotor 18 is set to be slightly larger. If the minute gap is set to be large, even if the adjustment at the time of assembly is insufficient and the minute gap on one side is adjusted to be slightly smaller, the rotor 18 will suddenly wear and the durability of the pump will decrease. Productivity is improved because it can be suppressed and inevitably the adjustment of minute gaps becomes easy.

However, in order to extend the seal length in the balanced vacuum pump 1, it is necessary to form a region having an arcuate cross section corresponding to the outer peripheral surface of the rotor 18 on the inner peripheral surface of the accommodation space 10. This arc-shaped region corresponds to a part of the inner peripheral surface of the accommodation space 10, and is referred to as a sealing surface A in the following description, and the region of the inner peripheral surface having an original ellipsoidal shape is referred to as an ellipsoidal surface B. Distinguish. The sealing surfaces A are formed on the left and right sides of the rotor 18, respectively, and the front and rear pump chambers 20 are partitioned by a minute gap between the sealing surfaces A and the outer peripheral surfaces of the rotor 18. However, at the boundary between both ends of each sealing surface A and the ellipsoidal surface B, the undulations become discontinuous due to a sudden change in the cross-sectional shape, so that the vane 21 during sliding cannot follow the undulations and the inner peripheral surface of the accommodation space 10 ( It may be separated from A or B).

That is, each operating vane 21 of the vacuum pump 1 receives centrifugal force accompanying the rotation of the rotor 18 and air pressure in the outer peripheral direction (pneumatic pressure acting on the base end-pneumatic pressure acting on the tip end). While sliding the tip of the tip against the inner peripheral surface of the accommodation space 10, it repeatedly appears and disappears in the vane groove 18b. However, when the vane 21 passes through both ends of each sealing surface A, the undulations are discontinuous, so that the acceleration of the vane 21 in the protruding direction becomes abrupt, and the centrifuge for making the vane 21 follow this acceleration change. Insufficient force and air pressure.

In particular, the carbon vane 21 of the present embodiment is originally lightweight and further reduces in weight as it wears, so that a shortage of centrifugal force is likely to occur. For this reason, the tip of the vane 21 during sliding contact is separated from the inner peripheral surface, causing air to leak.
In addition, while the air leak through the minute gap as described above is steady, the air leak due to the separation of the vanes 21 is instantaneously generated in synchronization with the rotation of the rotor 18.

In view of the above-mentioned new defects when the seal length is extended, the present inventor has considered the formation position of the seal surface A on the inner peripheral surface of the accommodation space 10.
As described above, the separation phenomenon of the vanes 21 occurs at both ends of each sealing surface A. Specifically, the tip of the vane 21 is generated in the process of migrating from the ellipsoidal surface B on the discharge side of one of the pump chambers 20 to the seal surface A, and then from the seal surface A to the suction side of the other pump chamber 20. It occurs in the process of transitioning to the ellipsoidal surface B of.

Since the left and right pump chambers 20 are partitioned by the minute gaps on the seal surface A, even if the vanes 21 are separated from each other, air leakage is prevented by the minute gaps. However, if the vanes 21 are separated from each other on the suction side of the pump chamber 20, they are directly connected to the leak because there is no element that blocks the air leak such as a minute gap. In conclusion, it is required to prevent the vanes 21 from separating in the process of migrating from the seal surface A to the suction side of the pump chamber 20 rather than the process of migrating the vanes 21 from the discharge side of the pump chamber 20 to the seal surface A. I understand.

On the other hand, in the above description, it is assumed that the undulations of the inner peripheral surface of the accommodation space 10 are discontinuous at both ends of each sealing surface A, but as described below, the undulations are discontinuous at each sealing surface A. It is also possible to set the shape of the accommodation space 10 so that it is limited to only one of both ends of the space. Therefore, the accommodation space 10 is allowed to allow discontinuity of undulations on the side where the priority of preventing separation of the vanes 21 is relatively low, and suppresses discontinuities of undulations on the side where the priority of preventing separation of vanes 21 is high. In the present invention, the shape of the inner peripheral surface of the above is set, and as specific examples thereof, the first to third embodiments will be sequentially described below.

