Patent Application
20230132581
The present disclosure relates to a scroll compressor configured to compress a working medium.
Hitherto known scroll compressors are each configured to compress a working medium in a plurality of compression chambers defined between scroll wraps of a fixed scroll and an orbiting scroll that are made to mesh with each other. The working medium is compressed when the orbiting scroll undergoes an orbital motion about the fixed scroll. Such a scroll compressor is disclosed by Patent Literature 1, in which a scroll start portion, also regarded as a scroll center portion, of a scroll wrap has a tiered shape whose thickness is reduced from the base toward the tip.
According to Patent Literature 1, among a plurality of compression chambers, an innermost compression chamber and a second compression chamber on the radially outer side of the innermost compression chamber are made to communicate to each other in a graded manner by employing the tiered scroll start portion. Thus, the stress generated at the base of the scroll start portion is reduced. However, discussions on some issues have not been made specifically, including which region of the scroll start portion is to be shaped in tiers. Therefore, whether the stress is reduced satisfactorily is unclear.
Moreover, if the fixed scroll and the orbiting scroll are made of respective materials having different coefficients of linear expansion, the difference in the amount of thermal expansion occurring with a temperature rise during operation may generate a great stress at the base of the scroll start portion. Such an issue is not discussed in Patent Literature 1.
The present disclosure is to solve at least one of the above problems and provides a scroll compressor in which the stress generated at the base of the scroll start portion is small.
A scroll compressor according to a first embodiment of the present disclosure is configured to compress a working medium in a plurality of compression chambers defined between an orbital scroll wrap of an orbiting scroll and a fixed scroll wrap of a fixed scroll that are made to mesh with each other. The working medium is compressed when the orbiting scroll driven through a main shaft undergoes an orbital motion about the fixed scroll. The orbital scroll wrap and the fixed scroll wrap include respective scroll start portions each having a bulbous shape defined by connecting an involute start point of an outer-surface involute curve and an involute start point of an inner-surface involute curve to each other with a plurality of arcs. At least one of the scroll start portions has a tiered shape in which an n number (where n≥2) of tiers each having the bulbous shape are stacked in an axial direction of the main shaft. Letting involute-start-point angles of the outer-surface involute curves in the respective tiers of the scroll start portion having the tiered shape be φos(1), φos(2), φos(3), . . . , and φos(n) in order from a tip toward a base of the scroll start portion, the following relationships are satisfied: φos(1)>φos(2)>φos(3)> . . . >φos(n); and 0.3π<φos(1)-φos(n)<0.7π.
A scroll compressor according to a second embodiment of the present disclosure is configured to compress a working medium in a plurality of compression chambers defined between an orbital scroll wrap of an orbiting scroll and a fixed scroll wrap of a fixed scroll that are made to mesh with each other. The working medium is compressed when the orbiting scroll driven through a main shaft undergoes an orbital motion about the fixed scroll. The orbital scroll wrap and the fixed scroll wrap include respective scroll start portions each having a bulbous shape defined by connecting an involute start point of an outer-surface involute curve and an involute start point of an inner-surface involute curve to each other with a plurality of arcs. At least one of the scroll start portions has a tiered shape in which an n number (where n≥2) of tiers each having the bulbous shape are stacked in an axial direction of the main shaft. The orbiting scroll and the fixed scroll are made of respective materials having different coefficients of linear expansion. Letting the tiers of the scroll start portion be defined as a first tier, a second tier, . . . , and an n-th tier in order from a tip toward a base of the scroll start portion; and a situation where the orbital scroll wrap and the fixed scroll wrap go out of contact with each other in the n-th tier of the scroll start portion and, among the compression chambers, two compression chambers that are not made to communicate with each other before the scroll wraps go out of contact with each other are made to communicate with each other be expressed as the n-th tier is opened, a relief is provided in an outer surface of the orbital scroll wrap or in the fixed scroll wrap such that while the orbiting scroll is undergoing the orbital motion from a crank angle at which the first tier is opened to a crank angle at which the n-th tier is opened, the outer-surface involute of the scroll wrap of the scroll that is made of the material having the greater coefficient of linear expansion and the inner-surface involute of the scroll wrap of the scroll that is made of the material having the smaller coefficient of linear expansion are out of contact with each other at least at an outermost one of a plurality of contact points where the two involutes are to come into contact with each other.
In the scroll compressor according to the first embodiment of the present disclosure, since the scroll start portion has the tiered shape, among the plurality of compression chambers, the innermost compression chamber and the second compression chamber on the radially outer side of the innermost compression chamber are made to communicate with each other in a graded manner. Thus, the stress generated at the base of the scroll start portion is reduced. Furthermore, satisfying the relationship of 0.3π<φos(1)-φos(n)<0.7π brings a satisfactory degree of strength improvement for the scroll start portion.
