Valve unit

Abstract

To provide a system configuration capable of effectively coping with refrigerant leakage if caused in a refrigeration cycle adopting natural refrigerant.SOLUTION: A refrigeration cycle includes a refrigerant circulation passage for circulating refrigerant, a compressor arranged in the refrigerant circulation passage for compressing and discharging the refrigerant, a first heat exchanger arranged on the downstream side of the compressor in the refrigerant circulation passage, and a second heat exchanger arranged on the upstream side of the compressor in the refrigerant circulation passage. A valve unit 114 includes an electric expansion valve 1 for applying decompression and expansion to the refrigerant flowing from a first heat exchanger to the second heat exchanger, and a sensor 162 for detecting refrigerant leakage from the refrigerant circulation passage.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a valve unit suitable for countermeasures against refrigerant leakage in a refrigeration cycle.

Background Art

[0002] With the recent spread of electric vehicles, the development of their air conditioning systems has also been promoted. Since electric vehicles do not have a heat source by an internal combustion engine, a heat pump type air conditioning device that performs cycle operation using a refrigerant for both cooling and heating is adopted (see Patent Document 1). Such an air conditioning device is configured by arranging a compressor, an outdoor heat exchanger, an expansion device, an evaporator, an indoor heat exchanger, etc. in a refrigerant circulation passage, but the configuration of the refrigerant circulation passage and the arrangement configuration of each device that are optimal vary depending on the type of refrigerant used.

[0003] In recent years, as part of measures against global warming, among fluorine-based refrigerants, those with a low ozone depletion potential and a low global warming potential are adopted, but the conversion to natural refrigerants with a smaller environmental load is also being considered. For example, propane, carbon dioxide, etc. are known as natural refrigerants with relatively high refrigeration effects.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, it is of course necessary to prevent such leakage of the refrigerant into the atmosphere. However, in the event of a leak, appropriate measures such as promptly detecting it and stopping the refrigeration cycle must be taken. Therefore, it is conceivable to provide a sensor for detecting refrigerant leakage, but care is required in installing the sensor. In particular, refrigerants mainly composed of hydrocarbons such as propane have high flammability (that is, they are highly flammable), and the usable capacity in the refrigerant circulation passage is regulated both at home and abroad. For this reason, it is necessary to reduce the capacity of the equipment and piping that make up the refrigerant circulation passage. On the other hand, since the compressor and its vicinity become hot, it is not suitable as the installation environment for the sensor.

[0006] One object of the present invention is to provide a suitable installation configuration for a sensor for detecting refrigerant leakage in a refrigeration cycle.

Means for Solving the Problems

[0007] One aspect of the present invention is a valve unit applied to a refrigeration cycle including a refrigerant circulation passage for circulating a refrigerant, a compressor disposed in the refrigerant circulation passage for compressing and discharging the refrigerant, a first heat exchanger disposed downstream of the compressor in the refrigerant circulation passage, and a second heat exchanger disposed upstream of the compressor in the refrigerant circulation passage. This valve unit integrally includes an electric expansion valve for decompressing and expanding the refrigerant flowing from the first heat exchanger toward the second heat exchanger, and a sensor for detecting refrigerant leakage from the refrigerant circulation passage.

[0008] According to this aspect, a sensor for detecting refrigerant leakage is integrated with an electric expansion valve. To operate a refrigeration cycle, a compressor, a first heat exchanger, a second heat exchanger, and an expansion device are minimally required. Here, a sensor is integrally provided in the electric expansion valve that functions as the expansion device. That is, since the compressor becomes hot, it is not suitable as an installation target for the sensor. Since heat exchangers generally have a heat sink structure (concave-convex structure) for heat exchange, dedicated jigs or the like are required to install the sensor. In this regard, the electric expansion valve has no such problem, and the sensor can be easily installed. Also, thereby, the piping that is not an installation target for the sensor can be made smaller or reduced, so it can be realized without problems even when using a highly flammable natural refrigerant.

Advantages of the Invention

[0009] According to the present invention, a suitable installation configuration can be provided for a sensor that detects refrigerant leakage in a refrigeration cycle.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, for convenience, the positional relationship of each structure may be expressed based on the illustrated state. Also, for the following embodiments and their modifications, substantially the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0012] In this embodiment, in a refrigeration cycle using a natural refrigerant, in the event of refrigerant leakage, it is detected by a sensor, and appropriate measures such as promptly stopping the refrigeration cycle are taken. When installing this sensor in the refrigerant unit, a suitable installation configuration using a valve unit is adopted. First, a specific example of the system to which this valve unit is applied will be described below, and then the details of the valve unit will be described.

[0013] FIG. 1 is a system configuration diagram of a vehicle air conditioner according to an embodiment. The air conditioner 100 has a refrigerant circulation circuit 101 that circulates a natural refrigerant and a coolant circulation circuit 102 that circulates a coolant, and is a heat pump type air conditioner that exchanges heat between them. In this embodiment, propane is adopted as the natural refrigerant. The coolant may be, for example, an aqueous solution (cooling water) mainly composed of ethylene glycol or propylene glycol.

[0014] In the process where the refrigerant circulates in the refrigerant circulation circuit 101 while changing its state, the air conditioner 100 cools or heats the coolant in the coolant circulation circuit 102 by using the heat of the refrigerant. The air in the vehicle interior is cooled or heated by the coolant to perform air conditioning in the vehicle interior. The air conditioner 100 also functions as a cooling device that appropriately cools the battery mounted on the vehicle. In a modification, the coolant circulation circuit 101 may have a circuit that warms the battery.

[0015] The air conditioner 100 includes a water-refrigerant heat exchanger 104 and a water-refrigerant heat exchanger 106 for performing heat exchange between a refrigerant circulation circuit 101 and a coolant circulation circuit 102. The water-refrigerant heat exchanger 104 functions as the "first heat exchanger", and the water-refrigerant heat exchanger 106 functions as the "second heat exchanger".

