JP2006170312A - Pulsation reducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulsation reducing device capable of reducing noise and vibration by preventing the resonance of a transmitted member from occurring. <P>SOLUTION: This pulsation reducing device 10 comprises a cylindrical wall 19 having an inner passage 11 for flowing a working fluid therein and closed at its one end. A piston 14 is installed in the inner passage 11. A cylinder chamber 16 is formed by the piston 14, an inner wall 15 as the closed end part of the inner passage 11, and the cylindrical wall 19. A spring 17 fixed, at its one end, to the inner wall 15 and energizing the piston 14 by coming into contact, at the other end, with the piston 14 is installed in the cylinder chamber 16. An outer passage 12 is formed between the cylindrical wall 19 and a pipe 9. The inner passage 11 communicates with the outer passage 12 through a communication hole 13 formed in the cylindrical wall 19. The cylinder chamber 16 communicates with the outer passage 12 through a restrictor 18 formed in the inner wall 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pulsation reducing device.

A conventional pulsation reducing device in various piping systems is described in Patent Document 1, for example. In this pulsation reducing device, as shown in FIG. 6, a sealed branch pipe 42 is provided at an appropriate position of a pipe 41 through which a working fluid flows. One end of the spring 44 is fixed to the center of the top wall 43 of the branch pipe 42, and a flat piston 45 is fixed to the other end of the spring 44, so that the piston 45 opens the pipe 41 and the branch pipe 42. The portion is closed while having a gap 46. Further, the pipe 41 and the branch pipe 42 are communicated with each other by a connecting pipe 47, and a throttle 48 is provided in the connecting pipe 47.
When the pressure of the working fluid in the pipe 41 increases, a force that pushes the piston 45 into the branch pipe 42 acts on the piston 45. When the piston 45 is pushed into the branch pipe 42 by this force, the working fluid inside the branch pipe 42 is pushed out to the pipe 41 through the gap 46 and the connecting pipe 47, but the working fluid passes through the gap 46 and the throttle 48. By creating resistance as it passes, a portion of the kinetic energy of the working fluid is consumed. On the other hand, when the pressure of the working fluid in the pipe 41 decreases, the working fluid in the pipe 41 moves into the branch pipe 42 through the gap 46 and the connecting pipe 47. At this time, a part of the kinetic energy of the working fluid is consumed by the same principle. Thus, when the pulsation of the working fluid occurs in the pipe 41, a part of the kinetic energy of the working fluid is consumed as the pressure rises and falls due to the pulsation, thereby reducing the pulsation in the pipe 41. .
Usually, when a fluid is sucked or discharged in a compressor or a pump, pulsation is generated due to pressure fluctuation or valve opening operation. This pulsation is transmitted through a pipe connected to a compressor and a pump. For example, in the case of a refrigeration circuit, the pulsation is transmitted to a member to be transmitted such as an evaporator or a condenser. At this time, if the resonance frequency of the pulsation coincides with the natural frequency of the member to be transmitted, the member to be transmitted resonates, which causes abnormal noise and vibration.

Japanese Patent Laid-Open No. 61-241591

  However, the pulsation reducing device according to Patent Document 1 is a technique for reducing pulsation by resistance generated when a fluid passes through the gap 46. In this case, although there is an effect of reducing the pulsation over the entire resonance frequency band, the closed branch pipe 42 or the closed end of the pipe 41 on the side face with respect to the flow path of the fluid, although in the pipe, is used. Since the pulsation reducing device is provided, there is a limit to the flow rate of the fluid that passes through the gap serving as a resistance, and there is a limit to the level at which pulsation can be reduced. For this reason, the resonance frequency of the pulsation that matches the natural frequency of the member to be transmitted cannot be sufficiently reduced, and there has been a problem that it is impossible to prevent abnormal noise and vibration associated with resonance of the member to be transmitted.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a pulsation reducing device that can prevent resonance of a transmitted member and reduce abnormal noise and vibration.