In the scroll compressor according to the second embodiment of the present disclosure, the scroll start portion of the scroll wrap made of the material having the greater coefficient of linear expansion is kept supported by the lateral face of the scroll wrap of the scroll made of the material having the smaller coefficient of linear expansion until the pressure is completely equalized between two of the compression chambers, namely the innermost compression chamber and the second compression chamber that are not made to communicate with each other before the scroll wraps go out of contact with each other. Such a configuration suppresses the generation of a great stress at the base of the scroll start portion of the scroll wrap made of the material having the greater coefficient of linear expansion. Furthermore, the scroll start portion of the scroll wrap made of the material having the smaller coefficient of linear expansion is designed such that, during operation, the gaps from the other scroll wrap made of the material having the greater coefficient of linear expansion become smaller than in a case where no relief is provided. Such a configuration suppresses the generation of a great stress at the base of the scroll start portion.
Embodiments of the present disclosure will now be described with reference to the drawings. Note that the present disclosure is not limited by the following embodiments. The same reference signs provided in the drawings denote the same or equivalent elements, which applies throughout this specification. The forms of the individual elements described throughout the entirety of this specification are only exemplary and are not limited thereto.
The scroll compressor, 1, will now be described with reference to
The shell 2 further houses a frame 6 and a sub frame 20, which are located across the motor 4 from each other. The frame 6 is located above the motor 4 and between the motor 4 and the compression unit 5. The sub frame 20 is located below the motor 4. The frame 6 and the sub frame 20 are fixed to the inner peripheral face of the shell 2 by a method such as shrink fitting or welding. The frame 6 is provided in a central part thereof with a main bearing 8a. The sub frame 20 is provided in a central part thereof with a counterbearing 8b. The counterbearing 8b is, for example, a ball bearing and is press-fitted to the sub frame 20. The main bearing 8a and the counterbearing 8b support the main shaft 7 while allowing the main shaft 7 to rotate.
The sub frame 20 is provided with a displacement oil pump 3. A pump shaft for transmitting a turning force to the oil pump 3 is integrated with the main shaft 7. The main shaft 7 has an oil hole 7b. The oil hole 7b extends through the center of the main shaft 7 from the lower end of the pump shaft to the upper end of the main shaft 7. The lower end of the oil hole 7b is connected to the oil pump 3.
The shell 2 includes three parts: an upper shell 2a, a middle shell 2b, and a lower shell 2c. The shell 2 is provided with a suction pipe 11, for suctioning the refrigerant; and a discharge pipe 12, for discharging the refrigerant. The refrigerant suctioned into the shell 2 through the suction pipe 11 flows through a suction port 6a, provided in the frame 6, and is suctioned into compression chambers 5a, provided in the compression unit 5 and to be described separately below.
The compression unit 5 is configured to compress the refrigerant suctioned thereinto through the suction pipe 11 and to discharge the compressed refrigerant to a high-pressure section provided in an upper part of the shell 2. The compression unit 5 includes a fixed scroll 30, an orbiting scroll 40, an Oldham ring 15, and other relevant elements. The Oldham ring 15 is configured to prevent the orbiting scroll 40 from spinning on its own axis while the orbiting scroll 40 is undergoing an eccentric circular motion (swirling motion).
The fixed scroll 30 is located on the upper side and is fixed to the shell 2 with the frame 6 interposed therebetween. The orbiting scroll 40 is located on the lower side and is supported by the main shaft 7 while being allowed to swirl.
The fixed scroll 30 includes a fixed base plate 30a and a fixed scroll wrap 30b. The fixed scroll wrap 30b has a scroll shape and is provided on one face of the fixed base plate 30a. The orbiting scroll 40 includes an orbital base plate 40a and an orbital scroll wrap 40b. The orbital scroll wrap 40b has a scroll shape and is provided on one face of the orbital base plate 40a. The fixed scroll wrap 30b and the orbital scroll wrap 40b are each shaped in conformity with, for example, an involute curve. The fixed scroll 30 and the orbiting scroll 40 are arranged in the shell 2 such that the fixed scroll wrap 30b and the orbital scroll wrap 40b are in mesh with each other. Between the fixed scroll wrap 30b and the orbital scroll wrap 40b are defined a plurality of compression chambers 5a. While the main shaft 7 is rotating, the capacities of the compression chambers 5a decrease in the radial direction from the outer side toward the inner side.
The fixed scroll 30 has in a central part thereof a discharge port 30f, through which the refrigerant having a high pressure by being compressed is discharged. On the exit side of the discharge port 30f is provided a discharge chamber 13. The discharge chamber 13 is provided at the outlet thereof with a discharge valve 13a, which has a reed-valve structure. Above the discharge chamber 13 is provided a muffler 14. The muffler 14 suppresses the pulsation of the working medium discharged from the discharge chamber 13.
The orbital base plate 40a of the orbiting scroll 40 has an orbital bearing 40f. The orbital bearing 40f is provided in a central part of the other face of the orbital base plate 40a that is opposite the face having the orbital scroll wrap 40b. The orbital bearing 40f has a bore, where a slider 9 to be described below is rotatably supported. The center axis of the orbital bearing 40f is parallel to the center axis of the main shaft 7.
The Oldham ring 15 is located between the orbiting scroll 40 and the frame 6. The Oldham ring 15 includes a ring portion, a pair of Oldham keys provided on the upper face of the ring portion, and another pair of Oldham keys provided on the lower face of the ring portion. The Oldham keys on the upper face are fitted in respective key grooves provided in the orbiting scroll 40 and are slidable in one direction. The Oldham keys on the lower face are fitted in respective key grooves provided in the frame 6 and are slidable in a direction intersecting the one direction. Such a configuration allows the orbiting scroll 40 to undergo an orbital motion without spinning on its own axis.
