阅读说明：本技术 叶片泵 (Vane pump ) 是由 小仓崇寛 于 2017-04-28 设计创作，主要内容包括：利用上板(8)封闭收容空间(10),由配设于内部的转子(18)划分出泵室(20),通过外周的叶片(21)使泵室(20)的容积随着转子(18)的旋转而变化,从而吸入、排出流体。将吸入端口(26)凹设于上板(8)的下表面并与收容空间(10)的外周侧的第二吸入路径(28)连接,另一方面,在泵室(20)内使吸入端口(26)一边在与收容空间的内周面之间保留有辅助滑动接触面(53)一边向叶片前进方向侧延伸设置。在延伸设置部位的基端侧形成有以收容空间(10)的内周面为基点越朝向叶片前进方向侧越向内周侧变位的大致直线状的斜状缓冲部(52a),从该斜状缓冲部(52a)向叶片前进方向侧延伸设置平行部(52b)。(The housing space (10) is closed by an upper plate (8), a pump chamber (20) is defined by a rotor (18) arranged inside, and the volume of the pump chamber (20) is changed by a vane (21) on the outer periphery in accordance with the rotation of the rotor (18), thereby sucking and discharging fluid. A suction port (26) is recessed in the lower surface of the upper plate (8) and connected to a second suction path (28) on the outer peripheral side of the housing space (10), and the suction port (26) is extended in the pump chamber (20) in the direction of blade advance while maintaining an auxiliary sliding contact surface (53) between the suction port and the inner peripheral surface of the housing space. An approximately linear oblique buffer part (52a) which is displaced towards the inner peripheral side towards the blade advancing direction side with the inner peripheral surface of the containing space (10) as a base point is formed at the base end side of the extending position, and a parallel part (52b) is extended towards the blade advancing direction side from the oblique buffer part (52 a).)

1. A vane pump is provided, which comprises a vane pump,

A rotor is disposed in a housing space provided in a pump housing, both side surfaces of the rotor are respectively made to correspond to both side surfaces of the housing space, a pump chamber is defined between an outer peripheral surface of the rotor and an inner peripheral surface of the housing space, and a capacity of the pump chamber is changed while a tip end of a vane is brought into sliding contact with the inner peripheral surface of the housing space in accordance with rotation of the rotor, and the vane pump sucks a fluid into the pump chamber from a suction port and discharges the fluid from a discharge port,

At least one of the suction port and the discharge port is recessed in one side surface of the housing space, opens into the pump chamber, and communicates with a fluid passage formed on an outer peripheral side of the housing space and guiding the fluid,

An inclined buffer portion is formed at a vane advancing side portion of a port opening portion recessed in one side surface of the housing space, and intersects with a front surface of the vane advancing in the pump chamber with rotation of the rotor at a predetermined angle.

2. The vane pump of claim 1,

The port opening portion protrudes into the pump chamber from the fluid passage beyond the inner peripheral surface of the housing space, and has a mountain shape protruding toward the inner peripheral side,

In the chevron-shaped region, a portion that is displaced toward the outer circumferential side as it goes toward the forward direction side of the blade functions as the oblique cushioning portion.

3. The vane pump of claim 1,

The port opening portion bulges from the fluid passage into the pump chamber beyond an inner peripheral surface of the housing space, and extends in the vane advancing direction while being spaced apart from the inner peripheral surface of the housing space toward the inner peripheral side, and a side surface of the housing space is left as an auxiliary sliding contact surface between the port opening portion and the inner peripheral surface,

In the region extending toward the blade forward direction side, a portion that is displaced toward the inner circumferential side of the blade forward direction side from the inner circumferential surface of the housing space as a base point functions as the angled cushion portion.

4. A vane pump as claimed in claim 3,

The oblique buffer portion is formed with a parallel portion that continues to the advancing direction side of the blade while being substantially parallel to the inner circumferential surface of the housing space.

5. vane pump according to one of claims 1 to 4,

The blades are made of a material with self-lubricating property.

