JP2011099388A - Vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum pump reducing sliding resistance between a vane and a pump chamber inner circumference surface with a simple structure. <P>SOLUTION: In the vacuum pump 10, a housing 12 includes the roughly cylindrical inner circumference surface and forms the pump chamber communicating an outside through an inlet 22 and an outlet 26. A rotor 14 is attached eccentrically to a center axis of the pump chamber and includes a vane groove 24 formed in a radial direction. The vane 16 is slidably fitted in the vane groove 24 and is attached so as to be rotated by rotation of the rotor 14 with a first side surface of the vane 16 along the inner circumference surface of the pump chamber. A communication passage providing communication between the inlet 22 and a vane back surface space 36 formed by a second side surface of the vane 16 and the vane groove 24 is formed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vane type vacuum pump in which a vane is attached to a rotor that rotates integrally with a drive shaft.

  Some vehicles such as automobiles are equipped with a vane vacuum pump as a negative pressure source such as a brake booster. The vane vacuum pump has a structure in which a groove is provided in a rotor arranged eccentrically in a cylindrical pump chamber, and a plurality of vanes are inserted in the groove so as to be movable in the rotor radial direction. . When the rotor rotates, the vane protrudes from the groove due to centrifugal force, and the vane is in sliding contact with the peripheral surface of the pump chamber, so that airtightness between adjacent pump chambers is maintained. At the same time, the volume of the closed space partitioned by the vanes increases and decreases, so that air is sucked, compressed, and discharged, and negative pressure is generated in the pump chamber.

  In the vacuum pump, in order to make the space partitioned by the vanes airtight, the vanes need to be in sliding contact with the circumferential surface of the pump chamber, and resistance is generated in the sliding contact portion.

  In Patent Document 1, a sliding contact bar is attached to an end portion of a vane, a spring for separating the sliding contact bar from the pump chamber peripheral surface is formed inside the vane, and between the sliding contact bar and the pump chamber peripheral surface. A vacuum pump that reduces the sliding resistance is disclosed. Patent Document 2 includes an automatic load control device for a vacuum pump that is provided with a pressure sensor that detects the negative pressure of a vacuum tank and that draws a vane into a rotor by an exciting coil when the negative pressure reaches a specified negative pressure. Is disclosed.

JP 2009-127553 A Japanese Utility Model Publication No. 3-59491

  However, the techniques described in these patent documents require additional elements such as a spring, a pressure sensor, and an exciting coil and a control device, which increases costs.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a vacuum pump that reduces sliding resistance between a vane and a pump chamber peripheral surface with a simple configuration.

  In order to solve the above-described problems, a vacuum pump according to an aspect of the present invention includes a housing having a substantially cylindrical inner peripheral surface and forming a pump chamber communicating with the outside by an intake port and an exhaust port, and a pump chamber A rotor having a radially formed groove and slidably fitted in the groove, and the rotation of the rotor causes the first side surface to be aligned with the inner peripheral surface of the pump chamber. And a vane attached to rotate along. The vacuum pump according to this aspect includes a communication passage that communicates the second side surface of the vane facing the first side surface, the space formed by the groove, and the intake port.

  According to this aspect, by communicating the space formed by the second side surface of the vane and the groove and the air inlet, the air in the space is sucked out, and the atmospheric pressure in the space can be made negative. With this negative pressure, a suction force can be applied to the vane inward in the radial direction of the rotor, and sliding resistance between the first side surface of the vane and the inner peripheral surface of the pump chamber is reduced. Thus, the resistance when the first side surface of the vane slides on the inner peripheral surface of the pump chamber can be reduced with a simple configuration in which a communication path that connects the intake port and the space is formed.

  The vacuum pump may further include a check valve provided in the communication path. Thereby, when the air pressure in the space formed by the second side surface of the vane and the groove becomes a negative pressure, the air pressure can be maintained.

  According to the present invention, the sliding resistance between the vane and the pump chamber peripheral surface can be reduced with a simple configuration.

It is a top view of the vacuum pump concerning an embodiment. It is sectional drawing of the vacuum pump which concerns on embodiment.

