TECHNICAL FIELD

The present invention relates to a capacity control valve configured to variably control a working fluid capacity, and for example, relates to a capacity control valve configured to control, according to a pressure, a discharge amount of a variable displacement compressor used for an air-conditioning system of an automobile.

BACKGROUND ART

A variable displacement compressor used for, e.g., an air-conditioning system of an automobile includes, for example, a rotary shaft to be rotatably driven by an engine, a swash plate coupled such that an inclination angle thereof with respect to the rotary shaft is variable, and a compression piston coupled to the swash plate. The inclination angle of the swash plate is changed, and accordingly, a stroke amount of the piston is changed. In this manner, a fluid discharge amount is controlled. Using a capacity control valve to be openably driven by electromagnetic force, the variable displacement compressor can control the internal pressure of a control chamber as necessary to continuously change the inclination angle of the swash plate while utilizing a suction pressure Ps of a suction chamber for sucking fluid, a discharge pressure Pd of a discharge chamber for discharging fluid pressurized by the piston, and a control pressure Pc of the control chamber housing the swash plate (see Patent Citations 1, 2, and 3).

In continuous drive (hereinafter sometimes merely referred to as “in continuous drive”) of the variable displacement compressor, energization of the capacity control valve is controlled by a control computer, and the capacity control valve moves a valve body in an axial direction by electromagnetic force generated by a solenoid to perform the normal control of opening/closing a main valve to adjust the control pressure Pc of the control chamber of the variable displacement compressor.

For example, a capacity control valve of Patent Citation 1 is configured such that a control chamber is connected to a discharge chamber through a stationary orifice, and controls a CS valve as a main valve to adjust the pressure of the control chamber with a suction pressure. Moreover, a capacity control valve of Patent Citation 2 is configured such that a control chamber is connected to a suction chamber through a stationary orifice, and controls a DC valve as a main valve to adjust the pressure of the control chamber with a discharge pressure. Further, a capacity control valve of Patent Citation 3 controls a CS valve and a DC valve to adjust the pressure of a control chamber.

In normal control of the capacity control valve, the pressure of the control chamber in the variable displacement compressor is controlled as necessary, and the inclination angle of the swash plate with respect to the rotary shaft is continuously changed. In this manner, the stroke amount of the piston is changed such that the fluid discharge amount for the discharge chamber is controlled, and the air-conditioning system is adjusted to have a desired cooling capacity. Moreover, in a case where the variable displacement compressor is driven with the maximum capacity, the main valve of the capacity control valve is closed such that the pressure of the control chamber decreases, and in this manner, the inclination angle of the swash plate becomes maximum.

CITATION LIST

Patent Literature

Patent Citation 1: JP 2017-129042 A (Page 9, FIG. 2)

Patent Citation 2: Japanese Patent No. 6206274 (Page 8, FIG. 2)

Patent Citation 3: Japanese Patent No. 4242624 (Page 7, FIG. 1)

SUMMARY OF INVENTION

Technical Problem

However, in Patent Citations 1 and 2, the capacity control valve can be configured with a simple configuration. However, the stationary orifice connected to the control chamber of the variable displacement compressor has a constant flow path sectional area. Thus, for adjusting the pressure of the control chamber only by control of the main valve (i.e., the CS valve or the DC valve) in normal control, there is room for improvement in controllability of the control pressure Pc. Moreover, in Patent Citation 3, the CS valve and the DC valve are arranged to enhance controllability. However, Patent Citation 3 fails to describe cooperation of the CS valve and the DC valve, and a favorable control efficiency in normal control cannot be always provided.

The present invention has been made in view of these problems, and is intended to provide a capacity control valve with a favorable control efficiency in normal control.

Solution to Problem

For solving the above-described problems, a capacity control valve according to a first aspect of the present invention is a capacity control valve for controlling a flow rate by energization of a solenoid, including: a valve housing formed with a discharge port through which discharge fluid with a discharge pressure passes, a suction port through which suction fluid with a suction pressure passes, and first and second control ports through which control fluid with a control pressure passes; a rod arranged in the valve housing and driven by the solenoid; a CS valve configured to control a fluid flow between the first control port and the suction port in accordance with a movement of the rod; and a DC valve configured to control a fluid flow between the second control port and the discharge port in accordance with the movement of the rod, wherein in a non-energization state of the solenoid, the CS valve is closed and the DC valve is opened, wherein as the energization of the solenoid becomes larger, the CS valve transitions from a closed state to an open state, and the DC valve is throttled from an open state and thereafter transitions to the open state, and wherein in a maximum current state of the solenoid, the CS valve is opened and the DC valve is opened. According to the aforesaid feature of the first aspect of the present invention, the flow rate is controlled by cooperation of the CS valve and the DC valve, and therefore, the control pressure can be controlled with a favorable efficiency. Moreover, the CS valve and the DC valve transition in opposite directions in a low energization current range, only a CS valve opening degree increases in an intermediate current range, and the CS valve and the DC valve transition in the same direction in a high current range. The control pressure is controlled based on a difference between the amount of adjustment of the control pressure by the CS valve and the amount of adjustment of the control pressure by the DC valve. Thus, the control pressure can be finely controlled in association with a current value. Particularly, as energization current increases, the control pressure can be more finely controlled in association with the current value.

It may be preferable that a state in which the DC valve is throttled in the energization of the solenoid is a closed state. According to this preferable configuration, a control range according to the energization current for the solenoid is broader in the CS valve than in the DC valve. That is, the CS valve is main, and the DC valve is auxiliary. Thus, a favorable control efficiency is provided.

It may be preferable that the DC valve has a spool valve structure, and includes a land portion of the rod and a DC valve seat provided at the inner periphery of the valve housing. According to this preferable configuration, the DC valve can be simply configured.

It may be preferable that the rod is arranged at the inner periphery of the valve housing to partition the suction port and the discharge port. According to this preferable configuration, the capacity control valve can be simply configured.

It may be preferable that the CS valve includes a pressure-sensitive body and a Cs valve seat, the pressure-sensitive body being arranged in a pressure-sensitive chamber formed with the first control port and configured to bias the rod, the CS valve seat being provided at the valve housing. According to this preferable configuration, a structure in which reactive force provided to the rod according to the suction pressure is increased/decreased is made, and controllability of the control pressure is enhanced.

It may be preferable that a spring configured to provide biasing force in an axial direction is arranged between the pressure-sensitive body and the rod. According to this preferable configuration, the spring can deformably move in the axial direction. Thus, even if an axial deformable amount of the pressure-sensitive body is small, the DC valve can be reliably operated.

It may be preferable that the discharge port, the second control port, the suction port, and the first control port or the second control port, the discharge port, the suction port, and the first control port are arranged in description order from a side of the solenoid. According to this preferable configuration, the valve housing can be simply configured.

A capacity control valve according to a second aspect of the present invention is a capacity control valve for controlling a flow rate by energization of a solenoid, including: a valve housing formed with a discharge port through which discharge fluid with a discharge pressure passes, a suction port through which suction fluid with a suction pressure passes, and first and second control ports through which control fluid with a control pressure passes; a rod arranged in the valve housing, driven by the solenoid, the rod forming a spool valve structure of a DC valve configured to control a fluid flow between the second control port and the discharge port by a land portion arranged at an outer periphery; and a pressure-sensitive body forming a CS valve configured to control a fluid flow between the first control port and the suction port in accordance with a movement of the rod. According to the feature of the second aspect of the present invention, the flow rate is controlled by cooperation of the CS valve and the DC valve, and therefore, the control pressure can be controlled with a favorable efficiency.

