JP2546551Y2 - Screw pump - Google Patents

Description

[Detailed description of the invention]

[0001]

This invention relates to a male rotor and a female rotor meshing with the male rotor. The male rotor has a first arc-shaped inner surface facing the male rotor and an arc-shaped first inner surface facing the female rotor. Second
An inner surface is rotatably supported by a housing having an inner surface having a cross-sectional shape formed continuously with the inner surface, and the housing has an axis passing through a meshing start position of the rotors at a position corresponding to a meshing portion of the rotors. A piston is movably disposed between a high compression position on the inner side and a low compression position on the outer side along a movement direction substantially orthogonal to the axes of the rotors, and extends along the movement direction of the piston. The present invention relates to a screw pump of a type in which a first inner end surface substantially continuous with a first inner surface and a second inner end surface substantially continuous with a second inner surface are provided at an inner end in a state where the piston is at a high compression position.

[0002]

2. Description of the Related Art A screw type pump of the above-mentioned type is already known, for example, from Japanese Utility Model Publication No. Sho 53-40727, etc., in which an opening provided in a side portion of a housing is closed at a high compression position of a piston and at a low compression position. Opening and closing control is performed so as to open, whereby a part of the suction gas is circulated to change the compression ratio.

[0003]

The present invention is to provide a hand of the type described above scan
Clew pumps, especially male rotors and female rotors
Across the piston for varying the compression ratio
Moves in a direction approximately perpendicular to the rotor axis as a circular surface
In the case of the structure to be made to
There are such technical issues. That is, a conventional disk having such a structure is used.
In the Liu type pump , as shown in FIG.
1 'moving direction 32' is set to a direction substantially perpendicular and straight line L connecting the centers C ₂ 'of the center C ₁ and the female rotor 8 of the' male rotor 7. Therefore, the height H ₁ ′ of the first inner end face 31 ′ b along the axis L _C of the piston 31 ′ is larger than the height H ₂ ′ of the second inner end face 31 ′ c, First inner end face 31'b to a plane including the axis
Is larger than the projected area of the second inner end face 31'c. Thus, on a plane perpendicular to the axis of the male rotor and the female rotor (a plane perpendicular to the plane of FIG. 5), the left and right sides of the piston 31 'are arranged along the axes of the rotors 7' and 8 '. Equivalent pressure acts at the corresponding position
However , the pressure applied to the area of the difference between the projection areas increases from the suction side to the discharge side (that is, along the axis).
Cormorant direction of some of the pressure difference occurs at different positions each other) because, 'the I Do to rotation moment about the axis acts, the piston 31' piston 31 whose axis
Easy to move shift around, moving direction 3 of Matapi piston 31 '
When the movement along 2 'is guided by a positioning pin fixed to the housing, there is a problem that the sliding contact between the pin and the piston is worn due to the reciprocal sliding of the piston.

[0004] The present invention has been made in view of the above circumstances, and is unique to the screw pump having the above structure.
It aims to solve technical problems .

[0005]

According to the present invention, in order to achieve the above-mentioned object, the present invention is designed to mesh with each other and have different outer diameters.
A circle in which the male rotor and the female rotor face the male rotor
Arc-shaped first inner surface and arc-shaped second inner surface facing the female rotor
A housing having an inner surface having a cross-sectional shape formed continuously with surfaces
The rotors are rotatably supported by the rotors, respectively.
At the position corresponding to the joint, the housing
Circular cross-section piston having an axis passing through the meshing start position
But along a movement direction substantially orthogonal to the axes of the two rotors.
Move between high compression position on the inside and low compression position on the outside
Inner end along the direction of movement of the piston
In the state where the piston is in the high compression position,
The first inner end surface substantially connected to the first inner end surface and the second inner surface substantially connected to the second inner surface.
(2) A screw type pump provided with an inner end surface, wherein a piston is disposed on a housing with an axis arranged in a direction substantially orthogonal to a common tangent of the first and second inner surfaces in a plane orthogonal to the axis of both rotors. Is established.

[0006]

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

FIG. 1 is a longitudinal sectional side view of a notch of a screw type pump, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG.
FIG. 4 is a sectional view taken along line 3 and FIG. 4 is an explanatory view for explaining the positional relationship between the piston and the housing.

In FIGS. 1, 2 and 3, the screw pump SP is used as a mechanical supercharger for an engine mounted on a vehicle, and meshes with each other and has an outer diameter.
Become phase male rotor 7 and the female rotor 8 that different is rotatably supported respectively on the housing 6 of the rotors 7 and 8 which is rotated by a not-shown engine,
Air sucked from the suction port 4 on one axial side of the housing 6 is discharged from the discharge port 5 on the other axial side.