The motor 4 includes a stator 4b and a rotor 4a. The stator 4b is fixed to the inner periphery of the shell 2. The rotor 4a is located on the inner side of the stator 4b. The rotor 4a is fixed to the main shaft 7 by shrink fitting or any other method. The stator 4b receives electric power through a power terminal 21, which is provided on the shell 2. When electric power is supplied to the stator 4b, the rotor 4a rotates together with the main shaft 7.
The main shaft 7 includes at the upper end thereof an eccentric shaft portion 7a. The eccentric shaft portion 7a is shifted from the center axis of the main shaft 7 in a predetermined direction of eccentricity. The eccentric shaft portion 7a is slidably fitted in the slider 9 to be described below.
The slider 9 serves as a variable crank mechanism that makes the radius of the orbital motion of the orbiting scroll 40 vary along the lateral face of the fixed scroll wrap 30b of the fixed scroll 30. The variable crank mechanism keeps the lateral face of the fixed scroll wrap 30b and the lateral face of the orbital scroll wrap 40b in contact with each other while the orbiting scroll 40 is undergoing the orbital motion.
An overall operation of the scroll compressor 1 will now be described briefly. When electric power is supplied to the stator 4b, the rotor 4a rotates. A rotational driving force generated by the rotor 4a is transmitted to the orbiting scroll 40 through the main shaft 7, the eccentric shaft portion 7a, and the slider 9. The orbiting scroll 40 having received the rotational driving force undergoes a swirling motion about the fixed scroll 30 while being prevented by the Oldham ring 15 from undergoing a spinning motion.
With the swirling motion of the orbiting scroll 40, low-pressure gas refrigerant is suctioned into the shell 2 through the suction pipe 11, is drawn into the compression chambers 5a through the suction port 6a provided in the frame 6, and is compressed in the compression chambers 5a. The compressed gas refrigerant now having a high pressure is discharged to the discharge chamber 13 through the discharge port 30f. The high-pressure gas refrigerant in the discharge chamber 13 pushes the discharge valve 13a upward, flows into the space in the muffler 14, and is discharged to the inside of the shell 2 through a discharge hole provided in the muffler 14. Then, the refrigerant is discharged to the outside of the scroll compressor 1 through the discharge pipe 12.
In
The fixed scroll 30 and the orbiting scroll 40 each include a scroll start portion, which is also regarded as a scroll center portion of the scroll wrap. The scroll start portion has a so-called bulbous shape defined by connecting the involute start points of respective involute curves forming the inner surface and the outer surface of the scroll start portion to each other with two arcs of a small circle and a large circle. The scroll start portion according to Embodiment 1 has a tiered shape in which a plurality of tiers each having the bulbous shape are stacked in the axial direction of the main shaft 7. Hereinafter, such a shape of the scroll start portion is also referred to as tiered bulbous shape.
As illustrated in
Among the small arc parts, the one that is nearest to the tip (the one in the first tier) is defined as small arc part 301, another one that is closer to the base than the first one (the one in the second tier) is defined as small arc part 301a, and the one that is nearest to the base (the one in the third tier) is defined as small arc part 301b. The small arc part 301a in the second tier is shifted from the small arc part 301 in the first tier in the direction toward the scroll-starting end. The small arc part 301b in the third tier is shifted from the small arc part 301a in the second tier in the direction toward the scroll-starting end. The radius of the large circle defining the scroll start portion 30e of the fixed scroll wrap 30b is the same for all of the first tier, the second tier, and the third tier. That is, large arc parts in the respective tiers of the scroll start portion 30e form a shared large arc part 302.
In such a configuration, the fixed scroll 30 comes into contact with the inner surface of the scroll wrap of the orbiting scroll 40 with different timings in the first tier, the second tier, and the third tier in that order.
As illustrated in
Among the small arc parts, the one that is nearest to the tip (the one in the first tier) is defined as small arc part 401, another one that is closer to the base than the first one (the one in the second tier) is defined as small arc part 401a, and the one that is nearest to the base (the one in the third tier) is defined as small arc part 401b. The small arc part 401a in the second tier is shifted from the small arc part 401 in the first tier in the direction toward the scroll-starting end. The small arc part 401b in the third tier is shifted from the small arc part 401a in the second tier in the direction toward the scroll-starting end.
The scroll start portion 40e of the orbital scroll wrap 40b of the orbiting scroll 40 is defined by large circles with respective radii. The first tier has a large arc part 402, which is defined by a large circle with the greatest radius. The second tier has a large arc part 402a, which is defined by a large circle with a radius smaller than the radius of the large circle defining the large arc part 402. The third tier has a large arc part 402b, which is defined by a large circle with a radius smaller than the radius of the large circle defining the large arc part 402a. In Embodiment 1, the involute-start-point angle of the inner-surface involute curve of the orbiting scroll 40 is the same for all of the first tier, the second tier, and the third tier. Accordingly, the radii of the large circles in the respective tiers of the orbiting scroll 40 vary with the radii of the small circles.