[First Embodiment]
FIG. 5 is a schematic view showing the shape of the accommodation space 10 of the first embodiment in a plan view.
Basically, the accommodation space 10 of the vacuum pump 1 of the present embodiment has an elliptical shape in a plan view as in Patent Document 2, for example, according to the following equation (1) on the planes of the X-axis and the Y-axis. Be expressed.
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 long axis of the accommodation space 10 corresponds to the "parallel direction of the pump chambers" of the present invention, and the short axis of the accommodation space 10 corresponds to the "direction orthogonal to the parallel direction" of the present invention.

The differences from the accommodation space of Patent Document 2 are as follows.
In the present embodiment, the inner dimension in the left-right direction, which is the minor axis direction of the accommodation space 10 having an elliptical shape with respect to the outer diameter of the rotor 18, is set shorter by the dimension Loff. Then, the accommodation space 10 is divided into two parts in the front-rear direction in the major axis direction with the center (= axis L) as a boundary, and these two-divided semi-elliptical regions are defined in each of the pump chambers 20. It is offset from the center of the accommodation space 10 in the minor axis direction toward the suction side in the opposite directions by the dimension Loff / 2. More specifically, as can be seen from the positional relationship between the center of each region indicated by L'in FIG. 5 and the center of the accommodation space 10, the region on the front side of the accommodation space 10 is to the right and the region on the rear side. Is offset to the left.

As a result, on the suction side of each pump chamber 20, the outer peripheral surface of the rotor 18 is inscribed with respect to the inner peripheral surface of the accommodation space 10. The inscribed figure represents a relationship in which the inner and outer arcs are in contact with each other, and the inscribed position is indicated by a point a in FIG. Therefore, each sealing surface A is a region biased from the center to the discharge side of the pump chamber 20 in the major axis direction of the accommodation space 10, that is, a region between points a and b shown in FIG. 5, and is the outer circumference of the rotor 18, respectively. It is formed in an arc shape with a cross section corresponding to the surface. Further, a region other than each sealing surface A on the inner peripheral surface of the accommodation space 10, in other words, a pair of regions defining the front and rear pump chambers 20 is an ellipsoidal surface B.

Therefore, the inner peripheral surface of the accommodation space 10 has undulations discontinuous at the boundary between the ellipsoidal surface B corresponding to the discharge side of each pump chamber 20 and each seal surface A indicated by the point b, but at the point a. The undulations are gently continuous at the boundary between each of the sealed surfaces A and the ellipsoidal surface B corresponding to the suction side of each pump chamber 20. In other words, the boundary of point a has a gentle cross-sectional shape similar to a simple elliptical accommodation space such as the vane pump of Patent Document 2.

During the operation of the vacuum pump 1 configured as described above, the undulations are discontinuous in the process in which the tip of the vane 21 at the point b shifts from the discharge side of either pump chamber 20 to the seal surface A. The tip of the vane 21 is momentarily separated from the sealing surface A. However, as described above, air leakage is prevented by a minute gap between each sealing surface A and the outer peripheral surface of the rotor 18.

Further, in the process in which the vane 21 indicated by the point a thereafter shifts from the sealing surface A to the suction side of the other pump chamber 20, the undulations are gently continuous from the curvature of the sealing surface A to the curvature of the ellipsoidal surface B. Therefore, the vane 21 is prevented from being separated from the ellipsoidal surface B. Therefore, even if there is no element that blocks the air leak such as a minute gap, the leak in each pump chamber 20 is prevented.
As a result, the separation of the vanes 21 due to the sealing surface A having an arcuate cross section formed on the inner peripheral surface of the accommodation space 10 and the instantaneous air leakage synchronized with the rotation of the rotor 18 due to the separation are surely prevented. can do.