Technical Field

The present invention relates to a vane pump, and more particularly, to a vane pump including: the rotor is disposed in the housing space of the pump housing, and defines a pump chamber, and the rotor rotates to change the volume of the pump chamber while bringing the tip of the vane, which is provided so as to be retractable and extendable on the outer peripheral surface, into sliding contact with the inner peripheral surface of the housing space, thereby sucking and discharging air.

Background

As such a vane pump, for example, patent document 1 describes a vacuum pump for supplying a negative pressure to a brake assist device of a vehicle. As shown in fig. 2 of patent document 1, a cam ring is disposed in a pump housing, and both upper and lower side surfaces of the cam ring are closed by an upper plate and a lower plate to form a housing space therein. A cylindrical rotor is disposed at an eccentric position in the housing space to define a crescent pump chamber, and a plurality of extendable and retractable vanes are provided on the outer peripheral surface of the rotor.

A suction port is recessed in the lower surface of the upper plate so as to open into the pump chamber, the suction port communicates with the joint via a suction path (shown in fig. 7 below) formed in the cam ring, and the brake assist device is connected to the joint via a pneumatic hose.

When the rotor is driven to rotate by the motor, the vanes gradually change the volumes of the pump chambers divided into a plurality of chambers while bringing the tips into sliding contact with the inner peripheral surface of the housing space. As a result, air from the brake assist device is drawn into the pump chamber from the suction port via the pneumatic hose, and is discharged from the pump chamber to the outside via the discharge port.

fig. 7 is a schematic diagram showing the relationship between the suction port and the vane of the vacuum pump of patent document 1.

The opening of the above-described suction path 102 is formed in the upper surface of the cam ring 101, and the suction path 102 communicates with the pump chamber 104 via a suction port 103 formed in the lower surface of the upper plate.

During the operation of the vacuum pump, the suction port 103 in the pump chamber 104 is opened and closed by the upper end surface of the vane 105. While the vanes 105 pass through the suction port 103 in accordance with the rotation of the rotor 106 in the arrow direction, the front and rear pump chambers 104 sandwiching the vanes 105 communicate through the suction port 103, and the vanes 105 divide the front and rear pump chambers 104 by closing the suction port 103 after passing. Therefore, pump chamber 104 on the front side of vane 105 reduces the volume while discharging the air inside toward the discharge port, and pump chamber 104 on the rear side of vane 105 expands the volume while sucking the air from suction port 103. As a result, as described above, air is transferred from the suction port 103 to the discharge port through the inside of the pump chamber 104.

Disclosure of Invention

Technical problem to be solved by the invention

In addition, in the vane pump, an operation without lubrication is required depending on the application, and the rotor 106 and the vane 105 made of carbon having self-lubricity and functioning even without lubrication are used in the vacuum pump of patent document 1.

However, carbon is weaker than a metal material such as aluminum, and particularly, when the plate-shaped vane 105 receives a force (hereinafter referred to as sliding contact resistance) generated by sliding contact in the pump chamber 104, a failure such as breakage is likely to occur. Since the inner peripheral surface of the cam ring 101, the lower surface of the upper plate, and the upper surface of the lower plate, which the vanes 105 slide in contact with, are substantially flat, variation in sliding contact resistance, which causes breakage or the like, hardly occurs. However, when the vane 105 passes through the suction port 103, the discharge port, the sliding contact resistance abruptly changes.

This is because the opening portions of the suction port 103 and the discharge port (hereinafter referred to as port opening portions) in the upper plate and the lower plate, and particularly, the portion on the advancing direction side of the vane 105 in the entire circumferential direction of the port opening portions (hereinafter referred to as a vane advancing side portion, indicated by E in fig. 7). For example, when the vane 105 starts to pass through the suction port 103 and the discharge port, the upper end surface and the lower end surface of the vane 105 (in detail, the edge portion formed between the vane front surface) are separated from the portion of the port opening portion on the opposite side of the advancing direction of the vane 105, and therefore the sliding contact resistance hardly varies.

