JP2003269103A - Scroll expansion machine and its driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an extreme reduction of energy generated from an introduced fluid by producing a volume ratio and an introduction volume corresponding to introduced pressure. <P>SOLUTION: This scroll expansion machine comprises a bypath port 14 for communicating a high pressure part 7 at its predetermined position with an operation chamber located between a minimum position side and a maximum position side and a valve mechanism 15 provided in the bypath port 14, which is open when the introduced pressure Ps as pressure in the high pressure part 7 is a set one or less. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scroll expander as a prime mover that is operated by a high-pressure compressible fluid to generate orbiting power.

[0002]

2. Description of the Related Art A scroll expander is a kind of positive displacement fluid machine, and its basic structure is, for example, Japanese Patent Laid-Open No. 8-2846.
It is known from Japanese Patent No.

As shown in FIG. 8, this device engages the wraps c and d of the fixed scroll a and the orbiting scroll b with each other and turns from one to the other by rotating the orbiting scroll b along the circular orbit. The working chamber e is formed to increase its volume while moving. By introducing the fluid of the high-pressure part f at the minimum position side of the working chamber e, the orbiting scroll b receives the orbiting force toward the side where the working chamber e becomes larger, and is swung around the axis L1 with the expansion of the fluid. The fluid is discharged to the low pressure portion g repeatedly on the maximum position side of the working chamber e to obtain the turning power. This turning power is eccentric bearing h
Is output as the rotation output of the shaft i.

[0004]

However, in the basic structure of the scroll expander as described above, the volume ratio and the introduction volume are defined by the geometric shapes of the wrap d of the orbiting scroll b and the wrap c of the fixed scroll a, Due to these factors, the energy obtained from the introduced fluid may be extremely reduced or the efficiency may be reduced.

Here, the effect of the constant volume ratio will be described. In FIG. 9 showing the behavior of the working chamber e for each rotation angle 90 deg about the center L2 of the fixed scroll a of the axis i, the volume of the working chamber e1 at the moment of being sealed is V
a, the volume of the working chamber e5 immediately before communicating with the low pressure part g is Ve
Then, Va and Ve depend on the number of turns and the height of the wrap d of the orbiting scroll b and the wrap c of the fixed scroll a,
It can be seen that the volume ratio (Va / Ve) is constant. Let Pa be the pressure of the working chamber e1 at the moment of being sealed, Pe be the pressure of the working chamber e5 immediately before communicating with the low pressure part g, and let the adiabatic index of the fluid be κ. The relationship is established.

[0006]

[Equation 1] On the other hand, the pressure Pa of the working chamber e1 at the moment of being sealed is equal to the pressure of the high pressure portion f, that is, the introduction pressure Ps of the expander.

Therefore, the pressure Pe of the working chamber e5 at the moment when it communicates with the low pressure portion g is equal to the introduction pressure Ps and the volume ratio (Va /
Ve). Therefore, the introduction pressure Ps and the low pressure part
When the scroll expander is operated under the condition that the expansion ratio, which is the ratio (Ps / Pd) of the discharge pressure Pd to g, is smaller than Pe <Pd, the fluid in the working chamber e has a pressure Pe lower than the discharge pressure Pd. After being expanded to a low pressure part g having a discharge pressure Pd higher than that. That is, overexpansion occurs.

Next, the loss due to overexpansion will be described. Figure 1
0 shows a PV diagram of the working chamber e in the case of overexpansion. Working chamber e
Even if the pressure of Pd becomes lower than the discharge pressure Pd, the fluid expands from Pd to Pe as shown in FIG.
The power for the area indicated by the shaded portion 13a is obtained. On the other hand, in order for the fluid to be discharged from the working chamber e whose pressure has dropped to Pe to the low-pressure portion g having a discharge pressure Pd higher than that, only the amount of the insufficient pressure is commensurate with FIG. 10B. Therefore, the power for the area indicated by the shaded portion 13b is required. Therefore, FIG. 1 corresponding to the difference (area 13b-area 13a)
The area indicated by the shaded portion 13c of 0 (c) is the overexpansion loss.

Next, the influence of the constant introduction volume will be described. Generally, the specific volume of the fluid becomes small under the condition of high introduction pressure Ps, and the specific volume of the fluid becomes large under the condition of low introduction pressure Ps. However, in the basic configuration of the conventional scroll expander described above, the introduction volume depends on the basic circle radius and height of the wrap d of the orbiting scroll b and the wrap c of the fixed scroll a and does not change, so that the orbit of the orbiting scroll b does not change. When the numbers are the same, the mass of the fluid introduced into the working chamber e having the same volume is large under the condition that the introduction pressure Ps is high, and the mass of the fluid introduced is small under the condition that the introduction pressure Ps is low. . For this reason, the working chamber
The energy obtainable from the fluid at e is large under the high introduced pressure Ps, but is small under the low introduced pressure Ps.

