JP2012167589A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum pump which is reduced in noise and vibration without increasing the size thereof.SOLUTION: A casing body 22 includes: a cylinder chamber S with a rotor 27 and a vane 28 sliding therein; an expansion chamber 33 for expanding compressed air discharged from the cylinder chamber S; and an exhaust route 40 for connecting the cylinder chamber S to the expansion chamber 33. The exhaust route 40 is provided with at least one folding portion 40C.

Description

  The present invention relates to a vacuum pump having a rotary compression element in a casing.

  In general, a vacuum pump having a rotary compression element in a casing is known. In this type of vacuum pump, a vacuum can be obtained by driving the rotary compression element with a drive device such as an electric motor. The vacuum pump is mounted, for example, in an engine room of an automobile and is used to generate a vacuum for operating a brake booster (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2003-222090

By the way, in this kind of vacuum pump, when the rotary compression element is driven and the air sucked into the casing is compressed and discharged from the discharge port, large noise and vibration are generated when the air is discharged from the discharge port. In the conventional configuration, in order to reduce these noises and vibrations, a silencer is provided at the exhaust port or attached to the vehicle via a robust bracket with anti-vibration rubber. There was a problem of increasing the size.
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a vacuum pump that reduces noise and vibration without increasing the size.

  In order to achieve the above object, the present invention provides a vacuum pump having a rotary compression element in a casing, wherein the casing includes a cylinder chamber in which the rotary compression element slides and compressed air discharged from the cylinder chamber. An expansion chamber to be expanded and an exhaust path connecting the cylinder chamber and the expansion chamber are provided, and at least one folded portion is provided in the exhaust path.

  According to this configuration, since at least one folded portion is provided in the exhaust path connecting the cylinder chamber and the expansion chamber, the length of the exhaust path can be made longer by that amount. For this reason, when the compressed air discharged from the cylinder chamber flows through the exhaust path having a long path length, the compressed air collides with the wall surface of the exhaust path and is diffusely reflected, whereby the sound energy of the compressed air can be attenuated. Furthermore, since the compressed air attenuated in the exhaust path flows into the expansion chamber, and further expands and disperses in the expansion chamber and is further attenuated, noise and vibration during exhaust can be reduced.

  In this configuration, the exhaust passage and the expansion chamber are arranged in parallel at a peripheral edge portion of the cylinder chamber in the casing. According to this configuration, the exhaust path, the expansion chamber, and the cylinder chamber can be integrally formed in the casing, and an increase in size of the vacuum pump can be suppressed.

  Further, the present invention is characterized in that a sound deadening member made of a porous material is disposed in the exhaust path. According to this configuration, the compressed air flowing through the exhaust path is rectified when passing through the silencing member, and the sound energy of the compressed air is absorbed by the silencing member, further reducing noise and vibration during exhaust. can do.

Further, according to the present invention, the casing includes a cylinder liner that forms the cylinder chamber, the cylinder liner includes an exhaust hole connected to the exhaust path, and the exhaust hole has an inner diameter of the cylinder chamber from the outside. It is also characterized in that it is formed in a tapered hole whose diameter decreases from the inside to the outside.
According to this configuration, since the exhaust hole formed in the cylinder liner is a tapered hole, the pulsation of the compressed air discharged from the cylinder chamber can be suppressed, and the noise and vibration during the exhaust accompanying the pulsation are reduced. can do.

  Further, the present invention is characterized in that a rotary shaft for driving the rotary compression element is provided, and a tip portion of the rotary shaft is supported by a bearing provided in the casing. According to this configuration, since the shake of the rotating shaft is suppressed, the operation noise can be reduced.

  According to the present invention, since at least one turn-back portion is provided in the exhaust path connecting the cylinder chamber and the expansion chamber, the path length of the exhaust path can be formed longer accordingly. For this reason, when the compressed air discharged from the cylinder chamber flows through the exhaust path having a long path length, the compressed air collides with the wall surface of the exhaust path and is diffusely reflected, whereby the sound energy of the compressed air can be attenuated. Furthermore, since the compressed air attenuated in the exhaust path flows into the expansion chamber, and further expands and disperses in the expansion chamber and is further attenuated, noise and vibration during exhaust can be reduced.

