JP2946652B2 - Variable displacement swash plate type compressor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a swash plate type compressor suitable for use in, for example, refrigerant compression in an air conditioner for an automobile, and particularly to capacity control.

[Conventional technology]

SUMMARY OF THE INVENTION The inventors of the present invention have previously proposed a variable displacement type swash plate type compressor in which a swash plate inclination angle is changed for capacity control by a spool which can be moved in the axial direction of the compressor by control fluid pressure. The present invention proposes a capacity control mechanism in which the axial position of the center of the swash plate is changed by the spool and the inclination angle of the swash plate changes in conjunction with the spool.

When changing the capacity of the compressor, not only the inclination angle of the swash plate but also the axial position of the center of the swash plate was changed because a large number of pistons reciprocally driven in the axial direction by the swash plate, Both ends are arranged on the left and right in the axial direction.
A double-headed piston inserted in each cylinder corresponding to one cylinder block.When reducing the inclination angle of the swash plate to reduce the discharge capacity of the compressor, only the inclination angle of the swash plate is reduced. Then, the stroke volumes of the left and right cylinders are simultaneously reduced in the same manner, and the head clearances at both ends of the pistons are increased. Thus, before the discharge capacity becomes sufficiently small, compression is performed to push and open the discharge valves on both the left and right sides. This is because the capacity of the compressor cannot be controlled in a region where the discharge capacity is small.

At the same time as changing the inclination angle of the swash plate, the center of the swash plate is moved in the axial direction in conjunction with it, and a large number of double-headed pistons are biased to one of the left and right sides in the axial direction. On the side, the head clearance of the piston does not increase, the discharge capacity is controlled to decrease, the inclination angle of the swash plate becomes small, and even if the stroke volume of the piston decreases,
High compression is performed to push and open the discharge valve. On the other side, the head clearance of the piston is increased and effective compression work is not performed. However, the effective compression work on the one side can control the discharge capacity even in a small discharge capacity area as a whole compressor. There are advantages that are possible.

In such a type of variable displacement swash plate compressor, the control spool for controlling the axial position of the center of the swash plate and simultaneously changing the inclination angle of the swash plate is a piston-shaped control spool. On one side, for example, the pressure obtained by adjusting the pressure on the discharge side of the compressed refrigerant to a required level by a control valve is used, and the control fluid moves the spool in the axial direction. And the pressure difference between the control fluid pressure and the pressure of the suction refrigerant acting on the other side of the spool acts as a control force in the axial direction on the support portion of the swash plate.

There are various types of forces acting in the opposite direction or in the same direction as the above-mentioned control force, and the position of the center of the swash plate, and thus the inclination angle of the swash plate, is determined as a state in which the various forces are balanced. It is decided. The main forces other than the control force are the inertial force of the reciprocating motion of the piston, the compression force (compression reaction force) of the fluid (refrigerant) compressed by the piston, the friction force acting on the sliding part of the control mechanism, The centrifugal force acting in the direction to decrease the inclination angle when the swash plate given the inclination angle rotates together with the shaft, the compression force (compression reaction force) of the sprung which is sometimes provided to regulate the movement of the spool, Etc.

[Problems to be solved by the invention]

Reducing the discharge capacity of the compressor means that the centrifugal force of the swash plate, the compression force of the piston, or the compression force of the sprung plate acting in the direction of reducing the inclination angle of the swash plate have been added. By reducing the control fluid pressure on the spool, and thus the control force, the centrifugal force and the like overcome the inertial force of the piston and the frictional force of the mechanism, and wait for the inclination angle of the swash plate to decrease. is there.

When the discharge capacity of the compressor is large, the control fluid pressure is also large, and there is no problem because the action of the control force is dominant. The other forces may be dominant relative to each other because of the smaller.

It is often necessary to reduce the discharge capacity when the rotational speed of the compressor is increasing, but in such cases, the reciprocating speed of the piston also increases and the inertia force increases, so that Acting in the direction of increasing the inclination angle of the swash plate, even if the already reduced control fluid pressure is changed more minutely, the spool does not respond (follow), and the discharge capacity can be reduced at high speed rotation. A situation can occur where it becomes impossible.

