Patent Description:
A variable displacement compressor used for an air conditioning system of an automobile, etc. includes a rotating shaft to be driven and rotated by an engine, a swash plate coupled to the rotating shaft in such a manner that a tilt angle is variable, compressing pistons coupled to the swash plate, etc., and by changing the tilt angle of the swash plate, changes a stroke amount of the pistons to control a discharge amount of a fluid. This tilt angle of the swash plate can be continuously changed by appropriately controlling pressure in a control chamber while utilizing suction pressure Ps of a suction chamber that suctions the fluid, discharge pressure Pd of a discharge chamber that discharges the fluid pressurized by the pistons, and control pressure Pc of the control chamber that houses the swash plate, with using a capacity control valve to be driven to open and close by electromagnetic force.

At the time of continuously driving the variable displacement compressor, the capacity control valve performs normal control in which energization is controlled by a control computer, a valve element is moved in the axial direction by electromagnetic force generated in a solenoid, and a main valve is opened and closed to adjust the control pressure Pc of the control chamber of the variable displacement compressor.

At the time of the normal control of the capacity control valve, the pressure of the control chamber in the variable displacement compressor is appropriately controlled, and by continuously changing the tilt angle of the swash plate with respect to the rotating shaft, the stroke amount of the pistons is changed to control the discharge amount of the fluid to the discharge chamber. Thus, the air conditioning system is adjusted to have a desired cooling ability.

The rod-shaped valve element is inserted into a guide hole slidably with respect to the guide hole, and a control port through which a control fluid of control pressure passes and a suction port through which a suction fluid of suction pressure passes are partitioned across a sliding region (see Patent Citation <NUM>).

To greatly improve the function for discharging foreign matter that enters between the outer peripheral surface of a valve body and the inner peripheral surface of a body, and to improve the centering function of the valve body, in Patent Citation <NUM> a volume control valve is provided with a valve housing, a valve body which is mounted in a guide passage of the valve housing and opens and closes a control passage. Further, a solenoid for driving opening and closing of said valve body is provided. The volume control valve is characterized in that one of the outer peripheral surface of the valve body and the guide surface of the guide passage is provided with a taper part and the other of said surfaces is provided with a helical groove, and in that the taper part is configured such that the gap between the outer peripheral surface of the valve body and the guide surface of the guide passage becomes larger on the low pressure side than on the high pressure side, and, over the entire range from the start point to the end point of the stroke of the valve body, the taper part and the helical groove are disposed such that the start point of the taper part is positioned inside of the region of the helical groove.

To provide a capacity control valve, for controlling the flow rate or pressure of a variable capacity compressor in accordance with the degree of opening of a valve unit, that improves the operation efficiency of the variable capacity compressor, in Patent Citation <NUM> a capacity control valve, for controlling the flow rate or pressure of the variable capacity compressor in accordance with the degree of opening of a valve unit, is provided. The capacity control valve includes: a valve main body which comprises a first valve chamber, a second valve chamber and a third valve chamber; a valve body which comprises an intermediate communication passage for allowing communication between the first valve chamber and the third valve chamber, a first valve unit arranged in the first valve chamber, a second valve unit for allowing and stopping communication between the third valve chamber and the second valve chamber, and a third communication hole for allowing communication between the third valve chamber and the intermediate communication passage; a solenoid which comprises a first plunger connected to the valve body; and a second plunger which is arranged between the solenoid and the valve body.

In the capacity control valve of Patent Citation <NUM>, by providing plural annular grooves on an outer peripheral surface of a shaft moved together with the valve element and forming a labyrinth seal between an inner peripheral surface of the guide hole and the outer peripheral surface of the shaft in the sliding region, the control fluid and the suction fluid are partitioned across the sliding region in a sealed manner. However, since contaminant, etc. coming in a clearance between the outer peripheral surface of the shaft and the inner peripheral surface of the guide hole sometimes remains in the sliding region, there is a fear that sliding resistance of the shaft with respect to the guide hole is increased and the valve element is not normally operated. When, in order to suppress contaminant, etc. from remaining in the sliding region, axial length of the sliding region is shortened and the clearance is enlarged to increase a flow rate of the fluid on the low-pressure side of the sliding region, there is a problem that an amount of the fluid leaked to the low-pressure side of the sliding region is increased and compression efficiency of the variable displacement compressor controlled by the capacity control valve is lowered.

The present invention is achieved focusing on such problems, and an object thereof is to provide a capacity control valve in which resistance to foreign substances can be enhanced while reducing leakage of a fluid to the low-pressure side of a sliding region.