It is a schematic diagram of a brake device using the vacuum pump concerning this embodiment. It is side part fragmentary sectional drawing of a vacuum pump. It is the figure which looked at the vacuum pump from the front side. FIG. 3 is a partially enlarged view of FIG. 2 showing exhaust holes formed in a cylinder liner. It is the table | surface which described the noise value corresponding to each structure. It is side part sectional drawing of the vacuum pump concerning another embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments according to the invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram of a brake device 100 using a vacuum pump 1 according to an embodiment of the present invention as a negative pressure source. The brake device 100 includes, for example, front brakes 2A and 2B attached to left and right front wheels of a vehicle such as an automobile, and rear brakes 3A and 3B attached to left and right rear wheels. Each of these brakes is connected to each other by a master cylinder 4 and a brake pipe 9, and each brake is operated by a hydraulic pressure sent from the master cylinder 4 through the brake pipe 9.
The brake device 100 includes a brake booster (brake booster) 6 connected to the brake pedal 5, and the vacuum tank 7 and the vacuum pump 1 are connected in series to the brake booster 6 through an air pipe 8. It is connected. The brake booster 6 uses the negative pressure in the vacuum tank 7 to boost the pedaling force of the brake pedal 5, and it is sufficient to move the piston (not shown) of the master cylinder 4 with a small pedaling force. The braking power can be pulled out.
The vacuum pump 1 is disposed in the engine room of the vehicle, discharges the air in the vacuum tank 7 to the outside of the vehicle, and puts the vacuum tank 7 in a vacuum state. In addition, the use range of the vacuum pump 1 used for a motor vehicle etc. is -60kPa--80kPa, for example.

  FIG. 2 is a side partial sectional view of the vacuum pump 1, and FIG. 3 is a view of the vacuum pump 1 of FIG. 2 as viewed from the front side (right side in the figure). However, FIG. 3 illustrates a state in which members such as the pump cover 24 and the side plate 26 are removed in order to show the configuration of the cylinder chamber S. In the following description, for convenience of explanation, the directions indicated by the arrows at the top of FIGS. 2 and 3 respectively indicate the top, bottom, front, back, left and right of the vacuum pump 1. The front-rear direction is also referred to as the axial direction, and the left-right direction is also referred to as the width direction.

  As shown in FIG. 2, the vacuum pump 1 includes an electric motor (driving machine) 10 and a pump main body 20 that operates using the electric motor 10 as a driving source. The electric motor 10 and the pump main body 20 are integrated with each other. In a connected state, it is fixedly supported on a vehicle body such as an automobile.

The electric motor 10 has an output shaft (rotary shaft) 12 that extends from the approximate center of one end (front end) of the case 11 formed in a substantially cylindrical shape toward the pump body 20 side (front side). The output shaft 12 functions as a drive shaft that drives the pump main body 20, and rotates with reference to a rotation center X1 extending in the front-rear direction. The front end portion 12A of the output shaft 12 is formed as a spline shaft, and engages with a spline groove 27D formed in a part of a shaft hole 27A penetrating in the axial direction of the rotor 27 of the pump body 20, The rotor 27 is connected to the rotor 27 so as to be integrally rotatable.
In the electric motor 10, when the power source (not shown) is turned on, the output shaft 12 rotates in the direction indicated by the arrow R (counterclockwise) in FIG. 3, thereby rotating the rotor 27 in the same direction around the rotation center X1 ( It is designed to rotate in the direction of arrow R).