[0016] The refrigerant circulation circuit 101 is configured by connecting a compressor 110, a water-refrigerant heat exchanger 104, a water-refrigerant heat exchanger 106, and an accumulator 112 with pipes. The water-refrigerant heat exchanger 104 is located on the downstream side of the compressor 110, and the water-refrigerant heat exchanger 106 is located on the upstream side of the compressor 110. A valve unit 114 is arranged on the upstream side of the water-refrigerant heat exchanger 106. The refrigerant circulation circuit 101 is provided outside the vehicle cabin.

[0017] The outlet (discharge chamber) of the compressor 110 is connected to the inlet of the water-refrigerant heat exchanger 104 via a first passage 201, and the outlet of the water-refrigerant heat exchanger 104 is connected to the inlet of the water-refrigerant heat exchanger 106 via a second passage 202. The outlet of the water-refrigerant heat exchanger 106 is connected to the inlet of the accumulator 112 via a third passage 203. The outlet of the accumulator 112 is connected to the inlet (suction chamber) of the compressor 110 via a fourth passage 204.

[0018] Since propane, which is a refrigerant, is highly flammable, the refrigerant filling amount in the refrigerant circulation circuit 101 is limited compared to the case of using a conventional fluorine-based refrigerant. For this reason, the volume of the pipes forming the refrigerant circulation circuit 101 is small, and the equipment arranged in the circulation passage is also minimized.

[0019] The compressor 110 is configured as an electric compressor that houses a motor and a compression mechanism in a housing. The compressor 110 introduces refrigerant at a suction pressure Ps through its suction chamber, compresses it, and discharges it as refrigerant at a discharge pressure Pd. The compressor 110 is driven by a supply current from a battery, and the discharge capacity of the refrigerant changes according to the rotational speed of the motor. Since the electric compressor itself is well-known, its description is omitted.

[0020] The water-refrigerant heat exchanger 104 functions as a condenser that dissipates heat from the refrigerant passing through its interior. The valve unit 114 functions as an expansion device (expansion valve) capable of decompressing and expanding the refrigerant that has passed through the water-refrigerant heat exchanger 104. The water-refrigerant heat exchanger 106 functions as an evaporator that evaporates the refrigerant passing through its interior during the cooling operation.

[0021] On the other hand, the coolant circulation circuit 102 is configured by connecting the water-refrigerant heat exchanger 106, the cooler core 120, the heater core 122, the water-refrigerant heat exchanger 104, the outdoor heat exchanger 108, etc. with pipes, and the first to fourth circulation passages (described later) are switched according to the operating state of the refrigeration cycle. Heat exchange occurs as the coolant circulates through the coolant circulation circuit 102. Outside the vehicle compartment, the outdoor heat exchanger 108 and the battery unit 140 are provided in the coolant circulation circuit 102. The fan 109 is arranged so as to face the outdoor heat exchanger 108. By driving the fan 109, outside air is introduced, and heat exchange is performed between the coolant flowing through the outdoor heat exchanger 108 and the outside air. The battery unit 140 includes a battery that is the power source of the vehicle and a heat exchanger for the battery.

[0022] An indoor air-conditioning unit 124 for performing heat exchange of air is provided in the vehicle compartment. The blower 126, the cooler core 120, and the heater core 122 are arranged in the duct constituting the indoor air-conditioning unit 124 from the upstream side in the air flow direction. An air mix door 128 is rotatably provided upstream of the heater core 122, and the ratio of the air volume passing through the heater core 122 to the air volume bypassing the heater core 122 is adjusted.

[0023] The coolant circulation circuit 102 has a first passage 221 where the heater core 122 is disposed, a second passage 222 where the water-refrigerant heat exchanger 104 is disposed, a third passage 223 where the water-refrigerant heat exchanger 106 is disposed, and a fourth passage 224 where the outdoor heat exchanger 108 is disposed. The connection of these passages is switched between the cooling operation and the heating operation. A first connection point with the first passage 221, the third passage 223, and the fourth passage 224 is provided at the upstream end of the second passage 222, and a switching valve 130 is provided at the first connection point. Also, a second connection point with the first passage 221, the third passage 223, and the fourth passage 224 is provided at the downstream end of the second passage 222, and a switching valve 132 is provided at the second connection point. The switching valves 130 and 132 are four-way valves. Pumps 134 and 136 for circulating the coolant are provided in the second passage 222 and the third passage 223, respectively.

[0024] A cooler core 120 is provided on the downstream side of the water-refrigerant heat exchanger 106 in the third passage 223. A branch point p1 is provided on the upstream side of the cooler core 120 in the third passage 223, and a confluence point p2 is provided on the downstream side. A bypass passage 226 is provided to connect the branch point p1 and the confluence point p2, and an on-off valve 142 is provided in the bypass passage 226. The on-off valve 142 is a solenoid-driven electromagnetic valve in the present embodiment, but it may also be a motor-driven electric valve. By opening the on-off valve 142, the coolant can flow so as to substantially bypass the cooler core 120. Since the pressure loss on the cooler core 120 side is large, the flow rate of the coolant flowing through the cooler core 120 when the on-off valve 142 is opened is small, and there is no substantial influence on the heat exchange. In a modification, a three-way valve may be provided at the branch point p1 instead of the on-off valve 142. By switching the flow path of the three-way valve, it is possible to completely bypass the cooler core 120.

[0025] Further, a battery unit 140 is provided between the switching valve 130 and the water-refrigerant heat exchanger 106 in the third passage 223. A branch point p3 is provided upstream of the battery unit 140, and a confluence point p4 is provided downstream thereof. A bypass passage 228 is provided so as to connect these branch point p3 and confluence point p4. An on-off valve 144 is provided between the branch point p3 in the third passage 223 and the battery unit 140. The on-off valve 144 is a solenoid valve in the present embodiment, but may be an electric valve. By closing the on-off valve 144, the coolant can flow so as to bypass the battery unit 140.

