JP2003222089A - Vane vacuum-pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vane vacuum-pump, in which waste rotation is restrained in a high speed rotation of a driving source. <P>SOLUTION: The vane vacuum-pump 1 comprises a casing 2, a rotor 4 rotatable eccentrically relative to the internal peripheral face of the casing 2, a vane 5 which is provided radially on the outside peripheral face of the rotor 4, and slide-contacts to the inside peripheral face of the casing 2, and a rotation shaft 3 for transmitting rotation torque of the driving source to the rotor 4. The rotor 4 has a driven magnetic part 45. The rotation shaft 3 has a driving magnetic part 30 facing to the magnetic part 45 to generate magnetic attraction force between the driven magnetic part 45 and the rotation shaft 3. When the driving source is in a operation of low-speed rotation, rotation torque is transmitted by magnetic attraction force from the rotation shaft 3 to the rotor 4 to rotate the rotor 4, When the driving source in a operation of high-speed rotation, the transmission of rotation torque is shut down by friction force between the vane 5 and the inside peripheral face of the casing 2, and the rotor is stopped. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vane type vacuum pump mounted on a vehicle and driven by an engine.

[0002]

2. Description of the Related Art A vane type vacuum pump is used, for example, in a large diesel vehicle such as a truck to drive a master cylinder for braking. FIG. 5 shows an axial sectional view of a conventional vane type vacuum pump. As shown in the figure, the vane type vacuum pump 100 includes a casing 1
01, a rotating shaft 102, a rotor 103, and a vane 104.

The casing 101 is an AC generator (not shown).
Are installed side by side. A suction port 105 is opened above the casing 101. Further, a discharge port 106 is opened below the casing 101. The rotating shaft 102 is
Also serves as the rotor shaft of the AC generator. That is, the rotating shaft 1
02 is the casing 101 from the housing of the alternator
It is stretched inward. The rotor 103 is fixed to the outer peripheral surface of the rotating shaft 102 by spline fitting. Rotor 1
A vane groove 107 that extends radially is formed on the outer peripheral surface of 03. The vane 104 is held in the vane groove 107 so as to be able to move in and out.

[0004]

By the way, the rotary shaft 10
2 is connected to the engine via the V-belt and the pulley on the alternator side. Therefore, the rotating shaft 1
02 rotates with a predetermined pulley ratio with respect to the engine.
That is, when the engine rotation speed is high such as when traveling on a highway, the rotation speed of the rotating shaft 102 also increases. On the other hand, when the engine rotation speed is low, such as during city driving, the rotation speed of the rotating shaft 102 also decreases.

Now, let us consider the frequency of use of the brake to which the vane type vacuum pump 100 is connected. The frequency of use of the brake is higher when the engine is rotating at a lower speed than when the engine is rotating at a high speed.
Specifically, the frequency of use of the brakes is higher when driving in urban areas than when driving on expressways. Therefore, the vane vacuum pump 100 is used more frequently when the engine rotates at a low speed than when the engine rotates at a high speed. Conversely, the vane type vacuum pump 100 is used less frequently when the engine rotates at high speed.

However, conventionally, the rotor 103 is fixedly attached to the rotary shaft 102. Therefore, the rotor 103
Was constantly rotating even when the engine was used at low speed and was rotating at high speed. And he was supplying enough negative pressure to the brakes. That is, the rotor 103 was uselessly rotating. As described above, the rotary shaft 102 is connected to the engine. Therefore, useless rotation of the rotor 103 becomes an engine load, which is one of the factors that reduce the fuel efficiency of the vehicle.

Moreover, the rotational speed of the rotor 103 is higher when the engine is rotating at a high speed than when the engine is rotating at a low speed.
Therefore, each member that constitutes the vane type vacuum pump 100 is required to have durability against wear, frictional heat, centrifugal force, and the like that accompany high-speed rotation. This problem also occurred in the vane type vacuum pump directly connected to the crankshaft timing gear of the engine.

The vane type vacuum pump of the present invention has been completed in view of the above problems. Therefore, an object of the present invention is to obtain a vane type vacuum pump capable of suppressing unnecessary rotation during high speed rotation of a drive source.