The case 11 includes a case main body 60 formed in a bottomed cylindrical shape and a cover body 61 that closes the opening of the case main body 60. The case main body 60 is formed by bending the peripheral edge portion 60A outward. Yes. The cover body 61 includes a disc portion (wall surface) 61A formed with substantially the same diameter as the opening of the case body 60, and a cylindrical portion 61B that is connected to the periphery of the disc portion 61A and fits on the inner peripheral surface of the case body 60. And a bent portion 61C formed by bending the peripheral edge of the cylindrical portion 61B outward, the disc portion 61A and the cylindrical portion 61B enter the case body 60, and the bent portion 61C The case body 60 is fixed in contact with the peripheral edge 60A. Thereby, one end part (front end) of the case 11 is recessed inward in the electric motor 10, and the fitting hole part 63 to which the pump main body 20 is attached by spigot fitting is formed.
Further, a through hole 61D through which the output shaft 12 passes and an annular bearing holding portion 61E extending inward of the case main body 60 are formed around the through hole 61D at the approximate center of the disc part 61A. The outer ring of the bearing 62 that supports the front side of the output shaft 12 is held on the inner peripheral surface 61F of the bearing holding portion 61E.

  As shown in FIG. 2, the pump body 20 includes a casing body 22 fitted in a fitting hole 63 formed on the front side of the case 11 of the electric motor 10, and a cylinder chamber disposed in the casing body 22. The cylinder liner 23 which forms S, and the pump cover 24 which covers the said casing main body 22 from the front side are provided. In the present embodiment, a casing body 22, a cylinder liner 23, and a pump cover 24 are provided to constitute a casing 31 of the vacuum pump 1.

  As shown in FIG. 3, the casing body 22 is made of, for example, a metal material having high thermal conductivity such as aluminum, and the shape seen from the front side is a substantially rectangular shape that is long in the vertical direction with the rotation center X1 as the center. Is formed. A communication hole 22A communicating with the cylinder chamber S provided in the casing main body 22 is formed in the upper portion of the casing main body 22, and a suction nipple 30 is press-fitted into the communication hole 22A. 2, the suction nipple 30 is a straight pipe extending upward, and negative pressure air is supplied to one end 30A of the suction nipple 30 from an external device (for example, the vacuum tank 7 (see FIG. 1)). A tube or tube for feeding is connected.

  The casing body 22 is formed with a hole 22B with respect to the axial center X2 extending in the front-rear direction, and a cylinder liner 23 formed in a cylindrical shape is press-fitted into the hole 22B. Instead of press-fitting the cylinder liner 23 into the hole 22B of the casing body 22, the casing body 22 may be cast with the cylinder liner 23 cast. The shaft center X2 is parallel to the rotation center X1 of the output shaft 12 of the electric motor 10 described above and, as shown in FIG. In this configuration, the shaft center X2 is eccentric so that the outer peripheral surface 27B of the rotor 27 centered on the rotation center X1 is in contact with the inner peripheral surface 23A of the cylinder liner 23 formed with the shaft center X2 as a reference.

The cylinder liner 23 is formed of the same metal material as the rotor 27 (in this embodiment, iron), and the inner peripheral surface 23A of the cylinder liner 23 is subjected to, for example, an electroless nickel plating process, The hardness of the inner peripheral surface 23A is increased.
In the present embodiment, the cylinder liner 23 can be accommodated within the longitudinal range of the casing body 22 by press-fitting (or casting) the cylinder liner 23 into the hole 22 </ b> B formed in the casing body 22. Therefore, the cylinder liner 23 is prevented from protruding from the casing body 22, and the casing body 22 can be downsized.
Further, the casing body 22 is formed of a material having higher thermal conductivity than the rotor 27. According to this, heat generated when the rotor 27 and the vane 28 are rotationally driven can be quickly transmitted to the casing body 22, so that the casing body 22 can sufficiently dissipate heat.

  The cylinder liner 23 is formed with an opening 23B that connects the communication hole 22A of the casing body 22 and the inside of the cylinder chamber S, and the air that has passed through the suction nipple 30 passes through the communication hole 22A and the opening 23B. To be supplied. Further, exhaust holes 22 </ b> C and 23 </ b> C that pass through the casing body 22 and the cylinder liner 23 and discharge air compressed in the cylinder chamber S are provided at the lower part of the casing body 22 and the cylinder liner 23. The exhaust holes 23C provided in the cylinder liner 23 will be described later.