In order to solve the foregoing problems, a capacity control valve according to the present invention is a capacity control valve including a valve housing provided with a discharge port through which a discharge fluid of discharge pressure passes, a suction port through which a suction fluid of suction pressure passes, and a control port through which a control fluid of control pressure passes, and a valve element configured to be brought into contact with and separated from a valve seat by a driving force of a solenoid to open and close a communication between the control port and the discharge port or a communication between the control port and the suction port, wherein a sliding region is formed by an inner peripheral surface of the valve housing and an outer peripheral surface of the valve element, a groove extending in a circumferential direction is formed in at least one of the inner peripheral surface of the valve housing and the outer peripheral surface of the valve element, and the sliding region has a structure in which a swirling current is generated in the groove by a fluid flowing from a high-pressure side to a low-pressure side in a clearance between the inner peripheral surface of the valve housing and the outer peripheral surface of the valve element, wherein a radial length of the clearance is within a range from <NUM>/<NUM> to <NUM>/<NUM> of an axial length of the sliding region, and the groove includes at least two threads of spiral grooves. According to the aforementioned feature of the present invention, the swirling current is generated in the groove by the fluid flowing from the high-pressure side to the low-pressure side in the sliding region, and hence becomes a fluid resistance portion with respect to the fluid flowing in the axial direction from the high-pressure side to the low-pressure side in the sliding region, so that an amount of the fluid leaked from the high-pressure side to the low-pressure side of the sliding region can be reduced. Therefore, by shortening axial length of the sliding region and enlarging the clearance of the sliding region, a flow rate of the fluid flowing from the high-pressure side to the low-pressure side in the sliding region can be enhanced and while reducing leakage of the fluid to the low-pressure side of the sliding region, it is possible to suppress contaminant, etc. from remaining and accumulating in the sliding region to enhance resistance to foreign substances.

According to the present invention a radial length of the clearance is within a range from <NUM>/<NUM> to <NUM>/<NUM> of an axial length of the sliding region. According to this configuration, the swirling current is generated by the fluid flowing from the high-pressure side to the low-pressure side in the sliding region and it is possible to reduce the amount of the fluid leaked to the low-pressure side of the sliding region.

It may be preferable that the radial length of the clearance is within a range from <NUM> to <NUM>. According to this preferable configuration, the swirling current is generated by the fluid flowing from the high-pressure side to the low-pressure side in the sliding region and it is possible to reduce the amount of the fluid leaked to the low-pressure side of the sliding region.

It may be preferable that a depth of the groove is larger than the radial length of the clearance. According to this preferable configuration, since the fluid flowing from the high-pressure side to the low-pressure side in the clearance of the sliding region is reliably guided into the groove, the swirling current is more easily generated. In addition, since contaminant, etc. can be pulled into the groove by the swirling current, it is possible to prevent contaminant, etc. from remaining and accumulating in the clearance of the sliding region.

It may be preferable that the groove is exposed on the low-pressure side of the sliding region in a stroke range of the valve element. According to this preferable configuration, it is possible to discharge contaminant, etc. pulled into the groove to the low-pressure side of the sliding region.

It may be preferable that the groove extends so as to form a spiral shape, and a pitch of the groove for one roll from a groove inlet is longer than the axial length of the sliding region. According to this preferable configuration, since the groove is exposed on the low-pressure side of the sliding region by a short distance of one roll from the groove inlet, it is possible to more easily discharge contaminant, etc. pulled into the groove.

According to the present invention the groove is a multiple-thread spiral groove. According to this configuration, since the fluid flows according to the flow rate from the high-pressure side to the low-pressure side in the plural spiral grooves, contaminant, etc. pulled into the grooves is more easily discharged.

Modes for carrying out a capacity control valve according to the present invention will be described below based on embodiments.

A capacity control valve according to a first embodiment of the present invention will be described with reference to <FIG>. Hereinafter, description will be given with the left and right sides seen from the front side of <FIG> being the left and right sides of the capacity control valve.

A capacity control valve V of the present invention is assembled into a variable displacement compressor M used for an air conditioning system of an automobile, etc. By variably controlling pressure of a working fluid (hereinafter, simply referred to as the "fluid") serving as a coolant, a discharge amount of the variable displacement compressor M is controlled and the air conditioning system is adjusted to have a desired cooling ability.

First of all, the variable displacement compressor M will be described. As shown in <FIG>, the variable displacement compressor M has a casing <NUM> including a discharge chamber <NUM>, a suction chamber <NUM>, a control chamber <NUM>, and plural cylinders 4a. A communication passage (not shown) providing direct communication between the control chamber <NUM> and the suction chamber <NUM> is provided in the variable displacement compressor M. A fixed orifice for adjusting to balance pressure between the suction chamber <NUM> and the control chamber <NUM> is provided in this communication passage.

The variable displacement compressor M also includes a rotating shaft <NUM> to be driven and rotated by an engine (not shown) installed outside the casing <NUM>, a swash plate <NUM> coupled to the rotating shaft <NUM> in an eccentric state by a hinge mechanism <NUM> in the control chamber <NUM>, and plural pistons <NUM> coupled to the swash plate <NUM> and fitted reciprocatably in the respective cylinders 4a. With using the capacity control valve V to be driven to open and close by electromagnetic force, a tilt angle of the swash plate <NUM> is continuously changed by appropriately controlling pressure in the control chamber <NUM> while utilizing suction pressure Ps of the suction chamber <NUM> that suctions the fluid, discharge pressure Pd of the discharge chamber <NUM> that discharges the fluid pressurized by the pistons <NUM>, and control pressure Pc of the control chamber <NUM> that houses the swash plate <NUM>. Thereby, a stroke amount of the pistons <NUM> is changed to control a discharge amount of the fluid. For convenience of description, the capacity control valve V assembled into the variable displacement compressor M is not shown in <FIG>.