[0009]

(1) In order to solve the above problems, a vane type vacuum pump according to the present invention comprises a casing, a rotor eccentrically rotatable with respect to an inner peripheral surface of the casing, and an outer peripheral surface of the rotor. A vane type vacuum pump comprising: a vane that is radially arranged on the inner peripheral surface and is in sliding contact with the inner peripheral surface;
The rotor has a driven magnetic portion, the rotation shaft has a drive magnetic portion facing the driven magnetic portion and generating a magnetic attraction force between the driven magnetic portion, and when the drive source rotates at a low speed, it rotates by the magnetic attraction force. When the rotation torque is transmitted from the shaft to the rotor and the rotor rotates and the drive source rotates at a high speed, the friction torque between the vane and the inner peripheral surface interrupts the transmission of the rotation torque and stops the rotor. To do.

In the vane type vacuum pump of the present invention, the driven magnetic portion of the rotor and the drive magnetic portion of the rotating shaft are arranged. A magnetic attraction force is generated between the driven magnetic portion and the driving magnetic portion. On the other hand, a frictional force is generated between the vane arranged on the rotor and the inner peripheral surface of the casing. That is, the magnetic attraction force and the friction force act on the rotor and the vane that are the rotating members. The vane type vacuum pump of the present invention,
By utilizing the magnitude of the magnetic attraction force and the friction force, the rotation torque transmitted from the rotation shaft to the rotor is interrupted.

The frictional force is proportional to the normal force applied to the inner peripheral surface of the casing. Corresponding to this normal force is the centrifugal force applied to the vane by the rotation. The centrifugal force applied to the vane increases as the rotation speed increases. Therefore, the frictional force between the vane and the inner peripheral surface of the casing also increases as the rotational speed increases.

Therefore, while the drive source is rotating at a low speed,
That is, the frictional force between the vane and the inner peripheral surface of the casing is relatively small while the rotating shaft is rotating at a low speed. Therefore, the magnetic attraction force between the rotating shaft and the rotor is larger than the friction force. Therefore, the rotation torque is transmitted from the rotation shaft to the rotor, and the rotor rotates. In this way, the vane type vacuum pump is driven by the drive source during low speed rotation.

On the other hand, when the drive source rotates at high speed, that is, when the rotary shaft rotates at high speed, the frictional force between the vane and the inner peripheral surface of the casing becomes large. Therefore, the magnetic attraction force between the rotating shaft and the rotor is smaller than the friction force. Therefore, the transmission of the rotational torque from the rotary shaft to the rotor is cut off. In this way, the vane type vacuum pump is stopped during high speed rotation.

FIG. 1 shows changes in the rotational speed of the rotor of the vane vacuum pump of the present invention and the rotor of the conventional vane vacuum pump with respect to changes in the rotational speed of the drive source. The horizontal axis in the figure represents time. The vertical axis represents the rotation speed of the drive source.

First, the vane type vacuum pump of the present invention will be described. When the rotational speed of the drive source increases and exceeds the set rotational speed n, the transmission of the rotational torque between the rotor and the drive source is cut off. Therefore, the vane type vacuum pump is stopped. On the other hand, the rotation speed of the drive source becomes low and the set rotation speed n
In the following cases, the rotation torque from the drive source is transmitted to the rotor again. Therefore, the vane type vacuum pump is started.

Next, a conventional vane type vacuum pump will be described. In the case of the conventional vane type vacuum pump, the rotor is fixed to the rotary shaft as described above. Therefore, the rotor continues to rotate at the predetermined pulley ratio of the drive source rotation speed regardless of the set rotation speed n. That is, the conventional vane type vacuum pump is continuously driven by the drive source.

According to the vane type vacuum pump of the present invention, the rotor and the vanes do not rotate when the drive source rotates at high speed. Therefore, no load is applied to the drive source during high-speed rotation. Further, it is not necessary for each member constituting the vane type vacuum pump to have durability against wear, frictional heat, centrifugal force, etc. due to high speed rotation of the drive source. Therefore, the degree of freedom in selecting the material forming each member is increased.