However, when the vane 105 passes through the suction port 103 and the discharge port, the upper end surface and the lower end surface of the vane 105 contact the vane advancing side portion E of the port opening portion, and the sliding contact resistance increases abruptly at the moment of the contact. The periphery of the port opening portion is formed to have a circular-angle shape in cross section, but the abrupt change in sliding contact resistance is not sufficiently suppressed only by the above-described countermeasure. Further, when a failure such as breakage of the vane 105 occurs, the pump efficiency is significantly reduced, and therefore, a fundamental measure has been desired from the past.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a vane pump capable of preventing a failure such as breakage and improving durability even when a vane made of a material weaker than a metal material such as carbon is used.

Technical scheme for solving technical problem

In order to achieve the above object, in a vane pump according to the present invention, a rotor is disposed in a housing space provided in a pump housing such that both side surfaces of the housing space correspond to both side surfaces of the rotor, and a pump chamber is defined between an outer peripheral surface of the rotor and an inner peripheral surface of the housing space, and the vane pump sucks and discharges a fluid from the suction port to the pump chamber and from the discharge port while changing a volume of the pump chamber by bringing a tip end of the vane into sliding contact with the inner peripheral surface of the housing space with rotation of the rotor, at least one of the suction port and the discharge port being recessed in one side surface of the housing space and opening into the pump chamber and communicating with a fluid passage formed on an outer peripheral side of the housing space and guiding the fluid, an inclined buffer part is formed at the blade advancing side part of the port opening part concavely arranged at one side surface of the accommodating space, the inclined buffer portion intersects with the front surface of the vane advancing in the pump chamber with the rotation of the rotor at a predetermined angle (claim 1).

As another aspect, it is preferable that the port opening portion is formed in a ridge shape protruding inward the pump chamber from the inner peripheral surface of the fluid passage beyond the accommodation space, and the portion displaced toward the outer peripheral side toward the advancing direction side of the vane in the ridge shape region functions as the tapered buffer portion (claim 2)

As another aspect, it is preferable that the port opening portion is raised from the fluid passage to the inside of the pump chamber beyond the inner peripheral surface of the housing space, and is provided so as to extend toward the vane advancing direction side while being spaced apart from the inner peripheral surface of the housing space toward the inner peripheral surface, a side surface of the housing space is left between the port opening portion and the inner peripheral surface to serve as an auxiliary sliding contact surface, and a portion that is displaced toward the inner peripheral side toward the vane advancing direction side from the inner peripheral surface of the housing space as a base point in a region provided so as to extend toward the vane advancing direction side functions as the tapered buffer portion (claim 3).

As another aspect, it is preferable that the oblique buffer portion has a parallel portion formed therein, and the parallel portion is continuous to the advancing direction side of the blade while being substantially parallel to the inner circumferential surface of the housing space (claim 4).

As another mode, it is preferable that the blade is made of a material having self-lubricity (claim 5).

Effects of the invention

According to the vane pump of the present invention, even when the vane is made of a material weaker than a metal material, such as carbon, the vane pump can prevent a failure such as breakage in advance and improve durability.

Drawings

Fig. 1 is a perspective view showing a vacuum pump according to an 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 the rotor and the blade in the housing space.

Fig. 4 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.

Fig. 5 is a schematic view showing the relationship between the suction port and the vane of the vacuum pump according to the first embodiment.

Fig. 6 is a schematic view showing the relationship between a suction port and a vane of a vacuum pump according to a second embodiment.

Fig. 7 is a schematic diagram showing the relationship between the suction port and the vane of the vacuum pump of patent document 1.

Detailed Description

Hereinafter, an embodiment in which the present invention is embodied as a vane type vacuum pump will be described.

Fig. 1 is a perspective view showing a vacuum pump according to 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 a housing space, and fig. 4 is a sectional view taken along line IV-IV of fig. 3 showing a coupling portion between the rotor and an output shaft of a motor.