Specifically, the higher the control pressure Pc in the control chamber <NUM> is, the smaller the tilt angle of the swash plate <NUM> with respect to the rotating shaft <NUM> becomes, and the more the stroke amount of the pistons <NUM> is reduced. However, when the pressure becomes fixed pressure or more, the swash plate <NUM> is brought into a substantially perpendicular state with respect to the rotating shaft <NUM>, that is, a state where the swash plate is slightly tilted from the exactly perpendicular state. At this time, the stroke amount of the pistons <NUM> becomes minimum, and pressurization of the fluid in the cylinders 4a by the pistons <NUM> becomes minimum. Therefore, the discharge amount of the fluid to the discharge chamber <NUM> is reduced, and the cooling ability of the air conditioning system becomes minimum. Meanwhile, the lower the control pressure Pc in the control chamber <NUM> is, the larger the tilt angle of the swash plate <NUM> with respect to the rotating shaft <NUM> becomes, and the more the stroke amount of the pistons <NUM> is increased. However, when the pressure becomes fixed pressure or less, the tilt angle of the swash plate <NUM> with respect to the rotating shaft <NUM> becomes maximum. At this time, the stroke amount of the pistons <NUM> becomes maximum, and the pressurization of the fluid in the cylinders 4a by the pistons <NUM> becomes maximum. Therefore, the discharge amount of the fluid to the discharge chamber <NUM> is increased, and the cooling ability of the air conditioning system becomes maximum.

As shown in <FIG>, the capacity control valve V assembled into the variable displacement compressor M adjusts an electric current energized in a coil <NUM> forming a solenoid <NUM> and performs open/close control of a main valve <NUM> and an auxiliary valve <NUM> in the capacity control valve V, and also performs open/close control of a pressure sensitive valve <NUM> by suction pressure Ps in an intermediary communication passage <NUM>, so that by controlling the fluid flowing into the control chamber <NUM> or flowing out from the control chamber <NUM>, the control pressure Pc in the control chamber <NUM> is variably controlled. The intermediary communication passage <NUM> passes through over the axial direction by connecting a main/auxiliary valve element <NUM> serving as a valve element and a hollow hole formed inside a pressure sensitive valve member <NUM>, and forms a flow passage for discharging a liquid coolant. In detail, partly due to liquefication of the fluid whose pressure is increased in the control chamber <NUM> by leaving the variable displacement compressor M in a stop state for a long time, but by closing the main valve <NUM> and opening the auxiliary valve <NUM> by start-up of the variable displacement compressor M and energization of the capacity control valve V, and further by contracting a pressure sensitive body <NUM> and opening the pressure sensitive valve <NUM> by high suction pressure Ps in the intermediary communication passage <NUM>, the liquid coolant of the control chamber <NUM> can be discharged to the suction chamber <NUM> via the intermediary communication passage <NUM> for a short time.

In the present embodiment, the main valve <NUM> is formed by the main/auxiliary valve element <NUM> and a main valve seat 10a serving as a valve seat which is formed in a valve housing <NUM>, and by bringing and separating an axially left end 51a of the main/auxiliary valve element <NUM> into contact with and from the main valve seat 10a, the main valve <NUM> is opened and closed. The auxiliary valve <NUM> is formed by the main/auxiliary valve element <NUM> and an auxiliary valve seat 82a formed on the inner diameter side of an axially left end surface which serves as an opening end surface of a fixed iron core <NUM>, and by bringing and separating an axially right end 51b of the main/auxiliary valve element <NUM> into contact with and from the auxiliary valve seat 82a, the auxiliary valve <NUM> is opened and closed. The pressure sensitive valve <NUM> is formed by a cap <NUM> forming the pressure sensitive body <NUM> and an annular pressure sensitive valve seat 52a formed in an axially left end of the pressure sensitive valve member <NUM>. By bringing and separating a sealing surface 70a formed on the outer diameter side of an axially right end of the cap <NUM> into contact with and from the pressure sensitive valve seat 52a, the pressure sensitive valve <NUM> is opened and closed.

Next, a structure of the capacity control valve V will be described. As shown in <FIG>, the capacity control valve V is mainly formed by the valve housing <NUM> made of a metal material or a resin material, the main/auxiliary valve element <NUM> arranged reciprocatably in the axial direction in the valve housing <NUM>, the pressure sensitive valve member <NUM>, the pressure sensitive body <NUM> that applies axially rightward bias force to the main/auxiliary valve element <NUM> and the pressure sensitive valve member <NUM> in accordance with the suction pressure Ps in the intermediary communication passage <NUM>, and the solenoid <NUM> connected to the valve housing <NUM>, the solenoid that applies drive force to the main/auxiliary valve element <NUM> and the pressure sensitive valve member <NUM>.