In the present embodiment, the outer peripheral surfaces of the rotor 18 face each other with a minute gap in the entire region of each sealing surface A. That is, a very long region corresponding to the seal surface A is secured as the seal length in the front-rear direction that partitions the front and rear pump chambers 20, so to speak, the surface contact with respect to the line contact of the vane pump of Patent Document 2. Can be expressed as. Therefore, when air leaks, it is necessary to pass through a long path with a minute gap corresponding to the seal length, so that the amount of steady air leak through the minute gap is significantly larger than that of Patent Document 2. Can be reduced to.

In particular, in the present embodiment, since the linear expansion coefficient is significantly different between the aluminum pump housing 2 in which the accommodation space 10 is defined and the carbon rotor 18, there is a remarkable tendency for the minute gaps to expand at high temperatures. .. However, even with such a specification of the vacuum pump 1, since air leakage can be reduced by securing a long seal length, wasteful air as a whole is combined with the above-mentioned action of preventing separation of the vane 21. Leakage can be significantly reduced and pump efficiency can be improved.

In addition, an advantageous feature for steady air leakage through the above-mentioned minute gaps is that the minute gaps between the sealing surface A of the accommodation space 10 and the outer peripheral surface of the rotor 18 may be set slightly larger. It means that the pump efficiency can be maintained. Therefore, when assembling the vacuum pump 1, it is possible to easily adjust the minute gap, and the productivity thereof can be improved.

Further, if the minute gap is set to be large, even if the adjustment at the time of assembly is insufficient and the minute gap on one side is adjusted to be slightly smaller, sudden wear of the rotor 18 can be avoided, so that the vacuum pump can be used. Another advantage is that the durability of 1 can be improved. As a result, according to the present embodiment, it is possible to achieve both pump efficiency and durability at a high level.

On the other hand, the pair of sealing surfaces A formed on the inner peripheral surface of the accommodation space 10 also have an effect of facilitating the position of the rotor 18 when the vacuum pump 1 is assembled. For example, in the elliptical accommodating space of Patent Document 2, when the rotor is arranged in the accommodating space for assembly, the inner peripheral surface of the accommodating space does not contribute to the positioning of the rotor in the front-rear direction. In order to fine-tune the minute gaps on both the left and right sides of the rotor, the rotor must be located in the center of the accommodation space in the front-rear direction. Therefore, in Patent Document 2, the minute gap is finely adjusted while keeping the rotor at the center position in the front-rear direction, which is a very complicated work.

On the other hand, since the accommodation space 10 of the present embodiment is provided with sealing surfaces A on both the left and right sides, the rotor 18 arranged in the accommodation space 10 is displaced in the front-rear direction by the sealing surfaces A on both the left and right sides. It is regulated and naturally set at the center position. Therefore, it is possible to concentrate on the fine adjustment of the minute gap without paying attention to the position of the rotor 18 in the front-rear direction. Can be carried out.

By the way, in the present embodiment, at the boundary between the ellipsoidal surface B corresponding to the discharge side of each pump chamber 20 and each seal surface A indicated by the point b, even if the vanes 21 are separated, air leakage is prevented by a minute gap. Based on the viewpoint, the discontinuity of undulations was tolerated.

As a result, as shown in the partially enlarged view of FIG. 6, in the process in which the tip of the vane 21 shifts from the ellipsoidal surface B corresponding to the discharge side of the pump chamber 20 to the seal surface A, the undulations are discontinuous from the seal surface A. Separate. Of course, at this time, air leakage is prevented by a minute gap, but since the vane 21 collides with the seal surface A immediately after separation and generates an abnormal noise, the vane 21 also at point b from the viewpoint of noise reduction of the pump 1. It is desirable to prevent the separation of.
Therefore, based on this embodiment, a second embodiment in which measures for preventing the vanes 21 from being separated at the point b are added will be described below.

[Second Embodiment]
FIG. 7 is a partially enlarged view corresponding to FIG. 6 showing the periphery of the cushioning surface of the accommodation space 10 of the second embodiment.
In the present embodiment, a cushioning surface C is formed at the boundary between the ellipsoidal surface B corresponding to the discharge side of each pump chamber 20 indicated by the point b and each sealing surface A. Each of these cushioning surfaces C has a circular arc shape with a radius Rc having a center p outside the accommodation space 10, and the arc surface B and the sealing surface A are connected via the cushioning surface C. By setting the position of the center p in this way, the cushioning surface C is curved in the direction opposite to the curved shape of the arc surface B and the sealing surface A. Specifically, the arcuate surface B and the seal surface A are concave when viewed from the inside of the accommodation space 10, while the cushioning surface C is convex when viewed from the inside of the accommodation space 10.