In such a configuration, the orbiting scroll 40 comes into contact with the inner surface of the scroll wrap of the fixed scroll 30 with different timings in the first tier, the second tier, and the third tier in that order. Note that when the tiers in the scroll start portion 30e of the fixed scroll wrap 30b and the tiers in the scroll start portion 40e of the orbital scroll wrap 40b do not need to be distinguished from each other, they are also simply referred to as the first tier, the second tier, and the third tier with no reference signs.
The first tier, the second tier, and the third tier of the fixed scroll 30 are defined by small circles having the same radius and large circles having the same radius, whereas the first tier, the second tier, and the third tier of the orbiting scroll 40 are defined by small circles having different radii and large circles having different radii. Specifically, the small circle defining the small arc part 401 in the first tier has the smallest radius, the small circle defining the small arc part 401a in the second tier has a greater radius than the small circle defining the small arc part 401, and the small circle defining the small arc part 401b in the third tier has a greater radius than the small circle defining the small arc part 401a. Conversely, the large circle defining the large arc part 402 in the first tier has the greatest radius, the large circle defining the large arc part 402a in the second tier has a smaller radius than the large circle defining the large arc part 402, and the large circle defining the large arc part 402b in the third tier has a smaller radius than the large circle defining the large arc part 402a. In Embodiment 1, the involute-start-point angle of the inner-surface involute curve of the orbiting scroll 40 is the same for all of the first tier, the second tier, and the third tier. Accordingly, the radii of the large circles in the respective tiers of the orbiting scroll 40 vary with the radii of the small circles.
The above configuration of the fixed scroll 30 regarding the involute-start-point angles of the outer-surface involute curves also applies to the scroll center portion of the orbiting scroll 40, which is not illustrated. Specifically, letting the involute-start-point angle of the outer-surface involute curve in the first tier be φos(1); the involute-start-point angle of the outer-surface involute curve in the second tier be φos(2); and the involute-start-point angle of the outer-surface involute curve in the third tier be φos(3), a relationship of φos(1)>φos(2)>φos(3) is established.
As illustrated in
The above situation where “the fixed scroll wrap 30b and the orbital scroll wrap 40b go out of contact with each other in the first tier, whereby the two compression chambers 5a, namely the second compression chamber 5a2 and the innermost compression chamber 5a1 that are not made to communicate with each other before the scroll wraps 30b and 40b go out of contact with each other, are made to communicate with each other through the passage 50 (see
As the crank angle increases from that in diagram (a) of
When the first tier is opened and the pressure starts to be equalized between the innermost compression chamber 5a1 and the second compression chamber 5a2, the second tier and the third tier are still kept in contact with the lateral face of the counterpart scroll wrap. As the crank angle further increases and by the time when the third tier is opened, the pressure equalization between the innermost compression chamber 5a1 and the second compression chamber 5a2 is complete. In such a state, the scroll start portion is out of contact with the counterpart scroll wrap over the entirety from the first tier to the third tier.
Now, a load that acts on the scroll start portion will be described. A known configuration employing a non-tiered scroll start portion and a variable crank mechanism will first be described as a comparative example. The scroll start portion in the known configuration has a shape obtained by omitting the first tier and the second tier from the scroll start portion according to Embodiment 1, so that the third tier extends continuously from the base to the tip. The following description relates to a case of a pressure acting on the scroll start portion of the orbital scroll wrap but also applies to a case of a pressure acting on the scroll start portion of the fixed scroll wrap.
In contrast, according to Embodiment 1, since the scroll start portion has a tiered bulbous shape, the stress generated at the base of the scroll wrap is reduced. Such a mechanism will now be described with reference to
Since the scroll compressor 1 according to Embodiment 1 includes a variable crank mechanism, the lateral face of the orbital scroll wrap 40b and the lateral face of the fixed scroll wrap 30b are in contact with each other when the scroll compressor 1 is in operation. However, when the contact point t reaches the involute-start-point angle φos(1) of the involute curve in the first tier, as described above, the fixed scroll wrap 30b and the orbital scroll wrap 40b go out of contact with each other in the first tier, whereby the pressure starts to be equalized through the passage 50. Immediately after the start of such pressure equalization, as illustrated in
When the orbital scroll wrap 40b is out of contact with the fixed scroll wrap 30b over the entirety from the first tier to the third tier, as illustrated in
In Embodiment 1, as the crank angle increases as represented by the solid line in
As can be seen from
Now, a structure that further reduces the stress generated at the base of the scroll start portion will be described. In Embodiment 1, the involute-start-point angles in the respective tiers that define the tiered bulbous shape of the scroll start portion are in a relationship of φos(1)>φos(2) . . . >φos(n), as described above. Furthermore, the tiered bulbous shape of the scroll start portion according to Embodiment 1 satisfies a relationship of 0.3π<φos(1)-φos(n)<0.7π. Satisfying this relationship further reduces the stress generated at the base of the scroll start portion. Before describing such a mechanism, how the tiered bulbous shape of the scroll start portion varies with the value of “φos(1)-φos(n)” will first be described.
Now, why satisfying the above relationship further reduces the stress generated at the base of the scroll start portion will be described. First, a case of the known configuration as the comparative example employing a non-tiered scroll start portion will be described.