A pulsation reducing device according to the present invention is a pulsation reducing device arranged inside a circuit through which a fluid flows, and is provided in a cylinder chamber in which fluid flowing in the circuit enters and exits through a throttle, and in the cylinder chamber, A piston slidable so that the internal volume of the cylinder chamber changes, and elastic means for urging the piston from the cylinder chamber side, the piston being driven by the pressure inside the circuit, the pressure in the cylinder chamber, and the elastic means The natural frequency of the pulsation reducing device that slides according to the difference from the biasing force and is determined by the elastic constant of the elastic means and the mass of the piston matches the natural frequency of the member to which the fluid pulsation is transmitted. It is characterized by. By matching the natural frequency of the pulsation reducing device with the natural frequency of the transmitted member to which the fluid pulsation is transmitted, the pulsation of the frequency that matches the natural frequency of the transmitted member is reduced in the pulsation reducing device. Therefore, the transmitted member does not resonate.
The piston preferably seals and isolates the cylinder chamber and the interior of the circuit. Since the fluid does not pass through the gap between the cylinder chamber and the circuit, the kinetic energy of the fluid is not consumed.
The circuit may comprise a hydraulic pump.
The circuit is a refrigeration circuit equipped with a compressor, the transmitted means is an evaporator, the pulsation reducing device is provided on the suction side of the compressor, and the natural frequency of the pulsation reducing device and the natural frequency of the evaporator are calculated. You may make it correspond.
The circuit is a refrigeration circuit provided with a compressor, the transmitted means is a condenser, and the pulsation reducing device is provided on the discharge side of the compressor, and the natural frequency of the pulsation reducing device and the natural frequency of the condenser are obtained. You may make it correspond.
The fluid may flow inside the circuit through the periphery of the cylinder chamber.

  According to the present invention, it is provided with a cylinder chamber through which fluid enters and exits through a throttle, a piston that slides in the cylinder chamber, and elastic means that urges the piston from the cylinder chamber side. The natural frequency of the pulsation reducing device that slides according to the difference between the pressure in the cylinder chamber and the urging force by the elastic means, and is determined by the elastic constant of the elastic means and the mass of the piston, Since it matches the natural frequency, resonance of the transmitted member can be prevented, and abnormal noise and vibration can be reduced.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
As shown in FIG. 1, the refrigeration cycle 1 for a vehicle includes a compressor 3, a condenser 4, an expansion valve 5, and an evaporator 6. The power of the engine 2 is transmitted to the compressor 3 via the transmission belt 7, whereby the compressor 3 is driven, and a working fluid such as chlorofluorocarbon is circulated through the refrigeration cycle 1. The compressor 3 and the condenser 4 are communicated with each other by a pipe 9, and a pulsation reducing device 10 is provided inside the pipe 9 so as to be connected to the discharge port 8 of the compressor 3. Here, the pipe 9 constitutes a circuit through which a fluid flows.

Next, the structure of the pulsation reducing device 10 will be described with reference to FIG. The pulsation reducing device 10 includes a cylindrical wall 19 that is concentric with the pipe 9 and is closed at one end. The cylindrical wall 19 includes an internal passage 11 through which a working fluid flows. A piston 14 is provided in the internal passage 11. A cylinder chamber 16 is formed by being surrounded by a piston 14, an inner wall 15 that is a closed end of the internal passage 11, and a cylindrical wall 19. The piston 14 seals and isolates the internal passage 11 and the cylinder chamber 16 by contacting a side surface of the piston 14 with the inner peripheral surface 19 a of the cylindrical wall 19. Inside the cylinder chamber 16, a spring 17 is provided that has one end fixed to the inner wall 15 and the other end contacting the piston 14 to urge the piston 14. Here, the spring 17 constitutes an elastic means. The piston 14 slides along the inner peripheral surface 19 a of the cylindrical wall 19 according to the magnitude relationship between the biasing force of the spring 17 and the force generated in the piston 14 due to the differential pressure between the internal passage 11 and the cylinder chamber 16. ing.
Further, an external passage 12 is provided between the cylindrical wall 19 and the pipe 9 so that the working fluid passes through the periphery of the cylinder chamber 16 and bypasses the cylinder chamber 16. The internal passage 11 and the external passage 12 communicate with each other via one or more communication ports 13 formed in the cylindrical wall 19. The cylinder chamber 16 and the external passage 12 communicate with each other via a throttle 18 provided in the inner wall 15.

