JPH07180658A - Cam plate type single head piston compressor - Google Patents

Abstract

PURPOSE:To provide a cam plate type single head piston compressor suppressing the wear of the sliding contact face of a piston and a cylinder bore without making a compressor large-sized and heavy. CONSTITUTION:A single head piston 9 is accommodated in a cylinder bore 1a formed at a cylinder block 1. A front housing 2 is jointed and fixed to the end face of the cylinder block 1. A rotatory-oscillating cam plate 12 is mounted to a rotary shaft 6, supported by the cylinder block l and the housing 2, through hinge mechanism K. The base end part of the piston 9 is moored to the cam plate 12 through a shoe 13. A swollen bore part 1c is further formed on the outer peripheral surface side of the cylinder block 1, in relation to the cam plate 12 side end part of the cylinder bore la. In the state of the piston 9 being at the bottom dead center, seal length L1 between the outer peripheral surface of the piston 9 and the inner peripheral surface of the cylinder bore 1a is made long without lengthening the whole length of a compressor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate type single-head piston compressor used in, for example, a vehicle air conditioner.

[0002]

2. Description of the Related Art As a conventional swing swash plate type variable displacement compressor, one shown in FIG. 7 has been proposed. In this compressor, a front housing 2 is joined and fixed to a front end surface of a cylinder block 1 having a plurality of cylinder bores 1a formed in parallel with each other, and a suction chamber 3a is provided at a rear end surface.
The rear housing 3 that defines the discharge chamber 3b is fixedly joined. A lug plate 10 is supported on the rotary shaft 6 supported by the cylinder block 1 and the front housing 2. A swing swash plate 12 that reciprocates in the front-rear direction via a hinge mechanism K is mounted on the lug plate 10. The swing swash plate 12 has a pair of front and rear shoes 13
The base end recess of the piston 9 is anchored via the. When the lug plate 10 is rotated by the rotation of the rotary shaft 6, the swing swash plate 12 is swung in the front-rear direction while rotating via the hinge mechanism K. Therefore, the piston 9 is reciprocated in the cylinder bore 1a, and the refrigerant gas sucked from the suction chamber 3a is compressed in the cylinder bore 1a and then discharged to the discharge chamber 3b.

Further, in the above-mentioned compressor, as is well known in the art, the swing swash plate 12 is acted on by the fluctuation of the differential pressure between the crank chamber pressure Pc acting on the rear surface of the piston 9 and the bore pressure Pb acting on the front surface. The turning moment is adjusted. Therefore, the inclination angle of the swash plate 12 is changed, the reciprocating stroke of the piston 9 is changed, and the discharge capacity is controlled.

[0004]

In this compressor, a large piston inertial force is applied to the swash plate when switching from the intake stroke to the discharge stroke, and the reaction force from the swing swash plate 12 causes the shoe 1 to move.
A large pressing force is applied to the piston 9 via 3 and the outer peripheral surface of the piston 9 is locally pressed against the crank chamber 5 side opening edge 1e of the inner peripheral surface of the cylinder bore 1a. Therefore, the outer peripheral surface of the piston 9 is damaged by the edge 1e. Further, since the end edge 9e of the tip end surface of the piston 9 on the rotary shaft 6 side is also locally pressed against the inner peripheral surface of the cylinder bore 1a on the rotary shaft 6 side, the inner peripheral surface of the bore is damaged.

In the above-mentioned compressor, the clearance between the piston 9 and the cylinder bore 1a is set strictly in order to suppress the blow-by of gas in the compression stroke and improve the compression efficiency. Therefore, a chamfered portion S is formed at the opening edge of the cylinder bore 1a in order to facilitate the work of fitting the piston 9 into the cylinder bore 1a and to reduce the corner contact when the piston 9 reciprocates. However, even if the chamfered portion S is provided, the above-mentioned problem is not so much solved as long as the corner portion exists at the portion S.