The stress at the base of the scroll start portion increases in proportion to the working load divided by the section modulus. Therefore, making the section modulus in the direction of the load satisfactorily large is highly effective in terms of strength improvement for the scroll start portion. To make the section modulus in the direction of the load satisfactorily large, the thickness of the scroll start portion in the direction of the load is to be made satisfactorily large. However, in the known configuration illustrated in
In the case illustrated in
In the case illustrated in
If the case where φos(1)-φos(n) is 0.2π is plotted in
In the case illustrated in
That is, if the bulbous shape of the scroll start portion is designed to satisfy the relationship of 0.3π<φos(1)-φos(n)<0.7π where the degree of reduction in the ratio of stress reduction is high, a satisfactory degree of strength improvement is achieved.
The greater the difference in the involute-start-point angle between the first tier and the n-th tier (φos(1)-φos(n)) is made, the more assuredly the pressure equalization between the innermost compression chamber 5a1 and the second compression chamber 5a2 is complete before the n-th tier is opened. The limit for completing the pressure equalization between the innermost compression chamber 5a1 and the second compression chamber 5a2 before the n-th tier is opened is expressed by the relationship of φos(1)-φos(n)>0.3π. To put it the other way round, if φos(1)-φos(n) 0.3π, the n-th tier is opened before the completion of pressure equalization between the innermost compression chamber 5a1 and the second compression chamber 5a2. The n-th tier that is opened before the completion of pressure equalization between the innermost compression chamber 5a1 and the second compression chamber 5a2 is no longer supported by the counterpart scroll wrap. Therefore, the relationship of φos(1)-φos(n)>0.3π is to be satisfied. Thus, the n-th tier is kept supported by the counterpart scroll wrap until the pressure equalization between the innermost compression chamber 5a1 and the second compression chamber 5a2 is complete to make the pressure difference between the two 0.
The sizes of the small circles in the respective tiers of the scroll start portion are determined with no restrictions. However, as illustrated in
Note that reducing the size of the small circle in the first tier leads to a reduction in the strength of the first tier. Such a reduction in the strength may be solved by employing a configuration illustrated in
As illustrated in
The ratio of the total height, Hn−1, of the first to (n−1)-th tiers of the scroll start portion to the total height, Hn, of the first to n-th tiers may be set to 25% to 50%. If the ratio is below 25%, the area of the passage for pressure equalization between the innermost compression chamber 5a1 and the second compression chamber 5a2 is insufficient. In such a case, when the n-th tier is opened, there remains a pressure difference between the innermost compression chamber 5a1 and the second compression chamber 5a2, failing in achieving a satisfactory degree of strength improvement. If the ratio is above 50%, the stress generated at the base of each of the first to (n−1)-th tiers increases. In such a case, the first to (n−1)-th tiers may be damaged before the base of the n-th tier is damaged.
In the above description, each of the fixed scroll 30 and the orbiting scroll 40 includes the tiered scroll start portion. Alternatively, only one of the fixed scroll 30 and the orbiting scroll 40 may include the tiered scroll start portion.
According to Embodiment 1, the scroll compressor is configured to compress a working medium in the plurality of compression chambers 5a defined between the orbital scroll wrap 40b of the orbiting scroll 40 and the fixed scroll wrap 30b of the fixed scroll 30 that are made to mesh with each other. The working medium is compressed when the orbiting scroll 40 driven through the main shaft 7 undergoes an orbital motion about the fixed scroll 30. The orbital scroll wrap 40b and the fixed scroll wrap 30b include respective scroll start portions each having a bulbous shape defined by connecting the involute start point of the outer-surface involute curve and the involute start point of the inner-surface involute curve to each other with a plurality of arcs. At least one of the scroll start portions has a tiered shape in which an n number (where n≥2) of tiers each having the bulbous shape are stacked in the axial direction of the main shaft 7. Letting the involute-start-point angles of the outer-surface involute curves in the respective tiers of the scroll start portion having the tiered shape be φos(1), φos(2), φos(3), . . . , and φos(n) in order from the tip toward the base of the scroll start portion, the following relationships are satisfied: φos(1)>φos(2)>φos(3)> . . . >φos(n); and 0.3π<φos(1)-φos(n)<0.7π.
Since the scroll start portion has the above tiered shape, among the plurality of compression chambers 5a, the innermost compression chamber 5a1 and the second compression chamber 5a2 on the radially outer side of the innermost compression chamber 5a1 are made to communicate with each other in a graded manner. Thus, the stress generated at the base of the scroll start portion is reduced. Furthermore, satisfying the relationship of 0.3π<φos(1)-φos(n)<0.7π brings a satisfactory degree of strength improvement for the scroll start portion that meets the cost increase required for the fabrication of the tiered structure. Furthermore, the n-th tier is kept supported by the counterpart scroll wrap until the pressure equalization between the innermost compression chamber 5a1 and the second compression chamber 5a2 is complete to make the pressure difference between the two 0.
Embodiment 2 will now be described, except some of the features that are the same as those described in Embodiment 1.