When the discharge pressure Pd is constant, the pressure difference between the discharge pressure Ps and the introduction pressure Ps under a low condition is small, and therefore the expansion ratio (Ps / Pd) is small, but the volume ratio is constant. Orbiting scroll b at (Va / Ve)
Since it is accompanied by expansion depending on the turning angle, the overexpansion is more likely to occur than in the case where the introduction pressure Ps is high, and therefore the above-described overexpansion loss is likely to occur and the efficiency is also reduced. As a result, there is a problem in that the energy obtained from the fluid in the working chamber e is extremely reduced due to the decrease in the mass of the fluid and the occurrence of overexpansion loss.

The object of the present invention is to solve the above-mentioned problems of the prior art by providing a volume ratio and an introduction volume corresponding to the introduction pressure, and preventing the energy obtained from the introduced fluid from being extremely reduced. An object of the present invention is to provide an efficient scroll expander and its driving method.

[0012]

In order to solve the above-mentioned problems, a method of driving a scroll expander according to the present invention is designed to move a volume while moving by orbiting a orbiting scroll formed between laps of a fixed scroll and an orbiting scroll. By introducing the fluid from the high pressure part at the minimum position side of the working chamber where the pressure changes, the orbiting scroll is given a swivel force to the side where the working chamber becomes larger and swirls with the expansion of the fluid, and the maximum position side of the working chamber A method for driving a scroll expander, which repeats discharging the fluid to a low-pressure part with a maximum of the working chamber,
The main feature is to introduce a fluid into the working chamber when the pressure of the high-pressure portion is equal to or lower than a set pressure at a predetermined position between the minimum positions.

In such a structure, fluid is introduced from the high-pressure portion into the working chamber between the fixed scroll and the orbiting scroll, and the orbiting scroll is caused to orbit by exerting the orbiting force to the side in which the operating chamber becomes larger. , Even if the pressure in the high-pressure part may drop for some reason, if the pressure in the high-pressure part falls below the set pressure, the working chamber is closed by introducing the fluid from the high-pressure part into the working chamber at a predetermined position. It compensates for the decrease in the introduction pressure, mass, and introduction volume of the fluid that is being introduced at the moment as the pressure in the high-pressure section falls below the set pressure.In addition, due to the low introduction pressure, the expansion ratio Therefore, it is possible to prevent the energy obtained from the fluid in the working chamber from being extremely reduced and the efficiency from being reduced due to the decrease in the mass of the fluid and the occurrence of the overexpansion loss.

Since the fluid in the working chamber expands by the amount of swirl from the minimum position to the maximum position and is at a pressure lower than the introduction pressure, no matter how much the high pressure portion is lowered, the fluid is not supplied thereto. A differential pressure for the introduction is obtained, only by passing the high-pressure section through the working chamber, and thus the above method is realized without a special high-pressure fluid source.

The introduction of the fluid by the differential pressure is performed at a plurality of predetermined positions. In a further configuration, when the predetermined position is different, the corresponding moving position of the working chamber is different, and the fluid for the introduction pressure there is different. It is possible to more finely introduce the fluid by the differential pressure by utilizing the different time points of the pressure decrease due to the expansion of the pressure.

The introduction of the fluid by the differential pressure at different predetermined positions is performed under different set pressures. In a further configuration, it is suitable to use the different pressure reduction points.

With a further configuration in which the set pressure is increased as the predetermined position is closer to the minimum position of the working chamber, there is the convenience that the differential pressure required for introducing the fluid can be easily obtained at any position.

In the scroll expander of the present invention, the wraps of the fixed scroll and the orbiting scroll are meshed with each other to form a working chamber in which the volume is changed between the wraps of the fixed scroll and the orbiting scroll by moving along the circular orbit of the orbiting scroll. The fluid of the high pressure part is introduced into the side working chamber, the orbiting scroll is orbited to the side where the working chamber becomes larger with the expansion of the fluid, and the fluid is discharged from the working chamber at the maximum position side to the low pressure part. In the scroll expander described above, a bypass port that allows a high-pressure portion to pass from a predetermined position to a working chamber between the minimum and maximum positions, and a valve mechanism that opens when the pressure in the high-pressure portion falls below a set pressure are provided in the bypass port. This is the main feature.

In such a structure, the above-mentioned method using the differential pressure can be automatically and stably achieved by utilizing the existing fluid in the high-pressure portion, which is also essential, in a timely manner by the bypass port and the valve mechanism. The structure of the scroll expander is particularly complicated because it is only necessary to newly provide a bypass port that allows the high-pressure portion to pass through the working chamber and a valve mechanism that opens the bypass port when the high-pressure portion falls below a predetermined pressure.
It can be provided inexpensively without increasing the size or weight.