As shown in <FIG>, the solenoid <NUM> is mainly formed by a casing <NUM> having an opening portion 81a which is open on the axially left side, the substantially cylindrical fixed iron core <NUM> inserted into the opening portion 81a of the casing <NUM> from the axially left side and fixed on the inner diameter side of the casing <NUM>, a drive rod <NUM> inserted into the fixed iron core <NUM> reciprocatably in the axial direction, the drive rod whose axially left end portion is inserted and fixed to the main/auxiliary valve element <NUM>, a movable iron core <NUM> to which an axially right end portion of the drive rod <NUM> is inserted and fixed, a coil spring <NUM> provided between the fixed iron core <NUM> and the movable iron core <NUM>, the coil spring biasing the movable iron core <NUM> to the axially right side which is the valve opening direction of the main valve <NUM>, and the excitation coil <NUM> wound on the outside of the fixed iron core <NUM> via a bobbin.

A recessed portion 81b in which the inner diameter side of an axially left end is recessed to the axially right side is formed in the casing <NUM>. An axially right end portion of the valve housing <NUM> is inserted and fixed to this recessed portion 81b in a substantially sealed manner.

The fixed iron core <NUM> is made of a rigid body which is a magnetic material such as iron or silicon steel, and includes a cylindrical portion 82b extending in the axial direction, the cylindrical portion where an insertion hole 82c into which the drive rod <NUM> is inserted is formed, and an annular flange portion 82d extending in the outer diameter direction from an outer peripheral surface of an axially left end portion of the cylindrical portion 82b. The auxiliary valve seat 82a is formed on the inner diameter side of the opening end surface of the fixed iron core <NUM>, that is, on an axially left end surface of the cylindrical portion 82b.

The fixed iron core <NUM> is inserted and fixed to a recessed portion 10b recessed to the axially left side on the inner diameter side of an axially right end of the valve housing <NUM> which is inserted and fixed to the recessed portion 81b of the casing <NUM> in a substantially sealed manner in a state where an axially right end surface of the flange portion 82d is abutted with a bottom surface of the recessed portion 81b of the casing <NUM>.

Next, a structure of the valve housing <NUM> will be described. As shown in <FIG>, a Pd port <NUM> serving as a discharge port which communicates with the discharge chamber <NUM> of the variable displacement compressor M, a Ps port <NUM> serving as a suction port which communicates with the suction chamber <NUM> of the variable displacement compressor M, and a Pc port <NUM> serving as a control port which communicates with the control chamber <NUM> of the variable displacement compressor M are formed in the valve housing <NUM>.

The valve housing <NUM> is formed in a substantially cylindrical bottomed shape by press-fitting a partition adjusting member <NUM> to an axially left end portion in a substantially sealed manner. The partition adjusting member <NUM> can adjust the bias force of the pressure sensitive body <NUM> by adjusting an installment position of the valve housing <NUM> in the axial direction.

A first valve chamber <NUM> communicating with the Pd port <NUM> where an axially left end portion of the main/auxiliary valve element <NUM> is arranged, a second valve chamber <NUM> communicating with the Ps port <NUM> where an axially right end portion of the main/auxiliary valve element <NUM> is arranged, and a pressure sensitive chamber <NUM> communicating with the Pc port <NUM> where the pressure sensitive body <NUM> is arranged are formed inside the valve housing <NUM>.

As shown in <FIG> and <FIG>, the main/auxiliary valve element <NUM> and the pressure sensitive valve member <NUM> connected to this main/auxiliary valve element <NUM> are arranged reciprocatably in the axial direction inside the valve housing <NUM>. An annular projected portion <NUM> projecting in the inner diameter direction from a part between the Pd port <NUM> and the Ps port <NUM> in the axial direction is provided on an inner peripheral surface of the valve housing <NUM>, and a small-diameter guide hole 10c on which an outer peripheral surface 51c of the main/auxiliary valve element <NUM> is slidable is formed by an inner peripheral surface 11a of this projected portion <NUM>. The projected portion <NUM> is formed to have a trapezoidal section by the inner peripheral surface 11a forming the guide hole 10c on which the outer peripheral surface 51c of the main/auxiliary valve element <NUM> is slidable and extending along the axial direction, a side surface 11b extending orthogonally to the axial direction on the side of the first valve chamber <NUM>, and a tapered side surface 11c whose diameter is gradually increased to the axially right side on the side of the second valve chamber <NUM>.

In such a way, inside the valve housing <NUM>, the first valve chamber <NUM> and the second valve chamber <NUM> are partitioned in a sealed manner by the outer peripheral surface 51c of the main/auxiliary valve element <NUM> and the inner peripheral surface 11a of the projected portion <NUM> forming the guide hole 10c, both the surfaces extending in parallel in the axial direction. A tiny clearance C (see <FIG>) is formed between the outer peripheral surface 51c of the main/auxiliary valve element <NUM> and the inner peripheral surface 11a of the projected portion <NUM> forming the guide hole 10c by slightly separating the surfaces from each other in the radial direction. The main/auxiliary valve element <NUM> is smoothly relatively movable in the axial direction with respect to the valve housing <NUM>.