Further, in order to prevent rotation of the piston 9 in the cylinder bore 1a between the outer peripheral portion of the base end portion of the piston 9 and the flat portion 2a formed on the inner wall of the front housing 2, the flat portion 2a is formed. A flat surface portion 9c is formed to be in contact with. However, if the contact at this portion is set strictly, it will be difficult to assemble the piston, and therefore the predetermined clearance C
Is provided. Therefore, the piston 9 slightly tilts due to the minute clearance between the cylinder bore 1a and the piston 9, and this causes the above-mentioned damage to the piston and the bore.

Here, an external force Fo mainly consisting of inertial force acting on the piston 9, a reaction force Fs received by the piston 9 from the swash plate 12, and a reaction force Fa, Fb received by the piston 9 from the inner peripheral surface of the cylinder bore 1a (hereinafter , Fa is a side force received from the edge 1e, and Fb is a side force received from the edge 9e),
Assuming that the seal length L ₁ at the bottom dead center of the piston 9 and the distance L ₂ from the center of both shoes 13 to the top end surface of the piston, the following equation holds.

Fs · cos θ = Fo Fs · sin θ−Fa + Fb = 0 L ₁ · Fa−L ₂ · Fs · sin θ = 0 where θ is the angle between the central axis of the piston 9 and the perpendicular to the slope of the swash plate 12. is there.

From these equations, the side forces Fa and Fb received by the piston 9 from the inner peripheral surface of the cylinder bore 1a are represented by the following equations. Fa = (L ₂ / L ₁ ) · Fo · tan θ ··· (1) Fb = [(L ₂ / L ₁ ) −1] · Fo · tan θ ··· (2) As is clear from the above equations. When the compressor rotates at high speed, the inertial force Fo of the piston 9 increases, and the side forces Fa and Fb of the piston 9 increase accordingly. In order to reduce the amount of wear of the piston 9 and the cylinder bore 1a during this high speed rotation, it is necessary to reduce the side forces Fa and Fb. For this purpose, the seal length L ₁ at the bottom dead center of the piston 9 may be extended according to the equations (1) and (2). However, simply extending it will increase the total length of the compressor,
There is a problem of large weight and large size, which makes it difficult to adapt to a small installation space in the engine room.

Further, in the compressor shown in FIG. 7, when the engine is stopped during a large capacity operation in which the swing swash plate 12 is held at the maximum tilt position, the swash plate 12 is interposed between the lug plate 10 and the swash plate 12. The spring 14 returns the swash plate 12 to the minimum tilt angle position. Then, the shock acting on the engine when the compressor is restarted is alleviated. However, if the seal length L ₁ at the bottom dead center of the piston 9 is short, the spring 14
Since the outer peripheral surface of the piston 9 is locally strongly pressed against the end edge 1e of the cylinder bore 1a by the elastic force of 1, the frictional resistance may increase and the minimum inclination angle may not be restored in some cases. To solve this problem, the spring 14
However, in this case, the tilt angle of the swash plate 12 is adjusted to affect the capacity control operation. That is, it becomes difficult to control the pressure difference between the pressure Pc in the crank chamber 5 and the pressure pb in the cylinder bore 1a to increase the inclination angle of the swash plate 12 and increase the capacity.

Although the compressor described above is a variable displacement single-head piston compressor, the fixed-capacity single-head piston compressor also has a fixed swash plate angle, so the piston during compression operation is not fixed. The problem of wear between the outer peripheral surface of the cylinder and the inner peripheral surface of the cylinder bore naturally occurs.

A first object of the present invention is to solve the above-mentioned problems of the prior art and to suppress wear of the sliding contact surfaces of the piston and the cylinder bore without increasing the size and weight of the compressor. To provide a single-headed piston compressor.

A second object of the present invention is, in addition to the above-mentioned first object, a swash plate type single-headed head which can easily return the swinging swash plate to the minimum tilt angle position by a spring when the compressor is stopped. To provide a piston compressor.