The housing 6 has a cylindrical body 9 having a bottom and closed at one end by an end wall 9a, and an end wall member 10 attached to the cylindrical body 9 so as to cover an open end thereof. And the suction port 4 is provided on the end wall 9. The cylindrical body 9 is formed in a cross-sectional shape corresponding to the rotation locus drawn by the radially outer ends of the rotors 7 and 8. That is, the cylindrical body 9 includes an arc-shaped first inner surface 9 b facing the outer periphery of the male rotor 7,
An arc-shaped second inner surface 9c facing the outer periphery of the female rotor 8 is provided.

The rotors 7 and 8 are fixed to rotating shafts 11 and 12, respectively.
One end of 2 is supported on the end wall 9a of the cylinder 9 via bearings 13 and 14, respectively. Further, a cover 15 that forms a gear chamber 16 between the end wall member 10 and the end wall member 10 is connected. The other ends of the two rotation shafts 11 and 12 pass through the end wall member 10. It is protruded into the gear chamber 16. Thus, a seal member 17 and a pair of bearings 18 are interposed between the rotating shaft 11 and the end wall member 10, and the rotating shaft 12 and the end wall member 10 are provided.
A seal member 19 and a pair of bearings 20 are interposed between them.

Gears 22 and 23 meshing with each other are fixed to both rotating shafts 11 and 12 in the gear chamber 16, and a gear 24 is fixed to the rotating shaft 11 in addition to the gear 22.
On the other hand, one end of a shaft 25 having an axis parallel to the rotating shafts 11 and 12 is rotatably supported on the end wall member 10 via a bearing 26. The shaft 25 extends through the cover 15 and extends outward. Protrude into. Thus, a seal member 27 and a pair of bearings 28 are interposed between the shaft 25 and the cover 15. Further, a gear 29 meshing with the gear 24 is fixed to the shaft 25 in the gear chamber 16, and a pulley 30 is fixed to an outer end of the shaft 25 protruding from the cover 15. Power from an engine crankshaft (not shown) is transmitted to the pulley 30 via an endless belt (not shown), whereby the male rotor 7 and the female rotor 8 mesh with each other and are driven to rotate. Will be.

At a position corresponding to the meshing portion of the male rotor 7 and the female rotor 8, a side portion of the cylindrical body 9 in the housing 6 has an inner side along a moving direction 32 substantially orthogonal to the axis of the screw rotors 7, 8. High compression position (see FIGS. 1 and 2
The piston 31 is provided so as to be movable between a position indicated by a dashed line in FIG. 1) and a low compression position on the outer side along the movement direction 32 (a position indicated by a solid line in FIGS. 1 and 2).

Referring to FIG. 4A, the moving direction 32 is a common direction connecting the outer circumferences of the rotors 7 and 8 in a plane perpendicular to the axis of the male rotor 7 and the female rotor 8. br /> is intended to be set in a direction substantially perpendicular to the tangent line L _T,
A guide cylinder portion 33 having a circular cross section substantially perpendicular to the axis of the rotors 7 and 8 and having an axis along the moving direction 32 is provided at a side portion of the cylinder 9 so that the meshing start position P of the both rotors 7 and 8 is established. _G is provided integrally with the piston 31
Can move along the movement direction 32 to enable the guide cylinder 3
3 are arranged coaxially. In addition, the piston 31 has an outer diameter smaller than the inner diameter of the guide cylinder 33 and is formed in a circular cross section, and is not supported by the guide cylinder 33.

The piston 31 is formed in a bottomed cylindrical shape with its closed end facing the inside of the housing 6, and has a flange portion 31 a extending outward in the radial direction at its open end, that is, the outer end. On the other hand, a large-diameter hole 33a is provided on the inner surface of the guide cylinder 33 near the outer end in the axial direction through a step 33b facing the outside so as to enable the flange 31a to move along the movement direction 32. The position of the piston 31 in the axial direction is regulated by the case 40 and the step 33b which are connected to the outer end of the guide cylinder 33. An axially extending groove 34 is provided at one circumferential position of the flange 31 a of the piston 31, and a rod-shaped positioning pin 37 having a circular cross section engaging with the groove 34 is provided in the guide cylinder 33. Are fitted. Accordingly, the piston 31 moves along the movement direction 32 while being prevented from rotating around its axis.