Further, for example, the structure becomes complicated when the rotational torque between the drive source and the rotor is interrupted by a meshing clutch or a friction clutch. Therefore, the number of constituent members of the vane type vacuum pump increases and the cost increases. On the other hand, in the vane type vacuum pump of the present invention, the rotational torque between the drive source and the rotor can be interrupted only by installing the drive magnetic part and the driven magnetic part. Therefore, the number of constituent members is small and the cost is low. In addition, the structure is simple and highly reliable.

(2) Preferably, the driven magnetic portion and the driving magnetic portion are arranged separately. In this configuration, the driven magnetic portion and the driving magnetic portion are held while retaining the magnetic attraction force.
It is arranged separately. When the drive source rotates at high speed, the rotating shaft rotates at high speed, so that the drive magnetic unit rotates. On the other hand, since the rotor and the vane are stopped, the driven magnetic unit is stopped. Therefore,
When the driven magnetic portion and the driving magnetic portion are in contact with each other, both members slide with each other. The sliding may cause a load on the drive source. Further, the friction shortens the lives of the driving magnetic member and the driven magnetic member. Furthermore, the noise of the vane type vacuum pump becomes louder.

On the other hand, the driven magnetic portion and the drive magnetic portion of this structure are separated from each other. Therefore, there is no possibility that a load will be applied to the drive source during high-speed rotation of the drive source. Further, since both members do not come into sliding contact with each other, there is no fear of wear.

(3) It is preferable that a rotor restricting portion for restricting the eccentricity of the rotor with respect to the rotating shaft be provided on the inner peripheral side of the rotor. On the outer peripheral side of the rotor,
A plurality of pump chambers that repeat suction, compression, and discharge are partitioned. Therefore, the rotor may be eccentric with respect to the rotating shaft due to the pressure difference between the pump chambers. In this respect, the vane type vacuum pump of this configuration is provided with the rotor restriction portion. Therefore, the eccentricity of the rotor with respect to the rotating shaft can be suppressed.

(4) Preferably, the drive magnetic portion is formed integrally with the rotary shaft. The rotary shaft constantly rotates as the drive source rotates. For this reason, the rotating shaft constantly applies a load to the drive source. In addition, the drive magnetic unit always receives the centrifugal force due to the rotation. When the drive magnetic portion is integrated with the rotary shaft, the weight of the rotary shaft is reduced as compared with, for example, a case where a separate drive magnetic portion is provided around the rotary shaft. Therefore, according to this configuration, the drive source load is further reduced. Further, when the drive magnetic portion is integrated with the rotation shaft, the drive magnetic portion is less likely to be separated from the rotation shaft due to centrifugal force.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a vane type vacuum pump of the present invention will be described below.

(1) First Embodiment A vane type vacuum pump according to this embodiment embodies the present invention as a pump for driving a master cylinder for a brake of a diesel vehicle. The vane type vacuum pump of this embodiment is driven by an engine. The vane type vacuum pump is directly connected to the AC generator.

First, the structure of the vane type vacuum pump of this embodiment will be described. FIG. 2 shows an axial sectional view of the vane type vacuum pump of this embodiment. As shown in the figure, the vane type vacuum pump 1 includes a casing 2, a rotating shaft 3, a rotor 4 and a vane 5.

The casing 2 comprises a housing 20 and an end plate 21. The casing 2 forms the outer shell of the vane type vacuum pump 1. The housing 20 is made of an aluminum alloy, and has a bottomed cylindrical shape that opens toward the end plate 21 (hereinafter, referred to as “front”), that is, a cup shape. From the upper outer peripheral surface of the housing 20,
The suction port 29 is provided so as to project. The suction port 29 communicates with a vacuum tank (not shown) that supplies a negative pressure to the vacuum brake booster. On the other hand, a discharge port 24 is provided so as to project from the lower outer peripheral surface of the housing 20.

