JPH0721372B2 - 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, the valve mechanism according to the present invention has a bore in which a spool valve is internally provided in the main body, and the bore substantially sandwiches the spool valve. It is divided into a front pressure chamber forming an operation air space and a back pressure chamber for applying a control pressure, and a spring for biasing the spool valve toward the back pressure chamber is interposed in the front pressure chamber, The downstream suction line and the upstream suction line of the valve mechanism are opened to communicate with each other in the axial direction of the front pressure chamber and in a direction substantially orthogonal to the axial direction, and the saturated pressure in the temperature-sensing cylinder installed near the valve mechanism is set. And a pressure difference between the upstream suction pipeline pressure and a pressure difference between the upstream or downstream suction pipeline and the compressor discharge pipeline to selectively communicate with the back 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 temperature sensing tube is arranged close to the upstream or downstream pipeline of the valve mechanism so as to more faithfully sense the intake refrigerant temperature.
For example, it is also possible to guide the temperature of the discharge portion or the discharge pipe line of the compressor directly or by using a coil or the like 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. In addition, by adjusting the flow rate of the valve mechanism, the saturated state can be maintained in the entire area of the evaporator, so that the evaporation temperature (cooling air temperature) can be stable.

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. For accurate and smooth operation.

[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.

In the main body 31 of the valve mechanism 30, a bore 32 having a circular hole with a bottom is bored, and a hollow valve with a bottom is formed in the bore 32 so that the spool valve is internally and movably installed. Across 33,
The pre-pressure chamber 32 that substantially forms the operating space of the spool 33.
a and a back pressure chamber 32b for exerting a control pressure. A spring for biasing the spool valve 33 toward the back pressure chamber 32b by contacting the inner bottom wall of the spool valve 33 in the front pressure chamber 32a. 34 are installed. Then, the downstream suction pipe line 22b is opened in the axial direction of the front pressure chamber 32a, and the upstream suction pipe line 22a is opened in the direction substantially orthogonal to the coaxial center, and both pipe lines 22b are opened by the spool valve 33. , 22a is controlled.

Reference numeral 40 denotes a switching valve that operates the spool valve 33 by sensing the degree of superheat of the suction refrigerant, and a suction pressure chamber that communicates with the upstream suction pipe line 22a through a pressure guiding path 42 in the housing 41 of the switching valve 40. 43 is provided, and the base of a bellows 45 whose end is sealed by a partition plate 44 is attached to the inner wall of the suction pressure chamber 43, whereby the suction pressure chamber 43 is separated by the bellows 45. It is confronted with room 46. 47 is the main intake pipe line 22a of 31
In the temperature-sensing cylinder arranged in a part, a refrigerant of the same kind as the circulating refrigerant or a slightly higher saturation pressure is enclosed in the temperature-sensing cylinder 47, and the saturation pressure of the enclosed refrigerant is a closed circuit through the closed pipe 48. Is connected to the pressure conversion chamber 46. 49 is a first pressure guiding chamber communicating with the discharge pipe 12 of the compressor 10 via the pressure guiding passage 50, 51 is an intermediate chamber communicating with the back pressure chamber 32b via the pressure guiding passage 52, and 53 is a pressure guiding passage. Five
This is a second pressure guiding chamber that communicates with the downstream suction pipe line 22b via 4, and these three chambers 49, 51, 53 are connected in series by a communication port 55 and a communication port 56.

