Valve apparatus

A valve apparatus includes a valve main body provided with a first inlet and outlet, a valve chamber to which a valve port is open, and a second inlet and outlet connected to the valve port. A valve shaft having a valve body portion for opening and closing the valve port is provided in the valve chamber. A relief valve is provided within the valve body portion to relieve a pressure of the valve chamber to the second inlet and outlet when a fluid pressure of the refrigerant within the valve chamber becomes a predetermined pressure or more in a fully closed state in which the valve port is closed by the valve body portion, thereby to automatically relieve a fluid within a valve chamber without causing a cost increase and an enlargement of size.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a valve apparatus such as an electrically operated valve, an electromagnetic valve or the like which is used by being incorporated in a heat pump type cooling and heating system or the like, and more particularly to a valve apparatus provided with a function of a relief valve which can relieve a fluid within a valve chamber in the case that the fluid within the valve chamber comes to a high pressure in a valve closed state.

2. Description of the Conventional Art

Conventionally, as a heat pump type cooling and heating system, there has been known a structure in which two expansion valves are provided for improving an energy saving efficiency or the like, the expansion valve being provided only one normally, in addition to a compressor, an outdoor heat exchanger, an indoor heat exchanger, a four-way switching valve and the like, and check valves are incorporated respectively in two expansion valves in parallel (a structure formed as an expansion valve with check valve) for reducing a pressure loss as much as possible (for example, refer to FIG. 6 of the Japanese Unexamined Patent Publication No. 2010-249246).

Further, there has been recently thought a matter that at least one of two expansion valves with check valve is replaced by an electronically controlled type electrically operated valve (refer to the Japanese Unexamined Patent Publication No. 2009-14056).

FIG. 4shows an example of a heat pump type cooling and heating system which is provided with an electronically controlled type electrically operated valve serving as the expansion valve with check valve mentioned above. A heat pump type cooling and heating system100in an illustrated example is provided with an expansion valve106with a check valve106B corresponding to one of two expansion valves with check valve mentioned above, an electronically controlled type electrically operated valve10′ serving as another of two expansion valves with check valve mentioned above, a distributor108, a refrigerant recovering tank120, and service valves for maintenance (manually operated)121and122, in addition to a compressor101, a four-way switching valve102, an outdoor heat exchanger103and an indoor heat exchanger104.

Describing in detail, the electrically operated valve10′ and the refrigerant recovering tank120are arrange in an outdoor side (the outdoor heat exchanger103side) which is right side of two service valves121and122(which are normally in a fully open state), and the expansion valve106with the check valve106B is arranged in an indoor side (the indoor heat exchanger104side) which is left side of two service valves121and122. A temperature sensitive type (a mechanical type) structure is used as an expansion valve106A of the expansion valve106with the check valve, and the check valve106B is arranged in parallel to the expansion valve106A.

In this cooling and heating system100, at a time of a cooling operation, a refrigerant which is compressed by the compressor101is introduced into the outdoor heat exchanger103via (ports a→d of) the four-way switching valve102as shown by a solid arrow in the drawing, and is heat exchanged with an ambient air so as to be condensed, and the condensed refrigerant flows into the expansion valve106via the distributor108, the electrically operated valve10′ (at a maximum opening degree at this time) and the service valve121, is adiabatically expanded here, thereafter flows into the indoor heat exchanger104, is heat exchanged with an indoor air in the indoor heat exchanger104so as to be evaporated, and cools a room inside. The refrigerant coming out of the indoor heat exchanger104is sucked into the compressor101via the service valve122and (ports b→c of) the four-way switching valve102.

On the contrary, at a time of a heating operation, the refrigerant which is compressed by the compressor101is introduced into the indoor heat exchanger104via (ports a→b of) the four-way switching valve102and the service valve122as shown by a broken arrow in the drawing, and is heat exchanged with the indoor air here so as to be condensed, heats up the room inside, thereafter flows into the electrically operated valve10′ (regulated its opening degree in correspondence to a cooling temperature at this time) through the check valve106B (bypass the expansion valve106A), is depressurized here, is thereafter introduced into the outdoor heat exchanger103via the distributor108, is evaporated here, and is thereafter sucked into the compressor101via (ports d →c of) the four-way switching valve102.