The vacuum pump 1 of the present embodiment is mounted on a vehicle to generate a negative pressure to be supplied to a brake assist device of the vehicle. In the drawings, the vacuum pump 1 is shown in a posture when installed in a vehicle, and in the following description, the front-rear, left-right, and up-down directions are shown with the vehicle as a main body.

the vacuum pump 1 is configured such that the motor 3 is fixed to the lower side thereof and the muffler case 4 is fixed to the upper side thereof, with the pump case 2 as the center.

the pump housing 2 is formed by aluminum die casting, has a cylindrical shape extending in the vertical direction, and has an inner circumferential wall 6 formed in a double positional relationship with the outer circumferential wall 5. The lower portion of the inner peripheral wall 6 is integrally formed and closed with the bottom wall 7, an upper plate 8 is fixed to an upward opening portion of the inner peripheral wall 6 by a screw 9, and a housing space 10 is defined by the inner peripheral wall 6, the bottom wall 7, and the upper plate 8. The housing space 10 has a racetrack shape with a major axis in the front-rear direction and a minor axis in the left-right direction in a plan view. However, the shape of the housing space 10 is not limited to this, and may be, for example, an elliptical shape in plan view.

The motor 3 is fixed to the lower surface of the pump housing 2 by screws 12, an output shaft 13 is disposed in the motor 3 along an axis L extending in the vertical direction, and the motor is rotatably supported by a pair of upper and lower bearings 14 (the upper bearing 14 is shown in fig. 4). A boss portion 15 is provided on the upper portion of the motor 3 so as to protrude upward about the output shaft 13, and a cylindrical tube portion 16 is provided on the lower surface of the bottom wall 7 of the pump housing 2 so as to protrude downward. The cylindrical portion 16 is fitted to the boss portion 15 with the 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 15a of the boss portion 15, and is positioned at the upper portion in the housing space 10 through the inside of the cylindrical portion 16 of the pump housing 2 and the shaft hole 7a of the bottom wall 7. In detail, the upper portion of the output shaft 13 is located at the center of the runway (both in the front-rear and left-right directions) of the housing space 10 in a plan view.

A cylindrical rotor 18 centered on the axis L is disposed in the housing space 10, and a shaft hole 18a is formed in the rotor 18 from below along the axis L so that the upper portion of the output shaft 13 can be inserted. Relative rotation between the output shaft 13 and the rotor 18 is restricted by a rotation restricting member 19 disposed in the shaft hole 18a, and the rotor 18 is driven by the motor 3 to rotate in a predetermined direction (counterclockwise direction in a plan view as indicated by an arrow in fig. 3).

The lower surface (two side surfaces) of the rotor 18 faces the bottom wall 7 (two side surfaces) of the housing space 10 with a slight gap therebetween, and the upper surface (two side surfaces) of the rotor 18 faces the lower surface (two side surfaces, one side surface) of the upper plate 8 with a slight gap therebetween. As a result, pump chambers 20 having a crescent shape in plan view are defined on both front and rear sides of the rotor 18 in the housing space 10.

Six equally divided portions on the outer peripheral surface of the rotor 18 are recessed with vane grooves 18b over the entire vertical width of the rotor 18, and the plate-like vanes 21 are respectively arranged in the vane grooves 18b so as to be capable of extending and retracting in the inward and outward directions around the axis L. The blades 21 are arranged such that the vertical width thereof is approximately equal to the vertical width of the rotor 18, and the tips (outer circumferential ends) thereof are inclined with respect to the base ends (inner circumferential ends) thereof in the rotational direction of the rotor 18.

As described below, during the operation of the vacuum pump 1, the rotor 18 and the vanes 21 are in sliding contact without lubrication in the housing space 10, and therefore, the rotor 18 and the vanes 21 are made of carbon having self-lubricity.

A muffler case 4 is fixed to the upper surface of the pump case 2 by screws 22, and although not shown, an expansion chamber and a resonance chamber are formed in the muffler case 4 to reduce pulsation of air discharged from the vacuum pump 1.

As shown in fig. 3, a connector 24 for supplying power to the motor 3 and a joint 25 connected to a brake assist device via an unillustrated pneumatic hose are provided on the front side of the outer peripheral wall 5 of the pump housing 2. 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 (as shown by the imaginary line in fig. 3). The shape of the suction port 26 is described in detail later since it is related to the gist of the present invention.