In a further configuration in which a plurality of working chambers are formed symmetrically and a plurality of bypass ports are provided so as to communicate with the symmetrical working chambers at the same time, in a further configuration,
It is possible to ensure the symmetrical pressure balance between the working chambers and the orbiting balance of the orbiting scroll even during driving accompanied by the introduction of the fluid through the bypass port due to the pressure drop in the high pressure portion.

In a further configuration in which four or more bypass ports are provided, it is suitable to realize introduction of fluid at the different predetermined positions in the closed working chamber, and the number of predetermined positions can be set. Can obtain both the pressure balance and the turning balance.

The volume of the working chamber is increased while moving from the central portion to the peripheral portion, and the closer to the central portion of the bypass port, the larger the set pressure is set. The larger the pressure, the smaller the degree of expansion of the fluid, and therefore the smaller the pressure drop, so that the fluid is introduced into the working chamber at the predetermined position, so that the necessary differential pressure is always obtained for a plurality of different pressure drops in the high pressure section. , It becomes easy to introduce the fluid suitable for the pressure drop into the working chamber.

In a further configuration in which the bypass port is provided in the end plate of the fixed scroll, the fluid from the high pressure portion at the back of the end plate to the working chamber is provided by a short and straight bypass port having a length corresponding to the thickness of the end plate. Since it can be introduced, it is easy to process and can be realized at a lower cost.

A further structure in which the valve mechanism is composed of a ball and a coil spring has the advantages that the structure is simple and the response is good, and the pressure can be set easily and accurately by the spring constant of the coil spring.

Further objects and features of the present invention will become apparent from the following detailed description and drawings. The respective features of the present invention can be employed alone or in combination in various combinations as much as possible.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to FIGS. However, the following description is a specific example of the present invention and does not limit the scope of the claims.

The scroll expander of this embodiment is shown in FIG.
As in the conventional case, the fixed scroll 5 and the wraps 5a, 3a of the orbiting scroll 3 are meshed with each other, and the circular orbits of the orbiting scroll 3 are mutually interposed, as in the case shown in FIGS. 3 and 5 and 6. A working chamber 6 is formed which changes its volume while moving by swirling along. Further, the fluid of the high-pressure portion 7 is introduced into the working chamber 6 at the minimum position side so that the orbiting scroll 3 is swung to the side where the working chamber 6 becomes larger with the expansion of the fluid, and the operation at the maximum position side is performed. The fluid is discharged from the chamber 6 to the low pressure section 10. As a result, the fluid is introduced from the high-pressure portion 7 into the working chamber 6 between the fixed and orbiting scrolls 5 and 3, and the orbiting scroll 3 is caused to orbit by exerting a turning force to the side in which the working chamber 6 becomes larger. Get power. In the present embodiment, the working chamber 6 has a large volume while moving from the central portion to the peripheral portion. But,
It is not limited to this.

As an example, the orbiting power of the orbiting scroll 3 is output as a rotation around the axis L1 of the shaft 2 connected to the orbiting scroll 3 via an eccentric bearing 2a as shown in FIG. Although it is driven, it can be driven quietly and smoothly. Orbiting scroll 3 of this shaft 2
The support member 1 bearing the end on the side of connection with the bearing 1a, and the fixed scroll 5 facing the support member 1 on the wrap 5a side.
Are fastened with bolts 21, the orbiting scroll 3 is sandwiched between the support member 1 and the fixed scroll 5, and the wrap 3a of the orbiting scroll 3 is fixed to the fixed scroll 5.
Wrap 5a and hold it,
Plural pairs of the working chambers 6 are formed between 3a as shown in FIGS. However, in principle, the number of working chambers 6 does not matter.

Between the back of the end plate 3b of the orbiting scroll 3 and the support member 1 for backing up the same, a rotation restraint member such as an Oldham ring 4 for restraining the rotation of the orbiting scroll 3 and allowing only the rotation along a circular orbit. It is sandwiched. A cover 8 is provided on the back of the end plate 5b of the fixed scroll 5, and the bolt 21 is shared to fasten the end of the end of the fixed scroll 5 to the end of the end of the end plate 5b. This high voltage part 7
An introduction pipe 9 for introducing a high-pressure fluid is connected to the cover 8. The end plate 5b of the fixed scroll 5 is formed with an inlet port 5c for introducing a high-pressure fluid from the high-pressure portion 7 into the working chamber 6 on the minimum position side. Further, the fixed scroll 5 is formed with a low pressure portion 10 which communicates with the working chamber 6 on the maximum position side and discharges the fluid in the final expanded state.
A discharge pipe 11 that guides the discharged fluid to another is connected to the low pressure section 10. However, the high pressure portion 7 and the low pressure portion 10 may be formed in any manner. Furthermore, axis 2
The mechanical seal 12 is provided at a portion where the support member 1 penetrates.
Sealing means such as is provided to prevent fluid from leaking from this portion.