Next, a description will be given of an example of the electronically controlled type electrically operated valve10′ which is used in the cooling and heating system100as mentioned above with reference toFIG. 3. The electrically operated valve10′ of the illustrated example is provided with a valve shaft25which has a lower large diameter portion25aand an upper small diameter portion25band is integrally provided with a valve body portion24having a specific shape (two stages of inverted circular truncated cone shapes respectively with predetermined center angles) in a lower end portion of the lower large diameter portion25a, a valve main body20which has a valve chamber21, a can40which is bonded in a sealing manner in its lower end portion to the valve main body20, a rotor30which is arranged in an inner periphery of the can40so as to be spaced at a predetermined gap α, a stator50which is outward fitted to the can40so as to rotationally drive the rotor30, and a screw feeding mechanism which is arranged between the rotor30and the valve main portion24and moves the valve body portion24close to and away from a valve port22aby utilizing a rotation of the rotor30, and is structured such as to regulate a passing flow rate of the refrigerant by changing a lift amount of the valve body portion24.

The valve chamber21of the valve main body20is provided with a valve seat22formed therein a valve port (an orifice)22awhich the valve body portion24comes close to and away from, a first inlet and outlet11constructed by a conduit pipe joint is provided in a side portion, and a lower portion of the valve main body20is provided with a second inlet and outlet12constructed by a conduit pipe joint so as to be connected to the valve port22a.

The stator50is constructed by a yoke51, a bobbin52, stator coils53and53, a resin mold cover56and the like, a stepping motor is constructed by the rotor30and the stator50, and an elevation driving mechanism for regulating a lift amount (=a valve opening degree) of the valve body portion24with respect to the valve port22ais constructed by the stepping motor, a screw feeding mechanism and the like. In this case, a lower end portion of the stator50is provided with a rotation preventing device46, and a tubular locking device47is firmly attached to a side portion of the valve main body20for locking the rotation preventing device46.

A support ring36is integrally connected to the rotor30, and an upper protruding portion of a lower opened and tubular valve shaft holder32which is arranged in an outer periphery of the valve shaft25and a guide bush26is fixed by caulking to the support ring36, whereby the rotor30, the support ring36and the valve shaft holder32are integrally connected.

The screw feeding mechanism is pressed into and fixed to a fitting hole42provided in the valve main body20in its lower end portion26a, and is constructed by a fixed thread portion (a male thread portion)28which is formed in an outer periphery of the tubular guide bush26to which (the lower large diameter portion25aof) the valve shaft25is inward inserted slidably, and a movable thread portion (a female thread portion)38which is formed in an inner periphery of the valve shaft holder32and is engaged with the fixed thread portion28.

Further, an upper small diameter portion26bof the guide bush26is inward inserted to an upper portion of the valve shaft holder32, and the upper small diameter portion25bof the valve shaft25is inserted to (a through hole formed in) a center of a ceiling portion of the valve shaft holder32. A push nut33is pressed into and fixed to an upper end portion of the upper small diameter portion25bof the valve shaft25.

Further, the valve shaft25is outward inserted to the upper small diameter portion25bof the valve shaft25, and is normally energized downward (in a valve closing direction) by a valve closing spring34which is constructed by a compression coil spring installed in a compression manner between the ceiling portion of the valve shaft holder32and an upper end terrace surface of the lower large diameter portion25ain the valve shaft25. A return spring35constructed by a coil spring is provided in an outer periphery of the push nut33on the ceiling portion of the valve shaft holder32.

To the guide bush26, there is firmly fixed a lower stopper body (a fixing stopper)27which constructs one of rotation and downward movement stopper mechanisms for inhibiting a further rotation and downward movement at a time when the rotor30is rotated and moved downward to a predetermined valve closing position, and to the valve shaft holder32, there is firmly fixed an upper stopper body (a movable stopper)37which constructs another of the stopper mechanisms.

In this case, the valve closing spring34is arranged for obtaining a desired seal pressure in a valve closed state in which the valve body portion24seats on the valve port22a(preventing a leakage), and for reducing an impact at a time when the valve body portion24comes into contact with the valve port22a.

