JPH0756260B2 - Variable capacity mechanism of compressor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a compressor suitable for vehicle air conditioning, and more particularly to a variable capacity mechanism of a compressor capable of changing the compression capacity according to a cooling load. .

[Prior Art] Generally, in a vehicle air-conditioning compressor, an intermittent operation of the compressor is performed by a clutch operation in order to prevent cooling failure due to excessive cooling or freezing of an evaporator. However, the intermittent operation of the compressor not only impairs the cooling feeling due to the extremely large temperature fluctuations of the cold air supplied to the passenger compartment, but also that the power source of the compressor depends on the vehicle driving engine. Due to fate, early wear of the clutch and deterioration of driving feeling were also inevitable problems.

In the invention of Japanese Patent Laid-Open No. 54-31612 focused on this point, a relief passage for bypassing a part of the refrigerant gas in the compression chambers formed in the front and rear 6 cylinders to the low pressure side is provided to change the compression capacity. A compressor adapted to do so is disclosed. That is,
As shown in FIG. 7, a relief hole d for bypassing a part of the refrigerant gas in the compression stroke of the compression chamber a to the low pressure side of the other compression chamber a, the oil reservoir chamber b, the swash plate chamber c, etc., during the suction stroke. , A lateral hole e, and a through hole f are provided, and the escape passage is opened and closed by a spool g that moves laterally in the lateral hole e, and the spool g has bellows h acting on both end surfaces thereof. Is operated by the pressure difference between the sealed fluid pressure and the suction pressure. Therefore, when the temperature in the vehicle interior decreases, the cooling load decreases, and the suction pressure decreases, the sealing fluid pressure of the bellows h overcomes the suction pressure and activates the spool g to open the relief passage, so that the piston i has a relief hole. The compression stroke until the valve d is blocked is disabled, and the compression capacity is reduced without reducing the number of effective cylinders.

[Problems to be Solved by the Invention] However, since the bellows h described above is arranged in the central portion of the compressor in proximity to the respective bores, the sealed fluid in the bellows h depends on the discharge temperature of the compressor. Is susceptible to temperature fluctuations, and this changes the sealed fluid pressure, weakening the correlation with the cooling load and disturbing accurate control. Moreover, since the spool g operates only by the balance between the suction pressure and the sealing fluid pressure, in addition to the fluctuation of the suction pressure and the influence of the fluctuation of the sealing fluid pressure which is unrelated to this, it is easy to repeat unnecessary fine movement, There is also a problem that this causes abnormal noise.

An object of the present invention is to solve the problem of reliably operating the spool irrespective of the fluctuation of the compressor temperature and developing a variable displacement mechanism having good response to a cooling load.

[Means for Solving the Problems] In order to solve the above technical problems, the present invention provides a cylinder block in which a plurality of cylinder bores are arranged around a shaft hole penetrating the center portion, a suction chamber, and A housing having a discharge chamber for closing the opening end of the cylinder block, a drive shaft fitted and supported in the shaft hole, a swash plate for driving a piston fixed to the drive shaft, and the swash plate. A compressor provided with a swash plate chamber that is housed and formed separately from the suction chamber and the discharge chamber, and a suction passage that guides return refrigerant from a refrigeration circuit to the suction chamber, the cylinder block By-pass hole that connects the shaft hole of and the compression chamber in each cylinder bore,
Spool valve means which is fitted in the shaft hole to normally close the bypass hole, and communicates the bypass hole with either the suction chamber or the swash plate chamber in response to the pressure difference between the swash plate chamber and the suction chamber. A throttle valve means that is incorporated in the suction passage and controls the flow rate of the return refrigerant in accordance with the pressure of the return refrigerant; and a pressure supply passage that communicates the suction passage upstream of the throttle valve means with the swash plate chamber. The configuration consists of.