In the scroll expander of this embodiment, the working chamber 6 whose volume changes while moving by the orbiting scroll 3 formed between the fixed scroll 5 and the wraps 5a, 3a of the orbiting scroll 3. By introducing the fluid from the high-pressure portion 7 at the minimum position side, the orbiting scroll 3 is given a swivel force to the side where the working chamber 6 becomes larger and swirled with the expansion of the fluid, and the fluid at the maximum position side of the working chamber 6 When the pressure of the high pressure part 7 is below a set pressure at a predetermined position between the maximum and minimum position sides of the working chamber 6, the operation is performed by repeatedly discharging the low pressure part 10 to the low pressure part 10. A drive method for introducing and replenishing the fluid in the chamber 6 is adopted. In principle, the introduction of the fluid for replenishment may be performed in any manner.

Thus, the fixed and orbiting scrolls 5, 3
The fluid of the high-pressure portion is introduced into the working chamber 6 in between to cause the orbiting scroll 3 to orbit by exerting a turning force to the side where the working chamber 6 becomes large, and while the turning power is obtained, the pressure of the high-pressure portion 7 is for some reason. Even if the pressure drops, if the pressure in the high-pressure portion 7 becomes equal to or lower than the set pressure, the fluid is introduced into the working chamber 6 at a predetermined position, so that the fluid introduced at the moment when the working chamber 6 is closed is introduced. It is possible to compensate for the decrease in the pressure, the mass, and the introduction volume as the pressure of the high-pressure section 7 falls below the set pressure, and to prevent the expansion ratio from decreasing due to the low introduction pressure. it can. As a result, it is possible to prevent the energy obtained by the orbiting scroll 3 from the fluid in the working chamber 6 from being extremely reduced and the efficiency from being reduced due to the decrease in the mass of the fluid and the occurrence of the excessive expansion loss.

The fluid expands by the amount of movement from the minimum position to the maximum side of the working chamber 6 and is at a pressure lower than the introduction pressure, and no matter how the pressure in the high pressure section 7 decreases, A differential pressure for introducing the fluid is obtained at. Therefore, simply by making the working chamber 6 communicate with the high pressure portion 7, that is,
The above method can be implemented without a special high pressure fluid source. However, it goes without saying that a special high pressure fluid source may be used.

If the introduction of the fluid by the differential pressure is carried out at a plurality of predetermined positions, if the predetermined position is different, the moving position of the working chamber 6 corresponding thereto is different, and a plurality of different different positions due to the expansion of the fluid with respect to the introduction pressure are provided. It is possible to more finely introduce the fluid by the differential pressure by utilizing the time point of the pressure decrease. Further, when the introduction of the fluid by the differential pressure at the different predetermined positions is performed based on the different set pressures, it is suitable to utilize the plurality of different pressure reduction points. Further, if the set pressure is increased as the predetermined position is closer to the minimum position of the working chamber 6, there is the convenience that the differential pressure necessary for introducing the fluid can be easily obtained at any position.

The scroll expander of the present embodiment realizes the driving method as described above, as shown in the examples shown in FIGS. 1 to 3 and the examples shown in FIGS. Bypass ports 14 and 19 for communicating the high-pressure portion 7 to the working chamber 6 between the position side at a predetermined position, and the bypass port 1
4 and 19 are provided with valve mechanisms 15 and 20 that open when the pressure in the high pressure section 7 becomes equal to or lower than a set pressure. This allows
The existing fluid, which is essential in the scroll expander, in the high-pressure section 7 is automatically and stably utilized by the bypass ports 14 and 19 and the valve mechanisms 15 and 20 in a closed working chamber 6 in a timely manner. It is possible to achieve the above-described driving method for introducing the fluid by the differential pressure, and to bypass the high-pressure portion in the working chamber 6 and the bypass ports 14 and 19 and the high-pressure portion 7.
Valve mechanism 15 or 2 that opens when the pressure drops below a predetermined pressure
Since it is only necessary to newly provide 0, the structure of the scroll expander does not become particularly complicated, large, or heavy, and can be provided at low cost.

Since the bypass ports 14 and 19 are provided on the end plate 5b of the fixed scroll 5, a short straight bypass port 14 having a length corresponding to the plate thickness of the end plate 5b from the high pressure portion 7 at the back of the end plate 5b. Since the fluid can be introduced into the working chamber 6 by means of or 19, the processing is easy and the cost is further reduced. The valve mechanism 15 or 20 is used for the ball 1
Since it is composed of the coil springs 5a and 20a and the coil springs 15b and 20b, the structure is simple and the response is good, and the pressure can be easily and accurately set by the spring constants of the coil springs 15b and 20b.