In the case of air conditioners not only for automobiles, the air conditioning load is large when the air conditioner starts up, but the air conditioning load decreases after the indoor temperature reaches the target temperature. In addition, it is necessary to control the refrigerant compressor to finely change the discharge capacity in a small discharge capacity area. In the case of automobiles, the driving force source of the compressor is a running engine, so the engine speed constantly changes from low to high according to running conditions. , A particularly high response is required.

Therefore, the present invention is to secure control responsiveness in a small discharge capacity region at the time of high rotation in this kind of compressor,
It is a solution of the invention.

[Means for solving the problem]

In order to solve the above-mentioned problems, the present invention provides a cylinder block having a cylinder bore therein, a rotating shaft supported in the cylinder block, a swash plate attached to the rotating shaft so as to be tiltable, A piston that is inserted into a cylinder bore and is reciprocated in the axial direction by the swash plate to form a working chamber that compresses fluid in the cylinder bore; and by supporting the center of the swash plate and moving it in the axial direction. A support member for changing the discharge capacity by inclining the swash plate to an arbitrary inclination angle, and being provided on the swash plate in a front-to-back unbalance offset from a center plane of the swash plate, and the inclination angle of the swash plate being zero. While generating an urging force for urging the swash plate in a direction,
A variable displacement type swash plate type compressor comprising at least one balance weight formed so that the biasing force in the same direction remains even when the inclination angle of the swash plate becomes zero. I do.

(Operation)

Since the compressor of the present invention has the configuration described in the section of the above-described means, it normally compresses the fluid in the same manner as a conventional compressor of this type, but it is necessary to reduce the discharge capacity during high-speed rotation, which is a problem. In the control, even if the moment due to the inertial force of the piston prevents the inclination angle of the swash plate from decreasing, the moment to overcome the moment is generated by the balance weight specially provided for the swash plate. The inclination angle is faithfully changed in accordance with the axial movement of the support member, and a minute change in the capacity in a low discharge capacity range becomes possible.

〔Example〕

FIG. 1 shows a longitudinal section of an embodiment of a variable displacement type swash plate type compressor according to the present invention.
Front cylinder block 1 and rear cylinder block 2
A front housing 3 and a rear housing 4 are attached to the front and rear thereof, and these parts are integrally fastened by several through bolts 5 to form a main body. At the corresponding positions of the front and rear cylinder blocks 1 and 2, several sets of cylinder bores 6 and 7 are bored at equal intervals on a virtual cylindrical surface.
One double-headed piston 8 is inserted over each of the pistons 7 and the working chamber is defined by their both end faces and cylinder bores 6 and 7.
9,10 are formed.

A rotating shaft 11 is inserted from the left side of FIG. 1 so as to pass through the center of the compressor body, is driven to rotate by an engine (not shown), and is supported by bearings provided on the front and rear housings 3, 4 and the cylinder block 1. Is done. A swash plate chamber 12 is formed between the cylinder blocks 1 and 2, and also serves as a chamber for receiving a fluid to be compressed, for example, a refrigerant gas for an air conditioner from an evaporator (not shown) or the like. The swash plate chamber 12 is provided with suction chambers 13, 14 provided in the housings 3, 4.
And the passages 15 and 16. Front and rear housing
Discharge chambers 17 and 18 are also formed in 3, 4 and these suction chambers are formed.
The discharge chambers 13 and 14 and the discharge chambers 17 and 18 can communicate with the working chambers 9 and 10 via suction valves and discharge valves (not shown) provided on the valve plates 19 and 20.

