Multiple Cylinder Rotary Compressor

1. Field of the Invention

The present invention relates to a multiple cylinder rotary compressor, and particularly to a multiple cylinder rotary compressor in which a capacity control is effected in response to a fluctuating load.

2. Description of the Prior Art

Heretofore, such an apparatus of the multiple cylinder rotary compressor type, as shown in FIGS. 1 and 2, has been proposed. However, such rotary compressor has various disadvantages as describes hereinbelow. Namely, in FIGS. 1 and 2, a driving shaft 1 has eccentric portions 1a and 1b, and cylinders 2a and 2b define compression spaces 3a and 3b being concentric with respect to the driving shaft 1 on the inner peripheral portions thereof. Rolling pistons 4a and 4b are driven by means of the eccentric portions 1a and 1b of the driving shaft 1 and roll along the inner peripheral walls of the cylinders 2a and 2b, respectively. Plate type vanes 5a and 5b urge the outer peripheral portions of the rolling pistons 4a and 4b in their axial directions and partition the compression spaces 3a and 3b into low-pressure and high-pressure sides. The vanes 5a and 5b mounted within the cylinders 2a and 2b are urged by means of springs 6a and 6b, respectively. A driving side plate 7 closes the driving side of the compression space 3a and at the same time, is supported on the driving shaft 1 through a bearing (not shown). On the other hand, an anti-driving side plate 8 closes the anti-driving side of the compression space 3b and at the same time, is supported on the driving shaft 1 through a bearing. A partition plate 9 isolates the compression spaces 3a and 3b from one another and closes openings thereof, respectively. A closed container 10 contains the compression elements as described hereinabove. A low-pressure gas suction pipe 11 supplies a low-pressure refrigerant gas to low-pressure parts of the compression spaces 3a and 3b.

Operation of the conventional rotary compressor as mentioned above will be described hereinbelow.

The rolling pistons 4a and 4b roll along the inner peripheral walls of the cylinders 2a and 2b in response to the rotation of the driving shaft 1. As the result, a low-pressure refrigerant gas is sucked into the low-pressure parts of the compression spaces 3a and 3b through the low-pressure suction pipe 11 to be compressed therein. Consequently such gas is fed to a refrigerating circuit disposed outside the closed container 10 from a high-pressure discharge pipe (not shown) as a refrigerant gas at a high temperature and high pressure. In this refrigerating circuit, the refrigerant gas at a high temperature and high pressure cools a load to be cooled thereby to discharge the energy. Thus, such refrigerant gas is converted to the one at a low temperature and low pressure, the resulting refrigerant gas is refluxed to the low-pressure gas suction pipe 11, and the same operation is again repeated, whereby cooling for the cooling load to be cooled is continued.

However, there is such a disadvantage in the conventional rotary compressor as mentioned above that in the case where rotation of the driving shaft is variable, e.g., a driving shaft for motorcars or the like, when the rotation of the driving shaft increases, a discharge of the refrigerant per unit time also increases so that it results in overcooling. Furthermore, there are also such disadvantages in the case where a rotational frequency of the driving shaft is constant that if atmospheric temperature is relatively low, it results in overcooling so that extra power is used wastefully and an ON-OFF frequency increases to bring about uncomfortableness in the car interior.

It is the principal object of the present invention to eliminate the disadvantages as mentioned above involved in conventional rotary compressors and to provide a rotary compressor by which a saving of energy to be consumed is intended by means of such control that a supply of a low-pressure refrigerant gas is interrupted with respect to either compression element of at least two compression elements in the multiple cylinder rotary compressor, or the like manner.

Another object of the present invention is to provide a rotary compressor in which a saving of energy to be consumed is contemplated by detecting a rotational frequency of the driving shaft or a temperature of the car interior and the like, whereby a supply of a low-pressure refrigerant gas is ceased with respect to some cylinders in a plurality of the cylinders.

According to an aspect of the present invention, there is proposed a multiple cylinder rotary compressor at least two rotary compression elements contained in a container are longitudinally arranged through a partition plate, each compression element is driven by means of a single driving shaft, and at the same time a suction pipe communicating with the aforesaid compression element and a suction passage for a low-pressure refrigerant gas are provided, characterized in that within the suction passage, having a suction port, of the compression element on the side of the downstream of a flow of the low-pressure refrigerant gas, a slidable cylindrical slider having a very small clearance defined with respect to the suction passage as well as a spring affording force along the axial direction of the aforesaid slider thereto are placed, and at the same time the anti-suction side of the slider is communicated with the high-pressure side through an openable and closable control valve.