[0014]

In order to achieve the first object of the present invention, a plurality of cylinder bores accommodating a piston in a cylinder block in a reciprocating manner are located on a circular locus, and Front housings that are parallel to each other and that form a crank chamber are joined and fixed to the front end surface of the cylinder block, a rear housing is joined and fixed to the rear end surface, and a rotary shaft is supported on the cylinder block and front housing. Then, a rotary rocking swash plate is attached to the rotary shaft so that the rotary rocking swash plate can be synchronously rotated. The rocking swash plate is swung back and forth to reciprocate the piston in the cylinder bore, and the refrigerant gas sucked from the suction chamber is compressed in the cylinder bore and discharged to the discharge chamber. In the swash plate type single-head piston compressor configured as described above, of the crank chamber side ends of the cylinder bore, the end portion on the cylinder block outer peripheral surface side is extended to the crank chamber side to form a bulging bore portion. ing.

Further, in order to achieve the above-mentioned second object, the invention according to claim 2 is characterized in that, in claim 1, a lug plate is fitted and fixed to a rotary shaft, and the lug plate is rotatably rocked via a hinge mechanism. The swash plate is mounted so as to be reciprocally swingable in the front-rear direction, and a spring for biasing the swash plate to the minimum tilt angle position is interposed between the lug plate and the rotary swing swash plate. .

[0016]

According to the first aspect of the present invention, when the rotary shaft is rotated, the rotary rocking swash plate is rotated, so that the piston moored to the swash plate is reciprocated in the cylinder bore to move from the suction chamber to the cylinder bore. The sucked gas is compressed and then discharged into the discharge chamber.

The rotary swing swash plate maximizes the inertial force acting on the piston near the bottom dead center, and the swash plate slopes from the slope to the base end of the piston toward the outer wall surface of the cylinder block. The pressing force acts in the tilt direction. At this time, the base end portion of the piston receives a component force toward the outer wall surface of the front housing, so that the piston receives a bending moment in the cylinder bore. This bending moment is supported by the outer peripheral edge of the tip of the piston and the tip edge of the bulging bore formed on the inner peripheral surface of the cylinder bore. Therefore, the seal length at the bottom dead center of the piston, that is, the distance between the outer peripheral edge of the tip and the tip edge of the bulging bore portion in the axial direction of the piston increases. Therefore, by the leverage principle, each pressing force at both ends of the seal length, that is, the above-mentioned side force is reduced, and abrasion of the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore is suppressed.

According to the second aspect of the present invention, when the differential pressure between the crank chamber pressure acting on the back surface of the piston and the bore pressure acting on the front surface of the piston fluctuates during the compression operation, the rotary swing swash plate is hinged. The tilt angle is changed in response to the turning moment around, the stroke of the piston is changed,
The discharge capacity of the compressor is adjusted.

According to the second aspect of the invention, since the seal length described above is large at the bottom dead center of the piston, the side force at both ends of the seal length is weakened by the biasing force of the spring when the compressor is stopped. Therefore, the spring reliably returns the rotary rocking swash plate from the large tilt angle to the minimum tilt angle, and the minimum capacity of the compressor can be started.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIG.
~ It demonstrates based on FIG. As shown in FIG. 1, a front housing 2 is joined and fixed to the front end surface of the cylinder block 1. A rear housing 3 is joined and fixed to a rear end surface of the cylinder block 1 via a valve plate 4. Cylinder bores 1a are formed in the cylinder block 1 at a plurality of locations in parallel with each other. A rotary shaft 6 is rotatably supported in a crank chamber 5 formed in the front housing 2 via bearings 7 and 8. A piston 9 is reciprocally fitted in each cylinder bore 1a. A lug plate 10 is fitted and fixed to the rotary shaft 6. A rotary swing swash plate 12 is mounted on the lug plate 10 via a hinge mechanism K so as to be swingable in the front-rear direction.

