VANE TYPE VACUUM PUMP
A vane type vacuum pump has a discharge port for discharging suctioned air, and a reed valve part that opens and closes the discharge port. The reed valve part includes a first reed valve that is installed to cover the opening of the discharge port, and a second reed valve that is superposed with the first reed valve. The first reed valve and the second reed valve have different resonance frequencies by having different thicknesses.
The present invention relates to a vane type vacuum pump that inhales a gas and discharges the gas from a discharge port.
A conventional vane type vacuum pump is described in Japanese Laid-Open Patent Publication No. 2012-057622. The vane type vacuum pump described in Japanese Laid-Open Patent Publication No. 2012-057622 includes a reed valve that is installed at a discharge port. The discharge port is opened and closed by deflecting the reed valve by a discharge pressure of the gas. In Japanese Laid-Open Patent Publication No. 2012-057622, it is also described that the reed valve is formed with a leaf spring which includes a single plate or a laminated plate.
In the above vane type vacuum pump, the reed valve sometimes resonates due to disturbance of a flow of the gas that is discharged from the discharge port. When the reed valve resonates, a pulsation occurs in the gas discharged from the discharge port. Then, by the pulsation of the gas, a pressure variation occurs in the installation space of the vane type vacuum pump. A wall surface of the installation space vibrates due to the pressure variation, and vibration energy of the wall surface vibration is radiated to an outer side as sound, and abnormal noise occurs.
SUMMARY OF THE INVENTIONThe vane type vacuum pump includes a first reed valve that is installed at the discharge port, and a second reed valve that is superposed with the first reed valve and has a resonance frequency which is different from that of the first reed valve.
Hereinafter, a vane type vacuum pump according to a first embodiment of the present invention will be described in detail with reference to
The vane type vacuum pump is installed inside a cylinder head of an engine in a state that a lower portion is soaked in oil. The vane type vacuum pump is coupled to a camshaft. When the camshaft has rotated, the vane type vacuum pump suctions air from a negative pressure actuator such as a brake booster, and discharges the air within the cylinder head.
As shown in
As shown in
The first reed valve 12 and the second reed valve 13 have the same materials and the same planar shapes, but have different thicknesses. In
The first reed valve 12 and the second reed valve 13 include fixed portions 12a and 13a, and valve body portions 12b and 12b. The fixed portions 12a and 13a are portions that are fixed to the pump body 17 with the bolt 16. The valve body portions 12b and 13b are elastically deformable portions in the first reed valve 12 and the second reed valve 13. The valve body portions 12b and 13b have shapes and sizes that cover a whole opening of the discharge port 10. The valve body portion 12b of the first reed valve 12 is brought into contact with a valve seat 18 that is provided at the peripheral edge of the opening of the discharge port 10. The first reed valve 12 and the second reed valve 13 are superposed with each other in a state that the valve body portions 12b and 13b are slide-contacted with each other.
The stopper member 14 is made of metal, and has a larger thickness than the thicknesses of the first reed valve 12 and the second reed valve 13. The stopper member 14 has a first end part that is fixed to the bolt 16, and a second end part located opposite to the first end part. The stopper member 14 is curved so as to be separated from the discharge port 10 as the stopper member 14 proceeds from the first end part to the second end part.
An operation of the reed valve part 11 of the vane type vacuum pump will be described with reference to
During the operation of the vane type vacuum pump, air is intermittently discharged from the discharge port 10. The reed valve part 11 operates to open the discharge port 10 during discharge of the air, and close the discharge port 10 during non-discharge of the air.
In the state shown in
When the inverse number of the cycle of opening and closing the discharge port 10 becomes close to the intrinsic vibration frequencies of the first reed valve 12 and the second reed valve 13, the first reed valve 12 and the second reed valve 13 resonate. When the first reed valve 12 and the second reed valve 13 resonate simultaneously, a pulsation occurs in the air that is discharged from the discharge port 10. Then, a pressure variation occurs in the space within the cylinder head cover in which the vane type vacuum pump is installed. The wall surface of the cylinder head cover vibrates due to the pressure variation, the vibration energy is radiated to the outer side as sound, and abnormal noise occurs.
In this respect, according to the vane type vacuum pump of the first embodiment, the first reed valve 12 and the second reed valve 13 have different resonance frequencies because they have different thicknesses. Therefore, the first reed valve 12 and the second reed valve 13 do not resonate simultaneously. Accordingly, even when one of the first reed valve 12 and the second reed valve 13 resonates, the vibration is suppressed by the other reed valve that does not resonate. Consequently, a vibration amplitude during resonance becomes smaller.
Further, at the time of opening and closing the discharge port 10, a relative sliding occurs between contact surfaces of the first reed valve 12 and the second reed valve 13 that are superposed with each other. Therefore, according to the vane type vacuum pump of the first embodiment, vibrations of the first reed valve 12 and the second reed valve 13 are attenuated by the friction between the contact surfaces due to relative sliding.
