Patent Grant
8956127
The present application is claiming priority of Japanese Patent Application No. 2011-001637, filed on Jan. 7, 2011, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a control valve that is suitable for controlling the discharging capacity of a variable displacement compressor for an automotive air conditioner.
2. Description of the Related Art
An automotive air conditioner generally includes a compressor, a condenser, an expander, an evaporator, and so forth. Here, the compressor discharges a high-temperature and high-pressure gas refrigerant produced by compressing a refrigerant flowing through a refrigeration cycle of a vehicle. The condenser condenses the gas refrigerant. The expander produces a low-temperature and low-pressure refrigerant by adiabatically expanding the condensed liquid refrigerant. The evaporator evaporates the refrigerant and thereby causes a heat exchange of the refrigerant with the air inside the vehicle. The refrigerant evaporated by the evaporator is again brought back to the compressor and thus circulates through the refrigeration cycle.
The compressor is, for example, a variable displacement compressor (hereinafter referred to simply as “compressor” also) capable of controlling the refrigerant discharging capacity in order to maintain a constant level of cooling capacity irrespective of the engine speed. This compressor has a piston for compression linked to a wobble plate that is mounted to a rotational shaft driven by an engine, and the compressor controls the refrigerant discharge rate by changing the stroke of the piston through changes in the angle of the wobble plate. The angle of the wobble plate can be changed continuously by changing the balance of pressure working on both faces of the piston as part of the discharged refrigerant is introduced into an airtight crankcase. The pressure within this crankcase (hereinafter referred to as “crank pressure”) Pc is controlled by a control valve for a variable displacement compressor (hereinafter referred to simply as “control valve” also), which is provided between the discharge chamber of the compressor and the crankcase or between the crankcase and the suction chamber thereof.
One of these control valves, such as one disclosed in Reference (1) in the following Related Art List, controls the crank pressure Pc through control of the amount of refrigerant introduced into the crankcase in accordance with a suction pressure Ps. This control valve includes a pressure-sensing section to develop a displacement by sensing the suction pressure Ps, a valve section for opening and closing the passage from the discharge chamber to the crankcase in response to a drive force from the pressure-sensing section, and a solenoid capable of changing the setting of the drive force from the pressure-sensing section by external electric current. The control valve like this opens and closes the valve section in such a manner as to maintain the suction pressure Ps at a pressure set by the external electric current. Generally, the suction pressure Ps is proportional to a refrigerant temperature at the exit of the evaporator, and thus the freezing or the like of the evaporator can be prevented by maintaining the pressure setting at or above a predetermined value. Also, when the engine load of a vehicle is high, the compressor can be operated at the minimum capacity by fully opening the valve section with the solenoid turned off and by setting the wobble plate substantially at a right angle to the rotational shaft with the crank pressure Pc set high.
It is to be noted that the pressure-sensing section of a control valve like this generally forms a reference pressure chamber surrounded by a pressure-sensing member such as a diaphragm or a bellows. And the pressure-sensing section of the control valve is provided with a spring disposed in the reference pressure chamber. Here, this spring exerts a load in such a direction that the pressure-sensing member extends. The drive force against a solenoidal force is created by the displacement of the pressure-sensing member that is caused by a pressure difference between the inside and the outside of the reference pressure chamber. The drive force against the solenoidal force is adjusted by the load setting for the spring of the pressure-sensing section. The load setting is normally accomplished through positional adjustments of the pressure-sensing section and its adjacent members assembled in the direction of axis line at a manufacturing stage of the control valve.
However, it is desirable that fine adjustment can be made to the suction pressure Ps after the control valve is installed if the suction pressure Ps is to be set with high accuracy. In this regard, a type having the pressure-sensing section disposed at one end of the control valve body allows such fine adjustment by physically deforming a part of the pressure-sensing section after installation in the direction of the axis line. However, it is difficult to accomplish such fine adjustment with the type having the pressure-sensing section disposed inside the control valve body such as one disclosed in Reference (1).
The present invention has been made in view of the foregoing problems, and a purpose thereof is to provide a technology that enables easy external adjustment of the setting of the drive force of a pressure-sensing section in a control valve for a variable displacement compressor, which is a so-called Ps sensing type having the pressure-sensing section inside the control valve body.
