JP2005249154A - Non-return valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to control a hunting phenomenon when a variable flow compressor is driven at a minimum capacity in a non-return valve that is fixed into the path where the cooling medium of the variable capacity compressor is discharged. <P>SOLUTION: It has the first valve part having a valve body 6 of small bore that opens and closes an inlet port 2 which introduces the compressed cooling medium to the direction to a valve seat 5 and the second valve part having a valve body 8 that can insert and withdraw freely to a valve hole 7 of large diameter on the downstream side and is formed integrally with a plug 4 that can slide a valve body 6, 8 in a body 1 in the axial direction and is biased to the valve-close direction by a spring 14. A taper part 10 is formed to the first valve part from the position where is spaced to the first valve part side only by the distance d from the open mouth end of the valve hole 7 when closing the first valve part on the valve body 8 of the second valve part. Thereby, the flow is throttled and the decrease of hunting phenomenon is controlled when the first valve part opens and the second valve part opens slightly. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a check valve, and more particularly to a check valve suitable for use in a variable capacity compressor of an automotive air conditioner.

  The automotive air conditioner includes a refrigerant compression compressor that is driven by a vehicle engine as a power source. In this compressor, since the rotational speed of the vehicle engine varies greatly depending on the running state of the vehicle, a variable capacity compressor is used so that the discharge capacity can be maintained at a set capacity regardless of the rotational speed. Yes. This variable capacity compressor is connected to the vehicle engine via an electromagnetic clutch. When the automobile air conditioner is not used, the electromagnetic clutch is disconnected to transmit the power of the vehicle engine to the variable capacity compressor. During use of the air conditioner for automobiles, the variable capacity compressor is driven by the vehicle engine by connecting an electromagnetic clutch.

  Providing the electromagnetic clutch increases the weight of the vehicle and increases the manufacturing cost. Furthermore, large electric power is consumed when the electromagnetic clutch is operated. For this reason, a so-called clutchless type variable displacement compressor is known in which the mounting of the electromagnetic clutch is abolished and is configured to be directly connected to the vehicle engine. Since this clutchless type variable displacement compressor is always driven to rotate by the vehicle engine, it is controlled so that the discharge capacity is minimized, especially when the automotive air conditioner is not activated. It is necessary. However, even if the variable capacity compressor is controlled to the minimum capacity operation state, since the discharge capacity is not zero, the variable capacity compressor will continue to discharge the minimum amount of refrigerant. In an evaporator in which the refrigerant is continuously circulated in the cycle and the cooled refrigerant is sent from the expansion valve, frost may adhere to the surface or freeze.

  Therefore, in the clutchless type variable capacity compressor, a check valve is provided in a passage through which the refrigerant is discharged from the discharge chamber. The check valve generally has a structure in which a valve body is arranged downstream of the refrigerant flow with respect to the valve seat, and the valve body is urged in the valve closing direction by a spring. In order to prevent pressure loss as much as possible, the spring acting in the valve closing direction has a weak spring load. On the other hand, the check valve used in the variable capacity compressor uses a spring having a strong spring load, and opens the valve to discharge the refrigerant when the discharge pressure becomes higher than a certain level.

  In the check valve used in such a variable capacity compressor, when the variable capacity compressor is operated at its minimum capacity, the check valve performs compression with the minimum capacity while closing the outlet of the discharge chamber. As a result, the pressure in the discharge chamber gradually increases. When the load acting in the valve opening direction due to the discharge pressure on the valve body of the check valve exceeds the load of the spring acting in the valve closing direction, the check valve starts to open. When the check valve opens, the refrigerant flows downstream and the pressure in the discharge chamber decreases, so the valve body is pushed by the load of the spring and the check valve starts to close. That is, when the variable capacity compressor is operating at the minimum capacity, a hunting phenomenon is generated in the check valve that repeatedly opens and closes a minute opening. When this hunting phenomenon occurs, the valve body strikes the valve seat, so that the hitting sound generates vibration and noise.

A check valve that suppresses such a hunting phenomenon has been proposed (see, for example, Patent Document 1). In this check valve, when the valve starts to open, the opening area of the passage through which the refrigerant is discharged from the discharge chamber is reduced, and the opening area of the passage is increased as the lift amount of the valve element increases as a result of being pushed by the discharge pressure. Is configured to be larger. As a result, the opening area of the passage is small when the valve starts to open and when the valve finishes closing, and the pressure in the discharge chamber does not decrease rapidly, so that the occurrence of the hunting phenomenon is suppressed.
JP 2000-346217 A

  In this way, in particular, in the check valve attached to the refrigerant discharge side of the variable capacity compressor of the clutchless type, the opening area when the valve is opened by the gradually increasing discharge pressure is made variable, and flows out downstream when the valve is opened. It is necessary to suppress the hunting phenomenon by providing a flow rate adjusting function for limiting the refrigerant flow rate.