[Operation] According to the present invention, by adopting the above configuration, when the pressure drop of the return refrigerant exceeds a predetermined value due to the fluctuation of the cooling load, the throttle valve means limits the refrigerant flow rate in the suction passage to reduce the compression capacity. At the same time, the pressure drop in the evaporator and the suction pipe line is suppressed, and when the degree of restriction of the refrigerant flow rate increases and the pressure in the suction chamber falls to a predetermined value, the pressure in the suction chamber is opposed to one end of the spool valve means. The pressure in the compression chamber is low until the bypass hole is opened and the piston closes the bypass hole due to an increase in the pressure difference between the pressure in the upstream region of the throttle valve means acting through the pressure supply passage and the swash plate chamber. The compression work is disabled by being communicated with the area, so that the compression capacity is further reduced. When the cooling load further decreases, the throttle valve means operates to a substantially closed state to further limit the refrigerant flow rate in the suction passage, so that excessive cooling is prevented in a very wide variable range.

[Embodiment] A first embodiment in which the present invention is embodied in a swash plate compressor will be described below with reference to FIGS. 1 to 4.

In the figure, 1F and 1R are front and rear cylinder blocks, and a drive shaft 3 is supported via a bearing in shaft holes 2F and 2R penetrating the center of the cylinder block. It is driven to rotate by the power of the engine through the connection. A plurality of cylinder bores 4F, 4R are provided on the outer peripheral portion of the shaft holes 2F, 2R so as to surround the coaxial holes 2F, 2R, and each cylinder bore 4F, 4R serves as a piston drive chamber and a suction chamber and a discharge chamber described later. Are aligned independently with each other with a swash plate chamber 5 defined independently therebetween, and a double-headed piston 6 is fitted in each pair of cylinder bores 4F, 4R. Then, in each cylinder bore 4F, 4R, a compression chamber 8F, 8R is provided between the head of each piston 6 and a valve plate described later.
Is formed. In addition, a swash plate 9 fixed to the drive shaft 3 is housed in the swash plate chamber 5 so as to be capable of swinging rotation, and the swinging rotation of the swash plate 9 is fixed to each piston 6 moored via a shoe 10 and balls 11. Transmitted as a reciprocating motion to. 12F and 12R are front and rear housings that cover the open ends of the cylinder blocks 1F and 1R with the front and rear valve plates 7F and 7R sandwiched between them. Both housings 12F and 12R have an appropriate number of through bolts 13 Both cylinder blocks 1F, 1R
Will be tightened together with. In both housings 12F and 12R, suction chambers 14F and 14R are provided on the outer peripheral side corresponding to the cylinder bores 4F and 4R.
Discharge chambers 15F and 15R are concentrically provided on the inner peripheral side with a substantially annular partition wall therebetween. Then, suction valves 17F and 17R for opening and closing the suction ports 16F and 16R corresponding to the suction chambers 14F and 14R are provided on the inner end surfaces of both valve plates 7F and 7R, and the discharge chambers 15F and 15R are also provided on the outer end surfaces. Discharge valves 19F and 19R for opening and closing the discharge ports 18F and 18R are mounted, respectively. The suction chambers 14F and 14R are communicated with an opening 22 of a suction flange 21 through a suction passage 20 penetrating through both cylinder blocks 1F and 1R and both valve plates 7F and 7R, and the discharge chambers 15F and 15R are Similarly, it is communicated with the opening 25 of the discharge flange 24 through the discharge passage 23.

An expanded diameter portion is provided near each valve plate of the shaft holes 2F, 2R, and an opening formed through the valve plates 7F, 7R and a void provided in the center of both housings 12F, 12R. Pressure action chambers 26F and 26R are formed over the range. Bypass holes 27F, 2 communicating with the compression chambers 8F, 8R for the expanded diameter portion.
Evacuation holes 28F and 28R communicating with the 7R and the swash plate chamber 5 are provided,
The bypass holes 27F and 27R are opened and closed by spool valves 29F and 29R that are slidably fitted in the expanded diameter portion. The spool valves 29F and 29R are connected to the pressure acting chambers 26F and 26R through the pressure guiding holes 30F and 30R, and the pressure of the suction chambers 14F and 14R and the spring 31.
The resultant force with the elasticity of F and 31R acts in the direction of closing the bypass holes 27F and 27R, while the pressure of the swash plate chamber 5 via the relief holes 28F and 28R is in the direction of opening the bypass holes 27F and 27R. To work.