An opening of the first suction path 27 is formed in the inner peripheral wall 6 of the pump housing 2, and the first suction path 27 communicates with the joint 25 through the inside of the pump housing 2. Further, an annular second suction passage 28 (fluid passage) is recessed in the lower surface of the upper plate 8 so as to surround the housing space 10, and the suction ports 26 are connected to 180 ° opposed portions of the second suction passage 28.

Therefore, one of the suction ports 26 close to the first suction path 27 communicates with the first suction path 27 so as to cross the second suction path 28 in the width direction, and the other suction port 26 distant from the first suction path 27 communicates with the first suction path 27 in the circumferential direction via the second suction path 28.

Further, discharge ports, not shown, are opened in the respective pump chambers 20, and the discharge ports communicate with the outside from the discharge path 29 via an extension chamber and a resonance chamber in the muffler case 4.

Therefore, when the rotor 18 is driven by the motor 3 to rotate in the housing space 10, the vanes 21 gradually change the volume of the pump chambers 20 divided into a plurality of chambers while bringing the tips thereof into sliding contact with the inner peripheral surface of the housing space 10. Accordingly, air from the brake assist device is sucked into the one pump chamber 20 from the one suction port 26 via the pneumatic hose, the joint 25, and the first suction path 27, and is sucked into the other pump chamber 20 from the other suction port 26 via the second suction path 28.

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 from the respective discharge ports into the muffler case 4 via the discharge path 29. The pulsation of the air is relaxed in the process of flowing through the extension 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 spaces 30 communicate with the outside through openings 31 formed on both the front and rear sides of the outer peripheral wall 5. Although not shown, an engine cooling fan is disposed in front of the vacuum pump 1, and part of the cooling air is blown to the vacuum pump 1. The cooling air flows into the annular space 30 from the front opening 31, is branched to the left and right, flows through both the left and right sides of the inner peripheral wall 6, merges, and is discharged to the outside from the rear opening 31. The temperature rise of the vacuum pump 1 can be suppressed by the flow of the cooling air.

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

The suction port 26 of the vacuum pump 1 of the present embodiment is also recessed in the lower surface of the upper plate 8, as in the suction port of patent document 1. Therefore, as described in "technical problem to be solved by the invention", after the vane 21 passes through the opening portion (port opening portion) of the suction port 26, the upper end surface of the vane 21 comes into contact with a portion (vane advancing-side portion) on the advancing direction side of the vane 21 of the port opening portion. Therefore, when no measure for protecting the blade is taken, the sliding contact resistance increases abruptly at the moment of contact, resulting in occurrence of a failure such as breakage of the blade 21.

Further, although the suction port 26 itself is open in the pump chamber 20, in order to guide air from the second suction path 28 surrounding the housing space 10 into the pump chamber 20, the suction port 26 extends beyond the inner peripheral surface of the housing space 10 to the second suction path 28 on the outer peripheral side. In other words, the suction port 26 needs to be formed in a shape that one side thereof must be connected to the inner peripheral surface of the housing space 10, which is also the same as the suction port 103 of patent document 1 shown in fig. 7.

Therefore, the tip of the vane 21 advancing through the suction port 26 is supported in a cantilever manner from the rotor 18 side without sliding contact with the lower surface of the upper plate 8, and the supported state of the vane 21 also becomes a cause of promoting contact with the vane advancing side portion of the port opening portion, and further a cause of promoting a rapid increase in sliding contact resistance.

In view of the above, the present inventors have focused on the period of contact (hereinafter referred to as contact period) that occurs as a cause of a sudden increase in sliding contact resistance. When the edge portions of the upper end surface and the front surface of the vane 21 come into contact with the vane forward side portion of the port opening portion, a substantial sudden increase in sliding contact resistance occurs. Further, the vanes 21 have predetermined regions in the longitudinal direction located in the port opening portions and advance in the rotational direction of the rotor 18, and the regions in the longitudinal direction of the vanes 21 located in the port opening portions increase or decrease as they advance.

after the vane 21 passes through the port opening portion, the area of the vane front surface at the port opening portion gradually decreases, and finally the area disappears, and the port opening portion is closed by the vane 21 (dividing the pump chamber 20 in front and rear). While this region is decreasing, the upper end surface of the vane 21 contacts the vane advancing side portion of the port opening portion, and the sliding contact resistance is rapidly increased, and therefore the above-described period is considered to be a contact period.

