JPH0721373B2 - 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 control pressure, and a spring for biasing a spool valve toward the back pressure chamber is interposed in the front pressure chamber, The downstream suction pipe line and the upstream suction pipe 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 center direction, and the saturation pressure in the temperature-sensitive cylinder is provided near the valve mechanism. And a pressure difference between the upstream suction pipeline and the upstream suction pipeline, and a novel configuration is provided in which a switching valve is provided to selectively connect the upstream suction pipeline and the downstream suction pipeline to the back pressure chamber.

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 accurately sense the suction 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. 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.

Note that the superheat gradually decreases from the high superheat state where the spool valve is fully opened, and when this falls below the set value, the switching valve operates and upstream suction pipe line pressure is added to the back pressure chamber, At this time, the throttle action by the spool valve is extremely small due to the fully opened state, and normally the differential pressure generated between the upstream suction pipe line pressure and the downstream suction pipe line pressure cannot be the operating force of the spool valve. . However, in the configuration of the present invention, since the upstream suction pipeline and the downstream suction pipeline facing the front pressure chamber are arranged substantially orthogonal to each other, the dynamic pressure based on the deflection of the refrigerant acts on the downstream suction pipeline to cause the spring. It produces a differential pressure that exceeds the biasing force.

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

FIG. 1 shows an outline of a refrigeration circuit and an embodiment of a valve mechanism, and the valve mechanism 30 shows a state in which the degree of superheat of 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 an evaporator 20 are sequentially provided in series, and a circulation path from the outlet of the evaporator 20 to the compressor 10 is functionally configured as a suction pipe path 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, and the front pressure chamber 32a is in contact with the inner bottom wall of the spool valve 33 and biases the spool valve 33 toward the back pressure chamber 22b. 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 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
An intermediate chamber communicating with the suction pressure chamber 43 by 50 and also communicating with the back pressure chamber 32b through the pressure guiding path 51, and the intermediate chamber 49 is further provided with a through hole 52 concentric with the through hole 50. Low pressure chamber 53
Is also connected to. The low pressure chamber 53 communicates with the downstream suction pipe line 22b through the pressure guiding passage 54, and the low pressure chamber 53
A ball valve 56 that closes the passage 52 by the urging force of a spring 55 is provided inside. On the other hand, the sludge rod 57 connected to the partition plate 44 extends through the through hole 50 and the intermediate chamber 49 into the through hole 52, and when the sludge rod 57 moves as the bellows 45 expands, The projecting end interferes with the ball valve 56 to open the through hole 52. Further, a taper valve portion 58 for opening and closing the through hole 50 is formed in the middle portion of the sludge rod 57, and the valve seat of the through hole 50 is closed contrary to the opening operation of the ball valve 56 at the time of advancement of the sludge rod 57. It is done like this. Reference numeral 59 denotes a spring which is interposed in the suction pressure chamber 43 and urges the bellows 45 in a direction in which the bellows 45 contracts by colliding with the partition plate 44, and the urging force of the spring 59 is substantially controlled to a superheat value. It is comparable and therefore the above-mentioned hammer
57 is configured to follow the direction in which the pressures of the inside and outside acting on both sides of the partition plate 44 are balanced.

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 superheat degree at the outlet of the evaporator 20 will rather fluctuate slightly in the lower direction, but as mentioned at the beginning, it depends on the length of the suction pipe line 22 from the evaporator 20 to the compressor 10 and the ambient temperature. The circulating refrigerant is further subjected 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.

