JP3456723B2 - Screw pump - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a housing having an intake port on one side in the axial direction and a discharge port on the other side in the axial direction, and a plurality of spiral tooth portions having relatively small intervals along the circumferential direction. And a second rotor having a plurality of spiral tooth portions with a relatively large circumferential spacing along the outer circumference.
The rotor and a rotor are rotatably supported by meshing their teeth with each other, and a piston for changing the compression ratio, a part of which faces the discharge port, is formed in a plane substantially orthogonal to the axes of the rotors. The present invention relates to a screw type pump that is arranged in a housing so as to be movable between a high compression position on one side and a low compression position on the outside.

[0002]

2. Description of the Related Art Conventionally, such a screw type pump is already known from, for example, Japanese Utility Model Laid-Open No. 4-111591.

[0003]

By the way, the piston for changing the compression ratio needs to be arranged in the housing so that at least the outer circumference thereof is in contact with the compression start line, and the compression start line on the first rotor side is provided. And the second
The compression start line on the rotor side is positioned so as to form a triangular shape so as to separate from each other from one point near the intake port of the meshing portion of both rotors toward the discharge port side. However, in the above-mentioned conventional one, the piston is arranged in the housing at a position corresponding to the meshing portion of the first and second rotors so that the outer periphery of the piston is in contact with the compression start lines of the first and second rotors. ing. For this reason, the piston becomes relatively large and
The driving means including a diaphragm for driving the piston is also increased in size.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a screw type pump in which the size of the piston and the driving means for driving the piston are reduced.

[0005]

In order to achieve the above object, the invention according to claim 1 has a housing having an intake port on one side in the axial direction and a discharge port on the other side in the axial direction. The first rotor having a plurality of spiral tooth portions having a relatively large distance along the outer circumference and the second rotor having a plurality of spiral tooth portions having a relatively small distance along the circumferential direction on the outer circumference are those tooth portions. , Which are rotatably supported by meshing with each other, and which partially face the discharge port, are used to change the compression ratio. In the screw-type pump which is arranged in the housing so as to be movable to and from the low compression position on one side, the piston is arranged in the housing on the side of the second rotor.

According to a second aspect of the present invention, in addition to the structure of the first aspect of the invention, the inner end surface of the piston has a curved surface shape corresponding to the rotation locus drawn by the outer edges of the teeth of the second rotor. Is formed.

According to the invention of claim 3, in addition to the structure of the invention of claim 1, the discharge port corresponds to the meshing portion of the first and second rotors on the other axial side of the housing. And the inner surface of the connecting cylinder provided on the other side in the axial direction of the housing on the side of the first rotor, and the outer end of the connecting cylinder has a joining flange that projects outward. It is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a screw type pump, and FIG.
Is a cross-sectional plan view of the screw type pump, and FIG.
3 is a sectional view taken along line 3 and FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG.

First, in FIG. 1, FIG. 2 and FIG. 3, the screw type pump SP is used as a mechanical supercharger for a vehicle-mounted engine, and has a plurality of spiral shapes with a relatively large circumferential interval. The male first rotor 7 having a tooth portion 7a on the outer periphery and the female second rotor 8 having a plurality of spiral tooth portions 8a having a relatively small circumferential interval on the outer periphery are the tooth portions. 7a and 8a are meshed with each other and rotatably supported by the housing 9.
8 is rotationally driven by an engine (not shown).

A screw type pump SP of such a type
In this case, as the first and second rotors 7 and 8 rotate, the spiral tooth portions 7a and 7 adjacent to each other in the first rotor 7
The spiral tooth portion 8 of the second rotor 8 is provided in the chamber formed between a.
a enters, and between the spiral tooth portions 8a, 8a adjacent to each other in the second rotor 8, the spiral tooth portion 7 of the first rotor 7
The volume of the room gradually decreases as a enters and advances from the one axial side of the housing 9 to the other axial side. As a result, the spiral tooth portion 7 is sucked through the suction port 5 provided on one side of the housing 9 in the axial direction.
The air introduced into the chamber between a, 7a; 8a, 8a is gradually compressed by the rotation of both rotors 7, 8 and is sent to the other side in the axial direction of the housing 9, and the other axial direction of the housing 9 It is led out from the discharge port 6 provided on the side.