From the shape of the suction port 103 of patent document 1 shown in fig. 7, it is determined that the region X0 of the front surface of the vane in the longitudinal direction of the port opening decreases and disappears while the vane 105 moves from the solid line to the virtual line, and the vane moving distance Y0 around the axis of the rotor 106 is very short. This is because the blade-forward-side portion E of the port opening has a shape along the blade front surface (a shape that hardly intersects with the blade front surface).

Therefore, the sliding contact resistance is concentrated and abruptly increased in a very short contact period, and the peak value of the sliding contact resistance becomes very high. As a result, the sliding contact resistance acting on the blade 105 before and after the contact period changes suddenly, which causes blade breakage and the like.

From the above viewpoint, the following findings were obtained: if the contact period (i.e., the blade movement distance Y0) is extended, the rapid increase in the sliding contact resistance occurring during the contact period is dispersed and the peak value of the sliding contact resistance is reduced, and as a result, a failure such as blade breakage can be avoided.

[ first embodiment ]

Fig. 5 is a schematic view showing a relationship between the suction port 26 and the vane 21 of the vacuum pump 1 according to the present embodiment, and shows an enlarged view of a region a in fig. 3. In the following description, the shape of one suction port 26 close to the first suction path 27 will be described, but the shape of the other suction port 26 distant from the first suction path 27 is also completely the same, and there is no difference in the operation and effect.

As described above, in order to introduce the air from the second suction passage 28, the suction port 26 needs to be formed in a shape having one side connected to the inner circumferential surface of the housing space 10, and the shape of the suction port 26 is set in addition to the above-described requirements.

The suction port 26 is connected to the second suction path 28 at a region of a certain length in the circumferential direction along the inner circumferential surface of the housing space 10, and rises into the pump chamber 20 beyond the inner circumferential surface of the housing space 10, which is referred to as a port outer circumferential portion 41. A region of approximately half of the port outer peripheral portion 41 on the blade advancing direction side further rises toward the inner peripheral side, and this portion is referred to as a port inner peripheral portion 42. The suction port 26 is constituted by the port outer peripheral portion 41 and the port inner peripheral portion 42.

The port inner peripheral portion 42 as a whole has a mountain shape projecting toward the inner peripheral side. That is, the second suction path 28 is substantially linearly displaced from the opposite side in the blade traveling direction to the port outer peripheral portion 41 as a starting point so as to be closer to the inner peripheral side (away from the inner peripheral surface of the housing space 10) toward the blade traveling direction side, and is substantially linearly displaced so as to be closer to the outer peripheral side (closer to the inner peripheral surface) toward the blade traveling direction side after passing through the peak of the chevron shape, and is connected to the outer peripheral side of the housing space 10. The substantially linear portion displaced toward the outer peripheral side as it goes toward the blade advancing direction is referred to as a tapered buffer portion 42 a.

During the operation of the vacuum pump 1, the suction port 26 in the pump chamber 20 is opened and closed by the upper end surface of the vane 21. While the vanes 21 pass through the suction port 26 as the rotor 18 rotates, the front and rear pump chambers 20 sandwiching the vanes 21 communicate through the suction port 26, and the front and rear pump chambers 20 are partitioned after the vanes 21 pass through the suction port 26. Therefore, the pump chamber 20 on the front side of the vane 21 reduces the volume while discharging the air inside toward the discharge port, and the pump chamber 20 on the rear side of the vane 21 expands the volume while sucking the air from the suction port 26. As a result, air is diverted from the suction port 26 through the pump chamber 20 to the discharge port, as described above.

according to the shape of the suction port 26 of the present embodiment, the region X1 of the vane front surface in the longitudinal direction of the port opening portion decreases and disappears while the vane 21 advances from the solid line to the imaginary line in fig. 5, and therefore the above-described period can be regarded as the contact period. Further, since the vane 21 in the contact period advances on the inclined buffer portion 42a of the port inner peripheral portion 42, the inclined buffer portion 42a is also the vane advancing side portion E of patent document 1, but as described below, the shape thereof can play a role of suppressing a rapid increase in sliding contact resistance.