  Side plates 25 and 26 for closing the opening of the cylinder chamber S are disposed at the rear end and the front end of the cylinder liner 23, respectively. The side plates 25 and 26 are set to have a diameter larger than the inner diameter of the inner peripheral surface 23A of the cylinder liner 23, and are urged by the wave washers 25A and 26A, respectively, to the front end and the rear end of the cylinder liner 23, respectively. It is pressed. As a result, a sealed cylinder chamber S is formed inside the cylinder liner 23 except for the opening 23 </ b> B and the exhaust holes 23 </ b> C and 22 </ b> C connected to the suction nipple 30. In addition, it is good also as a structure which provides a seal ring instead of wave washer 25A, 26A.

A rotor 27 is disposed in the cylinder chamber S. The rotor 27 has a columnar shape extending along the rotation center X1 of the electric motor 10, and has a shaft hole 27A through which the output shaft 12 that is a drive shaft of the pump body 20 is inserted, and radial direction from the shaft hole 27A. A plurality of guide grooves 27C are provided at equidistant intervals around the shaft hole 27A at intervals in the circumferential direction. A part of the shaft hole 27A is formed with a spline groove 27D that engages with a spline shaft provided at the distal end portion 12A of the output shaft 12, so that the rotor 27 and the output shaft 12 are spline-connected. Yes.
In the present embodiment, a cylindrical recess 27F having a diameter larger than that of the shaft hole 27A is formed around the shaft hole 27A on the front end surface of the rotor 27, and the tip of the output shaft 12 extends into the recess 27F. A push nut 70 is attached to this, and the push nut 70 restricts the rotor 27 from moving toward the tip end side of the output shaft 12.

The length of the rotor 27 in the front-rear direction is set to be approximately equal to the length of the cylinder chamber S of the cylinder liner 23, that is, the distance between the inner surfaces of the two side plates 25 and 26 facing each other. And the side plates 25 and 26 are substantially closed.
Further, as shown in FIG. 3, the outer diameter of the rotor 27 is such that the outer peripheral surface 27B of the rotor 27 maintains a minute clearance with the portion of the inner peripheral surface 23A of the cylinder liner 23 that is located obliquely downward to the right. Is set. As a result, the inside of the cylinder chamber S partitioned by the side plates 25 and 26 has a crescent shape between the outer peripheral surface 27B of the rotor 27 and the inner peripheral surface 23A of the cylinder liner 23, as shown in FIG. A space is constructed.

  The rotor 27 is provided with a plurality (five in this example) of vanes 28 that divide a crescent-shaped space. The vane 28 is formed in a plate shape, and its length in the front-rear direction is set to be approximately equal to the distance between the mutually facing inner surfaces of the two side plates 25, 26, similar to the rotor 27. ing. These vanes 28 are arranged so as to be able to protrude and retract from guide grooves 27C provided in the rotor 27. Each vane 28 protrudes outward along the guide groove 27 </ b> C by centrifugal force as the rotor 27 rotates, and a tip of the vane 28 comes into contact with the inner peripheral surface 23 </ b> A of the cylinder liner 23. As a result, the crescent-shaped space described above is divided into five compression chambers P surrounded by the two adjacent vanes 28, 28, the outer peripheral surface 27B of the rotor 27, and the inner peripheral surface 23A of the cylinder liner 23. Partitioned. These compression chambers P rotate in the same direction as the rotation of the output shaft 12 in the direction of the arrow R of the rotor 27. The volume of the compression chamber P increases in the vicinity of the opening 23B, and decreases in the exhaust hole 23C. That is, the air sucked into one compression chamber P from the opening 23B by the rotation of the rotor 27 and the vane 28 is compressed while being rotated with the rotation of the rotor 27, and is discharged from the exhaust hole 23C. In this configuration, the rotary compression element is configured by including the rotor 27 and the plurality of vanes 28.