[0026] The water-refrigerant heat exchanger 104 supplies the coolant heated by heat exchange with the refrigerant to the coolant circulation circuit 102. The water-refrigerant heat exchanger 106 supplies the coolant cooled by heat exchange with the refrigerant during the cooling operation to the coolant circulation circuit 102.

[0027] The cooler core 120 performs heat exchange between the coolant passing through the inside and the outside air during the cooling operation. The air introduced from the upstream side of the duct in the indoor air-conditioning unit 124 is cooled by the coolant. The air cooled at this time is distributed into the air that passes through the heater core 122 and the air that bypasses the heater core 122 according to the opening degree of the air mix door 128. The air passing through the heater core 122 is heated during the passing process. The air that has passed through the heater core 122 and the bypassed air are mixed on the downstream side of the heater core 122 and adjusted to the target temperature, and then supplied into the vehicle interior from an air outlet (not shown).

[0028] The air-conditioning device 100 configured as described above is controlled by a control unit 150. The control unit 150 calculates the control amount of the actuator of each device in order to realize the room temperature set by the vehicle occupant, and outputs a control signal to the drive circuit of each actuator. The control unit 150 determines the control amount (open / closed state) of each control valve, the drive amount of the compressor 110, etc. based on predetermined external information detected by various sensors such as the temperature inside and outside the vehicle compartment and the blown air temperature of the cooler core 120, and outputs a control command for driving them or supplies a control current.

[0029] The control unit 150 is an external control device that controls the valve unit 114, and may be a control device that comprehensively manages a plurality of electronic control units (hereinafter referred to as "ECUs") mounted on the vehicle and controlling each part, or may be an air conditioner ECU which is one of the plurality of ECUs. The air conditioner ECU controls each device constituting the air conditioning device 100. Alternatively, it may be a lower-level control device that operates in response to a command from the air conditioner ECU.

[0030] FIG. 2 is a diagram showing the operation of the air conditioning device 100. FIG. 2(A) shows the cooling operation, and FIG. 2(B) shows the heating operation. The thick lines and arrows in the figure indicate the flow of the refrigerant, and "×" indicates that the flow of the refrigerant is blocked (the same applies hereinafter).

[0031] (Cooling operation) As shown in FIG. 2(A), during the cooling operation, the expansion valve (to be described in detail later) of the valve unit 114 is in an open valve state (control state) in the refrigerant circulation circuit 101. The refrigerant discharged from the compressor 110 is condensed by passing through the water-refrigerant heat exchanger 104. At this time, heat exchange occurs in the water-refrigerant heat exchanger 104. The refrigerant led out from the water-refrigerant heat exchanger 104 is throttled and expanded by the expansion valve of the valve unit 114 to become low temperature and low pressure, and is introduced into the water-refrigerant heat exchanger 106. At this time, heat exchange occurs in the water-refrigerant heat exchanger 106, and the coolant is cooled. The refrigerant led out from the water-refrigerant heat exchanger 106 is gas-liquid separated by the accumulator 112, and the gas-phase component thereof is returned to the compressor 110.

[0032] On the other hand, in the coolant circulation circuit 102, the pumps 134 and 136 are driven, the on-off valve 142 is in a closed valve state, and the on-off valve 144 is in an open valve state. Further, the switching valves 130 and 132 are switched to a state of connecting the first passage 221 and the third passage 223 and connecting the second passage 222 and the fourth passage 224.

[0033] Therefore, a first circulation passage indicated by a two-dot chain line and a second circulation passage indicated by a dotted line are formed in the figure. The first circulation passage is a passage through which the coolant circulates, such as water-refrigerant heat exchanger 106 → cooler core 120 → heater core 122 → battery unit 140 → water-refrigerant heat exchanger 106. The second circulation passage is a passage through which the coolant circulates, such as water-refrigerant heat exchanger 104 → outdoor heat exchanger 108 → water-refrigerant heat exchanger 104.

[0034] At this time, the coolant cooled by passing through the water-refrigerant heat exchanger 106 is supplied to the cooler core 120 and exchanges heat with the air. Thereby, the air in the vehicle interior is cooled. The coolant is slightly warmed by passing through the cooler core 120, but is also supplied to the battery unit 140 via the heater core 122 to cool the battery. The coolant that has passed through the battery unit 140 is guided back to the water-refrigerant heat exchanger 106 again.

[0035] On the other hand, the coolant heated by passing through the water-refrigerant heat exchanger 104 dissipates heat when passing through the outdoor heat exchanger 108 and is guided back to the water-refrigerant heat exchanger 104 again. That is, the condensation heat of the water-refrigerant heat exchanger 104 is discharged to the atmosphere by the outdoor heat exchanger 108.

[0036] (Heating operation) As shown in Fig. 2(B), also during the heating operation, the expansion valve of the valve unit 114 in the refrigerant circulation circuit 101 is in an open state (control state) to exhibit an expansion function.

[0037] On the other hand, in the coolant circulation circuit 102, the pumps 134 and 136 are driven, the on-off valve 142 is in an open state, and the on-off valve 144 is in a closed state. Also, the switching valves 130 and 132 are switched to a state of connecting the first passage 221 and the second passage 222 and connecting the third passage 223 and the fourth passage 224.

[0038] Therefore, a third circulation passage indicated by a two-dot chain line and a fourth circulation passage indicated by a dotted line are formed in the figure. The third circulation passage is a passage through which the coolant circulates, such as water-refrigerant heat exchanger 104 → heater core 122 → water-refrigerant heat exchanger 104. The fourth circulation passage is a passage through which the coolant circulates, such as water-refrigerant heat exchanger 106 → outdoor heat exchanger 108 → water-refrigerant heat exchanger 106.

[0039] At this time, the coolant flowing through the third circulation passage is warmed when passing through the water-refrigerant heat exchanger 104 and supplied to the heater core 122. Thereby, the temperature of the heater core 122 rises, and the air supplied into the vehicle interior is warmed.

