JP2017036667A - Screw pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw pump improved in reliability of a sliding portion by reducing sliding loss and abrasion caused by eccentricity of a screw.SOLUTION: A screw pump 101 includes a male screw 4, a female screw 5, a motor 6, a receiving plate 12, a journal 7, a bearing member 8 and a case 2. The bearing 8 has a cylindrical main body portion rotatably supporting the journal 7. The case 2 has a case hole 21 accommodating the male screw 4 and the female screw 5, and a bearing accommodating portion 223 for accommodating the bearing member 8. In pressure-feeding a fluid, the bearing member 8 is disposed on an eccentric position eccentric to the journal 7, at a side opposite to a direction of movement of the journal 7 when the journal 7 receives force in a radial direction generating from a rear part to a front part in a rotating direction of the male screw 4 in a plane orthogonal to an axial direction of a rotating shaft P.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a screw pump that pumps fluid by rotation of a screw.

  2. Description of the Related Art Conventionally, a fluid pump that pumps fluid by rotationally driving an impeller or the like is known. For example, the water pump disclosed in Patent Document 1 rotates the impeller attached to the rotor of the electric motor by rotating the electric motor, and pumps the cooling water. Both ends of the rotor in the axial direction are supported by the casing so as to be rotatable via a dynamic pressure bearing.

JP 2003-328986 A

  When the cooling water is pumped by the water pump described in Patent Document 1, the pressure of the cooling water acts on the impeller, so that the rotor connected to the impeller is eccentric from the shaft center. Therefore, there is a possibility that the cooling water flows backward due to a gap between the impeller and the case in the pump unit, or the impeller contacts the case and the sliding loss increases.

  The above problem is not limited to the impeller pump, and the same applies to a screw pump that pumps fluid by rotating while a male screw and a female screw mesh with each other. In the screw pump, a journal bearing is integrally disposed between the output shaft of the driving means and the male screw connected to the output shaft. The tip of the male screw opposite to the output shaft is supported in point contact with a receiving plate provided on the lower cover.

  In such a meshing portion of the male screw and the female screw, at the same axial height of the case in which the screw is accommodated, the pressure of the fluid flowing in the groove portion at the rear in the rotational direction is higher than the pressure of the fluid flowing in the groove portion at the front in the rotational direction. Get higher. Due to such pressure distribution, a force acts on the male screw so as to be pressed from the high pressure side to the low pressure side in the case. In order to bear this force by the oil film reaction force between the bearing and the journal, the journal follows the male screw and is eccentric with respect to the bearing.

  However, when the screw is eccentric with respect to the case as described above, there is a problem that leakage occurs in the pump part, or sliding loss and wear increase, as in the impeller pump.

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a screw pump that improves the reliability of the sliding portion by reducing sliding loss and wear due to eccentricity of the screw. There is to do.

  The screw pump of the present invention is rotated by meshing one drive side screw constituted by one of the male screw or the female screw and one or more driven side screws constituted by the other of the male screw or the female screw, A screw pump that pumps fluid from a low-pressure side suction port to a high-pressure side discharge port.

  The screw pump includes a drive-side screw, a driven-side screw, drive means, a receiving plate, a journal, a bearing member, and a case. The drive means has an output shaft through which torque is transmitted to the drive side screw, and the drive side screw can be driven to rotate via the output shaft.

  The receiving plate is disposed so as to be orthogonal to the rotation axis on the leading end side of the driving side screw and the driven side screw, and rotatably supports the leading end of the driving side screw and the leading end of the driven side screw. The journal is rotatably provided integrally between the output shaft of the drive means and the drive side screw.

  The bearing member has a cylindrical main body that rotatably supports the journal. The case has a screw accommodating hole for accommodating the driving side screw and the driven side screw, and a bearing accommodating portion for accommodating the bearing member.

  During fluid pumping, the bearing member moves in a plane perpendicular to the axial direction of the rotating shaft when the journal receives a radial force generated from the rear to the front in the rotational direction of the drive side screw. It is arranged at an eccentric position that is eccentric with respect to the journal, on the opposite side of the direction.

  According to this configuration, when the fluid is pumped, the bearing member side, not the journal, is set to the eccentric position, so that a wedge-shaped minimum oil film portion is formed between the journal and the bearing member. Thereby, an oil film supporting action sufficient as a slide bearing can be obtained. In addition, the journal is eccentric with respect to the bearing member, but the screw is not eccentric with respect to the screw receiving hole. For example, in a conventional screw pump, sliding loss and wear due to eccentricity of the screw with respect to the hole are caused. Reduced. Thereby, the reliability of a sliding part can be improved.