When the scroll compressor 1 starts to operate, the orbiting scroll 40 and the fixed scroll 30 each come to have a high temperature, specifically 100 degrees C. or higher. Accordingly, the orbital scroll wrap 40b and the fixed scroll wrap 30b undergo thermal expansion. If the orbiting scroll 40 and the fixed scroll 30 are made of respective materials having different coefficients of linear expansion: for example, one of the two is aluminum while the other is cast iron, a high pressure may be applied to the base of each of the scroll start portions as to be described in detail below.
Embodiment 2 relates to a technique of reducing the stress generated at the base of each of the scroll start portions because of the difference in the coefficient of linear expansion between the material forming the orbiting scroll 40 and the material forming the fixed scroll 30. In Embodiment 2, the coefficient of linear expansion of the orbiting scroll 40 is greater than the coefficient of linear expansion of the fixed scroll 30.
The fixed scroll wrap 30b has an inner-surface involute 30c (hereinafter referred to as fixed-inner-surface involute 30c). The fixed-inner-surface involute 30c has the reliefs, 30c1. As illustrated in
The regions where the reliefs 30c1 are to be provided are defined by the following seven parameters:
the involute angle at the start point, 30c1a, of each relief 30c1: φia3;
the involute angle at the end point, 30c1b, of each relief 30c1: φib3;
the involute angle at the involute end point, 30c2, of the fixed-inner-surface involute 30c: φie3;
the involute-start-point angle of the inner-surface involute in the n-th tier of the fixed scroll wrap 30b: φis3(n);
the involute-start-point angle of the outer-surface involute in the first tier of the orbital scroll wrap 40b: φos4(1);
the involute-start-point angle of the outer-surface involute in the n-th tier of the orbital scroll wrap 40b: φos4(n); and
the number of contact points between the orbital-outer-surface involute 40d and the fixed-inner-surface involute 30c (the contact points are hereinafter referred to as orbital-outer-surface contact points): m=[(φie3−φis3(n))/2π], where [ ] indicates that the decimals are to be rounded down.
Letting the serial numbers of the orbital-outer-surface contact points be i (1, 2, 3, . . . , and m from the inner side), where m≥2, the reliefs 30c1 are provided in regions where the following relationships are satisfied:
“i≥2”, “φia3<(φos1(n)+π)+2π×(i−1)”, and “φib3>(φos1(1)+π)+2π×(i−1)”.
Specifically, the reliefs 30c1 are provided such that when the crank angle is between the involute-start-point angle φos(1) of the orbital-outer-surface involute 40d in the first tier and the involute-start-point angle φos(n) of the orbital-outer-surface involute 40d in the n-th tier, the orbital-outer-surface involute 40d and the fixed-inner-surface involute 30c are out of contact with each other at the orbital-outer-surface contact points expressed as i=2 or greater. In other words, the reliefs 30c1 are provided in the fixed-inner-surface involute 30c such that while the orbiting scroll 40 is undergoing the orbital motion from the crank angle at which the first tier is opened to the crank angle at which the n-th tier is opened, the orbital-outer-surface contact points, excluding the innermost one, on the orbital scroll wrap 40b that is made of the material having the greater coefficient of linear expansion are out of contact.
An effect produced by the above configuration will now be described. First, a configuration with no relief 30c1 will be described as a comparative example. The following description relates to the case of m=3.
In
As illustrated in
When the orbiting scroll 40 is made eccentric in the direction of the arrow illustrated in
However, when the scroll compressor 1 starts to operate, as described above, the orbiting scroll 40 and the fixed scroll 30 each come to have a high temperature, specifically 100 degrees C. or higher. Accordingly, the orbital scroll wrap 40b and the fixed scroll wrap 30b undergo thermal expansion. The orbital scroll wrap 40b, which is made of a material having a greater coefficient of linear expansion than the fixed scroll wrap 30b, expands to a greater extent than the fixed scroll wrap 30b as illustrated in
The changes δa in the gap sizes during operation from the gap sizes at room temperature increase in the direction from the scroll start portion toward the radially outer side as illustrated in
In the other direction from the scroll start portion that is opposite to the direction of eccentricity of the orbiting scroll 40, the sizes of the gaps δi1, δi2, and δi3 are greater during operation, illustrated in
The relationship of the sizes of the gaps during operation is expressed as δo3<δo2<δo1<δi1<δi2<δi3. What have been described above are the gaps at room temperature and the gaps during operation with the orbiting scroll 40 being made to uneccentrically mesh with the fixed scroll 30. In the actual operation, however, the orbiting scroll 40 is made eccentric in the direction of the arrow illustrated in
When the orbiting scroll 40 in the state illustrated in
The gap δo1 and the gap δi1 are the gaps at the scroll start portion. If the scroll compressor is operated with the gap sizes δs of the gap δo1 and the gap δi1 being not 0, the following problem arises. Before the pressure is equalized between the innermost compression chamber 5a1 and the second compression chamber 5a2, the fixed scroll wrap 30b and the orbital scroll wrap 40b lose their respective supports at the respective scroll start portions. Therefore, great stresses are generated at the bases of the respective scroll start portions. Hence, the gap sizes δs of the gap δo1 and the gap δi1 at the scroll start portion are required to be 0 or small. To make the gap sizes δs of the gap δo1 and the gap δi1 small, it is effective to make the gap size δ0 at room temperature as large as possible for each of the gap δo3 and the gap δo2, that is, for all but the gap δo1 at the scroll start portion among the gaps δo3, δo2, and δo1 on the side toward which the orbiting scroll 40 is made eccentric.