That is, as described above, the tapered buffer portion 42a is formed in a substantially straight line shape displaced toward the outer peripheral side as it goes toward the blade traveling direction side, and as a result, the tapered buffer portion 42a intersects the blade front surface at a large angle. Therefore, while the blade 21 is advancing from the solid line to the imaginary line on the slant buffer portion 42a, the blade moving distance Y1 around the axis L is much longer than that of patent document 1, and the contact period is inevitably extended. Therefore, the sudden increase in the sliding contact resistance generated during the contact period is dispersed, so that the peak value of the sliding contact resistance is lowered, and the sudden change in the sliding contact resistance acting on the blade 21 before and after the contact period is suppressed.

therefore, according to the vacuum pump 1 of the present embodiment, although the vane 21 made of carbon weaker than the metal material is used, it is possible to prevent failure such as breakage in advance and improve durability.

[ second embodiment ]

Fig. 6 is a schematic diagram showing the relationship between the suction port 26 and the vane 21 of the vacuum pump 1 according to the present embodiment. As in the first embodiment, the shape of one suction port 26 close to the first suction path 27 is described, and the shape and operational effects of the other suction port 26 are also completely the same.

The suction port 26 is constituted by a port outer peripheral portion 51 and a port inner peripheral portion 52. The port outer peripheral portion 51 has the same shape as the port outer peripheral portion 41 of the first embodiment, is connected to the second suction path 28, and rises into the pump chamber 20 beyond the inner peripheral surface of the housing space 10.

The port outer peripheral portion 41 is similar to the first embodiment in that about half of the area on the blade advancing direction side further bulges on the inner peripheral side to function as the port inner peripheral portion 52, but the shape of the port inner peripheral portion 52 is different.

The port inner peripheral portion 52 of the present embodiment extends in the blade advancing direction while being spaced apart from the inner peripheral surface of the housing space 10 toward the inner peripheral side. As a result, the lower surface (one side surface) of the upper plate 8 remains between the inner peripheral surface of the housing space 10 and the port inner peripheral portion 52, and this region is referred to as an auxiliary sliding contact surface 53.

In this way, the port inner peripheral portion 52 extending from the inner peripheral surface of the housing space 10 is constituted by the tapered buffer portion 52a on the proximal end side and the parallel portion 52b on the distal end side. The inclined buffer portion 52a has the following shape: the inner peripheral surface of the housing space 10 is displaced substantially linearly (corresponding to Y2 in fig. 6) so as to be closer to the inner peripheral side (away from the inner peripheral surface) toward the blade advancing direction side. The oblique buffer portion 52a is also the blade advance side portion E of patent document 1, as in the first embodiment, but can play a role of suppressing a sudden increase in sliding contact resistance.

The parallel portion 52b continuous from the oblique cushioning portion 52a extends in the blade advancing direction while being substantially parallel to the inner peripheral surface of the housing space 10, and has a semicircular end portion (hereinafter referred to as a semicircular end portion 52 c).

During the operation of the vacuum pump 1, the shape of the suction port 26 according to the present embodiment reduces the region of the vane front surface in the longitudinal direction of the port opening from X2 to X2' while the vane 21 advances from the solid line to the imaginary line in fig. 6, and therefore this period can be regarded as a contact period (hereinafter, referred to as a first contact period). In the first contact period, the vane 21 moves forward on the tapered buffer portion 52a of the port inner peripheral portion 52, and the tapered buffer portion 52a is substantially linear and displaced toward the inner peripheral side as it goes toward the vane moving direction side, and therefore intersects the vane front surface at a large angle.