The hinge mechanism K includes the lug plate 10
A pair of bearings 10a projecting forward (to the right in FIG. 1) near the outer periphery of the bearings and a pair of connecting pins 11 inserted in guide holes 10b of both bearings 10a so as to be tiltable in the front-rear direction.
In addition, the spherical portion 11a of both the connecting pins 11 has the guide hole 10b.
And the rod portion 11b is fitted and fixed in the engaging holes 12b formed in the pair of boss portions 12a integrally formed on the back surface of the rotary swash plate 12. The pair of bearings 10a, the connecting pin 11, and the boss portion 12a are arranged in a direction orthogonal to the plane of FIG.

As shown in FIG. 1, the rotary swing swash plate 12 anchors the piston 9 through a pair of front and rear shoes 13 in a state where the rotary swash plate 12 enters a recess 9a formed at the base end of the piston 9. . The spherical portions of both shoes 13 are engaged with a spherical guide recess 9b formed in the recess 9a. The plane of the shoe 13 is in sliding contact with the slope of the swash plate 12. Since the rotary rocking swash plate 12 is moored to the recesses 9a of the five or more pistons 9 via the shoes 13, for example, the rotary rocking swash plate 12 can rotate and rock in the front-rear direction, but in other directions. Is prevented from tilting.

A spring 14 is interposed between the lug plate 10 and the swash plate 12 so as to be wound around the rotary shaft 6. The spring 14 can return the inclination angle of the swash plate 12 from a large angle to the minimum inclination angle. This swash plate 12
A stopper 15 is mounted on the rotary shaft 6 in order to set the minimum tilt angle position of.

A suction chamber 3a and a discharge chamber 3b are formed in the rear housing 3 by partition walls. The valve plate 4 is provided with a suction valve mechanism 16 for sucking gas into each cylinder bore 1a and a discharge valve mechanism 17 for discharging the gas compressed in each bore 1a to the discharge chamber 3b. There is.

The rear housing 3 is provided with, for example, two capacity control valves (not shown). One of the capacity control valves opens and closes the air supply passage for supplying the refrigerant gas from the discharge chamber 3b to the crank chamber 5. Further, the other capacity control valve opens and closes the bleed passage that communicates from the crank chamber 5 to the suction chamber 3a. Then, by adjusting the differential pressure between the crank chamber pressure Pc acting on the front and rear of the piston 9 and the bore pressure Pb to control the inclination angle of the rotary swash plate 12 to change the stroke of the piston 9, It is designed to adjust the discharge capacity.

Next, the essential parts of the present invention will be described with reference to FIGS.
I will explain mainly. As shown in FIG. 3, the cylinder block 1 is formed with an insertion hole 1b for a bolt (not shown) for fastening and fixing the cylinder block 1 and the front housing 2 so as to be located between the cylinder bores 1a. Further, each bore 1a of the cylinder block 1 has a bulging bore portion 1 extending to the crank chamber 5 only on the outer peripheral surface side of the block 1.
c are integrally formed. The front end surfaces 1d of the bulged bore portions 1c are connected to each other on both sides so as to be flush with each other.

[0027] The in crank chamber 5 side base end edge of the cylinder bore 1a chamfered portion S ₁ is formed, to the distal end (left end in FIG. 4) edge 1e of the bulge bore portion 1c chamfered portion S ₂ form Has been done. The chamfered portion S ₁ is formed smaller toward the bulging bore portion 1c, and the chamfered portion S ₂ is formed with the same width as a whole.

On the outer peripheral portion of the base end of each piston 9, a flat surface portion 9 corresponding to a flat surface portion 2a for preventing rotation formed on the inner wall surface of the front housing 2 with a predetermined clearance C is provided.
c is formed.

