JPH0721371B2 - Valve mechanism for superheat control of suction refrigerant - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a valve mechanism arranged in a suction circuit in a refrigeration circuit, particularly in the vicinity of a compressor, and more specifically, to appropriately control the degree of superheat of suction refrigerant. To improve the valve mechanism.

[Prior Art] In a refrigeration circuit used for vehicle air-conditioning, the temperature type automatic expansion valve controls the superheat degree of the refrigerant at the outlet of the evaporator to a constant level, and on the other hand, it is arranged in a suction pipe line near the compressor. A management method is known in which the pressure of the refrigerant at the outlet of the evaporator is controlled to be constant by a throttle valve. However, unlike the evaporator arranged in the vehicle compartment, the throttle valve and the compressor are arranged in the engine room, which is most susceptible to heat, and
In the FF type vehicle, since it is necessary to extend the suction pipe line to the compressor located further forward of the engine in the layout, in addition to the amplification of the above heat effect, it is easy to cause fluctuations in the flow rate of the refrigerant. There is a fate. Therefore, the management of the refrigerant pressure at the outlet of the evaporator by the throttle valve becomes unstable at all, and as a result, various problems such as excess or deficiency of cooling, poor lubrication of the compressor, and abnormal rise of discharge temperature occur.

The inventors of the present invention focused on such a problem, the expansion valve is not a constant pressure expansion valve that always controls the evaporation pressure regardless of the cooling load, and the superheat degree of the suction refrigerant is controlled by a valve mechanism that is a modification of the throttle valve. I proposed a new solution first.

FIG. 3 shows a specific configuration thereof, and 10 in the figure is a compressor driven by an engine, for example.
A condenser 1 is installed in the refrigerant circulation line extending from the discharge line 12 of 10
4, the liquid receiver 16, the expansion valve 18, and the evaporator 20 are sequentially provided in series, and the circulation path from the outlet of the evaporator 20 to the compressor 10 is functionally configured as a suction pipe line 22. A valve mechanism 80 having a flow rate adjusting function described below is arranged in the suction pipe line 22 near the compressor 10. The expansion valve 18
Guide the refrigerant pressure at the outlet of the evaporator 20 by a pressure equalizing pipe 18a,
It is a conventionally known constant pressure expansion valve whose valve opening is determined by the balance with an adjustable spring force.

In the main body 81 of the valve mechanism 80, a bore 82 having a bottomed circular hole is bored so as to face the inlet side conduit portion, and a spool valve 83 for adjusting the refrigerant flow rate is provided in the bore 82. The head side is fitted into the inlet side conduit. The bottom of the bore 82 has a pressure chamber 84 for exerting a control pressure on the bottom side of the spool valve 83.
The pressure chamber 84 forms a sealed space further defined by a bellows 85 interposed between the bottom wall of the bore 82 and the bottom end surface of the spool valve 83. A temperature sensitive tube 86 in which a refrigerant of almost the same type as the circulating refrigerant is sealed is arranged in the inlet side pipe line portion, and the saturated pressure of the sealed refrigerant is conducted to the pressure chamber 84 via a sealed tube 87. . In addition,
Reference numeral 88 is a spring that controls the degree of superheat of the suction refrigerant, and acts in cooperation with the refrigerant pressure in the inlet side pipe line to urge the spool valve 83 in the bottom direction to reduce the valve opening.

Therefore, the valve opening of the spool valve 83 is the pressure in the pressure chamber 84 (saturation pressure of the refrigerant filled in the temperature-sensitive cylinder corresponding to the temperature of the inlet side conduit).
And the resultant pressure obtained by adding the biasing force of the spring 88 to the refrigerant pressure in the inlet side conduit portion. In other words, the suction refrigerant in the inlet side pipe portion is limited to a pressure lower than the saturation pressure of the same temperature by an amount corresponding to the biasing force of the spring 88, and as a result, the superheat degree of the suction refrigerant is controlled to be substantially constant.

[Problems to be Solved by the Invention] However, in the above-mentioned configuration, the biasing force of the spring for controlling the degree of superheat against the saturation pressure of the refrigerant filled in the temperature-sensitive cylinder and the pressure is
Both are directly involved in the opening / closing operation of the spool valve,
Moreover, since the biasing force of the spring substantially differs depending on the operating position of the spool valve, the biasing force (resistance) of the spring increases as the opening operation of the spool valve progresses, and the superheat degree is controlled to be higher. On the contrary, in the valve closing operation, the biasing force of the spring is gradually reduced and the superheat degree is controlled to be low. In other words, there is a dislike that the cooling feeling is deteriorated due to insufficient cooling due to excessive throttling at high cooling load, and overcooling phenomenon due to insufficient throttling at low cooling load.