  It is an object of the present invention to provide a check valve having another structure having such a flow rate adjusting function and capable of suppressing the hunting phenomenon when the variable capacity compressor is operated at the minimum capacity. To do.

  In the present invention, in order to solve the above problem, in a check valve used in a variable capacity compressor of an automotive air conditioner, the check valve is disposed on the side of an inlet port for introducing a refrigerant compressed by the variable capacity compressor. A first valve portion that receives pressure with a small pressure receiving diameter, and is disposed downstream of the first valve portion and has a larger pressure receiving diameter than the first valve portion, and the first valve portion is The first predetermined amount is fully closed until the second predetermined amount is lifted, and until the second predetermined amount is lifted, the opening area of the refrigerant passage is varied so as to continuously increase, and the lift exceeds the second predetermined amount. And a second valve portion in which the opening area increases rapidly to the fully open state.

  According to such a check valve, the second valve portion is fully closed until the first valve portion lifts the first predetermined amount, and further lifts the second predetermined amount. During this time, the opening area of the refrigerant passage is continuously variable. Thereby, when the variable capacity compressor is operated at the minimum capacity and the discharge pressure is gradually increased in a low state, the first valve portion is opened when the discharge pressure reaches a predetermined pressure and the second pressure is opened. When the valve portion opens, the refrigerant flows through the refrigerant passage having a small opening area. For this reason, there is little decrease in the discharge pressure, and the speed at which the first valve portion and the second valve portion are pushed back in the valve closing direction due to the decrease in the discharge pressure is suppressed. Is suppressed.

  In the check valve of the present invention, since the second valve portion does not open at the same time even when the first valve portion is opened, the second valve portion having a large pressure receiving area is introduced through the first valve portion. Thus, the discharged pressure can be reliably received, and the valve opening operation can be reliably performed. When the second valve portion begins to open, a variable flow rate adjustment is performed to reduce the decrease in the discharge pressure at the time of opening, so that the self-excited vibration is weakened and hunting reduction can be suppressed.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, taking as an example a case where the present invention is applied to a clutchless variable capacity compressor of an air conditioner for automobiles.
FIG. 1 is a sectional view showing the structure of a check valve according to the present invention in a closed state, FIG. 2 is a view showing characteristics of the check valve according to the present invention, and FIG. 3 is a diagram showing the structure of the check valve according to the present invention in an opened state. It is sectional drawing shown by.

  The check valve according to the present invention has a body 1 constituting a refrigerant passage, and has a small-diameter inlet port 2 for receiving a refrigerant having a discharge pressure Pd from a discharge chamber of a variable capacity compressor at one end thereof. Has a large-diameter outlet port 3 for sending the refrigerant that has passed through the check valve to the condenser. A plug 4 is disposed in the body 1 so as to be slidable in the axial direction. The plug 4 has a small-diameter valve body 6 disposed so as to face the valve seat 5 formed in the body 1 and a large-diameter disposed so as to be inserted into and removed from the valve hole 7 formed in the body 1. A valve body guide 8 having a diameter and a valve body guide 9 that slides on the inner wall of the body 1 and guides its axial movement in a determined state are integrally formed. The taper portion 10 has a diameter that decreases toward the upstream side. A part of the outer periphery of the valve body guide 9 of the plug 4 is cut off. That is, the outer periphery of the valve element guide 9 has, for example, three D-cut surfaces 11 in the circumferential direction, and a space formed by the D-cut surface 11 and the inner wall of the body 1 forms a refrigerant passage. .

  A holder 12 is fitted to the outlet port 3 of the body 1 and is fixed to the body 1 by caulking the tip of the body 1 inward. The holder 12 is integrally formed with a cylindrical portion 13 at the center thereof, and an end surface facing the plug 4 constitutes a stopper that restricts the movement of the plug 4 to the downstream side. A spring 14 that urges the plug 4 in the valve closing direction is disposed in the cylindrical portion 13 of the holder 12. The holder 12 is also formed with a plurality of communication holes 15 along the outer periphery of the cylindrical portion 13 to constitute a refrigerant passage.