The stopper member 14 regulates the opening of the first reed valve 12 and the second reed valve 13 not to exceed a constant amount of opening. Therefore, even when a discharge pressure of the air from the discharge port 10 has become excessively large, excessive opening of the first reed valve 12 and the second reed valve 13 can be regulated.
According to the vane type vacuum pump of the first embodiment, the following advantages can be obtained.
(1) According to the vane type vacuum pump, the first reed valve and the second reed valve are deflected by the discharge pressure of the gas so that the discharge port is opened and closed. When the inverse number of the cycle of opening and closing the discharge port becomes close to the resonance frequency of the first reed valve and the second reed valve, the first reed valve and the second reed valve resonate. In this respect, according to the vane type vacuum pump of the first embodiment, the reed valve that opens and closes the discharge port 10 is configured as follows. That is, the reed valve is configured by superposing the first reed valve 12 and the second reed valve 13 that have different resonance frequencies. According to this configuration, because the first reed valve 12 and the second reed valve 13 have different resonance frequencies, the first reed valve 12 and the second reed valve 13 do not resonate simultaneously. Accordingly, even when one of the first reed valve 12 and the second reed valve 13 resonates, the vibration is regulated by the other reed valve that does not resonate. As a result, resonance of the reed valve that becomes the cause of the abnormal noise can be suppressed.
(2) Therefore, vibrations of the first reed valve 12 and the second reed valve 13 are attenuated by friction between the contact surfaces of the first reed valve 12 and the second reed valve 13. As a result, resonance of the reed valves can be suppressed.
(3) At the outer side of the first reed valve 12 and the second reed valve 13, the stopper member 14 is provided to limit a valve open amount of the first reed valve 12 and the second reed valve 13. Therefore, it is possible to suppress excessive deformation of the first reed valve 12 and the second reed valve 13 and remaining of the deformation in the reed valve.
(4) Simply differentiating the thicknesses of the first reed valve 12 and the second reed valve 13 makes it possible to easily differentiate the resonance frequencies of the first reed valve 12 and the second reed valve 13. For example, in the case of stamping the first reed valve 12 and the second reed valve 13, it is possible to manufacture the first reed valve 12 and the second reed valve 13 by using the same stamping mold, by simply changing the thicknesses of metal materials.
Second EmbodimentNext, a vane type vacuum pump according to a second embodiment of the present invention will be described with reference to
As shown in
In the case of
In the second embodiment, the first reed valve 21 and the second reed valve 22 also have different resonance frequencies by having different planar shapes. Therefore, the first reed valve 21 and the second reed valve 22 do not resonate simultaneously, and resonance of the reed valve that becomes the cause of abnormal noise can be suppressed. Consequently, the advantages described in the above (1) to (3) can be also obtained by the vane type vacuum pump of the second embodiment.
In the example shown in
As shown in
As shown in
Next, a vane type vacuum pump according to a third embodiment of the present invention will be described with reference to
As shown in
In the third embodiment, the first reed valve 28 and the second reed valve 29 also have different resonance frequencies by being formed with different materials. Therefore, the first reed valve 28 and the second reed valve 29 do not resonate simultaneously, and resonance of the reed valve that becomes the cause of abnormal noise can be suppressed. Consequently, the advantages described in the above (1) to (3) can be also obtained by the vane type vacuum pump of the third embodiment.
The above embodiment may be changed as follows.
Shapes of the first and second reed valves and the stopper member may be changed to match the shape of the discharge port of the vane type vacuum pump that is applied.
The stopper member 14 may be omitted.
By differentiating two or all of thicknesses, shapes, and materials of the first and second reed valves, resonance frequencies of both reed valves may be differentiated.
In the above embodiments, although the first and second reed valves are different members, both reed valves may be integrally formed when the valve body portions can be slide-contacted with each other. For example, by folding one plate material into two portions, the reed valve may be configured such that two valve body portions are superposed to be able to be slide-contacted with each other.
Claims
1. A vane type vacuum pump that inhales a gas and discharges the gas from a discharge port, the vane type vacuum pump comprising:
- a first reed valve that is installed at the discharge port; and
- a second reed valve that is superposed with the first reed valve and has a resonance frequency which is different from that of the first reed valve.
2. The vane type vacuum pump according to claim 1, wherein
- the first reed valve and the second reed valve have different thicknesses.
3. The vane type vacuum pump according to claim 1, wherein
- the first reed valve and the second reed valve have different shapes.
4. The vane type vacuum pump according to claim 1, wherein
- the first reed valve and the second reed valve are formed with different materials.
5. The vane type vacuum pump according to claim 1, further comprising:
- a stopper member that is provided at an outer side of the first reed valve and the second reed valve to limit a valve open amount of the first reed valve and the second reed valve.
Type: Application
Filed: Dec 30, 2014
Publication Date: Jul 30, 2015
Inventor: Masaya OTSUKA (Miyoshi-shi)
Application Number: 14/585,979