  FIG. 1 is a plan view of a vacuum pump 10 according to the embodiment, and FIG. 2 is a cross-sectional view of the vacuum pump 10 according to the embodiment. The vacuum pump 10 functions as a negative pressure source for the brake booster. FIG. 1 shows a state in which the cover member 32 is removed from the vacuum pump 10, and the position when the inner cylinder portion 32a of the cover member 32 is attached and the position of the intake port 22 are indicated by dotted lines.

  The inner peripheral surface of the housing 12 is formed in a substantially cylindrical shape. The substantially cylindrical shape of the inner peripheral surface means that the cross section of the housing 12 is not limited to a true circle or an ellipse, but is a circle surrounded by a curve. The open end of the housing 12 is closed with a circular cover member 32, and a pump chamber is formed by the inner peripheral surface and the bottom surface of the housing 12 and the cover member 32. The housing 12 is fixed to a fixing member inside the vehicle.

  A cylindrical rotor 14 is accommodated in the pump chamber 28 so as to be rotatable about a shaft 14 a that is eccentric with respect to the central axis of the pump chamber 28. The rotor 14 has five vane grooves 24a, 24b, 24c, 24d, 24e (hereinafter referred to as “vane grooves 24” when they are not distinguished from each other) formed radially from the shaft 14a.

  In each vane groove 24, five vanes 16 a, 16 b, 16 c, 16 d, and 16 e (referred to as “vane 16” if they are not distinguished) formed in a flat plate shape advance and retreat in the radial direction of the cylindrical rotor 14. Are slidably fitted. The five vanes 16 are radially arranged at equal intervals.

  The first side surface located on the radially outer side of the vane 16 is in sliding contact with the inner peripheral surface of the housing 12 by the centrifugal force applied to the vane 16 when the rotor 14 rotates. The first side surface of the vane 16 is preferably configured as a curved surface corresponding to the curvature of the inner peripheral surface of the pump chamber 28. The second side surface of the vane 16 facing the first side surface is located on the radially inner side of the vane 16. The third side surface of the vane 16 on the cover member 32 side and the fourth side surface on the housing bottom surface side facing the third side surface are in contact with the cover member 32 and the housing bottom surface, respectively. In this way, the five vanes 16 are provided in the first pump chamber 28a, the second pump chamber 28b, the third pump chamber 28c, the fourth pump chamber 28d, and the fifth pump chamber 28e (if they are not distinguished, the “pump Room 28 "). In addition, the number of vanes fitted into the vane grooves and the vane grooves may be three or more, and need not be limited to five. For example, a three-vane vacuum pump in which three vanes are provided radially at intervals of 120 degrees on the rotor may be used.

  The pump chamber 28 communicates with the outside through the intake port 22 and the exhaust port 26. The exhaust port 26 is provided in the housing 12 so as to communicate with the pump chamber 28. On the other hand, the intake port 22 is provided in the cover member 32 so as to communicate with the pump chamber 28. An air inlet pipe 38 is connected to the intake port 22, and external air is drawn into the pump chamber 28. A valve (not shown) for preventing the backflow of air from the pump chamber 28 may be installed in the intake port 22. The exhaust port 26 is formed by cutting out the inner peripheral surface of the pump chamber 28 as shown in FIG.

  The shaft 14 a of the rotor 14 passes through a cylindrical portion 50 formed on the bottom surface of the housing 12, and is connected to the camshaft 30 of the engine (not shown) via the coupling 18. The cylindrical portion 50 of the housing 12 is provided with a bearing 20, and the bearing 20 rotatably supports the rotor 14 via the coupling 18. An oil passage connected to an oil supply device (not shown) passes through the camshaft 30.

  When the camshaft 30 is rotated by the engine and the rotor 14 is rotated in the clockwise direction in FIG. 1, the flat plate surface of the vane 16 slides along the vane groove 24 by centrifugal force, and the first side surface of the vane 16. Is in contact with the inner peripheral surface of the housing 12 and rotates along the inner peripheral surface of the housing 12 while maintaining the contact state. As the rotor 14 rotates, the volume of each pump chamber 28 is expanded or compressed, so that air is sucked into the pump chamber 28 from the intake port 22 and air in the pump chamber 28 is discharged from the exhaust port 26. Is done. This operation creates a negative pressure in the pump chamber.

  Specifically, the volume of the pump chamber 28 changes as the rotor 14 rotates. For example, the fifth pump chamber 28e shown in FIG. 1 is in the expansion process, the first pump chamber 28a is in the suction process, the second pump chamber 28b is in the compression process, the third pump chamber 28c, and the fourth pump chamber 28d. Is in the exhaust process.