  Since the pulsation reducing device 10 is provided to reduce the pulsation of the working fluid discharged from the compressor 3, the pulsation reducing device 10 reduces the pulsation of the working fluid so as to minimize the influence on the condenser 4. It is preferable. Here, the condenser 4 constitutes a transmitted member to which the pulsation of the working fluid discharged from the compressor 3 is transmitted. This pulsation is constituted by pressure fluctuations of various frequencies, and this object can be achieved by reducing the resonance frequency of the pulsation that coincides with the natural frequency of the condenser 4 among them. The pulsation reducing device 10 can adjust the frequency of the pressure fluctuation that can be reduced most by adjusting the natural frequency of the spring 17 based on the spring constant of the spring 17 that is an elastic constant and the mass of the piston 14. Therefore, the natural frequency of the spring 17 matches the natural frequency of the condenser 4 by adjusting the spring constant of the spring 17 and the mass of the piston 14.

Next, the operation of the pulsation reducing apparatus 10 according to the first embodiment will be described.
As shown in FIG. 1, when the engine 2 is started, the power is transmitted to the compressor 3 via the transmission belt 7, and the compressor 3 is started. The high-temperature and high-pressure working fluid gas discharged from the compressor 3 flows into the condenser 4 through the pipe 9. The high-temperature and high-pressure working fluid is changed into a liquid working fluid by being cooled in the condenser 4. After that, the working fluid gas is obtained again by the expansion valve 5, and heat exchange with the air going into the vehicle is performed in the evaporator 6.

As shown in FIG. 2, the working fluid gas discharged from the compressor 3 is introduced into the pulsation reducing device 10 through the discharge port 8.
Here, for convenience of explanation, it is assumed that the pressure of the working fluid gas discharged from the compressor 3 is constituted by the sum of a slowly varying average pressure P and an instantaneously varying pressure ΔP. The pulsation is caused by the fluctuation pressure ΔP, and the fluctuation pressure ΔP is eliminated by the pulsation reducing device 10, so that the working fluid gas having the pressure P with reduced pulsation flows out toward the condenser 4. Further, the resonance frequency of the fluctuating pressure ΔP is the same as the natural frequency of the condenser 4.

The working fluid gas discharged from the compressor 3 flows into the internal passage 11 through the discharge port 8. Thereafter, the working fluid gas in the internal passage 11 flows into the external passage 12 through the communication port 13 and flows through the pipe 9 toward the condenser 4.
Here, since the throttle 18 is a small hole that can be ignored as compared with the inner diameter of the pipe 9, the fluctuating pressure ΔP that fluctuates instantaneously is not transmitted to the cylinder chamber 16, but only the gently fluctuating average pressure P is transmitted. Thus, the cylinder chamber 16 has an average pressure P. Then, the piston 14 slides due to the force generated by the difference between the pressure P + ΔP of the working fluid flowing through the internal passage 11 and the pressure P of the cylinder chamber 16.
For example, when ΔP is a positive pressure, the piston 14 slides in a direction in which the spring 17 is compressed. Due to such sliding of the piston 14, the spring 17 biases the piston 14 in the direction opposite to the direction in which the working fluid flows. Thus, the piston 14 slides due to the magnitude relationship between the force due to the pressure difference (ΔP) through the piston 14 and the biasing force of the spring 17, and the piston 14 acts on the working fluid gas flowing in the internal passage 11. As a result, the fluctuating pressure ΔP is eliminated, and the working fluid gas having the pressure P flows into the external passage 12.
Conversely, when ΔP is negative, the piston 14 slides in the direction in which the spring 17 extends. Such sliding of the piston 14 causes the spring 17 to urge the piston 14 in the direction in which the working fluid flows. As in the case where ΔP is a positive pressure, the piston 14 acts on the working fluid gas flowing in the internal passage 11, whereby the fluctuating pressure ΔP of the working fluid gas is eliminated and becomes a working fluid gas having the pressure P. It flows into the external passage 12.

