JP4151996B2 - Scroll compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention generally relates to a scroll compressor, and more particularly to a scroll compressor suitable for use as an air compressor for a fuel cell.
[0002]
[Prior art]
For example, as described in Japanese Patent Application Laid-Open No. 60-30493, in a scroll type compressor that is a kind of fluid compressor, refrigerant compressed from a working chamber formed between a fixed scroll and a movable scroll is used. In order to prevent such fluid from leaking to the low pressure side, a tip seal is provided so as to be able to protrude and retract in the groove on the tip of the spiral tooth of each scroll, and the tip seal is urged by a biasing means such as a spring. The structure of pressing against the sliding surface of the other party has been performed in a scroll compressor for a car air conditioner. Generally, in a scroll type compressor provided with a tip seal, in order to reduce the frictional force caused by the sliding of the tip seal and the wear of the tip seal, the sliding surface between the tip seal and the other party is refrigerating oil. It is necessary to supply lubricating oil.
[0003]
[Problems to be solved by the invention]
However, for example, as in a fuel cell system using a scroll compressor, it is necessary to avoid the lubricant from entering the compressed air discharged from the compressor. May not be able to supply. In this way, in the tip seal of the scroll compressor when the lubricating oil cannot be supplied, the use limit value of the tip seal expressed as the product of the pressing force applied to the tip seal and the sliding speed becomes low. Therefore, if the pressing force of the tip seal is increased in order to improve the volumetric efficiency of the scroll compressor, there is a problem that durability is deteriorated due to wear of the tip seal in a high rotation range. On the other hand, if the pressing force of the chip seal is reduced, the durability in the high rotation range is improved, but another problem arises that the volumetric efficiency of the scroll compressor is reduced mainly in the low rotation range.
[0004]
The present invention addresses the above-mentioned problems that are difficult to solve at the same time in the prior art, and in a scroll compressor provided with a tip seal, does not supply any lubricant to the tip seal, or supplies the lubricant. To provide an improved scroll compressor capable of obtaining high volumetric efficiency over the entire operating range while maintaining sufficient durability in a high rotation range under operating conditions with a small amount. It is an object.
[0005]
[Means for Solving the Problems]
In the scroll compressor according to claim 1, a chip seal is fitted in a groove formed on an end surface of at least one of the movable scroll and the fixed scroll. and back pressure chamber is formed between, on its back pressure chamber, reducing the pressure in the back pressure chamber in response to the rotational speed of the crank shaft is increased, the back pressure chamber in response to the rotational speed decreases A varying control pressure is supplied by means of controlling by increasing the pressure. Therefore, in the high rotation range where the rotation speed of the crankshaft increases, the pressure of the back pressure chamber decreases, and it is possible to set so that the force pressing the tip seal against the wall surface of the other scroll is reduced. In the high rotation range, the frictional force of the tip seal and the resulting wear are both reduced, and not only the durability of the tip seal is improved, but also the low rotation at which the frictional force and wear acting on the tip seal are not a problem. In the region, since the force for pressing the tip seal against the wall surface of the other scroll automatically increases, the sealing ability of the tip seal is improved and high volumetric efficiency is obtained.
[0006]
More specifically, the pressure in the back pressure chamber, reducing the pressure in the back pressure chamber in response to the rotational speed of the crank shaft is increased, the control by increasing the pressure in the back pressure chamber in response to the rotational speed decreases As a means for performing this, a means for opening and closing the flow path by the action of the discharge pressure and the centrifugal force, which is provided in the flow path connecting the discharge chamber having the compressed discharge pressure air and the back pressure chamber of the chip seal, is used. be able to. Specifically, this means uses a valve provided at a position where the magnitude of the centrifugal force changes according to the change in the rotational speed of the crankshaft. In this case, since the valve is opened and closed by a balance between the centrifugal force acting on the valve and the force generated by the spring and the discharge pressure, the magnitude of the centrifugal force acting on the valve means changes according to the change in the rotation speed of the crankshaft. As a result, the opening of the valve means changes, and the magnitude of the control pressure supplied to the back pressure chamber changes even if the discharge pressure is constant. As a result, as described above, the magnitude of the frictional force of the chip seal can be changed according to the operating state.