The whole block diagram of the fuel supply system with which the screw pump of FIG. 2 is applied. The schematic sectional drawing of the screw pump by 1st Embodiment of this invention. The III-III sectional view taken on the line of FIG. 2 at the time of pressure feeding. IV-IV sectional view taken on the line of FIG. It is a figure for demonstrating the principle of a slide bearing, Comprising: Sectional drawing which shows a journal, a bearing member, and a male screw typically. VI-VI sectional view taken on the line of FIG. The figure which plotted oil film pressure. The schematic sectional drawing of the screw pump by 2nd Embodiment of this invention. IX-IX sectional view taken on the line of FIG. The axial direction fragmentary sectional view of the screw pump by 3rd Embodiment of this invention. The schematic sectional drawing of the screw pump by 4th Embodiment of this invention. XII-XII sectional view taken on the line of FIG. The axial direction fragmentary sectional view of the screw pump by other embodiment.

Hereinafter, screw pumps according to a plurality of embodiments of the present invention will be described with reference to the drawings. In the plurality of embodiments, substantially the same configuration is denoted by the same reference numeral, and description thereof is omitted.
(First embodiment)
First, an overall configuration of a fuel supply system to which a screw pump according to an embodiment of the present invention is applied and a schematic configuration of the screw pump will be described with reference to FIGS.

  As shown in FIG. 1, a fuel supply system 90 includes a liquid level sensor 92, a suction filter 93, a screw pump 101, a fuel filter (indicated as “F / F” in the figure) 94 provided in a fuel tank 91, It includes a pressure regulator 95 and a high-pressure pump 96, a fuel injection device 97, etc. provided in the vicinity of the engine 98 (denoted as “E / G” in the figure). To supply.

  The screw pump 101 sucks the fuel F in the fuel tank 91 filtered by the suction filter 93 from the suction port 11, raises the pressure thereof, and discharges the fuel F from the discharge port 32. The discharged fuel F is pumped to the high pressure pump 96 via the fuel filter 94. Further, the fuel F is returned to the fuel tank 91 through the pressure regulator 95 provided in the branch path after the fuel filter 94, so that the discharge pressure is adjusted.

  The high-pressure pump 96 further increases the pressure of the fuel pumped from the screw pump 101 and pumps it to the fuel injection device 97. The fuel injection device 97 includes a fuel injection valve (injector) and a control device that controls the fuel injection. The fuel injection device 97 injects high-pressure fuel into a cylinder of the engine 98 and an intake passage. As described above, the screw pump 101 of the present embodiment is provided in the fuel tank 91 in the fuel supply system 90 and plays a role conventionally performed by, for example, an impeller-type fuel pump.

  As shown in FIG. 2, the screw pump 101 includes a lower cover 1, a receiving plate 12, a case 201, an upper cover 3, a male screw 4 and a female screw 5, a motor 6 as a “driving means”, a journal 7, a bearing member 8, and the like. . In the present embodiment, the male screw 4 corresponds to a “drive-side screw” connected to the output shaft 64 of the motor 6, and the female screw 5 that is driven while meshing with the male screw 4 corresponds to a “driven-side screw”.

  In the present embodiment, the male screw 4 is driven to rotate about a rotation axis P in a rotation direction Rm (see FIG. 4) that is counterclockwise when viewed from the motor 6 side. Following this, the female screw 5 rotates around the rotation axis Q in a rotation direction Rf (see FIG. 4) which is a clockwise direction when viewed from the motor 6 side.

  The male screw 4 has a crest that is narrower than the groove, and the female screw 5 has a crest that is wider than the groove. The mountain portion of the female screw 5 meshes with the groove portion of the male screw 4. In the present embodiment, the male screw 4 is composed of a double thread screw, and the female screw 5 is composed of a triple thread screw.

  As the male screw 4 and the female screw 5 rotate while meshing with each other, the screw pump 101 boosts the low-pressure fuel sucked from the suction port 11 and discharges it from the discharge port 32. Hereinafter, as a reference for one side and the other side of the screw pump 101 in the axial direction, the lower side in FIG. 1 is referred to as “suction port 11 side”, and the upper side in FIG. 1 is referred to as “discharge port 32 side”. From the viewpoint of fuel pressure, the suction port 11 side corresponds to the “low pressure side” and the discharge port 32 side corresponds to the “high pressure side”.