A cylindrical storage case 32 having a bottom is fitted to the boss portion 21a of the suction flange 21, and a through hole 2 formed at the center of the boss portion 21a.
A cylindrical throttle valve 33 is slidably inserted in 1b.
A bellows 34 is connected between the base end portion 33a of the throttle valve 33 and the boss portion 21a, and a pressure chamber 35 formed between the throttle valve 33 and the bellows 34 is formed in the throttle valve 33. Induction line 33
It is communicated with the suction passage 20 'in the flange 21 by b. A spring 36 is interposed between the throttle valve 33 and the bottom surface of the storage case 32 to keep the throttle valve 33 always in the suction passage.
The valve hole 37 provided in the middle of 20 'is urged in the closing direction. The storage case in which the spring 36 is arranged
The inside of 32 is formed as an atmosphere chamber 38 that communicates with the outside air through a through hole 32a.

On the other hand, in the suction passage 20 'in the upstream region of the valve hole 37,
One end of the pressure supply passage 39 communicating with the swash plate chamber 5 is opened,
By restricting the flow rate of the refrigerant passing through the valve hole 37 by the throttle valve 33, the refrigerant in the suction passage 20 'kept at a predetermined pressure is introduced into the swash plate chamber 5.

The operation of the variable displacement mechanism of the swash plate compressor configured as described above will be described.

When the vehicle interior temperature is high and the cooling load is high, as in the initial stage of compressor startup, the temperature of the evaporator that performs heat exchange rises, so the saturation pressure of the refrigerant rises, and the suction pipe line (not shown) sucks it in. As the pressure in the passage 20 'rises, the pressure chamber
The pressure of 35 becomes high, and as a result, the pressure in the atmospheric chamber 38 and the spring 36
The throttle valve 33 is moved in the direction to open the valve resistance 37 of the suction passage 20 'against the resultant force with the elastic force of. Therefore, the pressure of the refrigerant in the upstream region above the valve hole 37 does not change and the suction chamber 14
The F and 14R and the swash plate chamber 5 have the same pressure. And the shaft hole
The pressure of the pressure action chambers 26F and 26R, which are in communication with the suction chambers 14F and 14R via the pressure guide holes 30F and 30R, act on the outer ends of the spool valves 29F and 29R fitted in the 2F and 2R, On the other hand, since the pressure of the swash plate chamber 5 having the same pressure as that of the suction chambers 14F, 14R acts on the inner end side through the relief holes 28F, 28R, the fluid acting in both sliding directions of the spool valves 29F, 29R. The pressure is balanced and the spool valve 29F, 2
9R is pushed to the position where the bypass holes 27F, 27R are closed by the elasticity of the springs 31F, 31R. That is, in this state, the compressor operates at full capacity.

After that, when the temperature inside the vehicle interior decreases and the cooling load decreases, the temperature of the evaporator begins to decrease and the saturation pressure also decreases. Simultaneously with the decrease of the saturation pressure, the pressure of the suction passage 20 '(suction line) is lowered and the pressure of the pressure chamber 35 is also lowered. When the pressure in the pressure chamber 35 falls below a predetermined value, the force relationship of the pressure in the pressure chamber 35 with respect to the resultant force of the pressure in the atmosphere chamber 38 and the elasticity of the spring 36 is reversed, and the throttle valve 33 is By moving the hole 37 in the closing direction, the opening for restricting the flow rate by the throttle valve 33 is maintained in a state where the force relationship is balanced. That is, the compression capacity is appropriately reduced, and at the same time, the pressure in the suction passage 20 '(suction line) in the upstream region of the valve hole 37 is prevented from dropping below a predetermined value.