In order to resolve the aforementioned problems, a control valve, for a variable displacement compressor, according to one embodiment of present invention is a control vale for the variable displacement compressor for varying a discharging capacity of the variable displacement compressor by controlling a flow rate of refrigerant to be introduced from a discharge chamber to a crankcase of the compressor in such a manner that a suction pressure of a suction chamber is kept at a pressure setting, and the control valve includes: a body having a crankcase communicating port that communicates with the crankcase from one end side thereof, a discharge chamber communicating port that communicates with the discharge chamber, and a suction chamber communicating port that communicates with the suction chamber, wherein the crankcase communicating port, the discharge chamber communicating port, and the suction chamber communicating port are arranged in this order from one end side of the body; a main valve element configured to open and close a main valve provided in a refrigerant passage communicating between the discharge chamber communicating port and the crankcase communicating port; a solenoid, provided at the other end side of the body, configured to drive the main valve element in a valve closing direction in accordance with an amount of current supplied; a pressure-sensing section including a pressure-sensing member displaced by sensing the suction pressure, wherein the pressure sensing section is provided inside an inner space surrounded by the body and the solenoid, and the pressure sensing section exerts a drive force against solenoidal force caused by a displacement of the pressure-sensing member; and a shaft configured to adjust the drive force of the pressure-sensing section by adjusting a fixed position at one end of the shaft, the shaft extending from one end side thereof to the other side thereof along an axis line, one end of the shaft being fixed to the one end side of the body and the other end of the shaft being joined with the pressure-sensing section.
By employing this embodiment, provided is the shaft extending along the direction of axis line from one end of the body toward the other end thereof, so that the fine adjustment of the drive force by the pressure-sensing section can be easily accomplished when the fixed position of the shaft is readjusted after the control valve has been assembled. Note that shaft may be fixed to the body using a press-fitting process. In such a case, the load setting of the pressure-sensing section can be fine-adjusted by adjusting a press-fitting amount thereof. Or the shaft itself may have a screw structure. In such a case, the load setting of the pressure-sensing section can be fine-adjusted by a screwing amount of the shaft.
Embodiments will now be described by way of examples only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several Figures in which:
The present invention will now be described in detail based on preferred embodiments with reference to the accompanying drawings. This does not intend to limit the scope of the present invention, but to exemplify the invention.
In the following description, for convenience of description, the positional relationship in each structure may be expressed as “vertical” or “up-down” with reference to how each structure is depicted in Figures.
The control valve 1 according to this embodiment is constituted as a control valve (electromagnetic valve) for controlling a not-shown variable displacement compressor (hereinafter referred to simply as “compressor”) to be installed for a refrigeration cycle of an automotive air conditioner. This compressor discharges a high-temperature and high-pressure gas refrigerant produced by compressing a refrigerant flowing through the refrigeration cycle. The gas refrigerant is then condensed by a condenser (external heat-exchanger) and further adiabatically expanded by an expander so as to become a misty, low-temperature and low-pressure refrigerant. This low-temperature and low-pressure refrigerant is evaporated by an evaporator, and the evaporative latent heat cools the air of an interior of a vehicle. The refrigerant evaporated by the evaporator is again brought back to the compressor and thus circulates through the refrigeration cycle. This compressor has a piston for compression coupled to a wobble plate which is mounted to a rotational shaft driven by an engine of the vehicle, and the compressor controls the refrigerant discharge rate by changing a stroke of the piston through changes in an angle of the wobble plate. The control valve 1 changes the angle of the wobble plate and further the discharging capacity of the compressor by controlling a flow rate of the refrigerant to be introduced from a discharge chamber to a crankcase of the compressor.
The control valve 1 is constituted as a so-called Ps sensing valve that controls the flow rate of the refrigerant to be introduced from the discharge chamber to the crankcase so that a suction pressure Ps of the compressor can be maintained at a pressure setting. The control valve 1 is constituted by integrally assembling a valve unit 2, which includes a valve section for opening and closing a refrigerant passage for leading part of discharged refrigerant to the crankcase, and a solenoid 3, which controls the flow rate of the refrigerant to be led into the crankcase by controlling the opening degree of the valve section. The valve unit 2 includes a body 5 of stepped cylindrical shape, a valve section disposed inside the body 5, and a power element (“pressure-sensing section”) 4, disposed inside the body 5, which generates drive force to open and close the valve section. The body 5 and the solenoid 3 are joined together by a connecting member 6.