Further, since the plurality of working chambers 6 are formed symmetrically and the plurality of bypass ports 14 and 19 are provided so as to communicate with the symmetrical working chambers 6 at the same time, the pressure drop of the high pressure portion 7 is caused in addition to the normal driving. Based on bypass port 14
It is possible to secure the symmetrical pressure balance between the working chambers 6 and the orbiting balance of the orbiting scroll 3 even during driving involving the introduction of the fluid through the or.

In the example shown in FIGS. 5 to 7, in particular, two bypass ports 14 and 19 are provided in total, four in total.
It is suitable to realize the introduction of the fluid at the different predetermined positions of the closed working chamber 6 by including more than one, and depending on the setting of the number of the predetermined positions, the pressure balance and the swirling balance may be combined. can get.

In the present embodiment in which the volume of the working chamber 6 increases while moving from the central portion to the peripheral portion, the closer to the central portion of the bypass ports 14 and 19, that is, to the axis L2 of the fixed scroll, Increase the set pressure. As a result, the larger the set pressure, the smaller the degree of expansion of the fluid. Therefore, the fluid is introduced into the working chamber 6 at the predetermined position where the pressure drop is smaller. On the other hand, the necessary differential pressure can always be obtained, and it becomes easy to introduce the fluid corresponding to the pressure drop into the working chamber 6.

Here, the examples shown in FIGS. 1 to 3 will be described in more detail. As shown in FIG. 3, the behavior of the working chamber 6 is shown for each rotation angle of the shaft 2 and the orbiting scroll 3 or every 90 degrees of the orbiting angle, the working chamber 6 is rotated from the central portion to the periphery with the counterclockwise orbiting of the orbiting scroll 3. The volume is increased while moving toward the respective working chambers 6 indicated by 6a to 6e. Thereby, the axis L2 of the fixed scroll 5
An inlet port 5c for introducing a high-pressure fluid from the high-pressure portion 7 into the working chamber 6 is provided in the section. The high-pressure fluid is introduced from the introduction pipe 9 to the high-pressure section 7, and then taken into the working chamber 6 through the introduction port 5c. A pair of working chambers 6a at the moment of being sealed
Since the fluid introduced therein has a high pressure, the wrap 3a of the orbiting scroll 3 and the wrap 5a of the fixed scroll 5 exert a force for increasing the volume of the working chamber 6a. As a result, the orbiting scroll 3 which is the movable side
And its wrap 3a swivels counterclockwise around the axis L2 of the fixed scroll 5 in the direction in which the volume of the working chamber 6 increases from the working chamber 6a to the working chamber 6b, and the shaft 2 passes through the eccentric bearing 2a. Are driven to rotate in the same direction. The volume of the working chamber 6 increased due to the movement to the outer peripheral side, and the pressure of the fluid decreased, but it was still higher than the pressure of the low pressure portion 10,
Since a force for further expanding the volume of the working chamber 6 is continuously applied, the working chamber 6 sequentially increases the working chamber 6c and the working chamber 6d in volume, and the working chamber 6e and the working chamber 6e immediately increase in volume to a low pressure. Go to Part 10. The expanded and low-pressure fluid flows from the working chamber 6 to the low-pressure portion 10, and then the discharge pipe 1
Emitted from 1.

In particular, the bypass ports 14 as shown in FIGS. 1 and 2 are provided on the end plate 5b of the fixed scroll 5 at symmetrical positions with respect to the axis L2 as shown in FIG. 3, and as shown in FIG. The valve mechanism 15 is provided. In addition,
By providing the bypass port 14 on the end plate 5b of the fixed scroll 5, a part of the working chamber and the high pressure part 7 can be communicated with each other by simple processing as described above, and almost the entire end part of the end plate 5b can be connected to the high pressure part 2b. , The degree of freedom in selecting the position where the bypass port 14 is provided is high, and it is easy to provide the bypass port 14 at each place. In the present example, the position where the bypass port 14 is provided is one in the vicinity of the outer wall within 360 deg from the winding start position of the wrap 5a of the fixed scroll 5, and the other from there to the end of 180 deg along the wrap 5a of the fixed scroll 5. It is near the moved inner wall.

The structures of the bypass port 14 and the valve mechanism 15 will be described. The valve mechanism 15 is a ball 15a
, A coil spring 15b, and a spring pedestal 15c having a flow path 15d. The bypass port 14 is machined from the end surface 5d of the end plate 5b of the fixed scroll 5 on the side of the working chamber 6 and does not penetrate the end surface 5e on the side of the high pressure portion 7, and the bottom surface of the cylinder portion 14a and the end surface on the side of the high pressure portion 7. 5e
It has a small hole 14b penetrating therethrough. Cylindrical part 14a
Inside, the ball 15a and the coil spring 15b are arranged in order from the high-voltage portion 7 side. Ball 15a is cylindrical portion 1
It has a diameter slightly smaller than 4a and is movable in the axial direction of the cylindrical portion 14a inside the cylindrical portion 14a. further,
From the inlet on the side of the working chamber 6 of the cylindrical portion 14a, the spring pedestal 15
c is inserted and fixed, and one end surface of the coil spring 15b is in contact with the spring seat 15c and the other end surface is in contact with the ball 15a.