Here, the line where the compression ratio of the air sucked from the suction port 5 is 1.0 (that is, the line where compression is started) is the position indicated by L ₁ and L ₂ in FIGS. 1 and 2. Become. That is, the compression start line L ₁ on the first rotor 7 side and the compression start line L _{1 on} the second rotor 8 side
₂ is 1 near the intake port 5 of the meshing part of both rotors 7 and 8
The positions are such that they are separated from each other toward the discharge port 6 side from the point to form a triangular shape. On the other hand, the first when the compression ratio of air becomes 1.3, for example.
The line L ₃ on the rotor 7 side and the line L ₄ on the second rotor 8 side are the same as the compression start lines L ₁ and L ₂ on the housing 9 side.
The position is parallel to the other side in the axial direction of. Since the discharge port 6 discharges the air in the chamber formed between the spiral tooth portions 7a, 7a; 8a, 8a, the opening edge of the discharge port 6 into the housing 9 has a spiral shape. It is desirable to efficiently draw out the air from the chamber by making it parallel or substantially parallel to the toothed portions 7a and 8a. In this embodiment, it is assumed that a compression ratio of 1.3 is obtained, and the discharge port 6 is introduced into the housing 9. opening edge is formed to be 1 and the line L ₃ of Figure 2, L the lines L ₃ in the vicinity of _4, L ₄ substantially triangular shape which is substantially approximated to a triangular shape formed by.

The housing 9 has a bottomed cylindrical body 10 having one end closed by an end wall 10a, and an end wall member 11 connected to the cylindrical body 10 so as to cover its open end. The suction port 5 is provided in the end wall 10a. Further, the cylindrical body 10 is composed of the spiral tooth portions 7 in both the rotors 7 and 8.
It is formed in a cross-sectional shape corresponding to the rotation locus drawn by the outer edges of a and 8a. That is, the tubular body 10 includes an arc-shaped first inner surface 10 b facing the outer circumference of the first rotor 7 and an arc-shaped second inner surface 10 c facing the outer circumference of the second rotor 8.

The two rotors 7 and 8 are fixed to the rotary shafts 12 and 13, respectively.
One end of the bearing 3 is attached to the end wall 10a of the cylindrical body 10 by the bearings 14, 1
It is supported through 5 respectively. A cover 17 that forms a gear chamber 16 with the end wall member 11 is coupled to the end wall member 11, and the other ends of the rotary shafts 12 and 13 penetrate the end wall member 11. It plunges into the gear chamber 16. A seal member 18 and a pair of bearings 19 are provided between the rotary shaft 12 and the end wall member 11, and the rotary shaft 13
A seal member 20 and a pair of bearings 21 are provided between the end wall member 11 and the end wall member 11.

Gears 22 and 23 meshing with each other are fixed to the rotary shafts 12 and 13 in the gear chamber 16, and a gear 24 is fixed to the rotary shaft 12 in addition to the gear 23.
On the other hand, one end of a shaft 25 having an axis parallel to the rotary shafts 12 and 13 is rotatably supported by the end wall member 11 via a bearing 26, and the shaft 25 penetrates the cover 17 rotatably. And project outward. Moreover, in the gear chamber 16, a gear 27 that meshes with the gear 24 is fixed to the shaft 25, and a pulley 28 is fixed to the outer end of the shaft 25 protruding from the cover 17. Power from a crankshaft (not shown) of the engine is transmitted to the pulley 28 via an endless belt (not shown), whereby the first rotor 7 and the second rotor 8 are transmitted.
Are meshed with each other and driven to rotate.

By the way, in such a screw type pump SP, in order to make the compression ratio of the compressed air derived from the discharge port 6 variable in the range of 1.0 to 1.3,
As described above, the opening edge of the discharge port 6 into the housing 9 is defined in the vicinity of the lines L ₃ and L ₄ where the compression ratio is 1.3, and the spiral tooth portions on the compression start lines L ₁ and L ₂ are described. The chamber between 7a, 7a; 8a, 8a may be connected to the discharge port 6.