Therefore, during the operation of the vacuum pump 1, the tip of the vane 21 shifts from the ellipsoidal surface B corresponding to the discharge side of the pump chamber 20 to the sealing surface A via the cushioning surface C. Then, by sliding the tip of the tip against the cushioning surface C, the vane 21 gently increases the acceleration in the protruding direction following the curvature of the cushioning surface C. As a result, the rapid increase in acceleration in the protruding direction that occurs when the ellipsoidal surface B is directly transferred to the sealing surface A at the point b in FIG. 6 is suppressed, and the tip of the vane 21 is separated from the sealing surface A. Maintain sliding contact without. Therefore, the phenomenon that the vane 21 immediately after separation collides with the seal surface A and generates an abnormal noise can be avoided.
Therefore, according to the present embodiment, it is possible to reduce the noise of the vacuum pump 1 during operation while achieving the same effects as those of the first embodiment.

The radius Rc of the cushioning surface C that exerts 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 while sliding the cushioning surface C depends on the curvature determined by the radius Rc of the cushioning surface C. On the other hand, the vane 21 that is in sliding contact with the cushioning surface C receives a centrifugal force centered on the axis L and is urged to the outer peripheral side by receiving air pressure in the outer peripheral direction. When the vane 21 is displaced in the protruding direction with an acceleration exceeding this urging force, the sliding contact with the cushioning surface C cannot be maintained and the tip is separated.

Therefore, the curvature of the cushioning surface C, and thus the radius Rc, is determined so that the vane 21 that has received the urging force is displaced in the protruding direction at an acceleration slightly smaller than the maximum acceleration that can maintain the sliding contact with the cushioning surface C. Has been done. By setting the radius Rc of the cushioning surface C in this way, the effect of the momentary air leak can be surely obtained.
In the present embodiment, the cushioning surface C is formed based on a single center p and radius Rc, but the present invention is not limited to this. For example, a plurality of arcs having different centers and radii may be combined to form a cross-sectional shape of the cushioning surface C.

By the way, in the vacuum pump 1 of the first and second embodiments, in order to divide the accommodation space 10 into two parts in the front-rear direction and offset them in the opposite direction, the accommodation space 10 is in the minor axis direction with respect to the outer diameter of the rotor 18. The internal dimensions are set shorter by the dimension Loff. Therefore, for example, when compared with the accommodation space of Patent Document 2 which has a simple elliptical shape, the volume of the accommodation space 10 of the present embodiment is slightly smaller under the condition that the front-rear and left-right dimensions of the accommodation space 10 are set to be the same. Along with this, the pump capacity also becomes smaller.
Therefore, a third embodiment based on the first embodiment and to which a measure for increasing the pump capacity without increasing the size of the pump 1 is added will be described below.

[Third Embodiment]
FIG. 8 is a schematic view showing the shape of the accommodation space of the third embodiment in a plan view.
Basically, the accommodation space 10 of the vacuum pump 1 of the present embodiment has a track shape in a plan view. In the present invention, a shape in which the ends of a pair of semicircles having a constant radius Rt are connected by a pair of straight lines is defined as a track shape. Since the accommodation space 10 has a width in the vertical direction, the accommodation space 10 of the present embodiment is expressed as a track-like cross section formed by connecting the ends of a pair of front and rear arc surfaces D with a pair of left and right parallel surfaces E. can.

Then, as in the first embodiment, the inner dimension in the left-right direction, which is the minor axis direction of the track-shaped accommodation space 10, is set shorter than the outer diameter of the rotor 18 by the dimension Loff. The accommodation space 10 is divided into two parts in the longitudinal direction with the center (= axis L) as a boundary, and these two divided semi-elliptical areas are on the suction side of the pump chamber 20 which is defined by each. The accommodation space 10 is offset in the opposite direction from the center in the minor axis direction by the dimension Loff / 2.