The body 5 has a port 12 (“crankcase communicating port”), a port 14 (“discharge chamber communicating port”), and a port 16 (“suction chamber communicating port”) in this order from top down. Formed within the body 5 are a first refrigerant passage communicating between the port 12 and the port 14 and a second refrigerant passage communicating between the port 12 and the port 16. Whereas a main valve is provided on the first refrigerant passage to open or close it, a sub-valve is provided on the second refrigerant passage to open or close it.
The port 14 communicates with the discharge chamber of the compressor, thereby introducing the refrigerant at a discharge pressure Pd. The port 12 communicates with the crankcase of the compressor, thereby leading out the refrigerant at the crank pressure Pc having passed the main valve toward the crankcase and, on the other hand, leading in the refrigerant at the crank pressure Pc discharged from the crankcase at the time of compressor startup. The refrigerant thus led in is led to the sub-valve. The port 16 communicates with the suction chamber of the compressor, thereby leading in the refrigerant at the suction pressure Ps and, on the other hand, leading out the refrigerant at the suction pressure Ps via the sub-valve toward the suction chamber at the time of compressor startup.
The body 5 has a main valve element 18 and a sub-valve element 20 disposed coaxially. The main valve element 18, which is of a stepped cylindrical shape with reduced diameter in an upper portion, is slidably supported by the body 5 in the upper portion. The sub-valve element 20 is cylindrical in shape, and a lower half thereof is slidably inserted in the reduced diameter portion of the main valve element 18. A flange portion extending radially outward is provided in an upper part of the sub-valve element 20, and a main valve seat 22 is formed on a lower surface of the flange portion. A communicating hole 23 communicating the inside and the outside of the sub-valve element 20 is provided in a side wall inside of the main valve seat 22 of the sub-valve element 20. The main valve is opened and closed with the top end of the main valve element 18 touching and leaving the main valve seat 22, thereby adjusting the flow rate of refrigerant flowing from the discharge chamber to the crankcase. The sub-valve element 20 communicates with the port 12 at an upper end opening, and the inside passage forms a first refrigerant passage at the opening of the main valve and forms a second refrigerant passage at the opening of the sub-valve.
The power element 4 is disposed inside a pressure chamber 25 (inner space) which is surrounded by the lower half of the body 5 and the solenoid 3. The power element 4 contains a bellows 24 that expands or contracts by sensing the suction pressure Ps. And the bellows 24, with its displacement, exerts a drive force against solenoidal force to the main valve element 18. The main valve element 18 is joined with the power element 4 in such a manner as to be able to move together. A detailed description of the power element 4 will be given later.
Provided in an upper half of the body 5 is a shaft 26 extending along the axis line thereof. The shaft 26 is secured with one end thereof press-fitted into an upper end of the body 5 and the other end thereof connected to the power element 4 via a valve seat forming member 28. The valve seat forming member 28 is disk-shaped and has a sub-valve seat 27 formed on the face thereof opposite to a lower end opening of the sub-valve element 20. The sub-valve is opened and closed with the sub-valve element 20 touching and leaving the sub-valve seat 27, thereby adjusting the flow rate of refrigerant being relieved from the crankcase to the suction chamber. Set between the valve seat forming member 28 and the power element 4 is a spring 29 (functioning as a “biasing member”) that biases the main valve element 18 in a valve opening direction. Set between the sub-valve element 20 and the body 5 is a spring 21 that biases the sub-valve element 20 in a valve closing direction of the sub valve.