When the flow rate restriction by the throttle valve 33 due to the pressure drop in the pressure chamber 35 further proceeds, the suction chamber 14 passes through the suction passage 20.
The amount of the refrigerant introduced into F and 14R is further reduced, and eventually the pressures in the suction chambers 14F and 14R and the pressure action chambers 26F and 26R drop below a predetermined value. On the other hand, the pressure in the suction passage 20 'in the upstream region of the valve hole 37 where a predetermined pressure is maintained by the flow rate control by the throttle valve 33 is directly guided to the swash plate chamber 5 by the pressure supply passage 39. Spool valve 29
The combined force of the pressure of the pressure action chambers 26F, 26R acting on the outer end side of F, 29R and the elastic force of the springs 31F, 31R is applied to the inner end side of the spool valves 29F, 29R via the relief holes 28F, 28R. Reaching the pressure of the swash plate chamber 5 that acts, the spool valves 29F and 29R are allowed to move, and the bypass holes 27F and 27R are opened. Therefore, the refrigerant in the compression chambers 8F, 8R during the compression stroke is kept in the bypass holes 27F, 2R until the head of the piston 6 closes the bypass holes 27F, 27R.
Since it flows from 7R to the compression chambers 8F and 8R during the intake stroke through the shaft holes 2F and 2R and the other bypass holes 27F and 27R and to the swash plate chamber 5 through the relief holes 28F and 28R, the compression work during that period is ineffective. The number of effective cylinders is reduced, and the operation shifts to a low capacity operation in which the compression capacity is further reduced.

If the cooling load is still reduced by continuing such a low capacity operation, the throttle valve 33 is further provided with a valve hole 37.
Is moved to the closed position to further reduce the compression capacity and secure the pressure in the suction pipe line. When the cooling load is recovered by the capacity control in each of the above steps, the control is relaxed in the reverse order of the description, and eventually the full capacity operation is restored.

In the above description, the structure in which the throttle valve means is provided in the intake flange 21 portion has been described, but as shown in FIG. 5, it may be installed in the housings 12F and 12R. In the figure, the reference numerals and the description of the interior of the front housing 12F are omitted.
134 is attached to the inner wall of the housing 12R, and a plate-shaped throttle valve 133 facing the opening 137 of the valve plate 7R forming a part of the suction passage 20 and capable of closing the opening 137 is attached to the tip of the bellows 134. The inside of the chamber is formed as an atmosphere chamber 138 that communicates with the outside air through a through hole 132a, and the opening 1 is always provided.
A spring 136 for urging the throttle valve 133 in the direction of closing 37 is provided. In this example, the suction passage 20 in the upstream region of the throttle valve 133 is directly communicated with the swash plate chamber 5 and the pressure supply passage 39 is eliminated, which is different from the above-described embodiment, but the throttle valve is different. Since the operation of the means is substantially the same as that of the embodiment, detailed description thereof will be omitted.

Subsequently, instead of the bypass mode in which the compression chambers 8F, 8R and the swash plate chamber 5 can communicate with each other, the compression chambers 8F, 8R and the suction chambers 14F, 1
The sixth embodiment of the second embodiment adapted to communicate with the 4R
It will be described with reference to the drawings.

In the drawing, the suction chamber 14 in both housings 12F and 12R
Contrary to the first embodiment, the arrangements of F, 14R and discharge chambers 15F, 15R are suction chambers 14F, 14R on the inner peripheral side and discharge chambers 15F, 1R on the outer peripheral side.
The pressure action chambers 26F, 26R are configured as immediate suction chambers 14F, 14R. The bypass holes 27F and 27R and the pressure action chambers 26F and 26R are formed on the peripheral walls of the spool valves 29F 'and 29R'.
Communication holes 40F and 40R capable of communicating with the pressure relief holes 28F and 28R of the first embodiment are provided in this embodiment. 28
It acts only as F ', 28R'. As can be seen from the figure, the springs 31F 'and 31R' are interposed between the inner bottom surfaces of the spool valves 29F 'and 29R' and the inner wall surfaces of the housings 12F and 12R.