Therefore, according to the present invention, the first and second
Of the rotors 7 and 8, the portion corresponding to the smaller circumferential interval of the spiral tooth portions 7a and 8a provided on the outer periphery of the rotors 7 and 8 has a compression ratio change to the side portion of the tubular body 10 in the housing 9. Is provided with a piston 30 for. Here, the male first rotor 7 is heavier than the female second rotor 8 because its spiral tooth portion 7a is larger than the spiral tooth portion 8a. The number of spiral teeth 7a on the side of the second rotor 8 is smaller than the number of spiral teeth 8a on the side of the second rotor 8, and the first rotor 7 is rotationally driven at a rotation speed higher than that of the second rotor 8. Conveniently, in this embodiment, the gears 2 mesh with each other to rotate the first rotor 7 faster than the second rotor 8.
The diameters 2 and 23 are determined, and the second rotor 8 is provided with four spiral tooth portions 8a, while the first rotor 7 is provided with five spiral tooth portions 7a. This makes the first
The spacing between the spiral tooth portions 8a, 8a on the second rotor 8 side is narrower than the spacing between the spiral tooth portions 7a, 7a on the rotor 7 side. Therefore, the piston 30 is disposed on the side portion of the cylindrical body 10 corresponding to the second rotor 8 so as to be movable between the high compression position on the inner side and the low compression position on the outer side.

Referring also to FIG. 4, the moving direction 31 of the piston 30 is set in a direction substantially orthogonal to the straight line connecting the axes of the first and second rotors 7 and 8, and A guide tube portion 32 having a circular cross section and having an axis extending along the moving direction 31 is integrally provided on a side portion of the body 10, and the piston 30 is allowed to move along the moving direction 31 in the guide tube portion 32. Will be placed. Moreover, the piston 30
The outer diameter is smaller than the inner diameter of the guide tube portion 32 and is formed in a circular cross section, and is not supported by the guide tube portion 32.

The piston 30 is formed in a cylindrical shape with a closed end facing the inside of the housing 9, and an opening end, that is, an outer end thereof, is provided with a flange portion 30a extending outward in the radial direction. On the other hand, on the inner surface of the guide tube portion 32 near the outer end in the axial direction, a large diameter hole portion 32a is provided with a step portion 32b facing the outside so that the collar portion 30a can be moved along the movement direction 31. The axial position of the piston 30 is regulated by the case member 43, which is provided and is coupled to the outer end of the guide tube portion 32, and the step portion 32b. Further, the regulation pin 34 having an axis parallel to the moving direction 31 is attached to the case member 43 and the step portion 32.
It is fixedly arranged between b and the rotation of the piston 30 around the axis is prevented by engaging the restriction pin 34 at a position displaced from the axis of the piston 30.

The piston 30 has its outer periphery on the second rotor 8
Side compression start line L₂Touch the second row
Is disposed in the housing 9 on the side of the controller 8 and a part thereof
Is arranged so that the discharge port 6 faces
Yes, the discharge port 6 is the other axial end of the housing 9.
And the lead-out path 35 provided in the end wall member 11
And the inner surface of the connecting tube 36. The lead-out path 35 is
At the other end of the tubular body 10 in the housing 9, the first and the first
2 First and second inner surfaces corresponding to the meshing portions of the rotors 7 and 8
A raised surface 10d protruding outward from 10b and 10c,
Consists of a curved surface 11a provided on the end wall member 11
The edge of the opening of the lead-out path 35 to the inner surface of the cylinder 10 is compressed.
Line L with reduction ratio of 1.3₃, L_FourThose in the vicinity of
Line L ₃, L_FourShaped into a substantially triangular shape corresponding to
Is made. In addition, the connecting tube 36 has an end wall on the first rotor 7 side.
It is provided on the member 11 and is provided on the outer end of the connecting tube 36.
Is a joint flange 36 for joining to a conduit not shown.
a is projected integrally to the outside.