In the electrically operated valve10′ structured as mentioned above, the rotor30and the valve shaft holder32are rotated in one direction with respect to the guide bush26which is fixed to the valve main body20, by supplying an electrifying and exciting pulse to the stator coils53and53in accordance with a first mode, and on the basis of a screw feeding of the fixed thread portion28of the guide bush26and the movable thread portion38of the valve shaft holder32, for example, the valve shaft holder32moved downward, the valve body portion24is pressed to the valve port22a, and the valve port22ais closed (a fully closed state).

At a time point when the valve port22ais closed, the upper stopper body37has not come into contact with the lower stopper body27yet, and the rotor30and the valve shaft holder32further rotate and move downward while the valve body portion24closes the valve port22a. In this case, the valve shaft25(the valve body portion24) does not move downward, however, the valve shaft holder32moves downward, whereby the valve closing spring34is compressed at a predetermined amount. As a result, the valve body24is strongly pressed to the valve port22a, the upper stopper body37comes into contact with the lower stopper body27on the basis of the rotation and the downward movement of the valve shaft holder32, and the rotation and the downward movement of the valve shaft holder32are forcibly stopped even if the pulse supply with respect to the stator coils53and53is thereafter carried on.

On the other hand, if the electrifying and exciting pulse is supplied in accordance with a second mode to the stator coils53and53, the rotor30and the valve shaft holder32are rotated in a reverse direction to that mentioned above with respect to the guide bush26which is fixed to the valve main body20, and the valve shaft holder32moves upward this time on the basis of the screw feeding of the fixed thread portion28of the guide bush26and the movable thread portion38of the valve shaft holder32. In this case, since the valve closing spring34is compressed at the predetermined amount as mentioned above, at a time point of starting the rotation and the upward movement of the valve shaft holder32(a time point of starting the pulse supply), the valve body portion24is not disconnected from the valve port22aand remains in the valve closed state (a lift amount=0) until the valve closing spring34extends at the predetermined amount mentioned above. Further, if the valve shaft holder32is further rotated and moved upward after the valve closing spring34extends at the predetermined amount, the valve body portion24is disconnected from the valve port22aand the valve port22ais opened, so that the refrigerant passes through the valve port22a. In this case, it is possible to optionally and finely regulate the lift amount of the valve body portion24, in other words, an effective opening area (=a valve opening degree) of the valve port22aon the basis of an amount of rotation of the rotor30. Further, since the amount of rotation of the rotor30is controlled by a supply pulse number, it is possible to control a flow rate of the refrigerant at a high precision (refer to the Japanese Unexamined Patent Publication No. 2010-249246).

Accordingly, in the case that the electrically operated valve10′ having the structure mentioned above is incorporated in place of the expansion valve with check valve into the heat pump type cooling and heating system100, it is set to a maximum opening degree (a maximum lift amount) in such a manner as to reduce the pressure loss as much as possible, at a time when the refrigerant is circulated in one direction (at a time of the cooling operation), and it is set such as to finely control the opening degree (the lift amount) in a specific range which is equal to or less than a predetermined value in such a manner as to carry out a flow rate control, at a time when the refrigerant is circulated in another direction (at a time of the heating operation) (refer to the Japanese Unexamined Patent Publication No. 2009-14056).

In this case, in the heat pump type cooling and heating system100provided with the electrically operated valve10′ as mentioned above, if the refrigerant leaks to the indoor side at a time of the maintenance, all the refrigerant within the system leaks into the room inside, and there is a risk that an oxygenless state is generated. Accordingly, the following operation is carried out at a time of the maintenance.

In other words, at a time of the maintenance, the service valve121is closed, the service valve122remains in being open, the four-way switching valve102is set to the same state (a→d, b→c) as the time of the cooling operation, the electrically operated valve10′ is set to the fully closed state (no electrifying state), the compressor101is started, and the refrigerant is sucked out of the indoor side so as to be discharged to the outdoor side. In accordance with this, the refrigerant pressure within the outdoor side piping becomes large, the refrigerant pressure (the high pressure) acts on the valve shaft25(the valve body portion24) from the second inlet and outlet12of the electrically operated valve10′, the valve shaft25(the valve body portion24) is pushed up against the energizing force of the valve closing spring34, and a part of the refrigerant is recovered into the refrigerant recovering tank120through the second inlet and outlet12of the electrically operated valve10′→the valve port22a→the valve chamber21→the first inlet and outlet11(at this time, the electrically operated valve10′ works like a relief valve). If approximately all the refrigerant is collected in the outdoor side (between the service valves122and121) including the tank120, a desired maintenance work is carried out by closing the service valve122and stopping the compressor101.