As a result, on the suction side of each pump chamber 20, the outer peripheral surface of the rotor 18 is inscribed with respect to the inner peripheral surface of the accommodating space 10 as shown by point a in FIG. A region between points a and b that is biased from the center to the discharge side of the pump chamber 20 in the long axis direction of the rotor 18 and is formed in an arc shape corresponding to the outer peripheral surface of the rotor 18, respectively. Further, a region other than each sealing surface A on the inner peripheral surface of the accommodation space 10, in other words, a pair of regions defining the front and rear pump chambers 20 is an arc surface D.
In this example, all the regions of the parallel surface E on the discharge side of the pump chamber 20 are replaced with the seal surface A, but the present invention is not limited to this.

Therefore, the inner peripheral surface of the accommodation space 10 has undulations discontinuous at the boundary between the arc surface D corresponding to the discharge side of each pump chamber 20 and each seal surface A indicated by the point b, but at the point a. The undulations are gently continuous at the boundary between each of the sealed surfaces A and the arc surface D corresponding to the suction side of each pump chamber 20.

The main action and effect of the vacuum pump 1 configured as described above are the same as those described in the first embodiment. That is, during the operation of the vacuum pump 1, it is possible to prevent momentary air leakage due to the separation of the vanes 21 from the inner peripheral surface of the accommodation space 10, and the inner peripheral surface of the accommodation space 10 and each seal surface A. The long seal length between can reduce the amount of steady air leaks through the microgaps. As a result, it is possible to improve the productivity by making it possible to easily adjust the minute gap at the time of assembly while achieving both pump efficiency and durability at a high level.

Comparing the shapes of the accommodation space 10 between the present embodiment and the first embodiment, the elliptical features of the first embodiment do not have a straight line region and no region having a constant radius Rt. The point is that the radius is not fixed based on 1). On the contrary, the track-like feature of the present embodiment is that it includes a straight line region and an arc region having a constant radius Rt.

Due to such a difference, the pump chamber 20 of the present embodiment shown by the solid line in FIG. 8 is the first embodiment shown by the virtual line under the condition that the front-rear and left-right dimensions of the accommodation space 10 are set to be the same. The volume is increased by the amount corresponding to the hatching regions at four locations as compared with the pump chamber 20 of the above. Further, even when compared with the accommodation space of Patent Document 2 which has an elliptical shape without offset, almost the same volume of the pump chamber 20 can be obtained, and a pump capacity comparable to that of the pump chamber 20 can be secured.

As a result, according to the vacuum pump 1 of the present embodiment, it is possible to realize a sufficient pump capacity while avoiding deterioration of mountability in a vehicle due to an increase in size.
The cushioning surface C described in the second embodiment can also be formed in the accommodation space 10 of the present embodiment, and in that case, the same effect on the noise surface as in the second embodiment can be obtained.

Although the description of the embodiment is completed above, the aspect of the present invention is not limited to this embodiment. For example, in each of the above embodiments, the vacuum pump 1 is applied to generate a negative pressure by sucking and discharging air as a fluid, but the type of vane pump is not limited to this. For example, it may be embodied as an air pump that supplies discharged air to an actuator to operate it, or it may be embodied as a pump that sucks in and discharges a liquid such as oil or fuel.

Further, in each of the above embodiments, the pump housing 2 is made of aluminum die-cast and the rotor 18 and vane 21 are made of carbon, but the materials are not limited thereto. The pump housing 2 may be made of stainless steel or iron, for example, as long as it is made of a material having good heat conduction. Further, the rotor 18 and the vane 21 do not necessarily have to be made of self-lubricating materials. For example, they may be made of aluminum on the premise of lubrication with oil, and even if they are not lubricated, they need to be limited to carbon. It may be made of other self-lubricating material such as resin.