  The working fluid gas that has flowed into the external passage 12 passes through the pipe 9 and reaches the condenser 4. In this working fluid gas, the pulsation resonance frequency that matches the natural frequency of the condenser 4 is reduced by the pulsation reducing device 10, so that the condenser 4 does not resonate, and abnormal noise and vibration accompanying the resonance also occur. No longer.

  Thus, by providing the pulsation reducing device 10 on the discharge side of the compressor 3 and matching the natural frequency of the pulsation reducing device 10 with the natural frequency of the condenser 4 provided downstream of the compressor 3, Since the resonance frequency of the pulsation is reduced, it is possible to prevent the condenser 4 from resonating, and it is also possible to prevent abnormal noise and vibration associated with the resonance.

Embodiment 2. FIG.
Next, a pulsation reducing device according to Embodiment 2 of the present invention will be described. In the second embodiment, the same reference numerals as those in FIGS. 1 and 2 are the same or similar components, and thus detailed description thereof is omitted.
The pulsation reducing device according to the second embodiment is different from the first embodiment in that a pulsation reducing device 10 is provided on the suction side of the compressor 3.
As shown in FIG. 3, the pulsation reducing device 10 is configured so that the suction side of the compressor 3 is connected to the suction port 31 of the compressor 3 in the pipe 30 that communicates the evaporator 6 and the compressor 3. Is provided. As shown in FIG. 4, the pulsation reducing device 10 is provided so that the piston 14 faces the evaporator 6. Other configurations are the same as those in the first embodiment.

As shown in FIG. 3, when the working fluid circulates in the refrigeration cycle 1 as in the first embodiment, the working fluid exiting the evaporator 6 passes through the pipe 30 and is compressed via the pulsation reducing device 10. Inhaled by machine 3. In FIG. 4, the path through which the working fluid passes through the pulsation reducing device 10 is indicated by arrows. The working fluid that has flowed through the pipe 30 from the evaporator 6 flows into the internal passage 11. The working fluid that has flowed into the internal passage 11 flows into the external passage 12 through the communication port 13 and is sucked into the compressor 3 through the suction port 31.
When the working fluid is sucked into the compressor 3, suction pulsation occurs on the suction side of the compressor 3, and the suction pulsation is transmitted to the evaporator 6 through the pipe 30. Then, the evaporator 6 resonates due to the resonance frequency of the suction pulsation that matches the natural frequency of the evaporator 6, and abnormal noise and vibration due to the resonance are generated.

  Here, when the natural frequency of the spring 17 of the pulsation reducing device 10 is matched with the natural frequency of the evaporator 6 in the same manner as in the first embodiment, when the working fluid passes through the pulsation reducing device 10, suction is performed. The resonant frequency of pulsation is reduced. Thereby, it can prevent that the evaporator 6 resonates and can prevent generation | occurrence | production of the noise and vibration accompanying resonance.

Embodiment 3 FIG.
Next, a pulsation reducing device according to Embodiment 3 of the present invention will be described. The pulsation reducing device according to the third embodiment is provided so as to be connected to the discharge port of the gear pump. As shown in FIG. 5, the gear pump 20 that is one of the hydraulic pumps includes a casing 21. The casing 21 is provided with a suction port 23 and a discharge port 24 that communicate with the interior 22 thereof. Further, in the interior 22 of the casing 21, a drive shaft 25 that is driven by a drive motor (not shown), a main drive gear 26 that is provided on the drive shaft 25 in the interior 22 of the casing 21 and that can rotate integrally with the drive shaft 25, A driven gear 27 is provided in the interior 22 of the casing 21 so as to be rotatable so as to mesh with the main driving gear 26. A pulsation reducing device 10 is provided in a connector 29, which is a circuit through which fluid flows while connecting the discharge port 24 and the pipe 9. The configuration of pulsation reducing apparatus 10 is the same as that of the first embodiment.