A lever 57 is coupled to the partition plate 44 that seals the end portion of the bellows 45, and the lever 57 extends so as to face the second pressure chamber 53 via the first pressure guiding chamber 49 and the intermediate chamber 51. Has been done. A spring 58 is provided in the suction pressure chamber 43 to urge the partition plate 44 to urge the bellows 45 in a contracting direction.
The urging force of is substantially equivalent to the value of the superheat degree to be controlled, so that the sludge 57 is driven (moved back and forth) in a direction in which the pressure acting between the inside and outside of the diaphragm 44 is balanced. Has been done. A ball valve 60 that closes the passage 56 by the urging force of a spring 59 is provided in the second pressure guiding chamber 53, and the ball valve 60 moves when the lever 57 moves as the bellows 45 extends. The through hole 56 is opened by the interference action of the tip end of the sludge rod 57. In addition, there is a passage near the center of the hammer 57.
A taper valve portion 61 that opens and closes the valve seat of 55 is formed, and when the lever 57 is advanced, the taper valve portion 61 closes the valve seat of the passage 55 contrary to the opening operation of the ball valve 60. It is configured.

In the refrigeration circuit including the valve mechanism of the present invention described above, the pressure inside the evaporator 20 is controlled to be constant by the expansion valve 18, and the set pressure is always maintained in a saturated state over the entire area of the evaporator 20. Since it is adjusted, the degree of superheat at the outlet of the evaporator 20 rather fluctuates slightly in the lower direction, but as described at the beginning, the suction pipe line 22 from the evaporator 20 to the compressor 10
Depending on the length and the ambient temperature, the circulating refrigerant is further subject to uncertain pipe resistance and thermal expansion. 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.

Now, the degree of superheat increases from the state shown in the figure, and the differential pressure between the saturated 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, and this When the set urging force of the spring 58 is exceeded, the partition plate 44 and the lever 57 move forward (leftward in the figure) as the bellows 45 expands, and the tip of the lever 57 interferes with the ball valve 60 to allow passage. 56
The valve seat of the passage 55 is closed by the seating of the taper valve portion 61. As a result, the pressure guiding path 50 and the first pressure guiding chamber 4
9, the high-pressure discharge pressure supplied to the back pressure chamber 32b via the passage 55, the intermediate chamber 51, and the pressure guiding passage 52 decreases, and instead, the pressure guiding passage
Since the supply of the downstream suction pipeline pressure via the 54, the second pressure guiding chamber 53, the passage 56 and the intermediate chamber 51 increases, the pressure in the back pressure chamber 32b sequentially approaches the downstream suction pipeline pressure. Therefore, the downstream suction pressure acts on both sides of the spool valve 33.
With the urging force of 34, it retreats in the direction to open the refrigerant flow path,
It functions to increase the amount of circulating refrigerant, that is, to reduce the degree of superheat of suction refrigerant.

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 due to the urging force of 58, and contrary to the above-described action, the lever 57 retracts (moves to the right in the drawing) to close the passage 56 and simultaneously open the valve seat of the passage 55. This makes the second
The downstream suction pipe line pressure, which was supplied from the pressure guiding chamber 53 to the back pressure chamber 32b via the through port 56 and the intermediate chamber 51, decreases, and instead of the first
Since the discharge pressure supplied from the pressure guiding chamber 49 through the passage 55 and the intermediate chamber 51 increases, the pressure in the back pressure chamber 32b becomes much higher than the downstream suction pipe line pressure. Therefore, the spool valve 33 advances in the direction of closing the refrigerant flow path against the biasing force of the spring 34, and functions to reduce 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 does not use the downstream suction pipeline pressure as the control pressure for operating the spool valve 33, but uses the upstream suction pipeline pressure that has been introduced to the suction pressure chamber 43 to detect the superheat as it is. The configuration is different from that of the first embodiment in that the control system including the switching valve 40A is intended to be simplified by using the above.

That is, in the casing 41A of the switching valve 40A, an intermediate chamber 51A that is adjacent to the suction pressure chamber 43 and communicates with the back pressure chamber 32b is provided, and the intermediate chamber 51A communicates with the suction pressure chamber 43 through a passage 62. Further, a through hole 63 and a pressure guiding passage 50A which are concentrically opened with the through hole 62.
It is also communicated with the discharge pipe line 12 via. On the other hand, a compound valve portion 64 is formed at the tip of a lever 57A which is joined to the partition plate 44 and extends through the passage 62 to the intermediate chamber 51A, and the valve portion 64 is moved forward and backward to open the passage. The valve seat (mouth edge) of 62 or the opening 63 is selectively sealed so that the flow with the intermediate chamber 51A can be alternately restricted.