[0040] On the other hand, the coolant flowing through the fourth circulation passage sequentially passes through the water-refrigerant heat exchanger 106 and the outdoor heat exchanger 108, substantially bypasses the cooler core 120, and also bypasses the battery unit 140. At this time, the water-refrigerant heat exchanger 106 absorbs heat from the coolant and evaporates the refrigerant. Conversely, the coolant is cooled by the evaporation of the refrigerant. The cooled coolant exchanges heat with the outside air and absorbs heat when passing through the outdoor heat exchanger 108, and then is guided back to the water-refrigerant heat exchanger 106 again. In addition, when the battery temperature rises, the on-off valve 144 may be opened to flow the coolant through the battery unit 140.

[0041] Next, the configuration of the refrigerant unit including the valve unit 114 will be described. In the present embodiment, as described above, highly flammable propane is adopted as the natural refrigerant used in the refrigerant circulation circuit 101. Therefore, in the event of refrigerant leakage, it is necessary to detect it promptly. Thus, in the present embodiment, a sensor for detecting refrigerant leakage is installed in the valve unit 114.

[0042] As shown in FIG. 1, the devices constituting the refrigerant circulation circuit 101 are integrated as a refrigerant unit 160, and a sensor 162 for detecting refrigerant leakage in the refrigerant unit 160 is provided. The refrigerant unit 160 includes a housing 166 that houses each device and piping constituting the refrigerant circulation circuit 101. The sensor 162 detects refrigerant leakage within the housing 166. When the sensor 162 detects refrigerant leakage, a detection signal indicating the same is output to the control unit 150. When the sensor 162 detects refrigerant leakage, the control unit 150 stops the operation of the refrigeration cycle by stopping the drive of the compressor 110, and causes a display device (not shown) to display a screen notifying of the occurrence of refrigerant leakage.

[0043] FIG. 3 is a perspective view showing the configuration of the refrigerant unit 160. FIG. 3(A) shows the internal structure with the housing 166 removed, and FIG. 3(B) shows the external structure including the housing 166. As shown in FIG. 3(A), the refrigerant unit 160 is configured by arranging the water-refrigerant heat exchanger 104 and the water-refrigerant heat exchanger 106 side by side, assembling the compressor 110 to the water-refrigerant heat exchanger 104, and assembling the valve unit 114 to the water-refrigerant heat exchanger 106.

[0044] An accumulator 112 is integrally provided on the compressor 110. The valve unit 114 is configured by assembling an expansion valve 1 to a block-shaped passage body 200. The expansion valve 1 has a motor unit 50 that drives the valve portion, and the sensor 162 is disposed inward of the motor unit 50. Although details will be described later, a first refrigerant passage and a second refrigerant passage are formed to penetrate the passage body 200.

[0045] A pipe 230 connected to the discharge chamber of the compressor 110 is connected to the inlet of the water-refrigerant heat exchanger 104. A pipe 232 connected to the outlet of the water-refrigerant heat exchanger 104 is connected to the inlet of the first refrigerant passage. The outlet of the first refrigerant passage is connected to the inlet of the water-refrigerant heat exchanger 106. The outlet of the water-refrigerant heat exchanger 106 is connected to the inlet of the second refrigerant passage. A pipe 234 connected to the outlet of the second refrigerant passage is connected to the inlet of the accumulator 112. The outlet of the accumulator 112 is connected to the inlet (suction chamber) of the compressor 110 (not shown).

[0046] These devices and pipes constituting the refrigerant circulation circuit 101 are housed in the housing 166 as shown in Fig. 3(B). A sensor 162 is disposed in a sealed space within the housing 166. Pipes 240 and 242 extend airtightly from the water-refrigerant heat exchanger 104 and penetrate the housing 166. These pipes constitute the second passage 222. Pipes 244 and 246 extend airtightly from the water-refrigerant heat exchanger 106 and penetrate the housing 166. These pipes constitute the third passage 223. The sensor 162 detects a refrigerant (propane) leak when the refrigerant leaks from these devices or pipes constituting the refrigerant circulation circuit 101 into the space within the housing 166.

[0047] Fig. 4 is a cross-sectional view showing the configuration of the valve unit 114. The valve unit 114 is configured by assembling an expansion valve 1 into a passage body 200. The passage body 200 is a block made of a metal such as an aluminum alloy and has a substantially prismatic shape. The expansion valve 1 is assembled on the upper surface of the passage body 200.

[0048] On the side of the passage body 200, an inlet port 252, an outlet port 254, an inlet port 256, and an outlet port 258 are provided. A pipe extending from the water-refrigerant heat exchanger 104 side is connected to the inlet port 252, and a pipe connected to the inlet of the water-refrigerant heat exchanger 106 is connected to the outlet port 254. A pipe connected to the outlet of the water-refrigerant heat exchanger 106 is connected to the inlet port 256, and a pipe extending to the accumulator 112 side is connected to the outlet port 258.

[0049] In the passage body 200, a first refrigerant passage 260 connecting the inlet port 252 and the outlet port 254, and a second refrigerant passage 262 (low-pressure passage) connecting the inlet port 256 and the outlet port 258 are formed. The first refrigerant passage 260 and the second refrigerant passage 262 are vertically separated by a partition wall 264.

[0050] The expansion valve 1 is a motor-driven electric expansion valve, and its valve portion is arranged in the middle of the first refrigerant passage 260. The expansion valve 1 has a motor unit 50, and the motor unit 50 includes a rotor unit 52 and a stator unit 54. Each of the rotor unit 52 and the stator unit 54 is fixed to the passage body 200. The stator unit 54 is fixed to the passage body 200 via a connecting member 12. An attachment hole 216 opens upward in the upper part of the passage body 200. The attachment hole 216 communicates with the first refrigerant passage 260. A female screw portion 218 is formed near the opening end of the attachment hole 216.