The end plate 21 is made of an aluminum alloy and has a ring shape. The end plate 21 is O
It is arranged in front of the casing 2 with the ring 210 interposed therebetween. An AC generator (not shown) is arranged further in front of the end plate 21. An insertion port 211 is formed in the end plate 21 so as to be eccentric to the center. The boss portion 9 of the AC generator is inserted into the insertion port 211 from the front.

The rotating shaft 3 is made of steel and extends from the housing of the AC generator. And the rotating shaft 3
Is rotatably inserted into the casing 2 via the inner peripheral side of the boss portion 9. The rotating shaft 3 is supported by bearings (not shown) of the AC generator.

The rotor 4 is made of iron-based metal and has a cylindrical shape. The rotor 4 has a cylindrical driven magnetic portion 45 made of a permanent magnet on the inner peripheral side. This driven magnetic part 4
5 is fixed to the inner peripheral surface of the rotor 4 by insert molding. The driven magnetic portion 45 faces the rotor insertion portion 30 of the rotating shaft 3. The rotor insertion part 30 is included in the drive magnetic part of the present invention. A vane groove 40 deep in the radial direction is formed on the outer peripheral surface of the rotor 4. The vane groove 40 is
In this case, a total of four are arranged at intervals of 90 ° in the circumferential direction. That is, the vane grooves 40 are arranged radially.

The vane 5 is made of carbon and has a rectangular plate shape. One end of the vane 5 is slidably housed in the vane groove 40. The other end of the vane 5 is in contact with the inner peripheral surface of the casing 2 by centrifugal force, as will be described later.

Next, the operation of the vane type vacuum pump of this embodiment will be described. FIG. 3 shows a sectional view taken along line I-I of FIG. The rotating shaft 3 is rotated by the driving force of the engine. When the engine is rotating at a low speed, the rotational torque is transmitted from the rotating shaft 3 to the rotor 4 by the magnetic attraction force between the rotor insertion portion 30 and the driven magnetic portion 45. The rotation torque causes the rotor 4 to rotate. When the rotor 4 rotates, the vanes 5 project from the vane grooves 40 due to centrifugal force, as shown in FIG. The vane 5 rotates while slidingly contacting the inner peripheral surface of the casing 2. When the vane 5 slides on the inner peripheral surface of the casing 2, the gap 6 is divided into four. That is, a total of four pump chambers 63 are defined by the inner peripheral surface of the casing 2, the outer peripheral surface of the rotor 4, and the vanes 5. The pump chamber 63 rotates in the casing 2 in a direction indicated by a white arrow in the drawing.

Here, the pump chamber 63 rotates while changing its volume. The pump chamber 63 communicates with the suction port 29 in the process of increasing the volume. Also, the pump room 6
3 communicates with the outlet 24 in the process of decreasing the volume. Air is sucked into the pump chamber 63 from the suction port 29 in the process of increasing the volume of the pump chamber 63. This process is an inhalation process. The sucked air is gradually compressed in the process of decreasing the volume of the pump chamber 63. This process is a compression process. The air is discharged from the outlet 24 at the end of the stroke when the volume of the pump chamber 63 decreases.
Emitted from. This process is the discharge process.

As described above, when the engine rotates at a low speed, the intake stroke, the compression stroke, and the discharge stroke are repeated as the rotor 4 rotates. The vane type vacuum pump 1 supplies a negative pressure to the vacuum brake booster via the suction port 29.

On the other hand, when the engine rotates at high speed, the centrifugal force applied to the vane 5 becomes large. For this reason,
The frictional force of the vane 5 on the inner peripheral surface of the casing 2 increases. Therefore, the engine speed reaches the set value,
When the frictional force becomes larger than the magnetic attraction force, the rotor 4 cannot rotate. Then, the rotation torque transmission from the rotating shaft 3 to the rotor 4 is cut off. That is, the vane type vacuum pump 1 is stopped.