In the present embodiment, a part in which the inner peripheral surface 11a of the projected portion <NUM> forming the guide hole 10c and the outer peripheral surface 51c of the main/auxiliary valve element <NUM> slide with each other will be described as a sliding region S. Axial length L1 of the sliding region S corresponds to axial length of the inner peripheral surface 11a of the projected portion <NUM> forming the guide hole 10c. The axial length L1 of the sliding region S in the present embodiment is set to be <NUM>, and radial length of the clearance C is set to be <NUM>. That is, the radial length of the clearance C is formed within a range from <NUM>/<NUM> to <NUM>/<NUM> of the axial length L1 of the sliding region S. The axial length L1 of the sliding region S is preferably within a range from <NUM> to <NUM>, and the radial length of the clearance C is preferably within a range from <NUM> to <NUM>.

As shown in <FIG>, in an energized state of the capacity control valve V, the main/auxiliary valve element <NUM> is moved to the axially left side by the drive force of the solenoid <NUM>, the axially left end 51a of the main/auxiliary valve element <NUM> is seated on the main valve seat 10a formed in the valve housing <NUM>, and the main valve <NUM> is closed, so that a flow of the fluid running from the first valve chamber <NUM> to the pressure sensitive chamber <NUM> is blocked (see a dotted arrow of <FIG>). Thus, a flow of the fluid running to the sliding region S is generated by a pressure difference (Pd > Ps) between the inside of the first valve chamber <NUM> to which the discharge pressure Pd is supplied form the Pd port <NUM> and the inside of the second valve chamber <NUM> to which the suction pressure Ps is supplied from the Ps port <NUM> (see a solid arrow of <FIG>). As shown in <FIG>, in a non-energized state of the capacity control valve V, by separating the axially left end 51a of the main/auxiliary valve element <NUM> from the main valve seat 10a formed in the valve housing <NUM> and opening the main valve <NUM>, the first valve chamber <NUM> communicates with the pressure sensitive chamber <NUM> to which the control pressure Pc is supplied from the Pc port <NUM>, and the fluid flows from the first valve chamber <NUM> to the pressure sensitive chamber <NUM> by a pressure difference (Pd > Pc) between the inside of the first valve chamber <NUM> and the inside of the pressure sensitive chamber <NUM> (see a solid arrow of <FIG>). Thus, the pressure difference between the inside of the first valve chamber <NUM> and the inside of the second valve chamber <NUM> is decreased, and the flow of the fluid running to the sliding region S is substantially not generated.

Next, a structure of the main/auxiliary valve element <NUM> will be described. As shown in <FIG>, the main/auxiliary valve element <NUM> is formed in a cylindrical shape. The axially left end portion of the drive rod <NUM> forming the solenoid <NUM> is inserted and fixed to the axially right end portion of the main/auxiliary valve element <NUM> via an adapter <NUM>, and the pressure sensitive valve member <NUM> of a separate body formed in a substantially cylindrical shape and a substantially artillery battery shape when seen from the side is inserted and fixed to the axially left end portion of the main/auxiliary valve element <NUM> in a substantially sealed manner. Both are movable in the axial direction.

As shown in <FIG>, a groove <NUM> is formed on the outer peripheral surface 51c of the main/auxiliary valve element <NUM>. The groove <NUM> is formed by two threads of spiral grooves <NUM>, <NUM> each of which extends on the outer peripheral surface 51c of the main/auxiliary valve element <NUM> for one and a half rolls while being tilted in the axial direction, the spiral grooves whose circumferential phases are displaced from each other by <NUM> degrees. That is, the groove <NUM> is formed as a so-called two-thread spiral groove. The spiral grooves <NUM>, <NUM> are not limited to the grooves extending on the outer peripheral surface 51c of the main/auxiliary valve element <NUM> for one and a half rolls but may be freely formed with the number of rolls of the spiral grooves <NUM>, <NUM>. However, in order to form the groove <NUM> in an annular shape, the number is preferably one or more. Further, the groove <NUM> is not limited to the groove formed as a two-thread spiral groove but the groove <NUM> may be formed by three or more threads of spiral grooves as a so-called multiple-thread spiral groove. Regarding the main/auxiliary valve element <NUM> in <FIG>, part of the outer peripheral surface 51c is shown in order to illustrate the groove <NUM>. For convenience of description, in the figures, one of the spiral grooves may be dotted in order to distinguish between the two threads of the spiral grooves.

As shown in <FIG> in particular, groove sections of the spiral grooves <NUM>, <NUM> are formed in a substantially isosceles trapezoid, width of the grooves is set within a range from <NUM> to <NUM>, depth is set within a range from <NUM> to <NUM>, a pitch is respectively set within a range from <NUM> to <NUM>, and a tilt angle of a groove side surface with respect to the axial direction is set within a range from not less than <NUM> degrees to less than <NUM> degrees. The depth of the spiral grooves <NUM>, <NUM> is larger than the radial length of the clearance C in the sliding region S. Further, a shape of the groove sections of the spiral grooves <NUM>, <NUM> is not limited to the substantially isosceles trapezoid but may be other shapes such as a trapezoid in which the tilt angle of the groove side surface is different, a rectangle, an arc, or a triangle.