[0051] The expansion valve 1 has a valve body 5 that encloses the valve portion. The valve body 5 has a stepped cylindrical shape and is configured by assembling a screw member 6 and a valve seat member 8 vertically. A seal ring 9 is attached to the outer peripheral surface of the valve seat member 8. A male screw portion 10 that can be screwed with the female screw portion 218 is formed on the outer peripheral surface of the screw member 6. When assembling the expansion valve 1 to the passage body 200, the valve body 5 is inserted into the attachment hole 216. The male screw portion 10 and the female screw portion 218 are screwed together to fasten the valve body 5 to the passage body 200.

[0052] An annular groove is provided on the upper surface of the passage body 200 so as to surround the mounting hole 216, and a seal ring 220 is fitted therein. When the valve body 5 is fastened to the passage body 200, the seal ring 220 is interposed between the upper surface of the passage body 200 and the valve body 5. The seal ring 220 restricts the leakage of the refrigerant from the inside to the outside of the passage body 200. The seal ring 9 seals between the upstream passage 270 and the downstream passage 272 of the valve portion.

[0053] The rotor unit 52 has a valve body 5. The valve body 5 is configured by coaxially assembling a resin screw member 6 and a metal valve seat member 8. A metal annular member 7 is coaxially assembled on the outer peripheral surface of the intermediate portion in the axial direction of the screw member 6. The annular member 7 is integrated with the screw member 6 by insert molding. An inlet port 20 is provided on the lower side surface of the screw member 6.

[0054] A valve hole 22 is formed in the upper part of the valve seat member 8, and a valve seat 24 is formed in the upper end opening of the valve hole 22. An outlet port 26 is provided in the lower part of the valve seat member 8. The inlet port 20 communicates with the introduction port 252, and the outlet port 26 communicates with the derivation port 254. A valve chamber 30 is formed inside the screw member 6. The inlet port 20 and the outlet port 26 communicate with each other through the valve chamber 30.

[0055] An operating rod 32 extending from the rotor 60 of the rotor unit 52 is inserted inside the valve body 5. The operating rod 32 penetrates the valve chamber 30. A needle-shaped valve body 34 is integrally provided at the lower part of the operating rod 32. The valve body 34 attaches to and detaches from the valve seat 24 from the valve chamber 30 side to open and close the valve portion.

[0056] A male thread 38 is formed on the upper outer peripheral surface of the screw member 6. The screw member 6 supports the operating rod 32 so as to be slidable in the axial direction by its inner peripheral surface, while supporting the rotating shaft 62 of the rotor 60 so as to be rotatably slidable by its outer peripheral surface.

[0057] The rotor 60 of the rotor unit 52 and the stator 64 of the stator unit 54 constitute a two-phase stepping motor. The rotor unit 52 has a bottomed cylindrical can 66. The can 66 is a bottomed cylindrical member that covers the space where the valve body 34 and its drive mechanism are arranged and encloses the rotor 60, defining an inner pressure space (internal space) where the refrigerant pressure acts and an outer non-pressure space (external space) where the refrigerant pressure does not act. The can 66 is made of non-magnetic metal, and its lower end surface abuts against the upper surface of the annular member 7. The valve body 5 and the can 66 are fixed by welding along the boundary between the can 66 and the annular member 7.

[0058] The stator 64 has a coil 68 and is enclosed in a resin case 70. The stator 64 is integrated with the case 70 by insert molding using a resin material. The stator unit 54 has a hollow structure, and the stator 64 is assembled to the rotor unit 52 while coaxially inserting through the can 66.

[0059] The rotor 60 includes a cylindrical rotor core 71 assembled to the rotary shaft 62, a rotor magnet 72 provided on the outer peripheral surface of the rotor core 71, and a sensor magnet 74 provided on the upper end surface of the rotor core 71, and is enclosed in the case 70.

[0060] The rotary shaft 62 has a bottomed cylindrical shape and is externally inserted into the threaded member 6. A female thread 40 is formed on the inner peripheral surface of the rotary shaft 62 and meshes with the male thread 38 of the threaded member 6. By the screw feed mechanism of these screw portions, the rotational movement of the rotor 60 is converted into the axial movement of the actuating rod 32. Thereby, the valve body 34 is driven in the axial direction, that is, the opening and closing direction of the valve portion.

[0061] The stator unit 54 has a circuit board 80 outside the can 66. The circuit board 80 is housed and fixed in the case 70. Various circuits that function as a control unit and a communication unit are mounted on the circuit board 80. Specifically, a drive circuit for driving a motor, a control circuit (microcomputer) that outputs a control signal to the drive circuit, a communication circuit for the control circuit to communicate with an external control device, a power supply circuit for supplying power to each circuit and the motor (coil), etc. are mounted. The control circuit drives the motor to control the valve opening degree of the expansion valve 1.

[0062] The upper end of the case 70 is closed by a resin lid 76. The lid 76 forms a part of the case 70. The circuit board 80 is disposed in the inner space S of the case 70. An annular groove is provided on the inner peripheral surface near the lower end of the case 70, and a seal ring 81 is fitted therein. By interposing the seal ring 81 between the case 70 and the can 66, the intrusion of moisture from the outside into the stator unit 54 is prevented.

[0063] A magnetic sensor 82 is provided on the lower surface (the surface facing the sensor magnet 74) of the circuit board 80. The magnetic sensor 82 axially faces the sensor magnet 74 through the bottom end wall of the can 66. As the rotor 60 rotates, the magnetic flux by the sensor magnet 74 changes. The magnetic sensor 82 detects the displacement amount (rotation angle of the rotor 60) of the rotor 60 by capturing this change in magnetic flux. The control unit calculates the axial position of the valve body 34 and thus the valve opening degree based on the displacement amount of the rotor 60.

[0064] And a sensor 162 is provided on the upper surface (the surface facing the lid 76) of the circuit board 80. A ventilation structure 90 for communicating the space S with the outside is provided on the surface of the lid 76 facing the sensor 162.