Therefore, while the blade 21 advances from the solid line to the imaginary line on the slant buffer portion 52a, the blade moving distance Y2 around the axis L is long, and the first contact period is inevitably also extended. Therefore, the sharp increase in the sliding contact resistance generated in the first contact period is dispersed to lower the peak value of the sliding contact resistance, and sudden changes in the sliding contact resistance acting on the blade 21 before and after the first contact period are suppressed, thereby preventing breakage of the blade 21 and the like.

Thus, after the first contact period has elapsed, the blade 21 advances on the parallel portion 52b and reaches the semicircular end portion 52 c. Since the area of the blade front surface in the longitudinal direction of the port opening portion is also reduced or eliminated in the advancing process of the semicircular end portion 52c, this period can be regarded as a contact period (hereinafter referred to as a second contact period). Further, since the semicircular end portion 52c does not have the function of the oblique cushion portion 52a, it becomes a cause of a rapid increase in sliding contact resistance, similarly to the blade advance side portion E of patent document 1.

However, the upper end surface of the vane 21 comes into sliding contact with the auxiliary sliding contact surface 53 while passing through the inclined buffer portion 52a, and in the subsequent parallel portion 52b, the sliding contact of the upper end surface of the vane 21 with the auxiliary sliding contact surface 53 is stabilized. That is, while advancing from the inclined buffer portion 52a to the parallel portion 52b, the tip of the blade 21 is supported by the auxiliary sliding contact surface 53, and the cantilever beam support is released.

Therefore, in the process of passing through the subsequent semicircular end portion 52c, the blade 21 also advances while being supported by the double support beams while being in sliding contact with the lower surface of the upper plate 8 across the inner and outer peripheral sides of the semicircular end portion 52. Of course, the upper end surface of the blade 21 is prevented from contacting the semicircular end portion 52c, and a sudden increase in sliding contact resistance can be suppressed. Therefore, even before and after the second contact period, it is possible to suppress a sudden change in the sliding contact resistance acting on the blade 21 and prevent the blade 21 from being broken or the like.

Further, although the blade 21 passing through the inclined buffer portion 52a suppresses a sudden increase in sliding contact resistance due to an extension of the contact period, a slight increase in sliding contact resistance cannot be avoided due to the cantilever beam type support. On the other hand, when passing through the semicircular end portion 52c, the blade 21 is supported by both arms, and therefore the sliding contact resistance hardly increases.

Therefore, as compared with the first embodiment, the sliding contact resistance acting on the vanes 21 in total can be further reduced, whereby failures such as breakage can be prevented, and the durability of the vacuum pump 1 can be improved.

However, the parallel portion 52b of the inner peripheral portion 52 of the port is not necessarily formed, and only the oblique buffer portion 52a on the base end side may be formed to have the semicircular end portion 52c at the end portion on the blade advancing direction side.

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

In each of the above embodiments, the pump housing 2 is made of aluminum die cast, and the rotor 18 and the vanes 21 are made of carbon. The pump housing 2 may be made of stainless steel or cast iron, for example, since it is only necessary to use a material having good heat conductivity. The rotor 18 and the blades 21 are not necessarily made of a material having self-lubricity, and may be made of aluminum, for example, on the premise of lubrication with oil, or may be made of a material having self-lubricity, for example, a resin, without being limited to carbon even if no lubrication is performed.

Further, in the above-described embodiment, the shape of the suction port 26 is applied, but may be applied to the discharge port in addition thereto, or to the ports of both.

In the above embodiment, 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, and for example, the inner peripheral wall 6 may be a cam ring of a separate member, and the bottom wall 7 may be a lower plate of a separate member, and these may be assembled to the pump housing 2.

(symbol description)

1 vacuum pump (vane pump)

2 Pump housing

10 accommodating space

18 rotor

20 pump chamber

21 blade

26 suction port

28 second suction route (fluid passage)

42a, 52a oblique buffer part

52b parallel portion

53 assist the sliding contact surface.