  The pump cover 24 is disposed on the front side plate 26 via a wave washer 26 </ b> A, and is fixed to the casing body 22 with bolts 66. As shown in FIG. 3, a seal groove 22D is formed on the front surface of the casing body 22 so as to surround a cylinder liner 23, an expansion chamber 33 and an exhaust path 40, which will be described later, and an annular seal material 67 ( FIG. 2) is arranged. The pump cover 24 is provided with an exhaust port 24 </ b> A at a position corresponding to the expansion chamber 33. This exhaust port 24A is for exhausting the air that has flowed into the expansion chamber 33 to the outside of the machine (outside the vacuum pump 1), and this exhaust port 24A prevents the backflow of air from the outside of the machine into the pump. A check valve 29 is attached.

As described above, the vacuum pump 1 is configured by connecting the electric motor 10 and the pump main body 20, and the rotor 27 and the vane 28 connected to the output shaft 12 of the electric motor 10 include the cylinder liner of the pump main body 20. 23 slides in. For this reason, it is important to assemble the pump body 20 in accordance with the rotation center X1 of the output shaft 12 of the electric motor 10.
For this reason, in this embodiment, the electric motor 10 has a fitting hole 63 formed around the rotation center X1 of the output shaft 12 on one end side of the case 11. On the other hand, as shown in FIG. 2, a cylindrical fitting portion 22 </ b> F projecting rearward around the cylinder chamber S is integrally formed on the back surface of the casing body 22. The fitting portion 22 </ b> F is formed concentrically with the rotation center X <b> 1 of the output shaft 12 of the electric motor 10, and has an outer diameter that fits in the fitting hole portion 63 of the electric motor 10. Accordingly, in this configuration, the center position can be easily adjusted by simply fitting the fitting portion 22F of the casing body 22 into the fitting hole portion 63 of the electric motor 10, and the electric motor 10 and the pump body 20 can be aligned. Assembly work can be performed easily. Further, a seal groove 22E is formed around the fitting portion 22F on the back surface of the casing body 22, and an annular seal material 35 is disposed in the seal groove 22E.

By the way, in the vane type vacuum pump 1, since the rotor 27 and the vane 28 rotate in the cylinder chamber S to compress the air, the compressed air is intermittently discharged from the exhaust holes 23C and 22C of the cylinder chamber S. Is done. For this reason, in the exhaust holes 23C and 22C of the cylinder chamber S, noise and vibration may occur due to the pressure pulsation caused by the constant pulsation.
In order to suppress this noise and vibration, the casing main body 22 has an exhaust passage 40 communicating with the exhaust holes 23C and 22C of the cylinder chamber S and an expansion chamber for expanding compressed air introduced through the exhaust passage 40. 33 is formed.
In the present embodiment, as shown in FIG. 3, the cylinder liner 23 is formed in the casing body 22 such that the axis X2 of the cylinder liner 23 is eccentrically inclined leftward and upward with respect to the rotation center X1. For this reason, a large space can be secured in the casing body 22 in a direction opposite to the direction in which the cylinder liner 23 is eccentric, and this space is connected to the exhaust path 40 along the peripheral edge of the cylinder liner 23. An expansion chamber 33 is formed. According to this, since the exhaust path 40 and the expansion chamber 33 can be integrally formed in the casing body 22, it is not necessary to provide the exhaust path 40 and the expansion chamber 33 outside the casing body 22. Therefore, the vacuum pump 1 can be reduced in size.

  The expansion chamber 33 is a space that expands and disperses the compressed air that has flowed in through the exhaust passage 40, and the compressed air that has flowed into the expansion chamber 33 expands and disperses and collides with the inner wall of the expansion chamber 33 to be diffusely reflected. Since the sound energy of the compressed air is attenuated, noise and vibration during exhaust can be reduced. In the present embodiment, the expansion chamber 33 is formed as a large closed space along the peripheral edge of the cylinder liner 23 from the lower side of the cylinder liner 23 to the upper side of the output shaft 12, and is formed in the pump cover 24. It communicates with the mouth 24A. The exhaust port 24A is provided so as to change the flow of exhaust air substantially perpendicularly to the air flow direction (arrow M direction) in the exhaust path 40 and the expansion chamber 33, and changes the direction of the air flow. Therefore, sound energy can be reduced.