Accordingly, in Embodiment 2, the inner-surface involute 30c is designed in view of the expansion of the orbital scroll wrap 40b that occurs during operation. Thus, the gap δo3 and the gap δo2 produced at room temperature and when the orbiting scroll 40 is made to eccentrically mesh with the fixed scroll 30 are originally made satisfactorily large, as illustrated in
In Embodiment 2, the fixed-inner-surface involute 30c has the reliefs 30c1. Therefore, as illustrated in
The above state where the gap size δs of the gap δo1 is 0 is maintained at least from when the first tier of the scroll start portion is opened until the n-th tier is opened. That is, before the pressure equalization between the innermost compression chamber 5a1 and the second compression chamber 5a2 is complete, the scroll start portion 40e of the orbital scroll wrap 40b is supported by the lateral face of the fixed scroll wrap 30b. Therefore, the generation of a great stress at the base of the scroll start portion is suppressed. Thus, strength improvement is achieved. Meanwhile, the gap size δs of the gap δi1 produced at the innermost contact point (i2=1) on the orbital-inner-surface involute 40c, in other words, the gap size δs of the gap δi1 at the scroll start portion 30e of the fixed scroll wrap 30b, is not reduced to 0 as illustrated in
In Embodiment 2, the relief 30c1 is provided at each of all the contact points on the orbital-outer-surface involute but the innermost one. Alternatively, the relief 30c1 may be provided only at the outermost contact point (i=3). Specifically, the relief 30c1 only needs to be provided in the fixed-inner-surface involute 30c such that while the orbiting scroll 40 is undergoing the orbital motion from the crank angle at which the first tier is opened to the crank angle at which the n-th tier is opened, at least the outermost one of the orbital-outer-surface contact points on the orbital scroll wrap 40b that is made of the material having the greater coefficient of linear expansion is out of contact with the fixed-inner-surface involute 30c at the orbital-outer-surface contact points.
If only the outermost contact point (i=3) has the relief 30c1, the gap size δs at the innermost contact point (i=1) on the orbital-outer-surface involute cannot be made exactly 0 but can be made smaller than in the case where no relief 30c1 is provided. Therefore, some effect of strength improvement is produced. Providing the relief 30c1 only at the outermost contact point is regarded as limitedly providing the relief 30c1 in a region where the pressure difference is relatively small and refrigerant leakage is less likely to occur. Therefore, the occurrence of refrigerant leakage is suppressed, and high performance is achieved. The number of regions where the reliefs 30c1 are to be provided may be determined flexibly in consideration of the strength and performance required for the final product.
The effect of strength improvement that is produced in Embodiment 2 by providing the relief 30c1 is enhanced in the configuration according to Embodiment 1 in which the tiered bulbous shape of the scroll start portion satisfies the relationship of 0.3π<φos(1)-φos(n)<0.7π. Note that Embodiment 2 does not necessarily need to be applied to the configuration according to Embodiment 1.
According to Embodiment 2, the scroll compressor is configured to compress a working medium in the plurality of compression chambers 5a defined between the orbital scroll wrap 40b of the orbiting scroll 40 and the fixed scroll wrap 30b of the fixed scroll 30 that are made to mesh with each other. The working medium is compressed when the orbiting scroll 40 driven through the main shaft 7 undergoes an orbital motion about the fixed scroll 30. The scroll compressor includes the variable crank mechanism that varies the radius of the orbital motion of the orbiting scroll 40. The orbital scroll wrap 40b and the fixed scroll wrap 30b include respective scroll start portions each having a bulbous shape defined by connecting the involute start point of the outer-surface involute curve and the involute start point of the inner-surface involute curve to each other with a plurality of arcs. At least one of the scroll start portions has a tiered shape in which an n number (where n≥2) of tiers each having the bulbous shape are stacked in the axial direction of the main shaft 7. The orbiting scroll 40 and the fixed scroll 30 are made of respective materials having different coefficients of linear expansion. The tiers of the scroll start portion are defined as the first tier, the second tier, . . . , and the n-th tier in order from the tip toward the base of the scroll start portion. The situation where the orbital scroll wrap 40b and the fixed scroll wrap 30b go out of contact with each other in the n-th tier of the scroll start portion and, among the compression chambers, two compression chambers that are not made to communicate with each other before the scroll wraps 40b and 30b go out of contact with each other are made to communicate with each other is expressed as the n-th tier is opened. The relief 30c1 is provided in the fixed scroll wrap 30b such that while the orbiting scroll 40 is undergoing the orbital motion from the crank angle at which the first tier is opened to the crank angle at which the n-th tier is opened, the outer-surface involute of the scroll wrap of the scroll that is made of the material having the greater coefficient of linear expansion and the inner-surface involute of the scroll wrap of the scroll that is made of the material having the smaller coefficient of linear expansion are out of contact with each other at least at the outermost one of the plurality of contact points where the two involutes are to come into contact with each other.