  First, the fourth pump chamber 28d is in a state where the indoor air is almost exhausted from the exhaust port 26. In the fifth pump chamber 28e that has been rotated, the volume of the room is expanded, and the air pressure in the room can be made negative by maintaining the airtightness in the room. Further, the first pump chamber 28 a that has further rotated communicates with the intake port 22, and therefore sucks air from the intake port 22. Thereby, negative pressure can be supplied to the outside connected to the intake port 22. In the second pump chamber 28b that has finished intake, the volume in the pump chamber 28 is reduced, and the atmospheric pressure in the chamber rises. The third pump chamber 28c, which has been rotated, communicates with the exhaust port 26, and indoor air is exhausted to the outside. As described above, the vacuum pump 10 generates a negative pressure while sucking and discharging air.

  When the rotor 14 rotates, the lubricating oil flows through an oil inlet pipe (not shown) provided inside the camshaft 30 due to a feed output by an oil supply device (not shown) and a negative pressure generated by the rotation of the vane 16. It flows into the flow path inside the rotor 14. Lubricating oil is supplied from the flow path inside the rotor 14 into the pump chamber 28 through a groove (not shown) formed in the bottom surface of the housing 12 or a groove (not shown) formed in the cover member 32. The lubricating oil that has flowed into the pump chamber 28 lubricates the space between the vane 16 and the pump chamber wall, and maintains airtightness between the partitioned pump chambers 28. The lubricating oil supplied into the pump chamber 28 is mixed into the air, and is discharged from the exhaust port 26 together with the air as the vane 16 rotates.

  A first vane back space 36a, a second vane back space 36b, a third vane back space 36c, and a fourth surface are defined by the second side surface, the vane groove 24, the surface of the cover member 32, and the bottom surface of the housing, which are located radially inward of the vane 16. A vane back space 36d and a fifth vane back space 36e (referred to as “vane back space 36” when these are not distinguished) are formed.

  Each vane back space 36 communicates with each other by a notch 40 formed in each vane 16. Specifically, an annular space 42 is formed by the notch 40 and the recess 44 formed in the rotor 14, and each vane back space 36 is connected by the annular space 42. Therefore, even if the vane 16 slides in the radial direction and the volume of each vane back space 36 changes, the pressure in each vane back space 36 can be made substantially equal. The vane back space 36 and the annular space 42 are hermetically sealed except for a communication passage 34 described later. FIG. 1 shows a state of the annular space 42 configured from the inner peripheral surface of the concave portion 44 of the rotor 14 to the outer peripheral surface (indicated by a dotted line) of the inner cylindrical portion 32 a of the cover member 32.

  In the vacuum pump 10 for an automobile as in the embodiment, since the rotor 14 is driven by the camshaft 30 of the engine, the vacuum pump continues to operate according to the driving of the engine. Therefore, the engine torque is lost as a result due to the sliding resistance generated between the first side surface of the vane 16 and the peripheral surface of the pump chamber (hereinafter sometimes referred to as “sliding resistance of the first side surface”). Yes. This torque loss contributes to worsening the fuel consumption of the engine.

  Therefore, the vacuum pump 10 according to the embodiment forms a communication passage 34 that communicates the intake port 22 and the vane back space 36 via the annular space 42. Thereby, the air pressure in the vane back space 36 can be made equal to the air pressure in the pump chamber 28 communicating with the intake port 22, and the air pressure in the vane back space 36 can be made negative. Due to the negative pressure in the vane back space 36, a force attracted to the vane 16 in the direction of the central axis of the rotor 14 is applied, and sliding resistance between the first side surface of the vane 16 and the inner peripheral surface of the housing 12 is reduced, and fuel efficiency is improved. To do.

  Further, if the sliding resistance generated between the first side surface of the vane 16 and the peripheral surface of the pump chamber is large, the sealing rate of the pump chamber 28 by the vane 16 is increased, and if the sliding resistance of the first side surface is decreased. The sealing rate of the pump chamber 28 is lowered. Here, when the pressure in the pump chamber 28 is not negative but open to the atmosphere, the sealing rate of the pump chamber 28 may be low. Therefore, if the sliding resistance of the first side surface is reduced, the engine torque loss is reduced. Can be reduced, which is preferable.