[0065] A terminal 84 connected to the coil 68 extends into the space S and is connected to the circuit board 80. Power supply terminals, ground terminals, and communication terminals (collectively also referred to as "connection terminals 85") extend from the circuit board 80, penetrate the side wall of the case 70, and are drawn out to the outside. A connector portion 86 is integrally provided on the side portion of the case 70, and the connection terminals 85 are arranged inside the connector portion 86. The connection terminals 85 are connected to the circuit board 80 via terminals 87.

[0066] A sensor 162 is also connected to the circuit of the circuit board 80. Thereby, power can also be supplied to the sensor 162, and the detection signal of the sensor 162 can be output to the control unit 150. An AD conversion circuit may be provided on the circuit board 80. Thereby, digital communication may be enabled between the circuit of the circuit board 80 and an external control device. The AD conversion circuit converts the analog signal output by the sensor 162 into a digital signal. When detecting refrigerant leakage, notification to the air conditioner ECU may be performed by digital communication. Note that if a digital output type sensor 162 is used, it is not necessary to separately provide an AD conversion circuit.

[0067] FIG. 5 is a diagram showing the ventilation structure 90. FIG. 5(A) is an enlarged view of part A in FIG. 4, and FIG. 5(B) is a view (plan view) seen in the direction of arrow B in FIG. 5(A). As shown in FIG. 5(A), the ventilation structure 90 includes a ventilation port 92 provided in the lid body 76 that communicates the space S with the outside, and a waterproof member 94 that closes the ventilation port 92 in a waterproof and breathable manner. As shown in FIG. 5(B), in this embodiment, the ventilation port 92 has a shape in which a circular hole is divided into four parts, but it goes without saying that it is not limited to this. The waterproof member 94 is made of a water-repellent non-woven fabric and is attached to the back surface of the lid body 76 so as to cover the ventilation port 92. In a modified example, a membrane or other breathable waterproof member processed from polytetrafluoroethylene (PTFE) or the like may be adopted.

[0068] As described above, according to the present embodiment, as the valve unit 114, a sensor 162 for detecting refrigerant leakage is integrated with the expansion valve 1. Since the sensor 162 is provided on the circuit board 80 built in the expansion valve 1, the sensor 162 can be installed more simply and stably than when installed in the water-refrigerant heat exchangers 104, 106, etc. In the present embodiment, since highly flammable propane is used as the refrigerant, there is a limit to the refrigerant capacity that can be used in the refrigerant circulation circuit 101. For this reason, it is necessary to configure the refrigerant unit 160, including the pipes 230 to 234, compactly. However, since the sensor 162 is provided on the expansion valve 1, it can be realized without any problems. Since the sensor 162 can be arranged separately from the compressor 110, a good operating environment for the sensor 162 can be maintained.

[0069] As described above, the preferred embodiments of the present invention have been described. However, it goes without saying that the present invention is not limited to the specific embodiments, and various modifications are possible within the scope of the technical idea of the present invention.

[0070] [Modification Example] FIG. 6 is a partially enlarged cross-sectional view showing the configuration of a valve unit according to a modification example. In the above embodiment, the sensor 162 is installed inside the motor unit 50. The valve unit 314 of this modification example has a configuration in which the sensor 162 is assembled from the outside of the motor unit 350 and integrated with the expansion valve 1.

[0071] The motor unit 350 includes a rotor unit 52 and a stator unit 354. The stator unit 354 has a case 370 that houses the circuit board 80. In addition to the connector portion 86 (first connector portion), a connector portion 386 (second connector portion) is integrally provided on the side portion of the case 370. A connection terminal 385 is arranged inside the connector portion 386. The connection terminal 385 is connected to the circuit board 80 via a terminal 387. A plurality of claw portions 390 are provided on the outer peripheral surface of the tip portion of the connector portion 386.

[0072] The sensor unit 300 is detachably attached to the motor unit 350. The sensor unit 300 has a resin case 312 that houses a sensor substrate 310 inside. A connector portion 315 is provided on one end side of the case 312, and the other end side opening is closed by a resin lid 316. The connector portion 315 is provided with a plurality of fitting holes 317 that can be fitted with the claw portions 390 of the connector portion 386. By connecting the connector portion 315 to the connector portion 386 and fitting the claw portions 390 and the fitting holes 317, the two can be fixed. When the connector portion 315 is connected to the connector portion 386, the sensor substrate 310 and the circuit board 80 are electrically connected. In a modified example, a single claw portion 390 may be provided on the connector portion 386, while a single fitting hole 317 may be provided on the connector portion 315, and the connector portion 315 may be fixed to the connector portion 386 by fitting these. A packing (not shown) is provided between the connector portion 315 and the connector portion 386 to prevent water from entering from the outside.

[0073] The lid 316 forms part of the case 312. A space S is formed inside the case 312, and the sensor substrate 310 is disposed therein. A sensor 162 is provided on the sensor substrate 310, and a circuit for operating the sensor 162 is mounted thereon. Specifically, a circuit for supplying power to the sensor 162, a circuit for outputting the detection signal of the sensor 162, etc. are mounted.

[0074] Power supply terminals, ground terminals, and communication terminals (collectively also referred to as "connection terminals 318") extend from the sensor substrate 310 and are respectively disposed inside the connector portion 315. The connection terminals 318 are connected to the circuit board 80 via the terminals 385, 387. When the sensor unit 300 is connected to the motor unit 350, the power supplied from the outside is also supplied to the sensor substrate 310 via the circuit board 80, and the detection signal of the sensor 162 can be output to the control unit 150 via the circuit board 80. A ventilation structure 320 for communicating the space S with the outside is provided on the surface of the lid 316 facing the sensor 162.