Next, the valve mechanism 1 of the bypass port 14
The operation of No. 5 will be described. Referring to FIG. 2, ball 15
Consider the balance of the forces acting on a. If the diameter of the flow passage 15d of the spring pedestal 15c is φd and the pressure of the working chamber 6 is Pv, the pressure Pv of the working chamber 6 acts only on the portion of the ball 15a facing the flow passage 15d, and on the other portions. Since the pressure of the high pressure portion 7, that is, the introduction pressure Ps acts, the ball 1
A force F due to a differential pressure expressed by the following equation acts on 5a.

[0043]

[Equation 2] If this force F is larger than the force of the coil spring 15b, the
As shown in (a), the ball 15a is the flow path 1 of the spring pedestal 15c.
5d is blocked, and the coil spring 1 is stronger than this force F.
If the force of 5b is large, the ball 15a will move as shown in FIG. 2 (b).
Moves away from the flow path 15d of the spring pedestal 15c. In other words, when the introduction pressure Ps becomes higher than the introduction set pressure P1 at which the spring force of the coil spring 15b and the differential pressure F acting on the ball 15a are balanced, the ball 15a moves through the flow path 15d.
Is closed, and if the height becomes lower, the flow path is separated from the flow path 15d. In this way, the bypass port 14 is closed by the valve mechanism 15 when the introduced pressure Ps is higher than the set pressure P1 and opened when it is smaller than the set pressure P1.

Next, the operation of the scroll expander of this example having the bypass port 14 and the valve mechanism 15 will be described. When the introduction pressure Ps is higher than the set pressure P1, the valve mechanism 15 of the bypass port 14 is closed, and the high-pressure fluid is introduced from the introduction pipe 9 to the high-pressure section 7 and then only through the introduction port 5c to the working chamber. Since it is taken into the interior of the expander 6, the working chamber 6 indicated by reference numeral 6a in FIG. 3 becomes a pair of working chambers at the moment when it is sealed, and when the volume is Va, the introduction volume of the expander is Va. On the contrary, the introduction pressure P
If s is smaller than the set pressure P1, bypass port 1
The valve mechanism 15 of No. 4 is opened, and the high-pressure fluid is introduced from the introduction pipe 9 to the high-pressure section 7 and then taken into the working chamber 6 through the introduction port 5c and the bypass port 14, and therefore is designated by 6c in FIG. When the working chamber 6 shown is a pair of working chambers 6a at the moment when it is sealed and its volume is Vc, the introduction volume of the expander is Vc. As is clear from FIG. 3, Vc
Since> Va, it can be seen that the introduction volume increases when the introduction pressure Ps becomes equal to or lower than the set pressure P1. At the same time, it can be seen that the volume ratio is decreased from (Ve / Va) to (Ve / Vc). Here, Ve is the volume of the working chamber 6e immediately before communicating with the low pressure portion 10.

Next, the effect of the scroll expander of this example will be described with reference to the PV diagram of the working chamber 6 shown in FIG. The area of the hatched portion 16 in FIG. 4A shows the energy obtained from the fluid in the working chamber 6 when the introduction pressure Ps is higher than the set pressure P1. In addition, the area obtained by subtracting the area of the shaded portion 17b from the area of the shaded portion 17a in FIG. 4B has an introduction pressure Ps ′ of the set pressure P1 in the conventional scroll expander having no bypass port 14.
It shows the energy gained from the fluid when lower than. Here, the area shown by the shaded portion 17b is the overexpansion loss. Comparing these figures, it can be seen that the introduction pressure decreases from Ps to Ps ′, and the energy obtained from the fluid is greatly reduced due to the constant introduction volume and the overexpansion loss. On the other hand,
The area indicated by the hatched portion 18 in FIG. 4C is the introduction pressure Ps ′ in the expander of this example provided with the bypass port 14.
Indicates the energy obtained from the fluid when is lower than the set pressure P1. Bypass port 14 and valve mechanism 15
Since the introduction volume was increased to Vc and the volume ratio was decreased to (Ve / Vc) by providing
The area indicated by the shaded area 18 in (c) is the shaded area 1 in FIG.
The area is larger than the area indicated by 7a, and the overexpansion loss corresponding to the area indicated by the shaded portion 17b is also eliminated. Therefore, it can be seen that more energy can be obtained from the fluid and the efficiency is improved as compared with the conventional scroll expander.