Also, as the effective stroke of the spool valve is ensured, the volume change of the pressure chamber will inevitably increase.Therefore, in order to absorb this change, the refrigerant enclosed in the temperature sensing cylinder must also have a corresponding increase in volume. As a result, the temperature sensing cylinder becomes large and the responsiveness deteriorates.

An object of the present invention is to solve the technical problems to be solved by stabilizing the cooling feeling and improving the superheat degree control accuracy by adopting a simple valve mechanism for controlling the superheat degree of the suction refrigerant.

[Means for Solving the Problems] In order to solve the above problems, a valve mechanism according to the present invention is provided in a main body for flow rate adjustment arranged so that the upstream suction pipe line pressure of the valve mechanism acts on its head side. A spool valve, a pressure chamber that exerts a control pressure on the bottom side of the spool valve, a spring that biases the spool valve toward the head side in the same manner, and a temperature-sensing cylinder saturation arranged near the valve mechanism. Adopting a novel configuration including a switching valve that operates by a pressure difference between the pressure and the pressure of the upstream suction pipeline and selectively connects the upstream suction pipeline and the downstream suction pipeline of the valve mechanism to the pressure chamber is doing.

The valve mechanism is a suction line near the compressor in a vehicle air conditioning refrigeration circuit formed in a closed circuit including a constant pressure expansion valve,
Preferably, it is arranged in a form attached to the suction part of the compressor. The spool valve may be of a general columnar shape, but it is hollow with a bottom and a cutout window is opened in a part of the peripheral wall, and the hollow portion and the cutout window are connected to the refrigerant passage. It can be configured to be a part, and by this, the increasing / decreasing action of the valve opening degree with respect to the operating direction of the spool valve can be arbitrarily selected. The temperature sensing tube is arranged close to the upstream or downstream pipeline of the valve mechanism so as to more accurately sense the suction refrigerant temperature.For example, the temperature of the discharge section of the compressor or the discharge pipeline temperature is guided directly or by a coil. It is also possible to sense the intake refrigerant temperature to be higher and consequently control the superheat degree of the intake refrigerant to be somewhat lower.

[Operation] In the refrigeration circuit having the valve mechanism of the present invention, the pressure in the evaporator is kept constant by the constant pressure expansion valve, and the saturated state is maintained over the entire area of the evaporator by adjusting the flow rate of the valve mechanism. As a result, a stable evaporation temperature (cooling air temperature) can be obtained.

Therefore, the refrigerant at the outlet of the evaporator changes from a saturated state to a slightly wet state, and the degree of wetness will fluctuate slightly, but external factors affect the refrigerant through the suction pipeline until it reaches the compressor. The degree of superheat of the refrigerant that is substantially sucked into the compressor, including fluctuations in the degree of superheat, is controlled by the flow rate adjustment of the valve mechanism that detects this. Can be deterred.

In particular, in the valve mechanism of the present invention, the saturation pressure of the refrigerant enclosed in the temperature sensitive cylinder acts only as an operation source for promoting the fine movement required for the switching valve, and the operation of the spool valve requiring a relatively large stroke for flow rate control. Circulating refrigerants having different pressures act alternately as a source, and a spring for urging the spool valve in response to the control pressure is provided in a form independent of the superheat sensing spring. Therefore, both the switching valve and the spool valve operate accurately and smoothly.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the outline of the refrigeration circuit and the first embodiment of the valve mechanism, and the valve mechanism 30 shows a state when the superheat degree of the suction refrigerant is low.

In the figure, 10 is a compressor driven by, for example, an engine, and a condenser 14, a receiver 16 and an expansion valve are provided in a refrigerant circulation path (closed circuit) extending from a discharge conduit 12 of the compressor 10. 18 and the evaporator 20 are arranged in series, and the circulation path from the outlet of the evaporator 20 to the compressor 10 is functionally configured as a suction pipe line 22. A valve mechanism 30 is disposed in the suction pipe line 22 near the compressor 10, whereby the suction pipe line 22 is divided into an upstream suction pipe line 22a and a downstream suction pipe line 22b of the valve mechanism 30. In addition, the expansion valve 18 is provided with an equalizer 20 through an equalizer tube 18a.
Is a constant pressure expansion valve that guides the refrigerant pressure at the outlet of the valve and determines the valve opening degree by balancing with the adjustable spring force.