In the swash plate chamber 12, a disc-shaped swash plate 22 that simultaneously engages all the pistons 8 via the shoes 21 has a spherical portion and a sleeve-like portion slidably inserted through the rotating shaft 11. On the support member 23, it is tiltably supported. The swash plate 22 is provided with a pair of arms 24 projecting from the left side thereof, and a pin shaft 25 bridged between the two arms 24 is provided on a block 26 integrated with the rotation shaft 11. It is engaged with the oblique cam groove 27. Therefore, when the support member 23 is moved in the axial direction, the center of the swash plate 22 supported by the spherical portion also moves in the axial direction, whereby the pin shaft 25 provided on the arm 24 of the swash plate rotates. Since the swash plate 22 moves in the cam groove 27 of the shaft block 26, the inclination angle of the swash plate 22 also changes at the same time. When the swash plate 22 is tilted, the stroke of the reciprocating motion of the piston 8 changes, and the stroke volume in the working chambers 9 and 10 also changes.

As described above, since the change in the inclination angle of the swash plate 22 occurs in conjunction with the axial movement of the swash plate 22, even if the stroke of the piston 8 changes, the piston 8 cannot be moved in the working chamber 10 of the rear cylinder block 2. If the head clearance is designed so that the value at the right end is at the top dead center is hardly changed, even if the compression pressure sufficient to push and open the discharge valve does not occur in the front working chamber 9 when the stroke becomes small. , Rear working chamber
In the case of 10, a compression pressure that pushes the discharge valve is generated while the discharge amount is small, and an operation region with a small discharge capacity is secured.

The end of the cylindrical portion of the control spool 28 is engaged with the support member 23 via a thrust bearing or the like in order to cause the inclination angle of the swash plate 22 and the axial movement of the center to occur. The disc portion is inserted into a control cylinder 29 formed in the rear housing 4 to control the control pressure chamber 30 and the aforementioned suction chamber 14.
And are divided. The control valve 31 attached to the rear housing 4 is operated by a control device (not shown) to
An arbitrary pressure between the discharge pressure (high pressure) of 18 and the suction pressure (low pressure) of the swash plate chamber 12 is created, and this is supplied to the control pressure chamber 30 as a control fluid pressure. Therefore, the spool 28 generates an axial control force by the differential pressure between the control fluid pressure having an arbitrary size and the substantially constant pressure of the suction chamber 14 as described above. By balancing with the force, the axial position and the inclination angle of the center of the swash plate 22 can be changed.

The structure described above is substantially the same as that of a conventional compressor of this type, but in accordance with the features of the present invention, the swash plate 22 is provided with balance weights 32 and 33 in the embodiment of FIG. I have. These balance weights 32 and 33 are mounted on the front and back unbalances so that each center of gravity is formed at a position as far as possible from the center plane of the disc-shaped swash plate 22, so that the swash plate 22 is inclined. When the plate 22 rotates together with the rotating shaft 11, a centrifugal force acting on the center of gravity of the balance weights 32 and 33 generates a large moment that acts to raise the swash plate 22 and reduce the inclination angle. It has become.

Next, the operation of the compressor shown in FIG. 1 will be described with reference to FIG. Now, it is assumed that the swash plate 22 is given an arbitrary inclination angle β by the operation of the control valve 31, and is driven to rotate with the rotation shaft 11 at an angular velocity ω.

When the swash plate 22 rotates together with the rotating shaft 11 in an inclined state, the pistons 8 slidingly engaged with the peripheral edge of the swash plate 22 via the shoes 21 at equal intervals are arranged in a pair of cylinder bores.
It reciprocates in 6, 7 and compresses the fluid (refrigerant) drawn into the working chambers 9, 10 from the suction chambers 13, 14. When each compression pressure in the working chambers 9 and 10 becomes higher than the pressure in the discharge chambers 17 and 18, the compressed fluid pushes open a discharge valve (not shown) to open the discharge chambers 17 and 1.
It is extruded to 8 and sent to, for example, a condenser of an air conditioner (not shown).