FIG. 1 is a longitudinal sectional view showing an essential part of a conventional multiple cylinder rotary compressor;

FIG. 2 is a sectional view showing a suction passage part of the rotary compressor in FIG. 1;

FIG. 3 is a sectional view showing a suction passage part of a multiple cylinder rotary compressor in accordance with the first embodiment of the present invention;

FIG. 4 is a sectional view showing another suction passage part of a rotary compressor according to the second embodiment of the present invention;

FIGS. 5 and 6 are sectional views each showing an essential part of a two cylinder rotary compressor according to the third embodiment of the present invention;

FIG. 7 is a sectional view showing an essential part of another rotary compressor in accordance with the fourth embodiment of the present invention;

FIG. 8 is a cooler system diagram in which a compressor according to the present invention is applied to a car air conditioner;

FIG. 9 is a graphical representation illustrating control characteristics of a control unit in the case where the present invention is applied to the cooler system of FIG. 8; and

FIG. 10 is a graphical representation illustrating temperature characteristics in the case where the present invention is applied to the cooler system of FIG. 8.

FIG. 3 is a sectional view illustrating the first embodiment of the present invention wherein the same reference numerals as those of FIGS. 1 and 2 designate the same or corresponding parts throughout the view in which a check valve 12 is provided in a suction passage 11a of a partition plate 9. The check valve 12 usually opens the suction passage 11a and is closed by gas pressure applied from the direction indicated by an arrow A. A conduit 13 is communicated with a high pressure side of a compression space 3a in a closed container 10 from the outside thereof through a control valve 14. The control valve 14 is composed of a magnetic valve which is opened and closed by means of an electrical signal. To the magnetic valve 14, a connecting pipe 15 communicated with a suction passage 11b is further connected. Moreover a first and second suction chambers 18a and 18b are defined at the opposite sides of the suction passage 11a of the aforesaid partition plate 9, respectively.

In a device as constructed above, the following operations are required in the case where it is intended to decrease a quantity of flow of a refrigerant gas circulating through a compressor and a refrigerating circuit whereby output of the compressor is reduced. Namely, the magnetic valve 14 is opened at first, so that a high pressure gas is applied to the check valve 12 in a direction indicated by the arrow A through the connecting pipe 15 to close the check valve 12. As a result, a low-pressure refrigerant gas does not feed to the compression space 3b of a cylinder 2b so that a rolling piston 4b races. Thus, the quantity of flow of the circulating refrigerant gas discharged from a discharge pipe decreases, and after all, power consumed reduces also.

Referring to FIG. 4 which is a sectional view illustrating the second embodiment of the present invention. Although the aforesaid first embodiment relates to a rotary compressor in which the magnetic valve 14 is provided on the outside of the closed container 10, in this second embodiment, a magnetic valve 14 is provided for inside a closed container 10 and a conduit 16 communicated with a high pressure side of a compression space 3a is connected to the magnetic valve 14 as shown in FIG. 4. As a consequence, a construction of the rotary compressor can simply be made in the second embodiment in which reference numeral 17 designates an enclosed terminal provided through the closed container 10 and for transmitting an electrical signal to the magnetic valve 14. As an electrical signal for actuating with magnetic valve 14, signals obtained in accordance with a rotational frequency of a driving shaft 1 or those obtained from a sensor and the like for detecting a temperature at the interior of a car are utilized.

It is to be noted that though the valve 12 is disposed in a suction passage 11a of a partition plate 9 in the second embodiment, the valve 12 may be placed on any other positions so far as it is within the suction passage 11a.

Next, the third embodiment of the present invention will be described by referring to FIGS. 5 and 6 wherein the same reference numerals as those of FIGS. 1 and 2 designate the same or corresponding parts throughout the views of FIGS. 5 and 6. In accordance with the rotary compressor of this third embodiment, an intake chamber 18b for a compression element 20b being downstream with respect to the flow of an intake refrigerant gas is provided with a cylindrical slider 21 having a very narrow clearance in reference to the intake chamber 18b and a spring 22 for affording force along the axial direction to the slider 21. The slider 21 is slid in the intake chamber 18b, whereby positional relationship of a suction port 23b and the slider 21 is established so as to open and close the suction port 23b. Suction port 23b is one of suction ports in the compressor and communicating a suction passage 11b with a low-pressure chamber of the compression element 20b. Furthermore a control valve 14 communicating openably and closably with the high-pressure side is provided on the anti-suction side of the slider 21. In the third embodiment, reference numeral 18a designates an intake chamber, 20a another compression element, and 23a another suction port, respectively.