The examples shown in FIGS. 5 and 6 will be described in detail. The behavior of the working chamber 6 is shown for each rotation angle of the fixed scroll 5 of the shaft 2 and the orbiting scroll 3 about the axis L2 or the orbiting angle 90 deg. In addition to the pair of bypass ports 14 having the valve mechanism 15 in the example, a pair of bypass ports 19 is added. The bypass port 19 allows the high-pressure portion 7 to pass through a part of the working chamber 6 and includes a valve mechanism 20 shown in FIG.

The position where the bypass port 19 is provided is 3 from the winding start position of the wrap 5a of the fixed scroll 5.
In the vicinity of the outer wall within 60 deg, and the winding start side and the other side of the bypass port 14 provided near the outer wall,
From there 180 along the wrap 5a of the fixed scroll 5
It is near the inner wall that has moved to the end of deg winding.

The configurations of the bypass port 19 and the valve mechanism 20 are the same as the configurations of the bypass port 14 and the valve mechanism 15 described in the previous example. The bypass port 19 is composed of a cylindrical portion 19a and a small hole 19b, and the valve mechanism 20 is composed of a ball 20a, a coil spring 20b, a spring pedestal 20c, and a passage 20d provided in the spring pedestal 20c. However, the coil spring 20 of the valve mechanism 20
For b, a spring having a larger spring force than the coil spring 15b of the valve mechanism 15 is used.

The operation of the valve mechanism 15 of the bypass port 14 is as described in the previous example. Further, the valve mechanism 20 of the bypass port 19 also performs the same operation. When the set pressure for opening / closing the valve mechanism 15 corresponding to the difference in spring force between the coil spring 15b and the coil spring 20b is P1 and the set pressure for opening / closing the valve mechanism 20 is P2, the spring force of the coil spring 20b of the valve mechanism 20 is set. Is larger than the spring force of the valve mechanism 15, the relationship of P1 <P2 is established. Other configurations are the same as the previous example, so
Common members are denoted by the same reference numerals, and duplicated illustration and description are omitted.

The operation of the scroll expander of this example will be described. When the introduction pressure Ps is higher than the set pressure P2, the valve mechanism 15 of the bypass port 14 and the valve mechanism 20 of the bypass port 19 are closed, and the high pressure fluid is introduced from the introduction pipe 9 to the high pressure section 7, Since it is taken into the working chamber 6 through only the introduction port 5c, the reference numeral 6a in FIG.
The working chamber 6 shown by is a pair of working chambers at the moment when it is sealed, and if the volume is Va, the introduction volume of the expander is Va.
Is. Next, when the introduction pressure Ps ′ is lower than the set pressure P2 and higher than the set pressure P1, the bypass port 19
The valve mechanism 20 of 1 is opened and the valve mechanism 15 of the bypass port 14 remains closed. At this time, the high-pressure fluid is introduced from the introduction pipe 9 to the high-pressure section 7, and then the introduction port 5
Since it is taken into the working chamber 6 through c and the bypass port 19, the working chamber 6 shown by reference numeral 6b in FIG. 5 becomes a pair of working chambers at the moment when it is sealed, and its volume is Vb. Becomes Vb. On the other hand, when the introduction pressure Ps ″ is lower than the set pressure P1, the valve mechanism 15 of the bypass port 14 is also opened, and the high-pressure fluid is introduced from the introduction pipe 9 to the high-pressure section 7, and then the introduction port 5c and the bypass. Since it is taken into the working chamber 6 via the port 14 and the bypass port 19, it becomes a pair of working chambers at the moment when the working chamber 6 shown by reference numeral 6c in FIG. 5 is sealed, and its volume is Vc. The volume is Vc. Figure 3
As is clear from the above, since Vc>Vb> Va, it can be seen that the introduction volume gradually increases as the introduction pressure Ps decreases. At the same time, the volume ratio is (Ve / V
It can be seen that the values are reduced from (a) to (Ve / Vb) and (Ve / Vc). Here, Ve is the volume of the working chamber 6e immediately before communicating with the low pressure portion 10.

Next, the effect of the scroll expander of the present embodiment will be described with reference to the PV diagram of the working chamber 6 shown in FIG. The area of AEDH in FIG. 7 indicates the energy obtained from the fluid in the working chamber 6 when the introduction pressure Ps is higher than the set pressure P2. In this case, the valve mechanism 15 of the bypass port 14 and the valve mechanism 20 of the bypass port 19 are closed. On the other hand, when the introduction pressure Ps ′ is lower than the set pressure P2 and higher than the set pressure P1, the valve mechanism 20 of the bypass port 19 is open, the introduction volume increases from Va to Vb, and the volume ratio also becomes (Ve / Va) to (Ve / Vb), the energy obtained from the fluid is the area of BEDG in FIG. 7. When the introduction pressure Ps ″ is lower than the set pressure P1, the valve mechanism 15 of the bypass port 14 and the valve mechanism 20 of the bypass port 19 are open, the introduction volume increases from Va to Vc, and the volume ratio also increases. Since the energy is reduced from (Ve / Va) to (Ve / Vc), the energy obtained from the fluid is the area of CEDF in FIG. 7. As described above, as can be seen from FIG. 7, the bypass port 1
By using the valve mechanism 15 of No. 4 and the valve mechanism 20 of the bypass port 19 together, it is possible to more finely change the introduction volume and the volume ratio in accordance with the change of the introduction pressure Ps. It can be seen that even more energy can be obtained from the fluid and the efficiency is improved.