The exhaust path 40 is a space formed with a path cross-sectional area smaller than that of the expansion chamber 33, and the compressed air flowing into the exhaust path 40 is positively collided with the inner wall of the exhaust path 40 so as to attenuate sound energy. Is. In the present embodiment, the casing body 22 includes a partition wall 41 provided outside the cylinder chamber S, and an exhaust path 40 is formed as a space partitioned by the partition wall 41.
Specifically, the partition wall 41 is formed in an arc shape substantially concentric with the cylinder chamber S, and one end 41A of the partition wall 41 is connected to the hole 22B at a position beyond the exhaust hole 22C. The other end 41 </ b> B of the partition wall 41 extends to a position where the space as the exhaust path 40 is not closed.
As a result, the exhaust passage 40 is formed between the partition wall 41 and the cylinder chamber S, the inner passage 40A into which the compressed air from the exhaust hole 22C flows, and the expansion chamber formed outside the partition wall 41 described above. The inner path 40A and the outer path 40B are connected on the other end 41B side of the partition wall 41 to form a folded portion 40C. Accordingly, the compressed air discharged from the cylinder chamber S through the exhaust holes 22C and 23C flows through the inner path 40A and then reverses at the folded portion 40C and flows through the outer path 40B as shown by the arrow M, and enters the expansion chamber 33. Inflow.
In this configuration, since the exhaust path 40 includes the folded portion 40C formed by the partition wall 41, the path length of the exhaust path 40 can be formed long, and the compressed air flowing through the exhaust path 40 has a long path length. When flowing through the exhaust path 40, the sound energy of the compressed air can be attenuated by colliding with the wall surface of the exhaust path 40 and performing irregular reflection. In this case, if the cross-sectional shape of the exhaust path 40 is a horizontally long shape extending in the axial direction, and the surface area of the wall surface of the exhaust path 40 is made as large as possible, the chance of air hitting the wall surface increases and the noise reduction effect increases.
Further, the compressed air attenuated in the exhaust passage 40 then flows into the expansion chamber 33, and further expands and disperses in the expansion chamber 33 to be further attenuated. Therefore, noise and vibration during exhaust are reduced. Can be achieved.

In the present embodiment, the exhaust path 40 includes silencers 44A and 44B at the inlet of the inner path 40A and the outlet of the outer path 40B, respectively. These silencing members 44A and 44B are porous members formed into a substantially rectangular shape by sintering metal particles such as copper and stainless steel, for example, and groove portions 45 and 46 provided on the side walls of the inner passage 40A and the outer passage 40B. It is inserted and fixed in each.
According to this configuration, the compressed air flowing through the exhaust path 40 is rectified when passing through the minute spaces of the respective silencing members 44A and 44B, and the sound energy of the compressed air is absorbed by the silencing members. The sound energy of the compressed air flowing into the expansion chamber 33 from the path 40 can be attenuated, and noise and vibration during exhaust can be further reduced. In this case, if one silencing member 44A is disposed near the exhaust hole 22C and the other silencing member 44B is disposed near the expansion chamber 33, a greater silencing effect can be obtained.