On the other hand, the solenoid 3 includes a cylindrical case 30, which functions as a yoke also, a sleeve 31, which is a bottomed cylinder fixed to the case 30, a cylindrical core 32, which is inserted in an upper half of the sleeve 31, a cylindrical plunger 33, which is housed in a lower half of the sleeve 31 in a position axially opposite to the core 32, an electromagnetic coil 34, which generates a magnetic circuit by externally supplied current, and an end member 35, which is provided to seal a lower end opening of the case 30. An insertion hole 38 is so formed as to penetrate the central part of the connecting member 6. And the core 32 is secured to the connecting member 6 in such a manner that an upper end part of the core 32 is swaged outward after passing through the insertion hole 38.
A cylindrical transmitting rod 36 is inserted in such a manner as to penetrate axially the center of the core 32. A lower end of the transmitting rod 36 is press-fitted coaxially in an upper end of the plunger 33. As a result, the transmitting rod 36 and the plunger 33 are fixed to each other, and an inner passage 37 is so formed as to penetrate both the aforementioned parts in the direction of axis line. An upper end of the transmitting rod 36 is joined with the power element 4, so that the transmitting rod 36 transmits the solenoidal force to the main valve element 18 by way of the power element 4.
The suction pressure Ps in the pressure chamber 25, on one hand, is led into the inner passage 37 through the clearance between the transmitting rod 36 and the power element 4 and then into a back pressure chamber 39 of the plunger 33 after passing through the inner passage 37. The suction pressure Ps in the pressure chamber 25, on the other hand, is led into the sleeve 31 through the clearance between the core 32 and the transmitting rod 36.
The sleeve 31, which is made of a nonmagnetic material, has a slightly protruding bottom center portion, as shown in
The end member 35 is installed in such a manner as to seal the entire structure inside the solenoid 3 contained in the case 30 from below. The end member 35 is molded (injection molding) of a corrosion-resistant resin, and the resin material is filled into gaps between the case 30 and the electromagnetic coil 34 also. With the resin material filled into the gaps between the case 30 and the electromagnetic coil 34, the heat release performance is improved because the heat occurring in the electromagnetic coil 34 can be easily conveyed to the case 30. The ends of the connection terminals 44 are led out from the end member 35 and connected to a not-shown external power supply.
The body 5 is constituted as an assembly of a first body 51 of a stepped cylindrical shape and a second body 52 of a bottomed cylindrical shape fitted on an upper end opening of the first body 51. With a lower half of the second body 52 press-fitted into an upper end portion of the first body 51, the assembly as a whole forms a bottomed and stepped cylindrical body 5. The port 12 is provided in the bottom of the second body 52. The insertion hole 54 is provided in the center of the bottom of the second body 52, where the shaft 26 is press-fitted. The shaft 26, which is locked to a bottom center of the second body 52, is supported by one end thereof and extends downward along the axis line.
The valve seat forming member 28 has a fitting section 55 protruding downward in a middle portion thereof, and the fitting section 55 assures the centering of the valve seat forming member 28 positioned at a lower end of the shaft 26 fitted thereinto. Since the fitting state is maintained by the biasing force of the spring 29, the valve seat forming member 28 is supported by the shaft 26.
The main valve element 18 has a larger diameter body part thereof disposed in the pressure chamber 25. Disposed inside the larger diameter part are the valve seat, forming member 28, the power element 4, and the spring 29. The upper part of the main valve element 18, which is of a smaller diameter, is slidably supported by the upper part of the first body 51, and the main valve is opened and closed with the end portion of the main valve element 18 touching and leaving the main valve seat. Provided in a position corresponding to the port 16 of the main valve element 18 is a communicating hole 56 communicating the inside and the outside of the main valve element 18.
Fitted on the outer periphery of the upper end portion of the sub-valve element 20 is an O-ring 70 for sealing. This prevents the high-pressure refrigerant introduced through the port 14 from leaking into the port 12 by passing through the gap passage between the sub-valve element 20 and the second body 52.