The vane type vacuum pump 1 of this embodiment is stopped when the engine is rotating at a high speed where the brake is not frequently used. For this reason, useless engine load can be suppressed. Therefore, the fuel efficiency of the vehicle can be improved. Moreover, the vane type vacuum pump 1 of this embodiment does not rotate at a high speed. Therefore, for example, the casing 2
Members such as the rotor 4, the vane 5, and the like are not required to have durability against wear, frictional heat, centrifugal force, and the like that accompany high-speed rotation. Therefore, according to the vane type vacuum pump 1 of the present embodiment, the degree of freedom in selecting the material forming the member is increased. Further, the rotating torque interrupting mechanism of the vane type vacuum pump 1 of the present embodiment utilizes the magnitude of the magnetic attraction force and the friction force. Therefore, the structure is simple. Therefore, the vane type vacuum pump 1 of the present embodiment has a small number of members, low cost, and high reliability against failure, as compared with a vane type vacuum pump using a rotating torque interrupting mechanism of another structure.

The vane type vacuum pump 1 of the present embodiment
Is the driven magnetic portion 45 and the drive magnetic portion (rotor insertion portion) 30.
And are separated. Therefore, there is no possibility that a load will be applied to the drive source during high-speed rotation of the drive source. Further, the driven magnetic part 45 and the drive magnetic part 30 are not worn. In the vane type vacuum pump 1 of this embodiment, the rear end of the rotary shaft 3 is used as it is as the drive magnetic portion 30. Therefore, the rotating shaft 3 is lightweight and the engine load is small. Further, there is little risk that the drive magnetic unit 30 will separate from the rotary shaft 3.

(2) Second Embodiment The difference between the vane type vacuum pump of the present embodiment and the vane type vacuum pump of the first embodiment is that the rotor is supported by bearings. Therefore, only this difference will be described in this section. The bearing is included in the rotor restriction portion of the present invention.

FIG. 4 shows an axial sectional view of the vane type vacuum pump of this embodiment. Members corresponding to those in FIG. 2 are indicated by the same symbols. As shown, the housing 20
A rear cylindrical portion 22 is provided so as to project from the inner surface of the bottom wall toward the front. A rear slide bearing 23 is annularly fixed to the outer peripheral surface of the rear cylindrical portion 22. Further, a front cylindrical portion 90 is provided so as to project rearward from the boss portion 9.
A front slide bearing 91 is annularly fixed to the outer peripheral surface of the front cylindrical portion 90.

According to this embodiment, the rotor 4 is supported by the front slide bearing 91 and the rear slide bearing 23.
For this reason, the rotor 4 is less likely to be eccentric with respect to the rotating shaft 3. Further, according to the present embodiment, it is possible to easily secure a gap having a predetermined width between the driven magnetic portion 45 and the rotor insertion portion 30. In other words, it is easy to dispose the driven magnetic portion 45 and the rotor insertion portion 30 apart from each other. Therefore, the driven magnetic portion 45 interferes with the rotor insertion portion 30 and is less likely to be worn.

(3) Others The embodiment of the vane type vacuum pump of the present invention has been described above. However, the embodiment is not particularly limited to the above embodiment. Various modifications and improvements that can be carried out by those skilled in the art can be applied.

For example, in the above embodiment, the rear end of the rotary shaft 3 is used as it is as the drive magnetic portion 30, but the rotary shaft 3 and the drive magnetic portion 30 may be formed separately. In the above embodiment, the driven magnetic portion 45 is made of a permanent magnet, and the driving magnetic portion 30 is made of steel.
However, the materials of the driven magnetic portion and the driving magnetic portion are not particularly limited. For example, steel may be used for the driven magnetic portion and a permanent magnet may be used for the driving magnetic portion. Further, an electromagnet may be used to generate a magnetic attraction force between the driving magnetic part and the driven magnetic part. Further, in the above embodiment, the drive magnetic portion 30 and the driven magnetic portion 45 are opposed to each other in the radial direction. However, the drive magnetic part and the driven magnetic part may be axially opposed to each other. Further, in the above embodiment, the drive magnetic portion 30 and the driven magnetic portion 45 are arranged separately. However, the drive magnetic portion and the driven magnetic portion may be brought into contact with each other. In the above embodiment, the driven magnetic portion 45 is fixed to the rotor 4 by insert molding. However, the method of fixing the driven magnetic portion 45 and the drive magnetic portion 30 is not particularly limited. For example, it may be fixed by press fitting.