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 extension of 45, the sludge 57 moves (moves to the left in the figure) to move the sludge.
When the tip of 57 interferes with the ball valve 56, the passage 52 is opened, and conversely, the taper valve portion 58 closes the valve seat of the passage 50. As a result, the upstream suction pipe line pressure supplied to the back pressure chamber 32b from the suction pressure chamber 43 via the through port 50 and the intermediate chamber 49 is reduced, and instead, the low pressure chamber 53 is opened from the pressure guiding passage 54. Since the downstream suction pipe line pressure supplied through the passage 52 and the intermediate chamber 49 increases, the pressure in the back pressure chamber 32b sequentially approaches the downstream suction pipe line pressure. Therefore, the spool valve 33, on which the pressure of the downstream suction pipe acts on both sides, retreats in the direction of opening the refrigerant passage by the biasing force of the spring 34, 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 59, and conversely to the above-mentioned action, the lever 57 retracts (rightward in the drawing) and the taper valve portion 58 opens the valve seat of the through hole 50, and at the same time, the lever 57 moves. The tip releases the interference with the ball valve 56 and closes the passage 52. As a result, the back pressure chamber 32 passes from the low pressure chamber 53 through the passage 52 and the intermediate chamber 49.
The pressure in the back pressure chamber 32b is reduced because the pressure in the downstream suction pipe, which was supplied to b, decreases, and instead, the pressure in the upstream suction pipe from the suction pressure chamber 43 through the passage 50 and the intermediate chamber 49 increases. The pressure gradually approaches the upstream suction line pressure. Therefore, a pressure difference exceeding the biasing force of the spring 34 is generated at both ends of the spool valve 33, and the spool valve 33
Moves toward the direction of closing the refrigerant flow path, and functions to reduce the amount of circulating refrigerant, that is, increase the degree of superheat of the suction refrigerant.

From the state of high superheat when the spool valve 33 is fully opened, when upstream suction pipe line pressure is applied to the back pressure chamber 32b by the operation of the switching valve that detects a decrease in superheat, the upstream acting on both ends of the spool valve 33. The suction line pressure and the downstream suction line pressure are very close to each other and cannot be an operating force enough to slide the spool valve in the closing direction.
The refrigerant that has flowed in from 22a passes through the front pressure chamber 32a and reaches the downstream suction pipe line 22.
When flowing deflected substantially at right angles to b, a dynamic pressure ^{F = ρ · Q · v 2} /2 (ρ ... density, Q ... flow, v ... velocity) so acts in a direction to close the spool valve 33 This overcomes the biasing force of the spring 34 and operates the spool valve 33.
When the spool valve 33 is actuated and the flow rate of the refrigerant is reduced, the differential pressure is further increased to assist the operation of the spool valve 33.

[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 spool valve operation, and the spool valve is operated reliably by utilizing the dynamic pressure of the suction refrigerant, the discharge pressure leaks to the suction side. There are no problems such as a decrease in refrigeration capacity and an increase in suction temperature, and the dynamic pressure limits the refrigerant flow rate by guiding the spool valve in the open position in the closing direction when the compressor is started, thus limiting the start shock. It also contributes to the prevention of liquid compression.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention arranged in a refrigeration circuit, and FIG. 2 is a sectional view showing a conventional valve mechanism arranged in a refrigeration circuit. 10 ... Compressor, 12 ... Discharge line 18 ... Constant pressure expansion valve, 20 ... Evaporator 22 ... Suction line 22a ... Upstream suction line 22b ... Downstream suction line 30 ... Valve mechanism, 32a ... Front pressure chamber 32b ... Back Pressure chamber, 33 ... Spool valve 34 ... Spring, 40 ... Switching valve 42, 51, 54 ... Pressure guide passage 43 ... Suction pressure chamber, 45 ... Bellows 46 ... Pressure conversion chamber, 47 ... Temperature sensing cylinder 49 ... Intermediate chamber, 53 … Low pressure chamber 56… Ball valve, 57… Mopping rod 58… Taper valve, 59… Spring

 ─────────────────────────────────────────────────── --- 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 refrigeration circuit forming 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 includes a front pressure chamber that substantially forms an operation space of the spool valve with the spool valve interposed therebetween, and a back for applying a control pressure. The front pressure chamber is provided with a spring for biasing the spool valve toward the back pressure chamber, and the valve is provided in the axial direction of the front pressure chamber and in a direction substantially orthogonal thereto. The downstream suction pipe line and the upstream suction pipe line of the mechanism are opened to communicate with each other, and the upstream suction pipe line is operated by the differential pressure between the temperature-sensing cylinder saturation pressure and the upstream suction pipe line pressure arranged near the valve mechanism. A suction valve, which is provided with a switching valve that selectively connects the pipeline and the downstream suction pipeline to the back pressure chamber. Of superheat control valve mechanism.