Further, in each of the above embodiments, the outer peripheral wall 5, the inner peripheral wall 6 and the bottom wall 7 of the pump housing 2 are integrally formed, but the present invention is not limited to this. A lower plate of a separate member may be used, and these may be assembled to the pump housing 2.

Further, in each of the above embodiments, the seal surface A is formed in the region between the points a and b biased from the center to the discharge side of the pump chamber 20 in the major axis direction of the accommodation space 10, but the present invention is not limited to this. do not have. For example, as shown in FIG. 9, even if the seal surface A extends beyond the center (= axis L) to the suction side of the pump chamber 20 on the opposite side in the major axis direction of the accommodation space 10, as a whole. It suffices that the seal surface A is formed in a region biased toward the discharge side of the pump chamber 20.

In this case, the undulations of the inner peripheral surface of the accommodation space 10 are slightly discontinuous on the suction side of the pump chamber 20 indicated by the point a, but the degree of the discontinuity is the opposite side of the pump chamber 20 indicated by the point b. This is mild compared to the undulations of the inner peripheral surface that occur on the discharge side of. Therefore, when the vane 21 shifts from the seal surface A to the suction side of the pump chamber 20, the vanes 21 can be prevented from being separated as in the above embodiment. Therefore, such a seal surface A is also included in the present invention.

Further, in the first and second embodiments, the accommodation space 10 has an elliptical shape, and in the third embodiment, the accommodation space 10 has a track shape, but the shape of the accommodation space 10 in a plan view is not limited to these. For example, it may be oval-shaped. The oval shape can be defined as an annular shape surrounded by a curve having at least one axisymmetric point, and corresponds to a superordinate concept including an elliptical shape and a track shape. Even in the case of such an oval-shaped accommodation space 10, by applying each requirement relating to the feature portion of the present invention described in each of the above embodiments, it is possible to obtain the corresponding action and effect.

1 Vacuum pump (vane pump)
2 Pump housing 10 Storage space 18 Rotor 20 Pump room 21 Vane A Seal surface C Buffer surface

Claims (3)

Cylindrical rotors are arranged in the accommodation space provided in the pump housing, pump chambers are defined on both sides of the rotor, and both sides of the outer peripheral surface of the rotor orthogonal to the parallel direction of the pump chambers. Are opposed to each other on the inner peripheral surface of the accommodation space via a minute gap, and the tip of a vane provided so as to appear and disappear on the outer peripheral surface of the rotor as the rotor rotates is slid on the inner peripheral surface of the accommodation space. In a vane pump that sucks and discharges fluid by changing the volume of each pump chamber while in contact with each other.
A pair of sealing surfaces having an arcuate cross section corresponding to the outer peripheral surface of the rotor are formed on the inner peripheral surface of the accommodation space, and the outer peripheral surfaces of the rotor face each other via the minute gap in each sealing surface region. and,
Before SL accommodating space, the arrangement direction of the pump chamber and a length axis, to name an elliptical or track-like direction and a short axis perpendicular to said parallel arrangement direction, is 2 minutes the minor axis as a boundary semi elliptical region, said compared to the outer diameter of the rotor is set inside dimension passing through the rotation center of the rotor in the minor axis direction is short Rutotomoni, minor axis toward the suction side of each of said pump chamber The shape is offset in the opposite direction from the center of the direction ,
Each of the sealing surfaces offsets the region of the accommodation space divided into two in the major axis direction in opposite directions from the center in the minor axis direction toward the suction side of the pump chamber defined by each. As a result, the vane pump is characterized in that it is formed in a region biased toward the discharge side of each of the pump chambers. Each of the sealing surfaces is in contact with the inner peripheral surface of the accommodation space on the suction side of each pump chamber, so that the outer peripheral surface of the rotor is inscribed in the longitudinal direction of the accommodation space. The vane pump according to claim 1, wherein the vane pump is formed in a region biased toward the discharge side. A cushioning surface having an arcuate cross section having a center outside the accommodating space is formed at the boundary between the region corresponding to the discharge side of each pump chamber and the sealing surface on the inner peripheral surface of the accommodating space. The vane pump according to claim 1 or 2, wherein the vane pump is provided.

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