The discharge port 5 cooperates with a lead portion 35 provided at the other axial end of the housing 6 at a position corresponding to the meshing portion of the male rotor 7 and the female rotor 8, and the piston 31. The lead-out section 35
Is a raised portion 9d provided at the other end of the cylindrical body 9 in the housing 6 so as to increase the amount of protrusion outward from the first and second inner surfaces 9b and 9c toward the other end in the axial direction.
And a lead-out cylinder 36 provided on the end wall member 10. On the other hand, the inner end of the piston 31 along the movement direction 32 is
Distance from the suction port 4 of the ejection start position P _E of the discharge port 5 when the piston 31 is in the high compression position,
The discharge start position P _E ′ when in the low compression position,
The first inner end surface 31b which is formed to be larger than the distance of P _E ′ from the suction port 4 and which is substantially continuous with the first inner surface 9b of the housing 6 when in the high compression position.
In addition, a second inner end surface 31 c substantially continuous with the second inner surface 9 c and a third inner end surface 31 d substantially continuous with the inner surface 35 a of the lead-out portion 35 are provided at the inner end along the movement direction 32 of the piston 31. That is, when the piston 31 is at the high compression position, the portion indicated by the oblique chain line at the lower right in FIG.
Become the first and second inner end surfaces 31b, 31c and the connecting portion is ejection start position P _E next to the third inner end face 31d, when the piston 31 is at a low compression position the first and second inner end surfaces 31b, 31c Is located outside of the first and second inner surfaces 9b and 9c of the housing 6, the portions indicated by oblique dashed lines of lower left and lower right in FIG. 4 become the discharge ports 5, and the groove portions of both rotors 7, 8 The first two positions that communicate with the discharge port 5 according to the rotation are the discharge start positions P _E ′ and P _E ′. Thus, the discharge start positions P _E ′, P _E ′ are set to the suction port 4 by setting the piston 31 to the low compression position.
Internal compression ratio ε becomes 1.0 when the deviation, the internal compression ratio ε is, for example 1 when a discharge start position P _E of the piston 31 as a high-compression position was separated from the intake port 4.
It becomes 3.

Referring again to FIGS. 1 and 2, a drive means 38 is connected to the piston 31. The drive means 38 forms a back pressure chamber 39 between the piston 31 and the piston 31 for guiding. A case 40 connected to the outer end of the cylindrical portion 33, a diaphragm 41 as a driving member housed in the case 40 with a peripheral edge held between the case 40, and a diaphragm 41 contracted between the diaphragm 41 and the case 40. And a spring 42. The case 40 is formed by connecting a pair of case members 43 and 44 to each other, and the periphery of the diaphragm 41 is sandwiched between the case members 43 and 44. Thus, the inside of the case 40 is partitioned by the diaphragm 41 into an atmospheric pressure chamber 45 on the inner side along the moving direction 32 of the piston 31 and a control chamber 46 on the outer side along the moving direction 32. The diaphragm 4 is provided on the side where the volume of the control chamber 46 is reduced.
It is housed in the atmospheric pressure chamber 45 so as to exert a spring force for urging 1. Further, a through hole 47 is formed at the center of a case member 44 that partitions the back pressure chamber 39 and the atmospheric pressure chamber 45 in the case 40.
A cylindrical bearing sleeve 48 is fitted and fixed in the through hole 47. On the other hand, the piston 31 is integrally provided with a connecting rod 31e extending along the moving direction 32. The connecting rod 31e is slidably penetrated through the bearing sleeve 48 and connected to the center of the diaphragm 41. You.

In this way, the piston 31 is not supported by the guide cylinder 33 but is supported by the driving means 38 via the connecting rod 31e.
The frictional loss can be reduced by reducing the sliding contact area when the piston is moved along the moving direction 32, and is caused by the deformation of the piston 31 due to the heat effect due to the proximity of the discharge port 5 where the temperature is relatively high. Guide tube part 3
3 can be prevented from sticking.

According to the driving means 38, the control room 46
Is increased, the piston 31 is moved to the high compression position against the spring force of the spring 42, and the control chamber 4
When the pressure of the piston 3 drops, the piston 3
1 will be moved to the low compression position.

A communication hole 49 for communicating the back pressure chamber 39 with the discharge port 5 is formed in the piston 31, and the pressure in the back pressure chamber 39 is equal to the discharge pressure of the discharge port 5.

A conduit 50 is connected to the control chamber 46, and the discharge pressure and the atmospheric pressure of the screw type pump SP are alternatively supplied to the conduit 50.
1 moves between the high compression position and the low compression position to control the compression ratio of the screw pump SP.