[0008]
In this way, in any case, the pressure of the back pressure chamber of the tip seal is automatically adjusted according to the change in the discharge pressure and the rotation speed of the crankshaft, and the frictional force and the wear are the least, And it becomes possible to adjust so as to obtain a high volumetric efficiency with sufficient sealing performance.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the scroll compressor according to the first embodiment of the present invention shown in FIG. 1, the crankshaft 4 is rotatably supported on the rear housing 2 side through bearings 7 and 14. The balancer 11 and the balancer 12 are supported by the shaft 4 so as to rotate together with the crankshaft 4. The movable scroll 3 is rotatably mounted via a bearing 6 on a crank portion 15 centering on an axis that is eccentric by a predetermined amount parallel to the center line of the crankshaft 4. On both sides of the end plate 3a of the movable scroll 3, spiral teeth (scroll teeth) 3b and 3c are formed. A shaft seal 13 is disposed between the rear housing 2 and the crankshaft 4 to prevent leakage of compressed air. When the crankshaft 4 rotates, the movable scroll 3 performs a revolving motion that draws a circular locus with the radius of the distance between the centerline of the crankshaft 4 and the centerline of the crank portion 15 with the crank portion 15 as the center of revolution. At this time, the movable scroll 3 is restricted from rotating with respect to the front housing 1 by a rotation prevention mechanism described later. That is, the movable scroll 3 is configured so as to perform only the revolving motion around the shaft 4 without the rotational motion.
[0010]
On the radially inner wall surfaces of the front housing 1 and the rear housing 2, spiral teeth 1a and 2a constituting a fixed scroll are formed so as to protrude in the axial direction. The spiral teeth 1a formed on the front housing 1 and the spiral teeth 3b formed on the movable scroll 3 are engaged with each other by shifting the center and the phase by 180 °, thereby allowing a plurality of teeth. A group of working chambers 16 is formed. Similarly, a plurality of working chamber groups 17 are also formed between the spiral teeth 2 a formed on the rear housing 2 and the spiral teeth 3 c formed on the movable scroll 3. A suction chamber 43 is formed in the outer peripheral portion of the integrated front housing 1 and rear housing 2, and a discharge chamber 44 is formed in the central portion. The working chamber is close to the outer peripheral portion and the central portion in a predetermined phase, respectively. 16 and 17 can be communicated.
[0011]
Next, the configuration of the rotation prevention mechanism will be described. By the bearings 8 and 9 held by the front housing 1, the rotating shaft portion 5b of the auxiliary crankshaft 5 having the auxiliary crank portion 5a that is eccentric by the same amount as the crank portion 15 of the crankshaft 4 is rotatably supported. A plurality of auxiliary crankshafts 5 are arranged around the crankshaft 4, and each auxiliary crank portion 5 a supports the movable scroll 3 via a bearing 10 so as to be rotatable.
In addition, as a rotation prevention mechanism used for the scroll type compressor of this invention, you may use the thing of another form, if the above functions are achieved.
[0012]
Next, the structural part corresponding to the characteristic feature of the present invention will be described. A spring 22 that can expand and contract in the radial direction with respect to the rotating shaft portion 4 a of the shaft 4 is installed inside the pressure chamber 24 formed by drilling in the balancer 11. The spring 22 presses the valve 21 disposed at a position away from the rotary shaft portion 4 a in the radial direction so as to receive a centrifugal force accompanying the rotation of the shaft 4 toward the valve stop plate 23. The valve 21 controls communication and blocking between the flow path 32 formed in the valve stop plate 23 and the pressure chamber 24. The pressure chamber 24 communicates with the pressure chamber 28 by a flow path 25. In addition, the shaft seals 26 and 27 installed on the movable scroll 3 prevent the discharge air from entering the pressure chamber 28. The pressure chamber 28 communicates with a groove 30 provided in a spiral shape on the tooth tip surfaces of the scroll teeth 3 b and 3 c through a flow path 29 disposed in the movable scroll 3. A chip seal 31 having the same shape as that of the groove is inserted into the groove 30 to form a back pressure chamber therebetween. The chip seal 31 is an end face of the housings 1 and 2 by the pressure of the back pressure chamber in the groove 30. Respectively. In order to supplement the pressing force of the chip seal 31, for example, a spiral spring plate 33 is disposed between the bottom surface of the groove 30 and the chip seal 31.
[0013]
In the configuration of the above embodiment, the operation as a general scroll compressor will be described first. For example, it comprises a stator 18 directly connected to the rear housing 2, a rotor 19 that is rotatably supported with the crankshaft 4 therein, and an end cap 42 that supports the end of the crankshaft 4 via a bearing 14. As a result of the shaft 4 receiving the rotational force by the motor unit 20 driven by the three-phase AC power, the movable scroll 3 performs a revolving motion while its rotation is restricted by the action of the rotation prevention mechanism. The air sucked into the working chambers 16 and 17 from the suction chamber 43 by the revolving motion of the movable scroll 3 is gradually compressed and discharged into the discharge chamber 44 as the working chamber moves toward the center of the scroll. Further, it is discharged through the discharge port 45.