The power element 4 is so structured that the upper end opening of the bellows 24 is closed by a first stopper 60 (“base member”) and the lower end opening of the bellows 24 is closed by a second stopper 62 (“base member”). The interior of the bellows 24 is an airtight reference pressure chamber S, and a spring 64 is interposed between the first stopper 60 and the second stopper 62 in such a manner as to bias the bellows 24 in an expanding direction. The reference pressure chamber S is in a vacuum state according to the present embodiment. Provided in the middle of a top surface of the first stopper 60 is a circular recess of a predetermined depth along the direction of axis line, where the fitting section 55 of the valve seat forming member 28 is joined in a fitted manner. Also provided in the middle of a lower surface of the second stopper 62 is a circular recess of a predetermined depth along the direction of axis line, where the upper end portion of the transmitting rod 36 is joined in a fitted manner. The main valve element 18 is secured such that the lower end portion of the main valve element 18 is press-fitted on the second stopper 62.
Since the spring 64 exerts a biasing force in such a manner as to move the first stopper 60 and the second stopper 62 apart from each other, the bellows 24 expands or contracts in the direction of axis line (opening/closing direction of the valve section) according to a pressure difference between the suction pressure Ps of the pressure chamber 25 and the reference pressure of the reference pressure chamber S. However, if the pressure difference becomes large, the end surfaces of the first stopper 60 and the second stopper 62 will abut against each other at a predetermined contraction of the bellows 24, thus restricting the contraction.
In this arrangement, if the suction pressure Ps in the pressure chamber 25 drops lower than a predetermined pressure setting Pset, the bellows 24 will be deformed in an expanding direction, and the first stopper 60 will be stopped by the valve seat forming member 28. As a result, there will be a force to press down the second stopper 62, which is a force working to reduce the solenoidal force of the solenoid 3. This pressure setting Pset is basically adjusted in advance by the spring load of the spring 64. And this pressure setting Pset is set as a pressure value at which the freezing of the evaporator can be prevented in view of the relationship between the temperature in the evaporator and the suction pressure Ps. The pressure setting Pset can be changed by varying the supply current (set current) to the solenoid 3. In the present embodiment, the load setting of the spring 64 can be fine-adjusted by readjusting a press-fitting amount of the shaft 26 when the assembly of the control valve 1 is nearly completed. By employing this method, the pressure setting Pset can be adjusted with accuracy.
According to the present embodiment, the sub-valve element 20 is so formed that an upper sliding portion of the sub-valve element 20 has an outside diameter B (which is equal to an inside diameter of O-ring 70) which is smaller, by a predetermined amount, than an effective pressure-receiving diameter A of the main valve element 18. Hence, the pressure difference (Pd−Pc) between the discharge pressure Pd and the crank pressure Pc works downward on the sub-valve element 20. Therefore, even when the discharge pressure Pd led in through the port 14 rises high and thus the pressure difference (Pd−Pc) becomes large in a closed state of the main valve with the main valve element 18 touching the main valve seat 22, a circumstance can be prevented in which the main valve is opened with the sub-valve element 20 compressing the spring 21. On the other hand, when the main valve is opened, the travel of the sub-valve element 20 will be stopped by the valve seat forming member 28. Accordingly, a situation in which the opening of the main valve is blocked by the follow-up motion of the sub-valve element 20 after the main valve element 18 can be avoided, too. When the compressor is under control, the state of the sub-valve element 20 touching the sub-valve seat 27 under the effect of the biasing force of the spring 21 (sub-valve being closed) will be maintained.
Now, an operation of the control valve will be explained.
While the solenoid 3 is not electrically conducting, namely while the automotive air conditioner is not operating, no suction power between the core 32 and the plunger 33 is in effect in the control valve 1. Also, since the spring 29 biases the second stopper 62 downward, the main valve element 18 is apart from the main valve seat 22 and therefore the main valve is fully opened, as shown in
At this time, the refrigerant, having the discharge pressure of Pd, which is introduced from the discharge chamber of the compressor passes through the fully opened main valve and flows into the crankcase from the port 12. Thus, the crank pressure Pc rises and then the compressor performs the minimum capacity operation. Since, at this time, the first stopper 60 is apart from the valve seat forming member 28 (i.e., the state in which any operation linkage is canceled), the power element 4 is substantially disabled.