Now, from the state shown in the figure, when the 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 57 moves as the bellows 45 expands, The valve portion 64 for opening opens the valve seat of the passage 62 and at the same time the passage 63
Close the valve seat of. As a result, the pressure guide passage 50A, the passage 63,
The discharge pressure supplied to the back pressure chamber 32b via the intermediate chamber 51A and the pressure guiding path 52 decreases, and instead, the suction pressure chamber 43 passes through.
Since the pressure of the upstream suction pipeline passing through 62 and the intermediate chamber 51A increases, the pressure of the back pressure chamber 32b sequentially approaches the upstream suction pipeline.
Therefore, the spool valve 33 is retracted by the urging force of the spring 34 in the direction of opening the refrigerant passage, and functions to increase the amount of circulating refrigerant, that is, reduce the degree of superheat of the sucked refrigerant.

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 58, and contrary to the above-mentioned action, the valve portion 64 retracts to close the valve seat of the passage port 62 and simultaneously open the valve seat of the passage port 63. This allows the suction pressure chamber
The upstream suction line pressure supplied from 43 to the back pressure chamber 32b via the communication port 62 and the intermediate chamber 51A decreases, and instead is discharged when supplied from the opened communication port 63 via the intermediate chamber 51A. As the pressure increases, the pressure in the back pressure chamber 32b becomes much higher than the downstream suction line pressure. Therefore, the spool valve 33 moves forward against the biasing force of the spring 34 in the direction of closing the refrigerant passage, and functions to decrease the circulating refrigerant, that is, increase the superheat degree of the sucked refrigerant.

[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 downstream suction pipe line provided in the axial direction of the front pressure chamber and the upstream suction pipe line facing the front pressure chamber are arranged substantially orthogonal to each other, the refrigerant is deflected when the compressor is started. As a result of the dynamic pressure acting on the downstream suction pipe to generate a differential pressure that exceeds the biasing force of the spring, the spool valve in the open position is instantaneously guided in the closing direction to limit the refrigerant flow rate and start. It contributes to the reduction of shock and the prevention of liquid compression.

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

[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 32a ... Pre-pressure chamber, 32b ... Back pressure chamber 33 ... Spool valve, 34 ... Spring 40, 40A ... Switching valve 42, 50, 50A, 52, 54 ... Pressure guide passage 43 ... Suction pressure chamber, 45 ... Bellows 46 ... Exchange pressure chamber, 47 ... Feeling Hot cylinder 49 ... First pressure guide chamber, 51, 51A ... Intermediate chamber 53 ... Second pressure guide chamber, 57, 57A ... Dredge 58 ... Spring, 60 ... Ball valve 61 ... Tapered valve part, 64 ... 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 (1)

[Claims] 1. A valve mechanism arranged in a suction pipe line in the vicinity of a compressor in a closed circuit including a compressor, a condenser, a liquid receiver, a constant pressure expansion valve and an evaporator. The valve mechanism has a bore in which a spool valve is installed in the main body, and the bore is for sandwiching the spool valve and forming a working space of the spool valve, and a front pressure chamber for applying a control pressure. A spring for urging the spool valve toward the back pressure chamber is interposed in the front pressure chamber, and the front pressure chamber is provided with a valve in the axial direction of the front pressure chamber and in a direction substantially orthogonal to the axial direction. The downstream suction pipe line and the upstream suction pipe line of the mechanism are opened to communicate with each other, and actuated by the differential pressure between the temperature-sensing in-cylinder saturation pressure and the upstream suction pipe line pressure arranged near the valve mechanism. A switching valve that selectively connects the downstream suction line and the discharge line of the compressor to the back pressure chamber is provided. Superheat control-like valve mechanism of the suction refrigerant.