Next, the operation of the variable displacement single-headed piston compressor constructed as described above will be described. When the compressor is stopped, as shown in FIG. 2, the rotary swash plate 12 is biased and held by the spring 14 at the minimum tilt angle position regulated by the stopper 15. When the rotary shaft 6 of the compressor is rotated by the power of the engine in this state, the swing swash plate 12 is rotated at the minimum inclination angle via the hinge mechanism K. Therefore, the piston 9 is reciprocated with the minimum stroke, and the refrigerant gas sucked into the cylinder bore 1a from the suction chamber 3a is compressed and discharged into the discharge chamber 3b. Since this is the minimum capacity at the time of starting, the starting shock is alleviated. This compressor also replaces the function of the clutch.

The pressure in the cylinder bore 1a gradually rises after the compressor is started, and the differential pressure between the pressure Pc of the crank chamber 5 acting on the back surface of each piston 9 and the bore pressure Pb acting on the front surface thereof decreases. The moment in the direction of increasing the tilt angle acting on the moving swash plate 12 increases, the tilt angle of the swash plate 12 increases as shown in FIG. 1, and the discharge capacity of the compressor increases.

At the beginning of the operation of the compressor, the cooling load in the passenger compartment is high and the suction pressure is high. Therefore, the pressure difference between the crank chamber pressure acting on the rear surface of the piston 9 and the bore pressure acting on the front surface of the piston 9 is large. The moving swash plate 12 is operated at the maximum inclination angle.

After that, when the temperature inside the vehicle compartment is reduced and the cooling load is reduced, and the pressure inside the suction chamber 3a is reduced, the differential pressure increases, the tilt angle of the swash plate 17 decreases, and the piston moves. The stroke of 9 is reduced and the discharge capacity of the compressor is reduced. Further, the discharge capacity of the compressor is also adjusted by adjusting the pressure in the crank chamber 5 by the above-mentioned not shown capacity control valve and changing the differential pressure.

The operation of the bulging bore portion 1c, which is the essential part of the present invention, will be described below. In FIG. 4, an external force Fo mainly consisting of inertial force acting on the piston 9, a reaction force Fs received by the piston 9 from the swash plate 12, side faces Fa and Fb received by the piston 9 from the inner peripheral surface of the cylinder bore 1a, and a lower side of the piston 9. The expressions (1) and (2) described above are established during the seal length L ₁ at the dead point and the distance L ₂ from the center of both shoes 13 to the top end surface of the piston.

Fa = (L ₂ / L ₁ ) · Fo · tan θ (1) Fb = [(L ₂ / L ₁ ) −1] · Fo · tan θ (2) As shown in FIG. The cylinder bore 1a has a bulging bore portion 1c.
Therefore, the seal length L ₁ between the piston 9 and the cylinder bore 1a increases when the stroke of the piston 9 is maximum and is at the bottom dead center. Therefore, the seal length L ₁
The side forces Fa and Fb received by the pistons at both ends (end edges 1e and 9e) of are reduced as is apparent from the equations (1) and (2). Therefore, abrasion of the outer peripheral surface of the piston 9 and the inner peripheral surface of the cylinder bore 1a is suppressed during the compression operation.

Further, in the above embodiment, since the bulging bore portion 1c is formed only on the outer peripheral portion of the cylinder block 1, the swash plate 12 is in the minimum inclination angle position as shown in FIG. The plate 12 does not collide with the bulging bore portion 1c. Therefore, in this embodiment, the wear of the piston 9 and the cylinder bore 1a can be suppressed without increasing the total length of the compressor.

Further, in the above embodiment, the cylinder block 1 and the front housing 2 are formed as separate members, and the two members are connected by the bolts.
It becomes easy to form the chamfered portions S ₁ and S ₂ with respect to the edge of a and the tip edge 1e of the bulged bore portion 1c.

Further, in the above embodiment, in the state shown in FIG. 4, when the compressor is stopped, the seal length L ₁ at the bottom dead center of the piston 9 is long, so that the side force Fa by the elastic force of the spring 14 is generated. , Fb also become smaller. Therefore, the spring 14
As a result, the rotary rocking swash plate 12 is reliably returned from the large capacity state to the minimum tilt angle equal to zero capacity, and the restart can be performed with the minimum capacity.