  For example, the atmospheric pressure in the third pump chamber 28c and the fourth pump chamber 28d in the exhaust process shown in FIG. 1 is a positive pressure or an atmospheric pressure. Since the air pressure on the first side surface of the vane 16c is atmospheric pressure and the air pressure on the second side surface is negative pressure, the differential pressure causes the vane 16c to be more affected by the negative pressure in the vane back space 36 than the other vanes 16. The sliding resistance can be further reduced. Therefore, the sliding resistance of the first side surface of the vane 16 can be efficiently reduced by setting the vane back space 36 to a negative pressure. The first side surface of the vane 16 c in the exhaust process may be separated from the inner peripheral surface of the pump chamber 28.

  Further, the configuration may be such that the lubricating oil is sucked into the vane back space 36 and sucked into the pump chamber 28 by making the pressure of the vane back space 36 negative. At this time, a path connecting the oil flow path in the rotor 14 and the vane back space 36 may be formed.

  The communication path 34 is provided in the cover member 32. When the intake port 22 is provided other than the cover member 32, the communication path 34 is formed in the member provided with the intake port 22.

  Here, since the vacuum pump 10 functions as a negative pressure source of the brake booster, the air pressure in the intake port 22 changes depending on the frequency of use of the brake. When the frequency of use of the brake is high, a large amount of air may flow into the intake port 22 and the pressure in the vane back space 36 may increase. Therefore, the vacuum pump 10 according to the embodiment includes a check valve (not shown) in the communication path 34.

  This check valve opens when the pressure in the vane back space 36 is higher than the pressure in the intake port 22, and closes when the pressure in the vane back space 36 is lower than the pressure in the intake port 22. Thereby, the atmospheric pressure in the vane back space 36 can be maintained at a negative pressure.

  An electromagnetic control valve may be provided instead of the check valve. That is, the vacuum pump 10 includes an electromagnetic control valve in the communication path 34. Thereby, the air pressure in the vane back space 36 can be controlled, and the timing at which the vane back space 36 and the air inlet 22 communicate with each other can be controlled. For example, when it is estimated by the control device that controls opening and closing of the electromagnetic control valve that the use frequency of the brake is higher than a predetermined threshold, the electromagnetic control valve is opened to increase the pressure in the vane back space 36, Control is performed to increase the sealing rate of the pump chamber 28. On the other hand, when it is estimated that the frequency of use of the brake is lower than a predetermined threshold, the electromagnetic control valve is closed to maintain the negative pressure in the vane back space 36, and the sliding resistance of the first side surface of the vane 16 is reduced. Control to lower. Further, the control device that controls the opening / closing of the electromagnetic control valve may control the air pressure in the vane back space 36 depending on the presence or absence of the brake operation by the driver.

  By providing such a check valve or electromagnetic control valve in the communication passage 34, the pressure in the vane back space 36 can be made closer to a vacuum, and the force for sucking the vane 16 toward the shaft 14a of the rotor 14 is increased. be able to.

  The present invention has been described based on some embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that modifications such as arbitrary combinations of the embodiments and combinations of the components of the embodiments are also within the scope of the present invention. By the way. The present invention is not limited to the above-described embodiment, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The configuration shown in each drawing is for explaining an example, and can be appropriately changed as long as the configuration can achieve the same function.

  10 vacuum pump, 12 housing, 14 rotor, 16 vane, 18 coupling, 20 bearing, 22 intake port, 24 vane groove, 26 exhaust port, 28 pump chamber, 30 camshaft, 32 cover member, 34 communication path, 36 vane Back space, 38 air inlet pipe.

Claims (2)

A housing having a substantially cylindrical inner peripheral surface and forming a pump chamber communicating with the outside by an intake port and an exhaust port;
A rotor having a groove formed so as to be eccentric with respect to the central axis of the pump chamber and formed in a radial direction;
A vane slidably fitted in the groove, and attached so that the first side surface rotates along the inner peripheral surface of the pump chamber by rotation of the rotor;
A vacuum pump characterized in that a communication path that communicates the second side surface of the vane facing the first side surface and the space formed by the groove and the intake port is formed.   The vacuum pump according to claim 1, further comprising a check valve provided in the communication path.

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