Then, in the main body 31 of the valve mechanism 30, a bore 32 having a bottomed circular hole is bored so as to face the upstream suction pipeline 22a, and in the bore 32, a spool valve 33 for adjusting the refrigerant flow rate is provided. It is inserted in such a manner that the side is directed toward the upstream suction pipe line 22a and can be moved back and forth.
The spool valve 33 is formed in a hollow shape with a bottom, and a cutout window 33a is opened in the center of the peripheral wall thereof, and the hollow portion and the cutout window 33a are both part of the refrigerant passage. .
The bottom portion of the bore 32 is configured as a pressure chamber 34 that exerts a control pressure on the bottom side of the spool valve 33, and the spool valve 33 is similarly provided in the pressure chamber 34 in the head side, that is, in the direction of increasing the valve opening degree. The biasing spring 35 is interposed.

Reference numeral 40 denotes a switching valve that operates the spool valve 33 by detecting the degree of superheat of the suction refrigerant.
A suction pressure chamber 43 communicating with 22a through a pressure guiding path 42 is provided, and a base portion of a bellows 45 whose end is sealed by a partition plate 44 is attached to an inner wall of the suction pressure chamber 43. Thus, the suction pressure chamber 43 is opposed to the exchange pressure chamber 46 separated by the bellows 45. Reference numeral 47 is a temperature-sensing cylinder disposed in the upstream suction pipe line 22a portion of the main body 31.In the temperature-sensing cylinder 47, a refrigerant of the same type as the circulating refrigerant or a slightly higher saturation pressure is enclosed, The saturation pressure is conducted to the pressure conversion chamber 46 by a closed circuit via a closed pipe 48. 49 is the entrance
The intermediate chamber 49 communicates with the suction pressure chamber 43 by means of 50, and also communicates with the pressure chamber 34 through the pressure passage 51, and the intermediate chamber 49 is further provided with a passage 52 and a passage 52 concentric with the passage 50. It communicates with the downstream suction pipe line 22b through the pressure line 53. On the other hand, a compound type valve portion 55 is formed at the tip of the lever 54 that is connected to the partition plate 44 and extends through the through hole 50 into the intermediate chamber 49, and the valve portion 55 moves back and forth. Thus, the valve seat (mouth end edge) of the communication port 52 or the communication port 50 can be selectively sealed to alternately limit the flow with the intermediate chamber 49. Reference numeral 56 is a spring that urges the bellows 45 in a direction in which the bellows 45 contracts by colliding with the partition plate 44 interposed in the suction pressure chamber 43. Therefore, the valve portion 55 is configured to follow the direction in which the pressures of the inside and outside acting on the partition plate 44 are balanced.

In the refrigeration circuit including the above-described valve mechanism of the present invention, the pressure inside the evaporator 20 is controlled to be constant by the expansion valve 18, and the set pressure is adjusted so that the saturated state is always ensured over the entire area of the evaporator 20. Therefore, the degree of superheat at the outlet of the evaporator 20 slightly fluctuates in the lower direction, but as described at the beginning, it is circulated depending on the length of the suction pipe line 22 from the evaporator 20 to the compressor 10 and the ambient temperature. Refrigerants are also subject to uncertain pipe resistance and thermal effects. Then, the superheat degree of the refrigerant after being affected by these environmental factors is accurately detected by the valve mechanism 30, and the superheat degree of the suction refrigerant becomes a constant value by adjusting the flow rate of the valve mechanism 30 that operates based on the detected value. It is controlled.

From the state shown in the figure, the degree of superheat of the suctioned refrigerant increases, and the differential pressure between the saturation pressure in the temperature sensing cylinder 47, that is, the pressure inside the pressure conversion chamber 46 and the upstream suction pipe line pressure, that is, the pressure inside the suction pressure chamber 43, increases. ,
When this exceeds the set biasing force of spring 58, the bellows
With the expansion of 45, the valve part 55 moves forward (downward in the drawing) together with the partition plate 44 and the lever 54 to open the valve seat of the passage opening 50 and at the same time close the valve seat of the passage opening 52. As a result, the pressure guiding path 53, the passage 5
2. The pressure of the downstream suction pipe, which has been supplied to the pressure chamber 34 via the intermediate chamber 49 and the pressure guiding passage 51, decreases, and instead, the suction pressure chamber 43
Since the supply of the upstream suction pipeline pressure via the through hole 50 and the intermediate chamber 49 increases, the pressure in the pressure chamber 34 sequentially approaches the downstream suction pipeline pressure. Therefore, the spool valve 33, on which the upstream suction pipe pressure acts on both ends, advances in the direction of opening the refrigerant passage by the urging force of the spring 35, increasing the amount of circulating refrigerant, that is, reducing the superheat degree of the suction refrigerant. It functions to make it.