In the spiral grooves <NUM>, <NUM>, groove inlets 57a, 58a serving as axially left ends and groove outlets 57b, 58b serving as axially right ends are respectively formed at the axially same positions on the outer peripheral surface 51c of the main/auxiliary valve element <NUM>. In the spiral grooves <NUM>, <NUM>, roll portions 57c, 58c between the groove inlets 57a, 58a and the groove outlets 57b, 58b have the same extension size, and axial length L2 of a pitch for one roll (see <FIG>) is also the same. As shown in <FIG>, the axial length L2 of the pitch for one roll of the spiral grooves <NUM>, <NUM> is longer than the axial length L1 of the sliding region S (L2 > L1).

As shown in <FIG> and <FIG>, in a stroke range of the main/auxiliary valve element <NUM>, the groove inlets 57a, 58a of the spiral grooves <NUM>, <NUM> are positioned in the sliding region S, and the groove outlets 57b, 58b are exposed at positions axially corresponding to the tapered side surface 11c in the projected portion <NUM> of the valve housing <NUM>, that is, in the second valve chamber <NUM> on the low-pressure side of the sliding region S. The groove outlets 57b, 58b are not limited to the groove outlets always exposed in the second valve chamber <NUM> but may be formed, for example, in such a manner that the groove outlets 57b, 58b are exposed from the inside of the sliding region S into the second valve chamber <NUM> by a stroke of the main/auxiliary valve element <NUM> according to the capacity control valve V being controlled from the energized state into the non-energized state.

As described above, by forming the groove <NUM> formed by the two threads of the spiral grooves <NUM>, <NUM> tilted in the axial direction on the outer peripheral surface 51c of the main/auxiliary valve element <NUM>, as shown in <FIG>, by the fluid flowing from the first valve chamber <NUM> on the high-pressure side to the second valve chamber <NUM> on the low-pressure side in the sliding region S, a swirling current W along the groove sections of the spiral grooves <NUM>, <NUM> are formed over the circumferential direction of the outer peripheral surface 51c of the main/auxiliary valve element <NUM>, and hence becomes a fluid resistance portion with respect to the fluid flowing in the axial direction from the high-pressure side to the low-pressure side in the sliding region S, so that an amount of the fluid leaked from the high-pressure side to the low-pressure side of the sliding region S can be reduced. Therefore, by shortening the axial length L1 of the sliding region S and enlarging the clearance C of the sliding region S, by the swirling current W, while reducing the amount of the fluid leaked to the low-pressure side of the sliding region S, it is possible to suppress contaminant, etc. from remaining and accumulating in the sliding region S to enhance resistance to foreign substances. Since the swirling current W is generated by optimizing the axial length L1 of the sliding region S and the clearance C of the sliding region S, it is possible to reduce the amount of the fluid leaked to the low-pressure side of the sliding region S. Since part of the swirling current W formed in the spiral grooves <NUM>, <NUM> comes over to the clearance C out of the spiral grooves <NUM>, <NUM>, the swirling current interferes as the fluid resistance portion against an axial flow X flowing in the axial direction from the high-pressure side to the low-pressure side in the clearance C of the sliding region S.

As shown in <FIG>, the swirling current W flowing from the groove inlets 57a, 58a of the spiral grooves <NUM>, <NUM> to the groove outlets 57b, 58b in the spiral grooves <NUM>, <NUM> forms a tornado flow consisting of a component which runs along outlines of the groove sections of the spiral grooves <NUM>, <NUM> and a component which runs along the extending direction of the spiral grooves <NUM>, <NUM>. Thus, the swirling current W is formed stably over the circumferential direction of the outer peripheral surface 51c of the main/auxiliary valve element <NUM>.

The clearance C of the sliding region S is formed to extend in parallel to the axial direction by the outer peripheral surface 51c of the main/auxiliary valve element <NUM> extending in parallel in the axial direction and the inner peripheral surface 11a of the projected portion <NUM> forming the guide hole 10c. Thus, in the sliding region S, it is possible to more easily generate the swirling current W in the spiral grooves <NUM>, <NUM>.

On the outer peripheral surface 51c of the main/auxiliary valve element <NUM> in the sliding region S, by forming the spiral grooves <NUM>, <NUM> whose depth is larger than the radial length of the clearance C of the sliding region S, the fluid flowing from the high-pressure side to the low-pressure side in the clearance C of the sliding region S is reliably guided into the roll portions 57c, 58c of the spiral grooves <NUM>, <NUM>. Thus, since the swirling current W is more easily generated and contaminant, etc. coming into the sliding region S together with the fluid can be pulled into the spiral grooves <NUM>, <NUM> by the swirling current W, it is possible to prevent contaminant, etc. from remaining and accumulating in the clearance C of the sliding region S to enhance resistance to foreign substances.