[0075] FIG. 7 is a diagram showing the configuration of the sensor unit 300. FIG. 7(A) is a sectional view, and FIG. 7(B) is a view taken in the direction of arrow C in FIG. 7(A). FIG. 8 is a diagram showing a method of attaching the sensor unit 300 to the expansion valve 1. As shown in FIGS. 7(A) and (B), the case 312 has a bottomed cylindrical shape and supports the sensor substrate 310 near its bottom. The connector portion 315 is provided at a position offset from the center of the bottom of the case 312.

[0076] The connector portion 315 has a connection portion 330 having a complementary shape to the connector portion 386, and a cylindrical fitting portion 332 provided so as to surround the connection portion 330. A fitting hole 317 is provided in the fitting portion 332. The connection terminal 318 extending from the sensor substrate 310 is inserted into the connection portion 330, and a connection piece 334 is provided at its tip. The connection piece 334 has a leaf spring structure capable of sandwiching the terminal 385 of the motor unit 350 (see FIG. 6).

[0077] A ventilation structure 320 is provided on the surface of the lid body 316 facing the sensor 162. The ventilation structure 320 includes a ventilation port 322 provided in the lid body 316 and a waterproof member 94 that closes the ventilation port 322 in a watertight and ventilable manner. The ventilation port 322 has a circular hole shape, and a circular shielding portion 324 is provided so as to face the ventilation port 322 with a predetermined interval therebetween. The shielding portion 324 is fixed to the lid body 316 via a plurality of leg portions 326. With such a configuration, the shielding portion 324 is positioned in front of the ventilation port 322, thereby suppressing the intrusion of foreign matter from the outside into the ventilation port 322. On the other hand, since the space between adjacent leg portions 326 is open, outside air can be introduced through the ventilation port 322.

[0078] According to this modification, since the sensor unit 300 can be integrated with the motor unit 350, the same effects as those of the above-described embodiment can be obtained. As shown in FIG. 8, the sensor unit 300 is detachable from the motor unit 350 and can be attached with one touch. By configuring the sensor unit 300 independently of the motor unit 350, the sensor 162 can also function optionally.

[0079] FIG. 9 is a diagram showing a system configuration according to a modified example. The reference numerals in the figure correspond to those in FIGS. 1, 6, etc. Although not described in the above embodiment, a vehicle control system to which the air conditioner 100 is applied may be realized in a configuration as shown in FIG. 9. In the vehicle control system of this modified example, ECUs 1 to 4 for controlling each system line are connected via an in-vehicle network.

[0080] ECU 1 controls the drive unit of the vehicle (such as a motor that drives an electric vehicle), and ECU 2 controls the braking device. ECU 3 controls the air conditioner 100, and ECU 4 controls the battery unit 140. In addition, there are ECUs that control each part of the vehicle. There may be an integrated ECU that comprehensively controls or manages these ECUs. ECU 3 may function as the control unit 150 (see FIG. 1).

[0081] Each ECU is connected via a communication line L1. ECU 3 is connected via a communication line L2 to the drive control units of the devices that make up the air conditioner 100. In this modified example, the communication line L1 of the main network is a CAN bus, and the communication line L2 of the sub-network is a LIN bus. That is, CAN (Controller Area Network) is adopted as the communication protocol of the main network, and LIN (Local Interconnect Network) is adopted as the communication protocol of the sub-network.

[0082] ECU 3 operates as a master node connected to the LIN bus. On the other hand, each device that makes up the air conditioner 100 operates as a slave node connected to the LIN bus. In other modified examples, CAN may be adopted for both the main network and the sub-network. Alternatively, a communication protocol other than CAN or LIN may be adopted for at least one of the main network and the sub-network.

[0083] The valve unit 314 (see FIG. 6) of the above modification example may be applied to the air conditioner 100 installed in such a system. In that case, the sensor 162 built in the sensor unit 300 may be any sensor that detects the state of the refrigeration cycle, and may be a gas sensor that detects refrigerant leakage, or a temperature sensor that detects temperature. Alternatively, it may be a pressure sensor that detects refrigerant pressure. By unitizing the sensor 162 so that it can be attached to and detached from the valve unit 314, the versatility of the sensor unit 300 is enhanced. In that case, the expansion valve 1 functions as a relay device that relays information (signals) transmitted between an external control device such as an air conditioner ECU and the sensor unit 300. In other modification examples, the sensor unit 300 and the valve unit 314 may be connected by a harness cable or the like. With such a configuration, the sensor unit 300 can be arranged at a position separated from the valve unit 314.

[0084] In this modification example, the expansion valve 1 has a circuit for making an electrical connection with the sensor unit 300 in addition to the circuit for making an electrical connection with the air conditioner ECU. In this way, the expansion valve 1 has a second electrical connection point in addition to the first electrical connection point with the air conditioner ECU, and a state detection member such as a sensor may be connected to the second electrical connection point. A plurality of second electrical connection points may be provided. Thereby, the problem of reducing the size and weight of the refrigerant unit including the devices and pipes constituting the refrigerant circulation passage can be solved.

[0085] Such a valve unit can be expressed, for example, as follows. A valve unit provided in the refrigerant circulation passage of a refrigeration cycle, an electric valve incorporating a first circuit board on which a circuit for communicating with an external control device is mounted, a sensor unit incorporating a second circuit board provided with a sensor for detecting the state of the refrigeration cycle and detachably attached to the electric valve, and comprising A valve unit characterized in that the sensor unit is attached to the electric valve, whereby the first circuit board and the second circuit board are electrically connected.

[0086] In this modification, the circuit board 80 shown in FIG. 6 functions as the "first circuit board", and the sensor board 310 functions as the "second circuit board". An AD conversion circuit for converting the detection signal (analog signal) of the sensor 162 into a digital signal may be provided on the circuit board 80.