SUMMARY OF THE INVENTION

As mentioned above, if the outdoor air temperature rises after recovering the refrigerant in the tank120at a time of the maintenance, the pressure of the refrigerant within the tank120is increased. In this case, since the outlet side of the tank120is occluded by the service valve121and the electrically operated valve10′, there is a risk that such a problem that the refrigerant leaks out to the outer portion or the like is generated if the pressure of the refrigerant within the tank120is increased. In order to avoid this, for example, there can be thought a strategy that a flow path bypassing the electrically operated valve10′ is provided, and a relief valve opening at a predetermined pressure or more is interposed in the flow path, however, in accordance with the strategy mentioned above, the number of the parts such as the piping, the joints and the like is increased, and it takes a lot of labor hour and time with a piping connecting work, so that a cost increase of the system is caused, and an occupied space of the electrically operated valve including the relief valve is increased, and an enlargement in size of the electrically operated valve is substantially caused.

Further, if the second inlet and outlet12of the electrically operated valve10′ is connected to the tank120and the first inlet and outlet11is connected to the distributor108, inversely to the illustrated example mentioned above, it is possible to automatically open the electrically operated valve10′ so as to relieve the refrigerant (the pressure) within the tank120to the outdoor side in the case that the pressure of the refrigerant within the tank120becomes higher. However, in accordance with this structure, it becomes hard to carry out a fine flow rate control at a time of the heating operation which is an inverse flow to the refrigerant recovering time and the cooling operation time (since the valve is opened at the low pressure).

The present invention is made by taking the actual condition into consideration, and an object of the present invention is to provide a valve apparatus such as an electrically operated valve, an electromagnetic valve or the like which can automatically relieve a fluid within a valve chamber in the case that a pressure of the fluid in the valve chamber becomes equal to or more than a predetermined pressure in a fully closed state, without causing a great cost increase and an enlargement of size.

In order to achieve the object mentioned above, a valve apparatus in accordance with the present invention is basically comprising:

a valve main body provided with a first inlet and outlet, a valve chamber to which a valve port is open, and a second inlet and outlet which is connected to the valve port;

a valve shaft having a valve body portion which is arranged within the valve chamber so as to open and close the valve port; and

an elevation driving mechanism moving up and down the valve body portion for opening and closing the valve port,

wherein a relief valve is provided within the valve body portion, the relief valve relieving a fluid pressure within the valve chamber to the second inlet and outlet in the case that the fluid pressure within the valve chamber becomes equal to or more than a predetermined pressure in a fully closed state in which the valve port is closed by the valve body portion.

The relief valve is preferably provided with a blank space formed within the valve body portion of the valve shaft, a communication passage and a relief valve port for communicating the blank space and the valve chamber, a relief valve body arranged in the blank space so as to open and close the relief valve port, and a spring member energizing the relief valve body in a direction of pressing it to the relief valve port.

Further, in the valve apparatus mentioned above, the elevation driving mechanism is provided with a stepping motor constructed by a rotor and a stator for controlling a lift amount of the valve body portion, and a screw feeding mechanism converting a rotation of the rotor into a linear movement of the valve shaft.

In the valve apparatus in accordance with the present invention, since the relief valve is provided within the valve body portion of the valve shaft, the relief valve opens and the fluid (the refrigerant) from the first inlet and outlet is relieved to the second inlet and outlet at a time when the pressure of the valve chamber becomes equal to or more than the predetermined pressure. Therefore, it is possible to make the valve apparatus be provided with the function of the relief valve, while preventing the valve apparatus from being enlarged in size.

Further, since the relief valve is provided within the valve body portion, it is possible to make a magnitude (an occupied space) of the electrically operated valve including the relief valve smaller in comparison with the case that the relief valve is provided in such a manner as to bypass the electrically operated valve, and any additional piping part and any piping connecting work are not necessary, so that it is possible to hold down a cost of the system.