The piston 30 is arranged so as to partially face the outlet passage 35 in the discharge port 6, and the piston 30 is provided with a notch 30b continuous with the raised surface 10d in the outlet passage 35. To be The inner end surface 30c of the piston 30 along the moving direction 31 faces the second rotor 8 and is formed into a curved surface corresponding to the rotation trajectory drawn by the outer edge of the spiral tooth portion 8a of the second rotor 8.

A drive means 38 is connected to the piston 30. The drive means 38 forms a back pressure chamber 39 between the piston 30 and the drive means 38 and is connected to the outer end of the guide cylinder 32. 40, a diaphragm 41 whose peripheral portion is sandwiched by the case 40 and accommodated in the case 40, and a spring 42 which is compressed between the diaphragm 41 and the case 40. The case 40 is composed of a pair of case members 43 and 44 coupled to each other, and the peripheral edge of the diaphragm 41 is sandwiched between the case members 43 and 44. Thus, the diaphragm 41 causes the piston 3 to move inside the case 40.
It is divided into an atmospheric pressure chamber 45 on the inner side along the moving direction 31 of 0 and a control chamber 46 on the outer side along the moving direction 31,
The spring 42 is housed in the atmospheric pressure chamber 45 in order to exert a spring force that urges the diaphragm 41 toward the side where the volume of the control chamber 46 is reduced. In the case 40, a cylindrical bearing sleeve 47 is fitted and fixed in the center of the case member 44 that divides the back pressure chamber 39 and the atmospheric pressure chamber 45. On the other hand, the piston 30 has a connecting rod 30 extending in the moving direction 31.
d is integrally provided, and the connecting rod 30d slidably penetrates through the bearing sleeve 47 and is connected to the central portion of the diaphragm 41.

According to the driving means 38, the control chamber 46
The increase in the pressure of causes the piston 30 to move to the high compression position (inward position along the moving direction 31) against the spring force of the spring 42, and when the pressure in the control chamber 46 decreases, the spring force of the spring 42 causes the piston 30 to move. The piston 30 is moved to the low compression position (outward position along the moving direction 31).

Since the piston 30 is provided with the notch 30b, the back pressure chamber 39 communicates with the discharge port 6, and the pressure of the back pressure chamber 39 becomes equal to the discharge pressure of the discharge port 6.

A conduit 48 is connected to the control chamber 46, and the discharge pressure and the atmospheric pressure of the screw type pump SP are selectively supplied to the conduit 48, whereby the piston 3 is supplied.
0 moves between the high compression position and the low compression position to control the compression ratio of the screw type pump SP.

Next, the operation of this embodiment will be described. In a state where atmospheric pressure is introduced into the control chamber 46 of the driving means 38, the piston 30 is located at the low compression position on the outer side along the moving direction 31 (see FIGS. 4), the chamber formed between the spiral tooth portions 7a, 7a at the compression start line L _{2 is} in communication with the discharge port 6, so that the compression ratio of the screw pump SP is 1. 0, and when the discharge pressure of the screw type pump SP is introduced into the control chamber 46, the piston 30 comes to a high compression position on the inner side along the moving direction 31, and the communication state is released. The compression ratio of the screw type pump SP becomes 1.3, for example.

In such a screw type pump SP, the piston 30 has a first rotor 7 having a plurality of spiral tooth portions 7a on the outer periphery having a relatively large circumferential spacing, and a relatively circumferential spacing. Among the second rotors 8 having a plurality of small spiral tooth portions 8a on the outer circumference, the second rotor 8 is disposed in the housing 9 on the side of the second rotor 8. Thus to piston 30, its causes some face the discharge port 6 is intended to be arranged in contact with the outer periphery to the compression start line L _2, the second compression start line of the rotor 8 side L ₂ and the discharge port The distance between the discharge ports 6 is smaller than the distance between the compression start line L ₁ on the first rotor 7 side and the discharge port 6. Therefore, by disposing the piston 30 in the housing 9 on the side of the second rotor 8, the piston is moved to the first rotor 7.
Side is placed in the housing, and both rotors 7,
It is possible to set the radius of the piston 30 to be smaller than that in the case where the piston is arranged in the housing at a position corresponding to 8 and the driving means 38 can be downsized in accordance with the downsizing of the piston 30. Becomes

The inner end surface 30c of the piston 30 has a second
The rotor 8 is formed in a curved surface shape corresponding to the rotation locus drawn by the outer edge of the spiral tooth portion 8a, and the piston is arranged at a position corresponding to the meshing portion of the first and second rotors 7, 8. Compared to the case where two curved surfaces corresponding to the rotation loci drawn by the outer edges of the first and second rotors 7 and 8 are formed on the inner end surface of the piston, the inner end surface 30c has a simple shape and is easy to machine. Become.