Next, the operation of this embodiment will be described. When the atmospheric pressure is introduced into the control chamber 46 of the drive means 38, the piston 31 is at the low compression position, and the discharge start positions P _E ′, P _E ′ are set. By approaching the suction port 4, the internal compression ratio ε of the screw type pump SP becomes 1.0, and when the state is switched to the state where the discharge pressure of the screw type pump SP is introduced into the control chamber 46, the piston 31 is highly compressed. becomes the position, the internal compression ratio of the screw-type pump SP is 1.3 ejection start position P _E is a position away from the suction port 4.

[0022] In such a screw pump SP, as shown in FIG. 4 (a), the axis L _C of the piston 31
That is, since the moving direction 32 is set in a direction substantially perpendicular to the common tangent L _T connecting the outer periphery of those rotors 7,8 in a plane perpendicular to the axis of the male rotor 7 and the female rotor 8, the piston 31 First inner end face 31b along axis L _C
Between the height H _1, it is approximately equal to the height H ₂ of the second inner end surface 31c. For this reason, the projected area of the first inner end surface 31b on a plane including the axis of the piston 31 is a portion indicated by oblique lines in FIG. 4B showing the right side of FIG. The projected area of the inner end surface 31c is a portion shown by oblique lines in FIG. 4C showing the left side surface of FIG.
Both projection areas are almost equal. Therefore, the male rotor 7
The rotational force obtained by the product of the pressure acting from the left and right sides of the piston 31 on the plane orthogonal to the axis of the female rotor 8 and the two projected areas is substantially equal between the left and right sides in FIG. The acting rotational moment about the axis can be kept small. As a result, the load applied to the positioning pin 37 can be reduced, so that sufficient durability can be obtained even when the positioning pin 37 is formed into a rod having a circular cross section that is easy to process, and the piston 31 and the positioning pin 37 can be obtained. Wear of the sliding contact portion between them can be suppressed as much as possible.

[0023]

[Effect of the Invention] As described above, according to the present invention, a male low
Peak of and compression ratio variable with different outer diameters of the motor and the female rotor
When the stone has a circular cross section and is almost perpendicular to the rotor axis
Screw pump with a structure to move
Here, the piston is disposed on the housing with its axis arranged in a direction substantially perpendicular to the common tangent line of the first and second inner surfaces in a plane perpendicular to the axis of both rotors. The heights of the first and second inner end surfaces along the inner surface are substantially equal to each other, and the rotational moment acting on the piston can be suppressed to a small value to prevent displacement of the piston around the axis.
Use a non-rotating locating pin to guide the piston movement
Even when the screw is located, the wear between the positioning pin and the piston can be suppressed.
The technical problems specific to the mold pump can be solved. Further
By making the heights of the first and second inner end faces approximately equal,
Since the pressure from both rotors is applied to both inner end surfaces almost uniformly,
The piston can be moved smoothly along its axis.
Wear.

[Brief description of the drawings]

FIG. 1 is a cutaway longitudinal side view of a screw pump.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is an explanatory diagram showing a positional relationship between a piston and a housing.

FIG. 5 is an explanatory diagram showing a positional relationship between a piston and a housing according to the related art.

[Explanation of symbols]

6 housing 7 male rotor 8 female rotor 9b first inner surface 9c second inner surface 31 the piston 31b first inner end face 31c second inner end surface 32 moving direction L _C axis L _T tangent P _G meshing starting position SP screw pump

Claims (1)

(57) [Scope of request for utility model registration] 1. A male mold which meshes with each other and has different outer diameters.
The rotor (7) and the female rotor (8 )
A housing (6) having an inner surface with a cross-sectional shape formed by connecting an arc-shaped first inner surface (9b) opposed to the inner surface and a second arc-shaped inner surface (9c) opposed to the female rotor (8).
Each of the rotors (7, 8) is supported rotatably.
A piston (31) having a circular cross section having an axis (L _C ) passing through the engagement start position (P _G ) of the rotors (7, 8) at a position corresponding to the engagement portion of The piston (7, 8) is movably disposed between a high compression position on the inner side and a low compression position on the outer side along a movement direction (32) substantially orthogonal to the axis of the rotor (7, 8). 31), the piston (3) is provided at the inner end along the movement direction (32).
The first inner end surface (31b) and the second inner surface (9c) which are substantially continuous with the first inner surface (9b) when 1) is at the high compression position.
Substantially continuous second inner end surface (31c) A screw pump provided the said piston (31), first and second inner surfaces (9b in a plane perpendicular to the axis of the rotors (7,8) to , 9c)
The axis (L _C ) in a direction substantially perpendicular to the common tangent (L _T )
The screw pump according to claim 1, wherein the screw pump is disposed on the housing (6).