As shown in <FIG> and <FIG>, in the stroke range of the main/auxiliary valve element <NUM>, the groove inlets 57a, 58a of the spiral grooves <NUM>, <NUM> are positioned in the sliding region S, and the groove outlets 57b, 58b are exposed in the second valve chamber <NUM> on the low-pressure side of the sliding region S. Thus, contaminant, etc. pulled into the spiral grooves <NUM>, <NUM> by the swirling current W is more easily discharged to the second valve chamber <NUM>. Not all contaminant, etc. pulled into the spiral grooves <NUM>, <NUM> is discharged from the groove outlets 57b, 58b to the second valve chamber <NUM>. However, as shown in <FIG>, for example, in the roll portion 57c of the spiral groove <NUM> positioned out of the sliding region S and exposed in the second valve chamber <NUM>, the force of the swirling current W is weakened. Thus, part of contaminant, etc. pulled into the spiral grooves <NUM>, <NUM> is sometimes discharged from the roll portions 57c, 58c to the second valve chamber <NUM>.

By forming the groove <NUM> by the two threads of the spiral grooves <NUM>, <NUM> as the so-called multiple-thread spiral groove, the fluid flows from the high-pressure side to the low-pressure side according to a flow rate in the plural spiral grooves <NUM>, <NUM>. Thus, contaminant, etc. pulled into the spiral grooves <NUM>, <NUM> is more easily discharged. Since the plural groove inlets 57a, 58a and the plural groove outlets 57b, 58b are formed, the fluid is more easily introduced into the groove <NUM> and the swirling current W is easily generated. Since contaminant, etc. can be dispersed over the plural spiral grooves <NUM>, <NUM>, it is possible to prevent contaminant, etc. from remaining and accumulating in the spiral grooves <NUM>, <NUM>. Further, since the groove <NUM> is the two-thread spiral groove formed by the two threads of the spiral grooves <NUM>, <NUM>, the axial length L2 of the pitch for one roll of the spiral grooves <NUM>, <NUM> can be respectively shortened. Thus, it is possible to more shorten the axial length L1 of the sliding region S (i.e., L2 > L1).

The groove inlets 57a, 58a of the spiral grooves <NUM>, <NUM> are positioned in the sliding region S, and not exposed in the first valve chamber <NUM> on the high-pressure side of the sliding region S. Thus, the first valve chamber <NUM> and the second valve chamber <NUM> do not directly communicate with each other by the spiral grooves <NUM>, <NUM>, and leakage of the fluid to the second valve chamber <NUM> on the low-pressure side of the sliding region S is reduced. The axial length L2 of the pitch for one roll of the spiral grooves <NUM>, <NUM> forming the groove <NUM> is longer than the axial length L1 of the sliding region S. Thus, in a state where the groove inlets 57a, 58a are positioned in the sliding region S, it is possible to reliably expose the groove outlets 57b, 58b and part of the roll portions 57c, 58c in the second valve chamber <NUM> on the low-pressure side of the sliding region S. In the spiral grooves <NUM>, <NUM>, part of the roll portions 57c, 58c are exposed in the second valve chamber <NUM> on the low-pressure side of the sliding region S by a short distance of one roll from the groove inlets 57a, 58a. Thus, it is possible to more easily discharge contaminant, etc. pulled into the spiral grooves <NUM>, <NUM>.

Since the groove <NUM> is formed on the outer peripheral surface 51c of the main/auxiliary valve element <NUM>, processing for forming the groove <NUM> is easily performed.

The plural spiral grooves forming the groove <NUM> are not limited to the spiral grooves formed by the same configurations but spiral grooves having different sectional shapes, width, depth, extension size, etc. may be combined.

By forming width of the groove outlets 57b, 58b of the spiral grooves <NUM>, <NUM> larger than width of the groove inlets 57a, 58a, contaminant, etc. pulled into the spiral grooves <NUM>, <NUM> by the swirling current W may be more easily discharged from the groove outlets 57b, 58b to the second valve chamber <NUM>.

Next, a capacity control valve according to a configuration not forming part of the present invention will be described with reference to <FIG>. The same constituent parts as the constituent parts shown in the first embodiment will be given the same reference signs and duplicated description will be omitted.

As shown in <FIG>, a groove <NUM> is formed on an outer peripheral surface 151c of a main/auxiliary valve element <NUM> serving as a valve element. The groove <NUM> is formed by one thread of a spiral groove <NUM> extending on the outer peripheral surface 151c of the main/auxiliary valve element <NUM> for one and a half rolls while being tilted in the axial direction as a so-called single-thread spiral groove. According to this, the groove <NUM> is formed as the single-thread spiral groove on the outer peripheral surface 151c of the main/auxiliary valve element <NUM>. Thus, processing for forming the groove <NUM> is easily performed.

Next, a capacity control valve according to an alternative configuration not forming part of the present invention will be described with reference to <FIG>. The same constituent parts as the constituent parts shown in the first embodiment will be given the same reference signs and duplicated description will be omitted.

As shown in <FIG>, a groove <NUM> is formed on an outer peripheral surface 251c of a main/auxiliary valve element <NUM> serving as a valve element. The groove <NUM> is formed by an endless annular groove <NUM> extending on the outer peripheral surface 251c of the main/auxiliary valve element <NUM> for one roll. According to this, a fluid less easily flows along the extending direction of the groove <NUM>, and it is possible to reduce an amount of the fluid leaked to a second valve chamber <NUM> from a sliding region S. In a non-energized state of the capacity control valve V, at the time of moving the main/auxiliary valve element <NUM> to the axially right side, by forming in such a manner that at least part of the annular groove <NUM> is exposed in the second valve chamber <NUM> on the low-pressure side of the sliding region S, contaminant, etc. pulled in the annular groove <NUM> by a swirling current W (see <FIG>) may be more easily discharged to the second valve chamber <NUM>.