[0052]

As described above, according to the present invention, even if the pressure in the high-pressure portion may drop for some reason, if the pressure in the high-pressure portion becomes equal to or lower than the set pressure, there will be a difference in the working chamber. Since the fluid is introduced by pressure, the introduction volume and the volume ratio of introduction and discharge can be changed according to the pressure drop in the high pressure part, and more energy can be obtained from the fluid, and overcompression loss can be prevented to improve efficiency. Can be improved.

Further, since the valve mechanism is constructed by using the ball and the coil spring, the valve mechanism can be constructed with a simple structure.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing one example of a scroll expander according to an embodiment of the present invention.

2 is a sectional view of a bypass port portion of the scroll expander of FIG.

FIG. 3 is a development view showing the behavior of the working chamber of the scroll expander of FIG. 1 for each turning angle.

FIG. 4 is a PV diagram in the working chamber of the scroll expander of FIG. 1.

FIG. 5 is a development view showing the behavior of the working chamber in another example of the scroll expander according to the embodiment of the present invention, for each turning angle.

6 is a sectional view of a bypass port portion of the scroll expander of FIG.

7 is a PV diagram in the working chamber of the scroll expander of FIG.

FIG. 8 is a vertical cross-sectional view of a conventional scroll expander.

9 is a cross-sectional view showing the behavior of the working chamber of the scroll expander of FIG. 8 for each turning angle.

10 is a PV diagram in the working chamber of the scroll expander of FIG.

[Explanation of symbols]

3 orbiting scroll 3a Orbiting scroll wrap 5 fixed scroll 5a Fixed scroll wrap 5b End plate 5c inlet 6, 6a-6e working chamber 7 High voltage part 14, 19 bypass ports 15, 20 valve mechanism 15a and 20a balls 15b, 20b coil spring

Claims (11)

[Claims] 1. A fixed scroll and a wrap of an orbiting scroll are meshed with each other to form a working chamber that changes a volume while moving by a rotation along a circular orbit of the orbiting scroll, and a high pressure is applied to the working chamber on the minimum position side. In the scroll expander in which the fluid of the part is introduced, the orbiting scroll is orbited to the side where the working chamber becomes large with the expansion of the fluid, and the fluid is discharged from the working chamber on the maximum position side to the low pressure part. A scroll expansion characterized in that a bypass port for allowing a high-pressure portion to pass through a working chamber between the minimum and maximum positions from a predetermined position and a valve mechanism that opens when the pressure in the high-pressure portion falls below a set pressure are provided in the bypass port. Machine. 2. The scroll expander according to claim 1, wherein a plurality of working chambers are formed symmetrically, and a plurality of bypass ports are provided so as to communicate with the symmetrical working chambers at the same time. 3. The scroll expander according to claim 1, wherein four or more bypass ports are provided. 4. The working chamber is configured to have a larger volume while moving from a central portion to a peripheral portion, and the set pressure is increased as it is closer to the central portion of the bypass port. Item 4. The scroll expander according to Item 3. 5. The scroll expander according to claim 1, wherein the bypass port is provided on the end plate of the fixed scroll. 6. The scroll expander according to claim 1, wherein the valve mechanism comprises a ball and a coil spring. 7. An orbiting scroll is actuated by introducing a fluid from a high-pressure portion at the minimum position side of the working chamber in which the volume changes while moving by the orbiting of the orbiting scroll formed between the fixed scroll and the orbiting scroll wrap. In the scroll expander drive method, in which a swirl force is applied to the chamber to increase the size of the fluid, the fluid is swirled with the expansion, and the fluid is discharged to the low pressure portion on the maximum position side of the working chamber. A method for driving a scroll expander, wherein fluid is introduced into the working chamber when the pressure in the high pressure portion is equal to or lower than a set pressure at a predetermined position between the minimum position sides. 8. The method of driving a scroll expander according to claim 7, wherein the fluid is introduced from the high pressure portion by a differential pressure when the high pressure portion communicates with the working chamber. 9. The method according to claim 7, wherein the fluid is introduced by the differential pressure at a plurality of predetermined positions.
Item 7. A method for driving a scroll expander according to item. 10. The method for driving a scroll expander according to claim 9, wherein the introduction of the fluid by the differential pressure at different predetermined positions is performed under different set pressures. 11. The driving method for a scroll expander according to claim 10, wherein the set pressure is increased as the predetermined position is closer to the minimum side of the working chamber.