By the swash plate 22 is rotated, the peripheral edge of the swash plate 22 centrifugal force F _S acts as shown in FIG. 2, thereby trying wake erected around the center O of the swash plate 22 which is inclined moment M _S is generated to. The balance weight 32 and 33 attached to the swash plate 22 also generates a moment M _B to be wake the swash plate 22 by the centrifugal force F _B as well. Second
In the case of the figure, the balance weights 32 and 33 are
The swash plate is offset from the center plane of the swash plate so that its center of gravity is biased so as to be located at an extra angle B. With respect to the center plane of the swash plate 22, no balance weight is provided at a position corresponding to the back surface of each of the balance weights 32 and 33, and the arrangement is unbalanced in that sense. Moment M _B by the balance weight 32, 33
Does not become 0 even in the restoration state in which the inclination angle β of the swash plate 22 becomes 0, and continues to be urged around the center O of the swash plate 22 in the same direction.

The piston 8 has an inertia force F _P by being reciprocated in the axial direction by the swash plate 22, which in turn exerts a moment M _P on the swash plate 22 in a direction in which the inclination angle β is further increased. The pressure P _{g of} the fluid compressed in the working chambers 9 and 10 acts on the piston 8, and the moment M _g due to the force is applied.
Is has the same direction as the previous moment M _S and M _B, an attempt is restored undergo upright swash plate 22. Control fluid pressure P _C which acts on the spool 28, by the differential pressure between the suction pressure and generates a control force as described above, but moves the center O of the swash plate 22 in the axial direction through the supporting member 23, the Swashplate by control force
22 generates a moment M _C direction tilting the. In addition,
Other main forces include a frictional force acting on a sliding portion of the mechanism, but are not shown in FIG. However, the moment M _C of this case, the control force may be understood as incorporating the friction force.

Next, the above description will be described in more detail. Swash plate 22
R is the outer radius, R ₀ is the inner radius, H is the thickness of the swash plate 22,
The density is ρ, the inclination angle of the swash plate 22 is β, the gravitational acceleration is g, the angular velocity of the rotating shaft 11 is ω, the number of the pistons 8 is n, and the weight is the same.
If W _P , the weight of the balance weights 32 and 33 is W _B , and the distance from the center O is R _B , the swash plate 22 is inclined or
Alternatively, the inclination moment M _P due to the inertia force F _P of the piston 8, which is the main moment to be restored, the restoration moment M _S due to the centrifugal force F _S of the swash plate 22, and the balance weight
Righting moment M _B due to the centrifugal force F _B of 32 and 33 can be respectively expressed as follows. (K ₁ , K ₂ and K ₃ are constants) How the respective moments, that is, the values of the above equations (1), (2) and (3), change with the change of the inclination angle β of the swash plate 22 depends on the changing part of the equations. This is apparent from FIG. 3 in which is shown as a diagram. That is, when the inclination angle β approaches zero, the value of formula (1) and (2), i.e. contrary to the approach the moment M _P and M _S also 0, the value of the expression (3), i.e. the balance weight 32, 33 the centrifugal force F righting moment M _B by _B does not become 0 although decreased, M _B becomes larger than the relatively M _P and M _S.

This is a special balance weight that is a feature of the present invention.
Since the swash plate 22 is provided with an effective restoring force in the direction of making the inclination angle zero even when the inclination angle β is close to zero, the swash plate 22 is controlled. fluid pressure P _C
If Uketomere the control force due to, the axial position and tilt angle β of the swash plate 22 uniquely determined, if the change control fluid pressure P _C is even minutely, the swash plate 22 orientation and position in response immediately The result is that it changes slightly. That is, an uncontrollable dead zone cannot be generated in the variable range of the displacement of the compressor.

When the arms 34, 35 are used as specific means for providing the balance weights 32, 33, the balance weights 32, 33 can be configured separately from the swash plate 22. In the case of separate components, it is possible to reduce the size by using a metal having a large specific gravity for the balance weights 32 and 33. If bolts are used for the arms 34 and 35, the attachment and detachment of the balance weights 32 and 33 are facilitated.