Then, operation of the rotary compressor in accordance with the third embodiment will be described hereinbelow.

First, in the case where the control valve 14 communicating openably and closably with the high-pressure side is closed, there is no difference in pressure between the suction and anti-suction sides of the slider 21. Consequently, the slider 21 is urged by means of the spring 22 along the direction of the anti-suction side to collide with the surface of wall of a reaction side plate 8. In this condition, the suction port 23b communicating the suction passage 11b with the low pressure chamber is opened. Thus, a low pressure refrigerant gas is supplied to the compression elements 20a and 20b, respectively, so that the rotary compressor according to the third embodiment is operated with the same performance as that of a conventional rotary compressor. On the other hand, in the case where the control valve 14 communicating openably and closeably with its high-pressure side is opened as shown in FIG. 6, if it is assumed that a sectional area of the slider 21 is S cm.sup.2 in the anti-suction side 21b and a difference in pressure between the high-pressure and suction sides is .DELTA.P kg/cm.sup. 2, force F=.DELTA.P.times.S kg acts on the slider 21 in a direction indicated by an arrow F in FIG. 6. In accordance with combinations of the force F and load characteristics of the spring 22, the slider 21 can be moved with an arbitrary difference in pressure. And when the slider 21 moves along the direction indicated by the arrow F, the suction port 23b communicating the suction passage 11b with the low-pressure chamber of the compression element 20b is closed. As a result, functions of compressing and discharging a low-pressure refrigerant gas upon one compression element 20b of two compression elements 20a and 20b are stopped. After all, it is possible that the air cooling capacity of the rotary compressor in the third embodiment is reduced substantially half the one in a conventional compressor and at the same time its power consumption is decreased.

Again, when the control valve 14 communicating with the high-pressure side is made to be closed, since there is a very narrow clearance between the slider 21 and the suction passage 11b as mentioned above, a high-pressure gas on the side of the anti-suction pipe leaks away gradually. Hence, when a difference in pressure in the front and in the rear of the slider 21 becomes small, the slider 21 is shifted by means of force of the spring 22 along the direction indicated by the arrow B shown in FIG. 5 so that it returns the rotary compressor to its usual operational condition.

In the above described embodiment, it is to be noted that the control valve for opening and closing the high-pressure side may be disposed either inside or outside the container containing the compression elements. In this case, a control is effected on the basis of a rotational frequency of the driving shaft or a result obtained by sensing a temperature in a car interior.

In addition, the slider may be any form by which the suction port can be opened and closed, and the spring may also be any type of the one which can afford force upon the slider along the axial direction thereof. Further the spring 22 may be a tension spring stretching the slider 21 towards the anti-suction side as shown in FIG. 7.

In the following, a control for a refrigerating cycle apparatus wherein the above-mentioned compressor is utilized, i.e., a car air cooling system, will be described by referring to FIGS. 8-10. In FIG. 8, the same reference numerals as those of FIGS. 3-7 designate the same or corresponding parts throughout the view thereof in which a rolling piston type capacity variable compressor 30 is provided with a single discharge port 31 and a suction pipe 11 having an intake for a cylinder. The compressor 30 is further provided with an electromagnetic clutch 32 being connected to a car engine 41 through a pulley 37. A condenser 33 for condensing a high-pressure gas fed from the discharge port 31 is connected to this discharge port of the compressor 30. A refrigerant liquid at a high temperature and pressure being condensed by means of the condenser 33 is transferred to a receiver/drier 34 and stored therein. A throttle device 35 composed of an expansion valve varying an amount of the refrigerant to be throttled in response to an evaporated state of the refrigerant is connected to the receiver/drier 34. Moreover a cooler 36 for evaporating the refrigerant liquid, which has been kept in a low temperature and pressure condition by means of the expansion valve 35 thereby to take ambient heat away, is disposed in between the expansion valve 35 and the suction pipe 11 of the compressor 30. A piping for introducing the refrigerant fed from the cooler 36 into the intake 11 for the compressor 30 is provided. The cooling cycle apparatus is further provided with a unit 38 for controlling the above-mentioned electromagnetic clutch 32 and the magnetic valve 14 by means of a temperature sensing part 39 and a temperature presetting means 40 disposed in the interior of a car. Control characteristics of the control unit 38 are as illustrated in FIG. 9. Then, operation of the car air cooling system constructed as stated above will be described hereinbelow.