In such a configuration, the scroll start portion of the scroll wrap made of the material having the greater coefficient of linear expansion is kept supported by the lateral face of the scroll wrap of the scroll made of the material having the smaller coefficient of linear expansion until the pressure is completely equalized between two of the compression chambers, namely the innermost compression chamber 5a1 and the second compression chamber 5a2 that are not made to communicate with each other before the scroll wraps go out of contact with each other. Such a configuration suppresses the generation of a great stress at the base of the scroll start portion of the scroll wrap made of the material having the greater coefficient of linear expansion. Thus, an effect of strength improvement for the scroll start portion is produced. Furthermore, the scroll start portion of the scroll wrap made of the material having the smaller coefficient of linear expansion is designed such that, during operation, the gaps from the other scroll wrap made of the material having the greater coefficient of linear expansion become smaller than in the case where no relief 30c1 is provided. Such a configuration suppresses the generation of a great stress at the base of the scroll start portion. Thus, an effect of strength improvement for the scroll start portion is produced.
Embodiment 3 will now be described, except some of the features that are the same as those described in Embodiment 1 or 2.
In Embodiment 2 described above, the fixed-inner-surface involute 30c has the reliefs 30c1. In Embodiment 3, the orbital-outer-surface involute 40d has reliefs 40d1.
The regions where the reliefs 40d1 are to be provided are defined by the following seven parameters:
the involute angle at the start point, 40d1a, of each relief 40d1: φoa4;
the involute angle at the end point, 40d1b, of each relief 40d1: φob4;
the involute angle at the involute end point, 30c2, of the fixed-inner-surface involute 30c: φie3;
the involute-start-point angle of the inner-surface involute in the n-th tier of the fixed scroll wrap 30b: φis3(n);
the involute-start-point angle of the outer-surface involute in the first tier of the orbital scroll wrap 40b: φos4(1);
the involute-start-point angle of the outer-surface involute in the n-th tier of the orbital scroll wrap 40b: φos4(n); and
the number of contact points between the orbital-outer-surface involute 40d and the fixed-inner-surface involute 30c: m=[(φie3−φis3(n))/2π], where [ ] indicates that the decimals are to be rounded down.
Letting the serial numbers of the contact points on the outer surface of the orbiting scroll be i (1, 2, 3, . . . , and m from the inner side), where m≥2, the reliefs 40d1 are provided in regions where the following relationships are satisfied:
“i≥2”,“φoa4<(φos1(n))+2π×(i−1)”, and “φob4>(φos1(1))+2π×(i−1)”.
Specifically, the reliefs 40d1 are provided such that when the crank angle is between the involute-start-point angle φos(1) of the orbital-outer-surface involute 40d in the first tier and the involute-start-point angle φos(n) of the orbital-outer-surface involute 40d in the n-th tier, the orbital-outer-surface involute 40d and the fixed-inner-surface involute 30c are out of contact with each other at the orbital-outer-surface contact points expressed as i=2 or greater. In other words, the reliefs 40d1 are provided in the orbital-outer-surface involute 40d such that while the orbiting scroll 40 is undergoing the orbital motion from the crank angle at which the first tier is opened to the crank angle at which the n-th tier is opened, the orbital-outer-surface contact points, excluding the innermost one, on the orbital scroll wrap 40b that is made of the material having the greater coefficient of linear expansion are out of contact with the fixed-inner-surface involute 30c at the orbital-outer-surface contact points.
In Embodiment 3, the relief 40d1 is provided at each of all the contact points on the orbital-outer-surface involute but the innermost one. Alternatively, the relief 40d1 may be provided only at the outermost contact point (i=3). Specifically, the relief 40d1 only needs to be provided in the orbital-outer-surface involute 40d such that while the orbiting scroll 40 is undergoing the orbital motion from the crank angle at which the first tier is opened to the crank angle at which the n-th tier is opened, at least the outermost one of the orbital-outer-surface contact points on the orbital scroll wrap 40b that is made of the material having the greater coefficient of linear expansion is out of contact with the fixed-inner-surface involute 30c at the orbital-outer-surface contact points.
The orbiting scroll 40 and the fixed scroll 30 according to Embodiment 3 are made of respective materials having different coefficients of linear expansion. The tiers of the scroll start portion are defined as the first tier, the second tier, . . . , and the n-th tier in order from the tip toward the base of the scroll start portion. The situation where the orbital scroll wrap 40b and the fixed scroll wrap 30b go out of contact with each other in the n-th tier of the scroll start portion and the two compression chambers that are not made to communicate with each other before the scroll wraps 40b and 30b go out of contact with each other are made to communicate with each other is expressed as the n-th tier is opened. The relief 40d1 is provided in the orbital scroll wrap 40b such that while the orbiting scroll 40 is undergoing the orbital motion from the crank angle at which the first tier is opened to the crank angle at which the n-th tier is opened, the outer-surface involute of the scroll wrap of one of the scrolls that is made of the material having the greater coefficient of linear expansion and the inner-surface involute of the counterpart scroll wrap are out of contact with each other at least at the outermost one of the plurality of contact points where the two involutes are to come into contact with each other.
The effects produced by Embodiment 3 are the same as those produced by Embodiment 2.
This application is a U.S. national stage application of International Patent Application No. PCT/JP2020/018962 filed on May 12, 2020, the disclosure of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/018962 | 5/12/2020 | WO |