The present invention is not limited to the above embodiment, but can be embodied as follows. (1) As shown in FIG. 5, the formation range of the bulged bore portion 1c is made narrower than that in the above-described embodiment so that the end faces of the bolt insertion holes 1b are flush with each other. In this case, the bolt insertion hole 1
The deburring work after the drilling of b can be easily performed.

(2) As shown in FIG. 6, the bulging bore portion 2b is integrally formed on the rear end surface of the front housing 2. (3) In the above-mentioned embodiment, the variable displacement single-head piston compressor of the minimum capacity starting type is embodied, but this may be embodied as the fixed capacity single-head piston compressor or the variable capacity single-head piston compressor of the maximum capacity starting type.

[0040]

As described in detail above, the invention according to claim 1 has an effect that it is possible to suppress the abrasion of the sliding contact surfaces of the piston and the cylinder bore without increasing the size and weight of the compressor.

In addition to the effect of the invention described in claim 1, the invention described in claim 2 allows the rotary rocking swash plate to be easily returned to the minimum tilt angle position by the spring when the compressor is stopped. ,
The compressor can be restarted with the minimum capacity to mitigate the starting shock.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a central portion in a maximum capacity state showing an embodiment in which the present invention is embodied in a swing swash plate type variable capacity compressor.

FIG. 2 is a vertical cross-sectional view of a central portion of a swing swash plate type variable displacement compressor in a minimum displacement state.

FIG. 3 is a perspective view of a cylinder block.

FIG. 4 is an enlarged cross-sectional view of a main part.

FIG. 5 is a perspective view of a cylinder block showing another example of the present invention.

FIG. 6 is a partial cross-sectional view showing another example of the present invention.

FIG. 7 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cylinder block, 1a ... Cylinder bore, 1c ... Swelling bore part, 1e ... Tip edge of the swelling bore part, 2 ... Front housing, 3 ... Rear housing, 5 ... Crank chamber, 6 ...
Rotating shaft, 9 ... piston, 9a ... base end recess 10 ... lug plate, 12 ... rotating swash plate, 13 ... shoe, 14 ... spring, the cylinder bores 1a in the peripheral surface at the bottom dead center of the L ₁ ... piston 9 And the outer peripheral surface of the piston 9, the seal length, K ... Hinge mechanism.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideta Hirota 2-1-1 Toyota-cho, Kariya-shi, Aichi Stock Company Toyota Industries Corp.

Claims (2)

[Claims] 1. A front having a plurality of cylinder bores for accommodating a reciprocating piston in a cylinder block formed so as to be located on a circular locus and parallel to each other, and a crank chamber being formed on a front end surface of the cylinder block. A housing is joined and fixed, a rear housing is joined and fixed to a rear side end surface, a rotary shaft is supported on the cylinder block and the front housing, and a rotary swing swash plate is attached to the rotary shaft so as to be synchronously rotatable. The base end recess of the piston is moored to the slope of the rotary rocking swash plate through a pair of front and rear shoes, and the rotary rocking swash plate is rocked back and forth by the rotation of the rotary shaft to move the piston in the cylinder bore. A swash plate type single-headed piston compressor that reciprocates to compress refrigerant gas sucked from a suction chamber in a cylinder bore and discharge the compressed refrigerant gas to a discharge chamber. Swash plate piece headed piston compressor forming the bulging bore by extending the end of the cylinder block outer peripheral surface on the crank chamber side of the end portion of the crank chamber side of the bore. 2. The lug plate according to claim 1, wherein a lug plate is fitted and fixed to a rotary shaft, and a rotary swing swash plate is attached to the lug plate via a hinge mechanism so as to be capable of reciprocating swing in the front-back direction. A swash plate type single-head piston compressor in which a spring for urging the swash plate to a minimum tilt angle position is interposed between the plate and the rotary swash plate.