The control unit 38 compares a temperature measured in the temperature sensing part 39 composed of a thermistor or the like by which either a suction temperature or a blow-off temperature of the cooler 36 is sensed with a temperature preset by means of the temperature presetting means 40 placed in the car interior, so that the control unit 38 transmits output to the electromagnetic clutch 32 and the magnetic valve 14 in accordance with the graphical representation illustrating the control characteristics in FIG. 9. More specifically, as illustrated in FIG. 9, both the electromagnetic clutch and a closing valve means (magnetic valve) are ON (state (A)) until the temperature reaches a preset temperature (or the preset temperature+.alpha.). Then, when the electromagnetic clutch 32 is turned ON, driving force of an engine is transmitted to the compressor 30, thereby operating the compressor. The closing valve means 14 is turned ON, whereby a stream of the refrigerant flowed from the cooler 36 is introduced into each cylinder of the compressor 30. Hence compression is effected in two cylinders so that the compressor cools rapidly the car interior with the maximum capacity to make a temperature in the car interior close to the preset temperature. As a consequence, when a temperature detected by the temperature detecting part 39 is lower than the preset temperature (or preset temperature+.alpha.), the electromagnetic clutch is kept in the ON state, whereas the closing valve means remains at OFF (state (B)). Upon turning the closing valve means OFF, a valve means disposed therein is driven to stop the introduction of a flow of the refrigerant which was flowing just now through each suction port of the compressor 30 into either of the cylinders. Because of such adjustment, the compressor 30 is actuated by means of one of the cylinders so that a capacity of the compressor 30 is reduced by half, and air cooling in the car interior is effected in this condition. Thereafter, if a required load in the car interior is well-balanced with the air cooling capacity in the operation by means of a single cylinder of the compressor 30, such compressor is operated with a state remaining unchanged. However, when the load in the car interior becomes larger than the air cooling capacity by a single cylinder operation, the compressor is again operated by means of two cylinders with the maximum capacity accompanied with a certain degree of hysteresis (indicated by 1 deg. in FIG. 9). On the contrary, when the load in the car interior is small and a temperature detected by the temperature detecting part 39 becomes lower than the preset temperature (or preset temperature+.alpha.) by .beta. degree (indicated by 2 deg. in FIG. 9), the electromagnetic clutch 32 is turned OFF so that the compressor 30 is operated by either one cylinder or two cylinders. Under the circumstance, a temperature difference between the preset temperature and the blow-off temperature (or suction temperature) in the control unit as described above is smaller than that of a conventional control unit. Furthermore, in this case of the compressor according to the present invention, a climbing gradient of a blow-off temperature (or suction temperature) is raised while the compressor 30 is operated by means of one cylinder so that the raise of which is gradually carried out. In addition, in the case where a load in the car interior is well-balanced with a capacity operated by means of one cylinder, a constant blow-off temperature (or suction temperature) is attained so that comfortable air cooling can be obtained. Besides, according to the control unit of the present invention, the compressor 30 is repeatedly driven by means of one cylinder and two cylinders during a season where air-conditioning or air cooling is generally performed. For this reason, the compressor 30 is always operated unlike such a case where operation of the compressor is sometimes ceased as in a conventional control unit, so that wasteful power at the time of starting the compressor can be saved. The rotary compressor according to the present invention detects a rotational frequency of the driving shaft, a temperature of the car interior or the like to carry out opening or closing of a control valve being openable and closable and communicating with the high-pressure side of the compressor on the basis of such signal detected as above, whereby a capacity of the compressor can be controlled. Accordingly a pertinent operation can be effected by the rotary compressor according to the present invention, if the compressor is applied to the case of over air cooling because of too much rotational frequency of its driving shaft or a case where a load in air cooling is small in a motorcar and the like wherein a rotational frequency of its driving shaft is variable. As the result, a required power can be reduced, and an ON-OFF frequency of the compressor can also be decreased so that comfortableness in air cooling can remarkably be improved in the rotary compressor according to the present invention.