[0014]
Next, the operation of the portion corresponding to the feature of the present invention will be described. As shown in FIG. 3A, the valve 21 has a pressing force Fs by the spring 22 in the radial direction against the rotating shaft portion 4a of the crankshaft 4, a centrifugal force Fr corresponding to the number of rotations of the shaft, and a flow path. A force (Pd−P) · S (where S is the valve 21) proportional to the pressure difference between the pressure in the pressure chamber 32, that is, the pressure Pd of the compressed air in the discharge chamber 44 and the pressure P in the pressure chamber 24. And the contact area between the valve stop plate 23 and the valve stop plate 23 are working. And as shown in Fig. 3 (2),
(Pd−P) · S> Fr + Fs
In this case, the valve 21 is separated from the valve stop plate 23, the flow path 32 and the pressure chamber 24 communicate with each other, and the pressure P in the pressure chamber 24 increases.
[0015]
The pressure P increases,
(Pd−P) · S <Fr + Fs
Then, as shown in FIG. 3A, the valve 21 is pressed against the valve stop plate 23, and the flow path 32 and the pressure chamber 24 are blocked. That is, the pressure P in the pressure chamber 24 is
P = Pd− (Fr + Fs) / S
The centrifugal force Fr increases as the rotational speed increases, and the pressure P gradually decreases.
[0016]
The pressure P controlled in the pressure chamber 24 passes through the communication hole (flow path) 25, the pressure chamber 28, and the communication hole (flow path) 29 to the tooth tip surfaces of the scroll teeth 3 b and 3 c of the movable scroll 3. As shown in FIG. 4, the chip seal 31 is pressed toward the wall surface of the housing by the resultant groove 30, that is, the back pressure chamber, and the resultant force of the pressing force of the spring 33 and the back pressure.
[0017]
FIG. 5 shows an example of a change in the pressing pressure acting on the tip seal 31 in the back pressure chamber in the groove 30 with respect to the number of rotations of the crankshaft 4 in the case where the control as described above is performed. . Conventionally, as shown by the broken line in FIG. 5, the tip seal 31 is pressed at a constant pressure by a spring or the like, and the tip seal pressing pressure value is set so as not to exceed the limit PV value of the tip seal at the maximum operating rotational speed. Since it was set, the pressure for pressing the tip seal at low rotation could not be set effectively. In contrast, in the present invention, the valve 21 is operated using centrifugal force so that the tip seal pressing pressure is reduced as the rotational speed of the shaft 4 increases. Reliability is not impaired, and leakage from the gap of the tip seal 31 can be reduced at low rotation.
[0018]
FIG. 6 shows a second embodiment of the present invention. In the first embodiment, the controlled pressure in the pressure chamber 24 is guided to the back pressure chamber in the groove 30 through the flow path 25, the pressure chamber 28, and the flow path 29, thereby being inserted into the movable scroll 3. The chip seal 31 is configured to be pressed against the wall surfaces of the housings 1 and 2. On the other hand, in the second embodiment, the controlled pressure in the pressure chamber 24 is guided to the pressure chamber 37 through the flow path 34 provided in the balancer 11. The pressure chamber 37 is prevented from entering and leaking discharge air by shaft seals 35 and 36 installed in the housing 2. The pressure chamber 37 communicates with a groove 39 formed in the tooth tip surfaces of the scroll teeth 1a and 2a of the housings 1 and 2 through the flow path 38.
[0019]
In the configuration of the second embodiment, similarly to the first embodiment, the pressure in the controlled pressure chamber 24 is applied to the tooth tip surfaces of the spiral scroll teeth 1a and 2a of the fixed scroll formed in the housings 1 and 2. The same effect as in the case of the first embodiment can be obtained by pressing the tip seal that is guided to the groove 39 (back pressure chamber) provided and fitted in the groove 39 against the end surface 3a of the movable scroll 3. Needless to say, by combining the first embodiment and the second embodiment, a back pressure chamber for pressing the tip seal may be provided on the distal end surfaces of the spiral teeth of both the movable scroll and the fixed scroll.