Further, when the degree of superheat of the suction refrigerant decreases and the differential pressure between the pressure inside the pressure conversion chamber 46 and the pressure inside the suction pressure chamber 43 decreases, the spring
The bellows 45 contracts by the urging force of 56, and contrary to the above-described action, the valve portion 55 retracts (moves upward in the drawing) to close the valve seat of the passage port 50 and simultaneously open the valve seat of the passage port 52. Let This allows the suction pressure chamber 43 to pass through the passage 50 and the intermediate chamber 49,
Since the upstream suction pipeline pressure supplied to 34 decreases, the downstream suction pipeline pressure after throttling that is supplied from the opened opening 52 through the intermediate chamber 49 increases instead. Is sufficiently lower than the upstream suction line pressure. Therefore, the spool valve 33 moves backward against the biasing force of the spring 35 in the direction to close the refrigerant passage, and functions to decrease the amount of circulating refrigerant, that is, increase the degree of superheat of the sucked refrigerant.

FIG. 2 shows a second embodiment of the valve mechanism.
A also represents the state when the superheat of the intake refrigerant is low. The valve mechanism 30A forms the spool valve 33A into a simple columnar shape, so that the spool valve 3 based on the urging force of the spring 35A is used.
The configuration is different from that of the first embodiment in that the forward movement of 3A is not the opening of the refrigerant flow path but is accompanied by the closing action. Therefore, the control pressure supplied to the pressure chamber 34 according to the degree of superheat of the suction refrigerant is completely opposite to that in the first embodiment, and the switching valve 40
The configuration of A also has a slight difference as described below.

That is, the suction pressure chamber 4 described above is provided in the housing 41A of the switching valve 40A.
3, the low-pressure chamber 60 is provided following the intermediate chamber 49, the low-pressure chamber 60
Is communicated with the intermediate chamber 49 through the passage 61, and is also communicated with the downstream suction conduit 22b through the pressure guiding passage 53. Then, in the low-pressure chamber 60, the passage 61 by the biasing force of the spring 62.
A ball valve 63 for closing the valve is inserted, and when the ball valve 63 moves as the bellows 45 expands, the ball valve 63
The through hole 61 is opened by the interference action of the projecting end. Further, a taper valve portion 64 for opening and closing the through hole 50A is formed in the middle portion of the sludge rod 54A, and the valve seat of the through hole 50A is closed contrary to the above opening operation of the ball valve 63 during the advance of the sludge rod 54A. Is configured to.

Now, from the state shown in the figure, the degree of superheat of the suction refrigerant becomes high, the differential pressure between the pressure inside the pressure conversion chamber 46 and the pressure inside the suction pressure chamber 43 becomes large, and the rod 54A advances as the bellows 45 expands. When the tip of 54A interferes with the ball valve 63, the passage 61 is opened, and conversely, the taper valve portion 64 closes the valve seat of the passage 50A. This allows the suction pressure chamber 43 to pass through the opening 50.
The upstream suction pipe line pressure that has been supplied to the pressure chamber 34 via A and the intermediate chamber 49 decreases, and instead, the downstream suction pipe that is supplied from the low pressure chamber 60 via the through hole 61 and the intermediate chamber 49. Since the line pressure increases, the pressure in the pressure chamber 34 becomes sufficiently lower than the upstream suction line pressure. Therefore, spool valve 33A is spring 35A
It retreats in the direction of opening the refrigerant flow path against the urging force of No. 1, and functions to increase the amount of circulating refrigerant, that is, reduce the degree of superheat of suction refrigerant.