[0087] [Other modifications] In the above embodiment, an example of adopting propane as the natural refrigerant was shown. In a modification, a natural refrigerant mainly composed of butane or other hydrocarbons may be adopted. Even if a flammable natural refrigerant is adopted, by adopting the system configuration of the above embodiment, the same effects as those of the above embodiment can be obtained. Alternatively, carbon dioxide may be adopted as the natural refrigerant. When carbon dioxide is adopted, there is no risk of ignition, but at least leakage into the passenger compartment needs to be avoided. By adopting the system configuration of the above embodiment, refrigerant leakage can be detected promptly when it occurs, so safety can be ensured. It should be noted that even when a fluorine-based refrigerant that is not a natural refrigerant is adopted, the valve unit in which the sensor for detecting refrigerant leakage and the electric expansion valve are integrated functions effectively as described above.

[0088] In the above embodiment, an example in which the on-off valve 142 for opening or closing the bypass passage 226 is configured by a solenoid valve was shown, but it may be configured by an electric valve. Similarly, an example in which the on-off valve 144 for opening or closing the bypass passage 228 is configured by a solenoid valve was shown, but it may be configured by an electric valve.

[0089] In the above embodiment, as shown in FIG. 1, an example in which an accumulator 112 is provided upstream of the compressor 110 in the refrigerant circulation circuit 101 was shown. In a modification, a liquid receiver (liquid tank) may be provided upstream of the water-refrigerant heat exchanger 106 (second heat exchanger) instead of the accumulator 112.

[0090] In the above embodiment, as shown in FIG. 3, an example of a configuration in which each device constituting the refrigerant unit 160 is connected by piping was illustrated. In a modified example, independent devices may be configured in a block shape, and by directly connecting each device, a configuration in which piping is substantially eliminated may be adopted.

[0091] In the above embodiment, the heat exchanger that exchanges heat with the air supplied into the vehicle interior was set as the cooler core 120 and provided in the coolant circulation circuit 102. This is because the refrigerant filling amount of the refrigerant circulation circuit 101 is restricted due to the use of highly flammable propane as the refrigerant. That is, since the piping length of the refrigerant circulation circuit 101 cannot be made sufficiently large due to the restricted refrigerant filling amount, it is difficult to install the evaporator of the refrigerant circulation circuit 101 in the vehicle interior. When a natural refrigerant for which the refrigerant filling amount is not restricted in this way is adopted, the evaporator of the refrigerant circulation circuit 101 may be provided in the vehicle interior. Thereby, the cooling function can be enhanced.

[0092] In the above embodiment, a configuration in which a drive circuit, a control circuit, a communication circuit, and a power supply circuit are mounted on the circuit board 80 was shown, but any one or all of these circuits may be integrated into a semiconductor (chip) as an SoC (System on Chip).

[0093] Note that the present invention is not limited to the above embodiment and modified example, and components can be modified and embodied without departing from the gist. Various inventions may be formed by appropriately combining a plurality of components disclosed in the above embodiment and modified example. Also, some components may be deleted from all the components shown in the above embodiment and modified example.

Explanation of Reference Numerals

[0094] 1 Expansion valve, 5 Valve body, 22 Valve hole, 24 Valve seat, 32 Actuating rod, 34 Valve body, 50 Motor unit, 52 Rotor unit, 54 Stator unit, 60 Rotor, 64 Stator, 70 Case, 80 Circuit board, 81 Seal ring, 84 Terminal, 85 Connection terminal, 86 Connector part, 87 Terminal, 90 Ventilation structure, 92 Vent hole, 94 Waterproof member, 100 Heating and cooling device, 101 Refrigerant circulation circuit, 102 Coolant circulation circuit, 108 Outdoor heat exchanger, 110 Compressor, 112 Accumulator, 114 Valve unit, 120 Cooler core, 122 Heater core, 130 Changeover valve, 132 Changeover valve, 134 Pump, 140 Battery unit, 142 On-off valve, 144 On-off valve, 150 Control unit, 160 Refrigerant unit, 162 Sensor, 166 Housing, 200 Passage body, 230 Pipe, 232 Pipe, 234 Pipe, 260 First refrigerant passage, 262 Second refrigerant passage, 300 Sensor unit, 310 Sensor board, 312 Case, 314 Valve unit, 315 Connector part, 316 Cover body, 318 Connection terminal, 320 Ventilation structure, 322 Vent hole, 324 Shielding part, 330 Connection part, 332 Fitting part, 350 Motor unit, 354 Stator unit, 370 Case, 385 Connection terminal, 385 Terminal, 386 Connector part, 387 Terminal, L1 Communication line, L2 Communication line, S Space.

Claims

1. A refrigerant circulation passage for circulating refrigerant, a compressor disposed in the refrigerant circulation passage for compressing and discharging the refrigerant, a first heat exchanger disposed downstream of the compressor in the refrigerant circulation passage, a second heat exchanger disposed upstream of the compressor in the refrigerant circulation passage, A valve unit applied to a refrigeration cycle comprising: An electric expansion valve for decompressing and expanding the refrigerant flowing from the first heat exchanger toward the second heat exchanger, and a sensor for detecting refrigerant leakage from the refrigerant circulation passage, integrally provided. A valve unit characterized by that.

2. A circuit board on which a control circuit for controlling the valve opening of the electric expansion valve, a power supply circuit for supplying power to the control circuit, and a communication circuit for communicating with an external control device are mounted, The valve unit according to claim 1, characterized in that power to the sensor is supplied via the circuit board.

3. The valve unit according to claim 2, characterized in that the sensor is provided on the circuit board.

4. The electric expansion valve is configured by assembling a body that houses a valve portion and a motor unit that drives the valve portion, The motor unit has a case that includes a rotor and a stator and houses the circuit board, The valve unit according to claim 3, characterized in that the case is provided with a vent for communicating a space for housing the circuit board with the outside, and a waterproof member that closes the vent in a watertight and breathable manner.

5. The valve unit according to claim 2, characterized in that output information of the sensor is transmitted to the external control device via the communication circuit.

6. The valve unit according to any one of claims 1 to 5, characterized in that the refrigerant is a flammable natural refrigerant mainly composed of hydrocarbon.

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