In the second embodiment, the slide bearing is used as the bearing, but a ball bearing or a magnetic bearing may be used. The location of the bearing in the second embodiment is not particularly limited. For example, the bearing may be fixed to the inner peripheral surface of the driven magnetic portion 45 and slidably contact the rotor insertion portion 30. Alternatively, conversely, the bearing is fixed to the outer peripheral surface of the rotor insertion portion 30,
It may be slidably contacted with the inner peripheral surface of the driven magnetic portion 45. Further, in the second embodiment described above, the bearing is arranged as the rotor restricting portion, but, for example, the outer peripheral surface of the rear cylindrical portion 22 and the front cylindrical portion 9
The rotor may be disposed directly between the outer peripheral surface and the outer peripheral surface of the rotor. In this case, the rear cylindrical portion and the front cylindrical portion are included in the rotor restriction portion. This reduces the number of parts as compared with the case where the bearing is arranged.

[0043]

According to the present invention, it is possible to obtain a vane type vacuum pump capable of suppressing wasteful rotation during high speed rotation of a drive source.

[Brief description of drawings]

FIG. 1 is a graph showing changes in rotation speed of a rotor of a vane vacuum pump of the present invention and a rotor of a conventional vane vacuum pump with respect to changes in rotation speed of a drive source.

FIG. 2 is an axial cross-sectional view of the vane type vacuum pump of the first embodiment.

FIG. 3 is a sectional view taken along line I-I of FIG.

FIG. 4 is an axial sectional view of a vane type vacuum pump according to a second embodiment.

FIG. 5 is an axial sectional view of a conventional vane type vacuum pump.

[Explanation of symbols]

1: Vane type vacuum pump, 2: Casing, 20: Housing, 21: End plate, 210: O-ring, 2
11: Insertion port, 22: Rear cylindrical part, 23: Rear sliding bearing (rotor restriction part), 24: Discharge port, 29: Suction port, 3:
Rotating shaft, 30: rotor insertion portion (driving magnetic portion), 4: rotor, 40: vane groove, 45: driven magnetic portion, 5: vane,
6: Gap, 63: Pump chamber, 9: Boss part, 90: Front cylindrical part, 91: Front plain bearing (rotor restriction part).

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3H029 AA05 AA17 AB06 BB42 BB44                       BB54 CC08 CC16 CC38 CC58                       CC62 CC65                 3H040 AA08 BB05 BB07 BB11 CC09                       CC14 DD10 DD31 DD32 DD36                       DD40

Claims (4)

[Claims] 1. A casing, a rotor eccentrically rotatable with respect to the inner peripheral surface of the casing, vanes radially arranged on the outer peripheral surface of the rotor and in sliding contact with the inner peripheral surface, and a drive source for the rotor. A vane type vacuum pump comprising a rotating shaft capable of transmitting a rotating torque, wherein the rotor has a driven magnetic portion, the rotating shaft faces the driven magnetic portion, and is between the driven magnetic portion. When the drive source rotates at a low speed, the drive magnetic unit that generates a magnetic attraction force is used. When the drive source rotates at a low speed, the rotation torque is transmitted from the rotation shaft to the rotor by the magnetic attraction force, the rotor rotates, and the drive source rotates at a high speed. In this case, the vane type vacuum pump is characterized in that the frictional force between the vane and the inner peripheral surface interrupts the transmission of the rotational torque to stop the rotor. 2. The driven magnetic portion and the drive magnetic portion are
The vane type vacuum pump according to claim 1, wherein the vane type vacuum pumps are arranged apart from each other. 3. The vane type vacuum pump according to claim 1, further comprising a rotor restricting portion that restricts eccentricity of the rotor with respect to the rotating shaft, on the inner peripheral side of the rotor. 4. The vane vacuum pump according to claim 1, wherein the drive magnetic unit is formed integrally with the rotary shaft.