The plural annular grooves <NUM> forming the groove <NUM> may be provided in the axial direction.

Next, a capacity control valve according to a second embodiment of the present invention will be described with reference to <FIG>. The same constituent parts as the constituent parts shown in the first embodiment will be given the same reference signs and duplicated description will be omitted.

A capacity control valve V in the second embodiment will be described. As shown in <FIG>, ,an outer peripheral surface 351c of a main/auxiliary valve element <NUM> serving as a valve element is formed in a flat curved surface, and no grooves are provided on this curved surface.

As shown in <FIG>, an annular projected portion <NUM> projecting in the inner diameter direction from a part between a Pd port <NUM> and a Ps port <NUM> in the axial direction is provided on an inner peripheral surface of a valve housing <NUM>, and a small-diameter guide hole 310c on which the outer peripheral surface 351c of the main/auxiliary valve element <NUM> is slidable is formed by an inner peripheral surface 311a of this projected portion <NUM>. A groove <NUM> is formed on the inner peripheral surface 311a of the projected portion <NUM>. In a configuration not forming part of the invention the groove <NUM> can be formed by one thread of a spiral groove <NUM> extending on the inner peripheral surface 311a of the projected portion <NUM> for one and a half rolls while being tilted in the axial direction as a so-called single-thread spiral groove. According to the second embodiment of the present invention the groove <NUM> is formed by a multiple-thread spiral groove such as two threads of spiral grooves as in the first embodiment.

The embodiments of the present invention are described above with the drawings. However, specific configurations are not limited to these embodiments but the present invention includes changes and additions within the range not departing from the scope of the present invention as defined by the appended claims.

For example, in the above embodiments, the auxiliary valve <NUM> is not necessarily provided. An axially right end of the main/auxiliary valve element is only required to function as a support member that receives a load in the axial direction and a sealing function is not necessarily required.

The example in which the main/auxiliary valve element and the pressure sensitive valve member <NUM> are formed as separate bodies is described. However, both may be integrated. The example in which the drive rod <NUM> and the main/auxiliary valve element are formed as separate bodies is described. However, both may be integrated. Further, the main/auxiliary valve element, the pressure sensitive valve member <NUM>, and the drive rod <NUM> may be integrated.

The communication passage providing direct communication between the control chamber <NUM> and the suction chamber <NUM> of the variable displacement compressor M and the fixed orifice are not necessarily provided.

The groove may be formed by combining spiral grooves as in the first embodiment or the second embodiment. Grooves may be formed on both the outer peripheral surface of the main/auxiliary valve element and the inner peripheral surface of the valve housing.

The projected portion provided on the inner peripheral surface of the valve housing may not have the tapered side surface but may be formed to have a rectangular section.

The main/auxiliary valve element is not limited to the main/auxiliary valve element formed to have the same diameter over the axial direction but may be a main/auxiliary valve element whose diameter is partly reduced but not in a range where the groove is formed. In this case, the axial length of the sliding region may be shorter than the axial length of the inner peripheral surface of the projected portion forming the guide hole of the valve housing.

Claim 1:
A capacity control valve (V) comprising:
a valve housing (<NUM>, <NUM>) provided with a discharge port (<NUM>) through which a discharge fluid of discharge pressure (Pd) passes, a suction port (<NUM>) through which a suction fluid of suction pressure (Ps) passes, and a control port (<NUM>) through which a control fluid of control pressure (Ps) passes; and
a valve element (<NUM>, , , <NUM>) configured to be brought into contact with and separated from a valve seat (10a) by a driving force of a solenoid (<NUM>) to open and close a communication between the control port (<NUM>) and the discharge port (<NUM>) or a communication between the control port (<NUM>) and the suction port (<NUM>), wherein
a sliding region (S) is formed by an inner peripheral surface (11a, 311a) of the valve housing (<NUM>, <NUM>) and an outer peripheral surface (51c, 351c) of the valve element (<NUM>, <NUM>),
a groove (<NUM>, <NUM>) extending in a circumferential direction is formed in at least one of the inner peripheral surface (11a, 311a) of the valve housing (<NUM>, <NUM>) and the outer peripheral surface (51c, 351c) of the valve element (<NUM>, <NUM>),
the sliding region (S) has a structure in which a swirling current (W) is generated in the groove (<NUM>, <NUM>) by a fluid flowing from a high-pressure side to a low-pressure side in a clearance (C) between the inner peripheral surface (11a, 311a) of the valve housing (<NUM>, <NUM>) and the outer peripheral surface (51c, 351c) of the valve element (<NUM>, , , <NUM>), characterized in that
a radial length of the clearance (C) is within a range from <NUM>/<NUM> to <NUM>/<NUM> of an axial length of the sliding region (S), and
the groove (<NUM>, <NUM>) includes at least two threads of spiral grooves (<NUM>, <NUM>).