  Here, the valve seat 5 and the valve body 6 arranged on the inlet port 2 side constitute a first valve portion having a small pressure receiving area, and the valve hole 7 and the valve body 8 arranged on the downstream side A second valve portion having a larger pressure receiving area than the first valve portion is configured. By reducing the pressure receiving area of the first valve portion, a spring 14 having a small spring load can be used as the spring 14 that urges against the discharge pressure Pd.

  The first valve portion and the second valve portion that are arranged in series in the refrigerant flow direction are interlocked to perform the same opening / closing operation, but are configured to perform different opening / closing operations in a region where the lift amount is small. Has been. That is, when the valve body 6 is seated on the valve seat 5 and the first valve portion is in the valve closing position, the second valve portion is also in the position where the valve body 8 is inserted into the valve hole 7 and is closed. doing. At this time, the valve body 8 is in a position inserted by a predetermined distance d from the opening end of the valve hole 7 except for the tapered portion 10. Therefore, even if the plug 4 is lifted and the first valve portion is opened, the second valve portion remains closed until the plug 4 is lifted by the distance d, and the plug 4 is lifted further. The first time the valve opens.

  In the check valve configured as described above, when the variable capacity compressor is in the minimum capacity operation state and the discharge pressure Pd is small, such as when the automotive air conditioner is stopped, the check valve is shown in FIG. As shown in FIG. However, since the variable capacity compressor continues to compress at its minimum capacity, the discharge pressure Pd gradually increases.

  At this time, first, the valve body 6 of the first valve portion receives the discharge pressure Pd in its pressure receiving area, but is acting in the valve closing direction rather than the load acting in the valve opening direction by the discharge pressure Pd. Since the load of the spring 14 is larger, the check valve maintains its closed state. When the discharge pressure Pd rises and the load acting in the valve opening direction by the discharge pressure Pd exceeds the load of the spring 14 acting in the valve closing direction, the first valve portion starts to open. Even if the first valve portion is opened, the second valve portion is still closed, so that the discharge pressure Pd is introduced downstream of the first valve portion, and this time, the second valve portion is moved to the first valve portion. The discharge pressure Pd is received in a pressure receiving area larger than the pressure receiving area of the valve portion. At this time, the load acting in the valve opening direction due to the discharge pressure Pd is larger than the load in the valve closing direction of the spring 14, so that the plug 4 quickly moves in the valve opening direction and tries to open the check valve.

  When the plug 4 moves in the valve opening direction and exceeds the distance d, the second valve portion starts to open next. In the second valve portion, the outer diameter of the valve body 8 substantially equal to the inner diameter of the valve hole 7 is formed so as to decrease toward the first valve by the taper portion 10, so that the valve body 8 is formed in the valve hole 7. Until it exits, the opening area gradually changes. Therefore, since the opening area of the refrigerant passage is small at the beginning of the opening of the second valve portion, the flow rate of the refrigerant flowing downstream through the second valve is limited to be small. For this reason, when the second valve is opened, the discharge pressure Pd, which is the pressure on the upstream side, does not rapidly decrease. When the discharge pressure Pd decreases due to the opening of the second valve, the load in the valve opening direction due to the discharge pressure Pd decreases, and when the load in the valve closing direction of the spring 14 becomes smaller, the plug 4 The load returns to the valve closing direction, the second valve portion is closed, and the first valve portion is closed. Here, when the discharge pressure Pd is restored, the first valve portion is opened, and then the second valve portion is opened. In this way, this check valve causes hunting by the self-excited vibration of the plug 4 in a small lift range between the closed position and the position where the second valve portion is slightly opened. The stroke is small, and the discharge pressure Pd itself for driving the check valve plug 4 in the valve opening direction is much smaller than when the variable capacity compressor is operating in the variable capacity range. It can be greatly reduced.

  The second valve portion has a flow rate adjusting function that allows the tapered portion 10 of the valve body 8 to continuously change the opening area of the flow path, so that the check valve has the characteristics as shown in FIG. doing. In this figure, the horizontal axis indicates the differential pressure before and after the plug 4, and the vertical axis indicates the change in the opening area. According to this characteristic, when the discharge pressure Pd of the discharge chamber increases and the differential pressure increases, the second valve portion starts to open by opening the first valve portion at a certain differential pressure, and the opening area increases. start. For a while, the flow rate adjusting function by the taper portion 10 of the second valve portion works, and the opening area gradually increases. When the taper part 10 of the second valve part comes out of the valve hole 7 and the flow rate adjustment function by the taper part 10 does not work, the rate of increase of the opening area increases rapidly, and when the pressure difference exceeds a certain pressure, the opening area increases. The check valve is fully open. As described above, in the change range of the minute area in which the opening area gradually increases, the change in the opening area with respect to the change in the differential pressure is small, and the movement of the valve body 8 of the second valve portion is also small. Hunting can be suppressed.