Further, a connection port 36 forming a part of the discharge port 6 is provided on the first rotor 7 side on the other side in the axial direction of the housing 9, and the piston 30 and the driving means 38 are provided on the second rotor 8 side. In combination with the arrangement, the amount of outward protrusion of the joint flange 36a at the outer end of the connecting cylinder 36 can be made sufficiently large, which can contribute to the improvement of joint strength with the conduit.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims. It is possible to do.

[0031]

As described above, according to the first aspect of the invention, since the piston is arranged in the housing on the side of the second rotor, the size of the piston and the size of the driving means for driving the piston are reduced. The size of the screw pump can be reduced.

According to a second aspect of the invention, in addition to the structure of the first aspect of the invention, the inner end surface of the piston has a curved surface shape corresponding to the rotation locus drawn by the outer edge of the tooth portion of the second rotor. Since it is formed in the shape described above, the shape of the inner end surface of the piston can be made relatively simple and the processing can be facilitated.

Further, according to the invention of claim 3, in addition to the structure of the invention of claim 1, the discharge port corresponds to the meshing portion of the first and second rotors on the other axial side of the housing. And a connecting flange that extends outwardly at the outer end of the connecting cylinder. Since the piston is provided, the piston is arranged on the side of the second rotor, and the amount of protrusion of the joint flange at the outer end of the connecting cylinder toward the outside is sufficiently increased.
The strength of the joint flange can be increased sufficiently.

[Brief description of drawings]

FIG. 1 is a plan view of a screw type pump.

FIG. 2 is a cross-sectional plan view of a screw type pump.

3 is a sectional view taken along line 3-3 of FIG.

FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG.

[Explanation of symbols]

5 Inhalation port 6 discharge ports 7 First rotor 7a, 8a teeth 8 Second rotor 9 housing 30 pistons 30c inner end face 35 Derivation route 36 Connection tube 36a Joint flange SP screw type pump

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-280584 (JP, A) JP-A-6-280773 (JP, A) JP-A-4-1487 (JP, A) JP-A-57- 20585 (JP, A) Actual development 60-28291 (JP, U) Actual development 4-1-1591 (JP, U) Actual public 53-40727 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F04C 18/16 F02B 33/36

Claims (3)

(57) [Claims] 1. A housing (9) having an intake port (5) on one side in the axial direction and a discharge port (6) on the other side in the axial direction. First rotor (7) having a portion (7a) on the outer circumference
And a second rotor (8) having a plurality of spiral tooth portions (8a) on the outer circumference with relatively small intervals along the circumferential direction, are rotatable by meshing these tooth portions (7a, 8a) with each other. The compression ratio changing piston (30) partially supported by the discharge port (6) faces the discharge port (6) and is highly compressed on the inner side in a plane substantially orthogonal to the axes of the rotors (7, 8). In a screw pump arranged in the housing (9) allowing movement between a position and an outer low compression position, the piston (30) comprises a housing (9) on the side of the second rotor (8). A screw type pump, characterized in that 2. The inner end surface (30c) of the piston (30)
The screw type pump according to claim 1, wherein is formed in a curved surface shape corresponding to a rotation locus drawn by an outer edge of the spiral tooth portion (8a) of the second rotor (8). 3. The discharge port (6) comprises a housing (9).
A lead-out path (35) provided at a position corresponding to the meshing portion of the first and second rotors (7, 8) on the other side in the axial direction of
It is formed by the inner surface of the connecting cylinder (36) provided on the other side in the axial direction of the housing (9) on the rotor (7) side, and is joined to the outer end of the connecting cylinder (36) by projecting outward. A flange (36a) is provided, characterized in that
The described screw type pump.