  When the drive shaft 25 is rotated by a drive motor (not shown), the main driving gear 26 is rotated integrally with the drive shaft 25. Further, the driven gear 27 is rotated by the rotation of the main driving gear 26. The fluid that has flowed into the suction port 23 flows into the interior 22 of the casing 21, is pumped by the rotation of the main driving gear 26 and the driven gear 27, and is then discharged to the discharge port 24. The fluid discharged to the discharge port 24 flows downstream through the internal passage 11, the communication port 13, and the external passage 12 of the pulsation reducing device 10. Here, in the same manner as in the first embodiment, the natural frequency of the spring 17 of the pulsation reducing device 10 is matched with the natural frequency of an arbitrary transmitted member downstream of the gear pump 20, thereby reducing the pulsation reducing device 10. Reduces the resonant frequency of the pulsation that matches the natural frequency of the transmitted member. Thereby, it can prevent that the to-be-transmitted member resonates, and can prevent generation | occurrence | production of the noise and vibration accompanying resonance. As an arbitrary transmitted member, for example, a body that clamps a discharge pipe or a suction pipe, or a control valve that adjusts a pressure can be considered.

  In the first to third embodiments, the pulsation reducing device according to the present invention has been described by taking the example of reducing the pulsation of the fluid discharged or sucked by the compressor and the gear pump. However, the present invention is not limited to these. . The pulsation reducing device can be used for all types of compressors, pumps, and the like as long as the device generates pulsation in the fluid. Moreover, the pulsation reducing device according to the present invention can also be used for a compressor, a pump, or the like provided for flowing a fluid in a pipe not limited to a vehicle.

  In the first to third embodiments, the pulsation reducing device is provided so as to be connected to the discharge port or the suction port of the compressor or gear pump, but is not limited to this. It may be provided in the compressor or the gear pump so as to be connected to the discharge port or the suction port, or may be provided in a pipe away from the discharge port or the suction port.

It is a block diagram of the refrigerating cycle which concerns on Embodiment 1 of this invention. 1 is a cross-sectional view illustrating a configuration of a pulsation reducing device according to Embodiment 1. FIG. 6 is a configuration diagram of a refrigeration cycle according to Embodiment 2. FIG. 6 is a cross-sectional view showing a configuration of a pulsation reducing device according to Embodiment 2. FIG. FIG. 6 is a cross-sectional view illustrating a configuration of a pulsation reducing device according to a third embodiment. It is sectional drawing which shows the structure of the conventional pulsation reduction apparatus.

Explanation of symbols

  3 compressor, 4 condenser, 6 evaporator, 9, 30 piping (circuit), 10 pulsation reducing device, 14 piston, 16 cylinder chamber, 17 spring (elastic means), 29 connector (circuit).

Claims (6)

A pulsation reducing device disposed inside a circuit through which a fluid flows,
A cylinder chamber through which the fluid flowing in the circuit enters and exits through a restriction;
A piston provided in the cylinder chamber and slidable so that the internal volume of the cylinder chamber changes;
Elastic means for biasing the piston from the cylinder chamber side;
The piston slides according to the difference between the pressure inside the circuit, the pressure in the cylinder chamber and the biasing force by the elastic means,
The pulsation reducing device according to claim 1, wherein a natural frequency of the pulsation reducing device determined by an elastic constant of the elastic means and a mass of the piston coincides with a natural frequency of a transmitted member to which the pulsation of the fluid is transmitted.   The pulsation reducing device according to claim 1, wherein the piston seals and isolates the cylinder chamber and the inside of the circuit.   The pulsation reducing device according to claim 1, wherein the circuit includes a hydraulic pump. The circuit is a refrigeration circuit with a compressor;
The transmitted means is an evaporator,
The pulsation reducing device is provided on the suction side of the compressor,
The pulsation reducing device according to claim 1 or 2, wherein the natural frequency of the pulsation reducing device and the natural frequency of the evaporator are matched. The circuit is a refrigeration circuit with a compressor;
The transmitted means is a condenser;
The pulsation reducing device is provided on the discharge side of the compressor,
The pulsation reduction device according to claim 1 or 2, wherein the natural frequency of the pulsation reduction device and the natural frequency of the condenser are matched.   The pulsation reducing device according to claim 1, wherein the fluid flows inside the circuit through the periphery of the cylinder chamber.

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