Further, in the valve apparatus mentioned above, if the elevation driving mechanism is structured such as to control the lift amount of the valve body portion, it is possible to automatically relieve the pressure of the refrigerant within the tank by the relief valve within the electrically operated valve even if the outdoor air temperature rises and the pressure of the refrigerant within the tank is increased after recovering the refrigerant in the tank at a time of the maintenance, by using it in place of the conventional electrically operated valve which has been employed in the heat pump type cooling and heating system shown inFIG. 4mentioned above, whereby it is possible to prevent such a trouble that the refrigerant leaks out to the outer portion from being generated.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

A description will be given below of an embodiment in accordance with the present invention with reference to the accompanying drawings.

FIG. 1is a partly omitted side elevational view showing an embodiment in the case that the present invention is applied to an electrically operated valve, andFIG. 2is an enlarged view of a substantial part of the electrically operated valve shown inFIG. 1. An electrically operated valve10in accordance with an illustrated embodiment is used in place of the electrically operated valve10′ in accordance with the conventional art in a heat pump type cooling and heating system100shown inFIG. 4. Since a basic structure thereof is approximately the same as the electrically operated valve10′ in accordance with the conventional art shown inFIG. 3mentioned above, an overlapping description is omitted by attaching the same reference numerals to the portions corresponding to the respective portions of the electrically operated valve10′ in accordance with the conventional art shown inFIG. 3here, and a description will be given below mainly of a lower portion of a valve shaft25and a valve main body which correspond to a substantial part (a feature portion).

The electrically operated valve10in accordance with an illustrated embodiment is structured, in the same manner as the conventional example shown inFIG. 3, such that a valve main body20is provided with a first inlet and outlet11, a valve chamber21to which a valve port22ais opened, and a second inlet and outlet12which is connected to the valve port22a, a valve body portion24for opening and closing the valve port22ais provided in a lower portion of the valve shaft25(within the valve chamber21), and a relief valve60is provided within the valve body portion24, the relief valve60relieving a pressure of the valve chamber21to the second inlet and outlet12in the case that a refrigerant pressure within the valve chamber21becomes equal to or more than a predetermined pressure in a fully closed state in which the valve port22ais closed by the valve body portion24.

The relief valve60is provided with a lower surface opened blank space62which is formed within the valve body portion24of the valve shaft25, a communication passage (a transverse hole)63and a relief valve port64for communicating the blank space62and the valve chamber21, a relief ball valve body65which is arranged in an upper portion of the blank space62so as to open and close the relief valve port64, and a circular truncated cone shaped coil spring66which energizes the relief ball valve body65in a direction of pressing it to the relief valve port64.

A ceiling surface of the blank space62is formed as a conical surface, and the relief valve port64is formed in the center of the conical surface. Further, a spring bearing member67is fitted and fixed to a lower end portion of the blank space62in accordance with a press fitting or the like. A relief outlet68is formed in the center of the spring bearing member67.

In the electrically operated valve10in accordance with the present embodiment structured as mentioned above, since the relief valve60having the structure mentioned above is provided within the valve body portion24of the valve shaft25, the relief valve60opens at a time when the pressure of the valve chamber21becomes equal to or more than a predetermined pressure, and the refrigerant from the first inlet and outlet11is relieved to the second inlet and outlet12. Therefore, in the heat pump type cooling and heating system100shown inFIG. 4mentioned above, it is possible to automatically relieve the pressure of the refrigerant within the tank120by the relief valve60within the valve shaft25even if the outdoor air temperature rises and the pressure of the refrigerant within the tank120is increased after recovering the refrigerant in the tank120at a time of the maintenance, by using it in place of the conventional electrically operated valve10′, whereby it is possible to prevent such a trouble that the refrigerant leaks out to the outer portion from being generated.

Further, since the relief valve60is provided within the valve shaft25, it is possible to make a magnitude (an occupied space) of the electrically operated valve including the relief valve smaller in comparison with the case that the relief valve is provided in such a manner as to bypass the electrically operated valve, and any additional piping part and any piping connecting work are not necessary, so that it is possible to hold down a cost of the system.

In this case, in the embodiment, there is exemplified the case that the electrically operated valve to which the present invention is applied is incorporated in the heat pump type cooling and heating system, however, it goes without saying that the incorporated case is not limited to the heat pump type cooling and heating system.

Further, the embodiments shows the case that the present invention is applied to the electrically operated valve, however, it goes without saying that the present invention is not limited to this, but may be applied to any type of valve apparatus such as an electromagnetic valve or the like as long as the relief valve is provided in the valve body portion opening and closing the valve port.