It is also possible to manufacture the swash plate 22 and the balance weights 32, 33 and the like integrally, and FIG. 4 shows an embodiment thereof. FIG. 4 (b) is a cross-sectional view as viewed from the front, in which the left side is shown as (a) and the right side is shown as (c). As shown in FIGS. 8B and 8C, the balance weight is formed on the right side surface of the swash plate 22 as an arc-shaped ridge only at the upper portion.
36 are integrally formed. This corresponds to the balance weight 32 shown in FIG. 1 and FIG. 2, but as a counterpart to the balance weight 33, a pin 25 is attached to the left side surface of the swash plate 22.
Lower part 37 of two arms 24 formed integrally to support
Is larger than the upper part 38, and the same function as the balance weight 33 is given by adding weight to this part 37. Needless to say, the balance weights do not need to be provided as a pair like 32 and 33, and the object of the present invention can be achieved by only one of them.

FIG. 5 shows an embodiment of the present invention and a compressor (without balance weights 32 and 33) according to the prior art.
The change in volume efficiency η _V (%) was measured by changing the rotation speed (rpm) of the rotating shaft 11 and the inclination angle β of the swash plate 22. The suction pressure was 2 kg / cm ² · G and the discharge was Pressure is 6kg / cm ²・ G
The rotating shaft 11 was driven by increasing the output rotation of the engine. As is apparent from FIG. 5, with regard to the controllability of the discharge capacity in the problematic high-speed rotation range, the conventional compressor could not control the volumetric efficiency to near 0 at 4,500 rpm or more. In the case of the embodiment, the rotational speed is 7,
Even at a high speed of 500 rpm, the inclination angle β of the swash plate 22 could be set to zero. Therefore, the arrows in FIG. 5 indicate the controllable range of the present invention and the conventional example. It can be seen from FIG. 5 that the controllable range was significantly expanded toward the high-speed rotation range by the present invention. it can.

〔The invention's effect〕

According to the present invention, a simple improvement of adding a special balance weight to the swash plate or slightly changing the design of the swash plate allows a high-speed rotation, which is a weak point of such a variable displacement type swash plate compressor, to be achieved. The controllability of the low discharge capacity region at the time can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the compressor of the present invention, FIG. 2 is a conceptual diagram for explaining the operation of FIG. 1, FIG. The figure shows an embodiment of a swash plate, where (a) is a left side view, (b) is a front sectional view,
(C) is a right measurement diagram, and FIG. 5 is a diagram showing the effect of the present invention in comparison with a conventional example. 1 ... front cylinder block, 2 ... rear cylinder block, 3 ... front housing, 4 ... rear housing, 5 ... through bolt, 6, 7 ... cylinder bore, 8 ... double-headed piston, 9,10 ... … Working chamber, 11… rotating shaft, 12… swash plate chamber, 13, 14… suction chamber, 15, 16… passage, 17, 18… discharge chamber, 19, 20… valve plate, 21… Shoe, 22 swash plate, 23 support member, 24 arm, 25 pin shaft, 26 block, 27 cam groove, 28 control spool, 29 control cylinder, 30 cylinder ... control pressure chamber, 31 ... control valve, 32, 33 ... balance weight, 34, 35 ... arm, 36 ... balance weight, 37 ... lower part, 38 ... upper part.

Claims (1)

(57) [Claims] A cylinder block having a cylinder bore therein; a rotation shaft supported in the cylinder block; a swash plate mounted to be tiltable with respect to the rotation shaft; and the swash plate inserted into the cylinder bore. A piston which is reciprocated in the axial direction to form a working chamber for compressing a fluid in the cylinder bore, and which supports the center of the swash plate and moves it in the axial direction to tilt the swash plate at an arbitrary inclination. A support member that changes the discharge capacity by inclining the swash plate to an angle, and the swash plate is provided on the swash plate so as to be offset from the center plane of the swash plate and to be unbalanced on both sides, and the swash plate is in a direction in which the inclination angle of the swash plate becomes zero And at least one balance weight formed so that the biasing force in the same direction remains even when the inclination angle of the swash plate becomes zero. Variable displacement swash plate type compressor, characterized by that example.