[0020]
FIG. 7 shows a third embodiment of the present invention. In 1st Embodiment, it was set as the structure which controls the pressure guide | induced to the groove | channel 30 using the centrifugal force which the valve 21 receives. On the other hand, in the third embodiment, as shown in FIG. 8, a fan-like groove 41 is formed in the boss portion 3 d of the movable scroll 3, and the channel 40 is communicated with or blocked by the rotational position of the shaft 4. It is assumed to be configured. The groove 41 communicates with the groove 30 formed on the end surfaces of the spiral teeth 3 b and 3 c of the movable scroll 3 through the flow path 29.
[0021]
Next, the operation of the third embodiment having the above configuration will be described. The pressure in the groove 41 is controlled by the communication time with the flow path 40. When the discharge pressure guided to the flow path 40 is transmitted to the groove 41, the pressure rise in the groove 41 is accompanied by a time delay as shown in FIG. 9 due to the inertia and viscosity of the air in the flow path 40. Therefore, during low rotation with a long communication time between the flow path 40 and the groove 41, the discharge pressure in the flow path 40 is sufficiently transmitted to increase the pressure in the groove 41, but as the rotational speed increases, the groove Since the communication time between the channel 41 and the flow path 40 is gradually shortened, the transmitted pressure becomes lower. The pressure transmitted to the groove 41 is transmitted to the groove 30 through the flow path 39, and the pressing pressure of the tip seal 31 gradually decreases as the number of rotations increases. Therefore, the same effect as in the first embodiment can be obtained. .
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an overall configuration of a first embodiment.
FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1 for illustrating the configuration of the valve.
FIGS. 3A and 3B are partially enlarged cross-sectional views taken along line AA showing different operating states of the first embodiment. FIGS.
FIG. 4 is an enlarged cross-sectional view of a tip seal part.
FIG. 5 is a diagram for explaining the effect of the first embodiment;
FIG. 6 is a longitudinal sectional view showing an overall configuration of a second embodiment.
FIG. 7 is a longitudinal sectional view showing an overall configuration of a third embodiment.
FIGS. 8A and 8B are partially enlarged cross-sectional views taken along line BB in FIG. 7 showing different operating states of the third embodiment.
FIG. 9 is a diagram showing a pressure change in a groove in the third embodiment.
[Explanation of symbols]
1, 2 ... Housing 1a, 2a ... Spiral teeth (fixed scroll)
3 ... movable scroll 3a ... end plates 3b, 3c ... spiral teeth 4 ... crankshafts 11, 12 ... balancer 15 ... crank parts 16, 17 ... working chamber group 20 ... motor part 21 ... valve 22 ... spring 23 ... valve stop Plates 24, 28 ... pressure chamber 30 ... groove (back pressure chamber)
31 ... Tip seal 33 ... Leaf spring 37 ... Pressure chamber 39 ... Groove (back pressure chamber)
41 ... Fan-shaped groove 43 ... Suction chamber 44 ... Discharge chamber

Claims (1)

A housing forming a suction chamber and a discharge chamber, a fixed scroll made of spiral teeth formed on an inner wall surface of the housing, and a spiral tooth formed on a movable end plate, the fixed scroll A movable scroll incorporated so as to engage with each other while shifting its center and phase with respect to each other, a plurality of working chambers formed between the fixed scroll and the movable scroll engaged with each other, and rotatably supported by the housing And a crankshaft that includes a crank portion that is eccentric by a predetermined amount with respect to the shaft center, thereby imparting a revolving motion to the movable scroll, and a rotation prevention mechanism that allows only the revolving of the movable scroll and prevents rotation. And fitted into a groove formed on the end surface of the spiral tooth of at least one of the movable scroll and the fixed scroll. A tip seal that is, the a back pressure chamber formed by said tip seal and formed on said end face of the spiral tooth, the pressure of the back pressure chamber, the rotational speed of the front Symbol crankshaft up The pressure of the back pressure chamber is lowered according to the pressure, and the control is performed by increasing the pressure of the back pressure chamber according to the decrease in the rotational speed.
The pressure of the back pressure chamber, before Symbol lowering the pressure in the back pressure chamber in response to the rotational speed of the crankshaft increases, as a means of controlling by increasing the pressure in the back pressure chamber in response to the rotational speed decreases And means for controlling the opening and closing of the flow path connecting the discharge chamber and the back pressure chamber by discharge pressure and centrifugal force, and the opening and closing of the flow path connecting the discharge chamber and the back pressure chamber is controlled by the discharge pressure and As a means for controlling by the centrifugal force, a valve that is disposed at a position to receive a centrifugal force having a magnitude corresponding to the rotational speed of the crankshaft and opens and closes by balancing the centrifugal force and the force of the spring and the pressing force of the discharge air A scroll type compressor characterized by having.

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