Therefore, in the present embodiment, the suction chambers 14F and 14R and the pressure action chamber are
When the pressure in 26F, 26R drops below a predetermined value and the spool valves 29F ', 29R' are moved due to the pressure difference with the pressure in the swash plate chamber 5, the compression chambers 8F, 8R coincide with the bypass holes 27F, 27R. Pressure acting chambers 26F, 26R (intake chambers 14F, 1
4R) causes a respiratory action and shifts to the same low capacity operation as described above.

The above description has been made on an embodiment in which the present invention is embodied in a swash plate type compressor including a cylinder bore aligned front and rear and a double-headed piston that slides in the bore. Of course, it can be applied to a swash plate compressor.

[Effects of the Invention] As described in detail above, the variable displacement mechanism of the compressor according to the present invention has the following excellent effects.

(1) The variable range of the variable capacity mechanism is controlled by the cooperation of the throttle valve means for controlling the amount of the refrigerant introduced into the suction chamber and the spool means for opening and closing the bypass hole to disable a part of the compression work. It can be expanded significantly.

(2) Since the throttle valve means and the spool valve means are actuated by the change of the suction pressure itself, a variable displacement mechanism that is accurately correlated with the cooling load can be realized without being caught by the temperature fluctuation of the compressor.

(3) Since the throttle valve means also supervises the opening / closing control of the spool valve means, simplification of the structure can be achieved.

(4) Since the control based on the change in the suction pressure correlates with the cooling load as well as the rotation speed of the compressor, it responds well to sudden acceleration of the vehicle and contributes to the reduction of the engine load.

(5) In particular, according to the second embodiment, during the low-capacity operation, the compression chamber causes a breathing action between the compression chamber and the suction chamber of a lower pressure via the bypass hole, so that the compression efficiency is improved.

[Brief description of drawings]

FIG. 1 shows a swash plate type compressor according to the first embodiment of the present invention.
A sectional front view corresponding to a section taken along line I-I of the drawing, and FIG.
II-II sectional side view of the drawing, FIG. 3 is a III-III line partial sectional view of FIG. 2, FIG. 4 is a IV-IV line partial sectional view of FIG. 1, and FIG. A partial sectional view showing a modified example, FIG. 6 is a sectional front view of a swash plate compressor similarly showing a second embodiment of the present invention, and FIG. 7 is a sectional front view of a conventional swash plate compressor. 4F, 4R ... Cylinder bore, 5 ... Swash plate chamber, 6 ... Piston, 8F8R ... Compression chamber, 12F, 12R ... Housing, 14F, 1
4R ... Suction chamber, 15F, 15R ... Discharge chamber, 20,20 '... Suction passage, 21 ... Suction flange, 26F, 26R ... Pressure action chamber,
27F, 27R …… Bypass hole, 28F 28R …… Escape hole, 29F, 29R
...... Spool valve, 30F, 30R ...... Pressure guide hole, 31F, 31R ...... Spring, 33,133 ...... Throttle valve, 34,134 ...... Bellows, 35 ......
Pressure chamber, 36, 136 ... Spring, 37 ... Valve hole, 38, 138 ... Atmosphere chamber, 39 ... Pressure supply passage

Claims (1)

[Claims] 1. A cylinder block in which a plurality of cylinder bores are arranged around an axial hole penetrating through the center, and a housing having a suction chamber and a discharge chamber for closing the open end of the cylinder block. , A drive shaft fitted and supported in the shaft hole, a swash plate for driving a piston fixed to the drive shaft, the swash plate, and a partition formed independently of the suction chamber and the discharge chamber A swash plate chamber and a suction passage that guides the return refrigerant from the refrigeration circuit to the suction chamber, and a bypass hole that communicates the shaft hole of the cylinder block with the compression chamber in each cylinder bore. , A spool valve which is fitted in the shaft hole to always close the bypass hole, and communicates the bypass hole with either one of the suction chamber and the swash plate chamber in response to a pressure difference between the swash plate chamber and the suction chamber. Means and the return cooling device incorporated in the suction passage. A throttle valve means for controlling the flow rate in response to the pressure, the variable capacity mechanism of the compressor comprising a feed pressure passage communicating with said suction passage of the upstream region of the narrowed valve means the swash plate chamber Prefecture.