FIG. 4 is a partially enlarged view of FIG. 2 showing the exhaust hole 23 </ b> C formed in the cylinder liner 23. As described above, it is known that the noise and vibration generated when exhausting are caused by pulsation of compressed air from the exhaust holes 23C and 22C of the cylinder chamber S as the rotor 27 and the vane 28 rotate. .
In order to reduce the pressure pulsation, the applicant measured the noise value by changing the shape of the exhaust hole 23C variously. As shown in FIG. 4, the exhaust hole 23C has a hole diameter d1 inside the cylinder chamber S. It has been found that noise is suppressed when formed in a tapered hole having a tapered surface 23C1 which is larger than the outer hole diameter d2 and is reduced from the hole diameter d1 to d2.
Specifically, the hole diameter d1 inside the cylinder chamber S of the exhaust hole 23C is set to be substantially the same as the hole diameter d3 of the exhaust hole 22C of the casing body 22 (10.5 mm in this embodiment). Further, the outer hole diameter d2 is desirably about 70% of the above-described hole diameter d1, and in this embodiment, the diameter is set to 7 mm. Further, the angle α of the tapered surface 23C1 is set to 120 °.
In this configuration, the exhaust hole 23 </ b> C formed in the cylinder liner 23 is a tapered hole having a tapered surface 23 </ b> C <b> 1 that has an inner hole diameter d <b> 1 larger than the outer hole diameter d <b> 2 and decreases from the inner side toward the outer side. As a result, the exhaust amount from the cylinder chamber S can be reduced without extremely increasing the exhaust resistance from the exhaust hole 23C, so that the pulsation of the compressed air discharged from the cylinder chamber can be suppressed. Noise and vibration at the time of exhausting due to pulsation can be reduced.

Next, the effect of reducing the noise value by the above configuration will be described.
FIG. 5 shows a noise value corresponding to each configuration. For this noise value, a plurality of (for example, ten) measurement microphones are arranged around the vacuum pump 1, and the noise value when the vacuum pump 1 is operated in this state is measured for each microphone. Is an average value of.
According to FIG. 5, the noise value (63.4 dB) is 8.3 dB (about 12%) by providing the exhaust passage 40 with respect to the noise value (71.7 dB) of the configuration in which only the expansion chamber 33 is provided. Reduced. Further, by arranging the silencer members 44A and 44B in the exhaust path 40, the noise value (59.7 dB) is further reduced by 3.7 dB (about 6%), and a configuration in which the exhaust hole 23C is a tapered hole is added to this configuration. As a result, the noise value (58.6 dB) was further reduced by 1.1 dB (about 1.9%).
As described above, the vacuum pump 1 with a reduced noise value can be realized by various means, and when the vacuum pump 1 is mounted on a vehicle, the discomfort caused by the noise of the vacuum pump 1 is suppressed. can do.

  As described above, according to the present embodiment, the casing body 22 includes the cylinder chamber S in which the rotor 27 and the vane 28 slide, the expansion chamber 33 that expands the compressed air discharged from the cylinder chamber S, and the cylinder chamber S. Since the exhaust path 40 is connected to the expansion chamber 33 and at least one folded portion 40C is provided in the exhaust path 40, the length of the exhaust path 40 can be increased by the amount folded by the folded portion 40C. it can. For this reason, when the compressed air discharged from the cylinder chamber S flows through the exhaust path 40 having a long path length, the compressed air collides with the wall surface of the exhaust path 40 and is diffusely reflected to attenuate sound energy of the compressed air. Can do. Furthermore, since the compressed air attenuated in the exhaust passage 40 flows into the expansion chamber 33 and further expands and disperses in the expansion chamber 33 and is further attenuated, noise and vibration during exhaust are reduced. be able to.

  In addition, according to the present embodiment, the exhaust path 40 and the expansion chamber 33 are arranged in parallel to the peripheral edge portion of the cylinder chamber S in the casing body 22, and therefore the exhaust path 40, the expansion chamber 33, and the cylinder The chamber S can be formed integrally, and an increase in the size of the vacuum pump 1 can be suppressed.

  Further, according to the present embodiment, since the sound deadening members 44A and 44B made of a porous material are disposed in the exhaust path 40, the compressed air flowing through the exhaust path 40 is rectified when passing through the sound deadening members 44A and 44B. At the same time, since the sound energy of the compressed air is absorbed by the silencer members 44A and 44B, noise and vibration during exhaust can be further reduced.

  Further, according to the present embodiment, the casing main body 22 and the cylinder liner 23 that forms the cylinder chamber S are provided. The cylinder liner 23 includes the exhaust hole 23 </ b> C connected to the exhaust path 40, and the exhaust hole 23 </ b> C is provided in the cylinder chamber S. Since the inner hole diameter d1 is larger than the outer hole diameter d2 and is formed in a tapered hole having a tapered surface 23C1 that decreases in diameter from the inside to the outside, the pulsation of the compressed air discharged from the cylinder chamber S is suppressed. It is possible to reduce the noise and vibration at the time of exhausting due to this pulsation.