Further, when the degree of superheat of the suction refrigerant becomes low and the pressure difference between the pressure inside the pressure conversion chamber 46 and the pressure inside the suction pressure chamber 43 becomes small, the bellows 45 contracts due to the urging force of the spring 56, and On the contrary, the taper valve portion 64 retracts to open the valve seat of the through hole 50A, and at the same time, the interference with the ball valve 63 by the lever 54A is released to close the through hole 61. As a result, the low-pressure downstream suction pipeline pressure supplied from the low-pressure chamber 60 to the pressure chamber 34 via the passage 61 and the intermediate chamber 49 is reduced, and instead, the suction pressure chamber 43 to the passage 50A and the intermediate chamber. Since the upstream suction pipeline pressure via 49 increases, the pressure in the pressure chamber 34 sequentially approaches the upstream suction pipeline pressure. Therefore, the spool valve 33A, on which the upstream suction pipe pressure acts on both ends, moves forward in the direction of closing the refrigerant passage by the urging force of the spring 35A, decreasing the circulating refrigerant amount, that is, increasing the superheat degree of the suction refrigerant. It functions to make it.

[Effects of the Invention] Since the intake refrigerant superheat degree control valve mechanism of the present invention has the above-described unique structure, the following excellent effects can be obtained.

(1) Since the entire area of the evaporator can be used in a saturated state, the temperature of the evaporator can be stabilized, that is, a good cooling feeling can always be obtained.

(2) Poor lubrication and seizure that occur due to abnormal overheating of the refrigerant sucked into the compressor can be suppressed, and in addition, reduction in refrigerating capacity due to an increase in specific volume can be reliably prevented.

(3) Since the saturation pressure of the refrigerant filled in the temperature sensing cylinder acts only as an operation source that promotes the fine movement required for the switching valve, the temperature sensing cylinder is downsized, the responsiveness is improved, and the freedom of structure selection is increased. Can be increased.

(4) Since the upstream suction pipe line pressure introduced into the switching valve for sensing the degree of superheat is also used as the control pressure for spool valve operation, the structure of the switching valve is greatly simplified.

(5) Since the discharge pressure of the compressor is not used as the control pressure for operating the spool valve, there is a complete problem that the discharge pressure leaks to the suction side during the operation of the switching valve, which reduces the refrigeration capacity and raises the suction temperature. To be wiped out.

(6) When the spool valve is biased by the spring in the direction of operation for closing the refrigerant flow rate, the amount of refrigerant sucked at the time of startup is limited by the spool valve that secures the closed position while the compressor is stopped, and the start shock may occur. It is extremely effective for reduction.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention arranged in a refrigeration circuit, FIG. 2 is a sectional view showing a second embodiment of the present invention, and FIG. 3 is arranged in a refrigeration circuit. FIG. 7 is a cross-sectional view showing a conventional valve mechanism that has been prepared. 10 ... Compressor, 12 ... Discharge line 18 ... Constant pressure expansion valve, 20 ... Evaporator 22 ... Suction line 22a ... Upstream suction line 22b ... Downstream suction line 30, 30A ... Valve mechanism 33, 33A ... Spool valve 34 … Pressure chamber, 35, 35A… Spring 40, 40A… Switching valve 42, 51, 53… Pressure passage 43… Suction pressure chamber, 45… Bellows 46… Pressure conversion chamber, 47… Temperature sensing cylinder 49… Intermediate chamber, 54 , 54A ... hammer 55 ... valve part, 56 ... spring 60 ... low pressure chamber, 63 ... ball valve 64 ... taper valve part

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Hiroyuki Deguchi 2-chome Toyota-cho, Kariya city, Aichi Prefecture Toyota Industries Corporation (56) Reference JP-A-63-231139 (JP, A) JP Patent Sho 63-25466 (JP, A) Actually opened Sho 63-198971 (JP, U)

Claims (2)

[Claims] Claim: What is claimed is: 1. A valve mechanism arranged in a suction pipe line near a compressor in a vehicle air-conditioning refrigeration circuit that forms a closed circuit including a compressor, a condenser, a liquid receiver, a constant pressure expansion valve and an evaporator. That is, the valve mechanism includes a spool valve for flow rate adjustment arranged in the main body so that the upstream suction pipeline pressure of the valve mechanism acts on the head side thereof, and a pressure for applying a control pressure to the bottom side of the spool valve. The chamber, a spring for urging the spool valve toward the head in the same manner, and a differential pressure between the saturated pressure in the temperature-sensing cylinder and the upstream suction line pressure arranged near the valve mechanism. A valve mechanism for controlling the degree of superheat of suction refrigerant, comprising: a switching valve that selectively connects an upstream suction pipe line and a downstream suction pipe line of the mechanism to the pressure chamber. 2. The valve mechanism according to claim 1, wherein the urging force of the spring acts in a direction in which the spool valve closes the refrigerant passage.