On the other hand, when a maximum control current is supplied to the coil 34 of the solenoid 3 at the startup or the like of the automotive air conditioner, the plunger 33 is attracted by a maximum suction force of the core 32. Then, as shown in
In other words, supplying the starting current to the solenoid 3 causes the main valve to be closed and thereby restricts the introduction of discharged refrigerant into the crankcase. At the same time, supplying the starting current thereto displaces the main valve element 18 and immediately opens the sub-valve so as to promptly relieve the refrigerant in the crankcase into the suction chamber. In the present embodiment, although the pressure of the crankcase is reduced via a decompression passage (e.g., an orifice joining the crankcase to the suction chamber) formed in the compressor, the decompression responsiveness can be maximally enhanced by quickly opening the sub-valve in this manner and therefore the compressor can be promptly started.
Here, in a controlled state where the value of current supplied to the solenoid 3 is set to a predetermined value, the main valve element 18 operates as an element different from the sub-valve element 20 and adjusts the opening degree of the main valve, as shown in
As, for example, the refrigeration load becomes large and the suction pressure Ps becomes higher than the pressure setting Pset, the bellows 24 contracts with the result that the second stopper 62 and eventually the main valve element 18 are displaced relatively upward (in the valve closing direction). As a result, the valve opening degree of the main valve becomes small and therefore the compressor operates in a such manner as to increase the discharging capacity. As a result, a change is made in a direction that the suction pressure Ps drops. Conversely, as the refrigeration load becomes small and the suction pressure Ps becomes lower than the pressure setting Pset, the bellows 24 expands. As a result, the biasing force by the power element 4 works in such a direction as to decrease the solenoidal force. As a result, the force toward the main valve element 18 in the valve closing direction is reduced and the valve opening degree of the main valve becomes large. Thus, the compressor operates in such a manner as to reduce the discharging capacity. As a result, the suction pressure Ps is maintained at the pressure setting Pset, thereby preventing excess cooling.
In the control valve 1 as described above, provided is the shaft 26 extending along the direction of axis line from one end of the body 5 toward the other end thereof, and thereby the fixed position of the shaft 26 is readjusted after the control valve 1 has been assembled. Hence, the fine adjustment of the drive force by the power element 4 can be accomplished with ease. That is, the pressure setting Pset of the suction pressure Ps can be accurately adjusted using a simple structure.
Also, in the control valve 1, the transmitting rod 36 and the main valve element 18 are rigidly joined together by way of the second stopper 62 without the medium of an elastic member or the like disposed therebetween, and thereby solenoidal force is directly conveyed to the main valve element 18. Thus, the main valve can be immediately closed when the solenoid 3 is switched from on to off and thereby the starting current is supplied to the solenoid 3. Also, the main valve seat 22 is formed integrally with the sub-valve element 20, so that the sub-valve element 20 can also function as a movable valve seat. Thus, the sub-valve is opened simultaneously when the main valve is closed. This not only restricts the introduction of refrigerant into the crankcase but also allows discharging the refrigerant from the crankcase, so that the compressor can be promptly started.
A description is now given of a second embodiment of the present invention. A control valve according to the second embodiment shares many common features with the first embodiment except for the structure and arrangement of main valve and sub-valve. Thus, the structural components of the second embodiment similar to those of the first embodiment are given the identical reference numerals and the description thereof is omitted as appropriate.
As shown in
As shown in
Now, an operation of the control valve will be explained.
While the solenoid 3 is not electrically conducting, no solenoidal force works in the control valve 201. Thus, as shown in
On the other hand, when a maximum control current is supplied to the coil 34 of the solenoid 3 at the startup or the like of the automotive air conditioner, the solenoidal force is directly transmitted to the main valve element 218 by way of the transmitting rod 36 and the second stopper 62, as shown in
Then, in the controlled state where the value of current supplied to the solenoid 3 is set to a predetermined value, the suction pressure Ps is relatively low. Thus, the bellows 24 expands with the sub-valve element 220 seated on the first sub-valve seat 230 and thereby the sub-valve being closed, as shown in
A description is now given of a third embodiment of the present invention. A control valve according to the third embodiment shares many common features with the first embodiment except for the structure and arrangement of main valve and sub-valve. Thus, the structural components of the third embodiment similar to those of the first embodiment are given the identical reference numerals and the description thereof is omitted as appropriate.
As shown in
As shown in
Now, an operation of the control valve will be explained.