Next, another embodiment will be described.
FIG. 6 is a partial cross-sectional side view of a vacuum pump according to another embodiment.
The vacuum pump 80 according to this embodiment differs from the above-described embodiment in that it includes a pilot bearing that supports the tip of the output shaft 12 that rotates the rotor 27. About the same structure, the same code | symbol is attached | subjected and description is abbreviate | omitted.
In this embodiment, the output shaft 12 is integrally provided with a bearing mounting portion 12A1 to which a pilot bearing 81 is mounted at the tip end portion 12A. The bearing mounting portion 12A1 is formed of the through hole 26B of the front side plate 26 and the pump cover 84. It extends through the bearing holding hole 84 </ b> A to the outside of the pump body 20. A bearing holding hole 84A is formed on the inner surface of the pump cover 84, and the pilot bearing 81 is held in the bearing holding hole 84A. In this configuration, since the bearing holding hole 84A having a depth enough to hold the pilot bearing 81 is formed on the inner surface, the plate thickness of the pump cover 84 is formed thick.
According to this configuration, since the tip end portion of the output shaft 12 is supported by the pilot bearing 81, the rotor 27 and the vane 28 are stably rotated in the cylinder chamber S by suppressing the shake of the output shaft 12. Can be made. Therefore, it is possible to reduce the operating noise of the rotor 27 and the vane 28.

  Although the best embodiment for carrying out the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications and changes can be made based on the technical idea of the present invention. It is. For example, in the present embodiment, the exhaust path 40 is configured to include one folded portion 40C, but two or more folded portions may be provided as long as it can be installed. Further, in the present embodiment, the configuration has been described in which the two silencing members 44A and 44B are arranged in the exhaust path 40, but the number of the silencing members may be one or three or more. Moreover, although the sintered metal thing which sintered the metal particle was illustrated as a silencing member, if the temperature conditions are prepared, the silencing member formed with sintered resin can also be arrange | positioned.

1, 80 Vacuum pump 10 Electric motor 11 Case 12 Output shaft (rotary shaft)
20 Pump body 22 Casing body 22A Communication hole 22B Hole 22C Exhaust hole 23 Cylinder liner 23C Exhaust hole 23C1 Tapered surface 24, 84 Pump cover 27 Rotor (rotary compression element)
28 Vane (Rotary compression element)
31 Casing 33 Expansion chamber 40 Exhaust path 40A Inner path 40B Outer path 40C Folded part 41 Bulkhead 41A One end 41B Other end 44A, 44B Silencer member 81 Pilot bearing 84A Bearing holding hole S Cylinder chamber

Claims (5)

In a vacuum pump with a rotary compression element in the casing,
The casing includes a cylinder chamber that slides the rotary compression element, an expansion chamber that expands compressed air discharged from the cylinder chamber, and an exhaust path that connects the cylinder chamber and the expansion chamber. A vacuum pump characterized in that at least one folded portion is provided in an exhaust path.   2. The vacuum pump according to claim 1, wherein the exhaust path and the expansion chamber are arranged in parallel at a peripheral portion of the cylinder chamber in the casing.   The vacuum pump according to claim 1 or 2, wherein a silencer member made of a porous material is disposed in the exhaust path.   The casing includes a cylinder liner that forms the cylinder chamber, and the cylinder liner includes an exhaust hole connected to the exhaust path. The exhaust hole has a larger inside diameter than the outside inside the cylinder chamber, and the outside from the inside to the outside. The vacuum pump according to any one of claims 1 to 3, wherein the vacuum pump is formed in a taper shape with a diameter reduced toward the center.   The vacuum pump according to any one of claims 1 to 4, further comprising: a rotary shaft that drives the rotary compression element, wherein a tip portion of the rotary shaft is supported by a bearing provided in the casing.

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