  When the automobile air conditioner is started or when the variable capacity compressor shifts from the minimum capacity operation to the variable capacity operation, the discharge pressure Pd of the refrigerant discharged from the discharge chamber increases rapidly. The valve shifts from the fully closed state to the fully opened state as shown in FIG. 3 in a very short time without vibration of the plug 4.

FIG. 4 is a cross-sectional view showing a state in which the check valve is mounted on the variable capacity compressor.
The check valve according to the present invention is mounted in a head shell 21 attached to a compressor body 20 of a variable capacity compressor. That is, a passage 23 is formed in the head shell 21 so as to be aligned with the passage 22 into which the discharge pressure Pd is introduced from the discharge chamber of the compressor body 20, and the check valve is a passage in the head shell 21. It is mounted in the variable capacity compressor by being press-fitted into 23.

  When the automotive air conditioner is shut down, the check valve is closed as shown in the figure, so that a small discharge pressure Pd is introduced into the passage 22, and when this discharge pressure Pd reaches a predetermined pressure, The plug 4 moves to the downstream side against the urging force of the spring 14. As a result, the first valve portion is opened and the second valve portion is further opened, whereby the refrigerant in the passage 22 flows downstream of the check valve, and the discharge pressure Pd is reduced. At this time, the refrigerant flow rate of the second valve portion is limited by the taper portion 10, and the decrease in the discharge pressure Pd due to the opening of the second valve portion is small, so that the plug 4 is closed by the spring 14. The speed pushed back in the direction is suppressed. Thereby, the load which the plug 4 collides with the body 1 is relieved, and the vibration sound by the plug 4 carrying out self-excited vibration is suppressed.

It is sectional drawing which shows the structure of the non-return valve by this invention in a valve closing state. It is a figure which shows the characteristic of the non-return valve by this invention. It is sectional drawing which shows the structure of the non-return valve by this invention in a valve opening state. It is sectional drawing which shows the mounting state to the variable capacity compressor of a non-return valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Body 2 Inlet port 3 Outlet port 4 Plug 5 Valve seat 6 Valve body 7 Valve hole 8 Valve body 9 Valve body guide 10 Tapered part 11 D cut surface 12 Holder 13 Cylindrical part 14 Spring 15 Communication hole 20 Compressor main body 21 Head Shell 22 passage 23 passage Pd discharge pressure

Claims (4)

In a check valve used for a variable capacity compressor of an automotive air conditioner,
A first valve portion disposed on the side of an inlet port for introducing the refrigerant compressed by the variable capacity compressor and receiving a discharge pressure with a small pressure receiving diameter;
Disposed downstream of the first valve portion and having a larger pressure receiving diameter than the first valve portion, fully closed until the first valve portion lifts a first predetermined amount, 2 until the predetermined amount of 2 is lifted, and the opening area of the refrigerant passage is varied so as to continuously increase, and when the lift exceeds the second predetermined amount, the opening area rapidly increases to the fully open position. And
A check valve characterized by comprising:   The first valve body is arranged so as to be able to contact and separate from the downstream side so as to open and close the inlet port with respect to the inlet port formed on the upstream side of the body constituting the refrigerant passage. The second valve portion is formed by the body on the downstream side of the first valve portion and has a larger diameter than the inlet port, and is detachable with respect to the valve hole. A second valve body having a large diameter disposed on the opening of the valve hole when the first valve portion lifts the first predetermined amount. The first valve body and the second valve body are slidable in the axial direction in the body, and have a tapered portion whose diameter decreases from the corresponding position toward the upstream side; And is formed integrally with a plug biased in the direction of the inlet port. Motomeko 1 check valve described.   The spring is disposed between the plug and a holder that is fixed to an outlet port on the downstream side of the body and has a communication hole through which the refrigerant that has passed through the second valve portion passes. The check valve according to claim 2, wherein: The plug has a valve body guide integrally formed so as to slide in the axial direction in the body while locating the first valve body and the second valve body. 3. The check valve according to claim 2, wherein a part of the outer periphery is cut away to form at least one refrigerant passage extending in the axial direction between the inner wall of the body.

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