While the solenoid 3 is not electrically conducting, no solenoidal force works in the control valve 301. Thus, as shown in
On the other hand, when a maximum control current is supplied to the coil 34 of the solenoid 3 at the startup or the like of the automotive air conditioner, the solenoidal force is directly transmitted to the main valve element 318 by way of the transmitting rod 36 and the base member 330, as shown in
Then, in the controlled state where the value of current supplied to the solenoid 3 is set to a predetermined value, the suction pressure Ps is relatively low. Thus, the bellows 24 expands with the sub-valve element 320 seated on the first sub-valve seat 327 and thereby the sub-valve being closed, as shown in
The description of the present invention given above is based upon illustrative embodiments. These embodiments are intended to be illustrative only and it will be obvious to those skilled in the art that various modifications could be further developed within the technical idea underlying the present invention and that such additional modifications are also within the scope of the present invention.
In the above-described embodiments, the bellows is used, for example, as a pressure-sensing member of the power element but, for example, a diaphragm may be used instead.
In other words, a control valve 401 according to the present modification is constituted by integrally assembling a valve unit 402 and a solenoid 3. A power element 404 of the control valve 401 includes (1) a hollowed housing 460, (2) a diaphragm 450 serving as a pressure-sensing member so disposed that the interior of the housing 460 is partitioned into an enclosed space S1 (which functions as “reference pressure chamber”) and an open space S2, and (3) a spring 64 disposed in the enclosed space S1.
The housing 460 is formed such that a first housing 461 and a second housing 462 are joined together. The housing 460 is formed in the shape of a vessel or the like such that while the diaphragm 450 is held between the first housing 461 and the second housing 462, the outer periphery of the first housing 461 and the second housing 462 is welded along its joint part thereof. Since the welding is performed in a vacuum atmosphere, the enclosed space S1 is in a vacuum state. However, the enclosed space S1 may be filled with air, instead.
A sub-valve element 420 is joined to a top surface of the first housing 461. A communicating hole 234 communicating the inside and the outside of a sub-valve element 420 is provided in a side wall of the sub-valve element 420. The first housing 461 is of a stepped cylindrical shape such that the diameter thereof contracts upward, and a side wall of the sub-valve element 420 is supported by the first housing 461 on the upper end thereof. The main valve element 218 is fixed to the first housing 461 in a fitted manner. Provided in the first housing 461 is a communicating hole 56 communicating the inside and the outside of the first housing 461. The second housing 462, which is of a bottomed cylindrical shape, is joined with the first housing 461 on an upper end of the second housing 462. A disk is each placed in the diaphragm 450 on a surface thereof at a second housing 462 side and on the bottom of the second housing 462, and a spring 64 used to adjust the load setting is set between these disks.
In this modification, if the suction pressure Ps in the pressure chamber 25 drops lower than a predetermined pressure setting Pset, the diaphragm 450 will expand in such a manner as to enlarge the enclosed space S1 and drive the sub-valve element 420 in a valve closing direction. This pressure setting Pset is adjusted in advance by the spring load of the spring 64. And this pressure setting Pset is set as a pressure value at which the freezing of the evaporator can be prevented in view of the relationship between the temperature in the evaporator and the suction pressure Ps. The spring load of the spring 64 can be adjusted using a press-fitting amount of the shaft 26. Note that the operation performed by the control valve 401 is similar to that described in the second embodiment and therefore the description thereof is omitted here.
In this modification, a description has been given of an example where the bellows used in the second embodiment is replaced by the diaphragm. However, this should not be considered as limiting and, for example, the bellows may be replaced by a diaphragm or the like in the first and the third embodiment.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-001637 | Jan 2011 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6439858 | Kume et al. | Aug 2002 | B1 |
| 20050201866 | Hirota | Sep 2005 | A1 |
| 20060039799 | Hirota | Feb 2006 | A1 |
| Number | Date | Country |
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| 2836521 | Aug 2003 | FR |
| 2008-045526 | Feb 2008 | JP |
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| European Search Report from application No. 12150307.2-1608/2474737 dated Nov. 14, 2014 (6 pages). |
| Number | Date | Country | |
|---|---|---|---|
| 20130001450 A1 | Jan 2013 | US |