  The lower cover 1 has an inlet 11 at one end, and a receiving plate 12 is provided between the case 201 and the inlet 11. The receiving plate 12 is formed with a suction passage (not shown) that connects the suction port 11 and the case hole 21.

  The receiving plate 12 is arranged on the front end side of the male screw 4 and the female screw 5 so as to be orthogonal to the rotation axes P and Q. The receiving plate 12 supports both the tip 41 of the male screw 4 and the tip 51 of the female screw 5. The distal end 41 of the male screw 4 and the distal end 51 of the female screw 5 are formed in a conical protrusion shape, and are in point contact with the surface of the receiving plate 12.

  The case 201 has a case hole 21 that penetrates in the axial direction and serves as a screw accommodation hole that accommodates the male screw 4 and the female screw 5. In the radial cross section shown in FIG. 4, the case hole 21 has a shape in which a portion that accommodates the male screw 4 and a portion that accommodates the female screw 5 are connected in a dharma shape. Here, a virtual plane corresponding to a dharma-shaped symmetry plane is defined as a “reference plane V”. The male screw 4 and the female screw 5 are meshed with each other at a meshing portion 50 between the rotation shaft P and the rotation shaft Q. In an ideal state where the male screw 4 and the female screw 5 are not inclined, the rotation axis P of the male screw 4 and the rotation axis Q of the female screw 5 are included in the reference plane V.

  Referring to FIG. 2 again, the bearing housing portion 23 is recessed in the end surface 34 of the case 201 on the motor 6 side. A communication passage (not shown) that connects the case hole 21 and the discharge chamber 31 in the upper cover 3 is formed at a location different from the bearing housing portion 23.

  The upper cover 3 is formed with a discharge chamber 31 in which fuel pressure-fed from the communication path is accommodated, and a discharge port 32 for discharging fuel from the discharge chamber 31 to the outside. A motor 6 is installed inside the upper cover 3.

  The motor 6 includes a stator 62 in which a coil 61 is wound to generate a rotating magnetic field, and a permanent magnet N-pole and S-pole are alternately arranged in the circumferential direction, and a rotor 63 that rotates according to the rotating magnetic field generated by the stator 62. And have. An end portion 65 on the discharge port 32 side of the shaft of the rotor 63 is rotatably supported by the shaft holding portion 33 of the upper cover 3. The end of the rotor 63 shaft on the inlet 11 side is connected to the journal 7 as an “output shaft 64”.

  The journal 7 is rotatably provided between the output shaft 64 of the motor 6 and the male screw 4. The torque of the motor 6 is transmitted from the output shaft 64 to the male screw 4 via the journal 7.

  The bearing member 8 is accommodated in the bearing accommodating part 23, and supports the journal 7 rotatably. The bearing member 8 is supported by the case 201 by the support pin 10 so as to be slightly rotatable in a plane orthogonal to the axial direction. As shown in FIG. 3, the bearing member 8 can be rotated within a range shown by a broken line and a solid line by the action of a differential pressure chamber 24 to be described later. In FIG. 3, the bearing member 8 is rotated during pressure feeding. The direction Rb is counterclockwise. FIG. 3 shows a state in which the bearing member 8 is in an eccentric position that is eccentric with respect to the center Oj of the journal 7 during pressure feeding. That is, the center Oj of the journal 7 and the center Ob of the bearing member 8 do not coincide. Details of the eccentric position will be described later.

  The bearing member 8 includes a main body 81 having a cylindrical shape, and a protrusion 82 provided to protrude radially outward from the main body 81. The protruding portion 82 has a shape in which the protruding tip is gently curved, and the tip is formed as a seal portion 83 that forms a point seal with the bearing housing portion 23. Further, the bearing member 8 includes a low-pressure receiving surface portion 84 that is on the rotation direction side among the side surface portions that extend in the protruding direction, and a high-pressure receiving surface portion 85 that is on the opposite side to the rotation direction among the side surface portions extending in the protruding direction. Have.

  The case 201 is formed with a differential pressure chamber 24 that rotatably accommodates the protruding portion 82. The differential pressure chamber 24 is partitioned by the seal portion 83 into a suction pressure chamber 25 and a discharge pressure chamber 26 during pressure feeding. The suction pressure chamber 25 is a room on the low pressure receiving surface portion 84 side, and communicates with the suction port 11 via the lower communication hole 27 (see FIG. 2) and the low pressure side portion of the case hole 21. Further, the stopper portion 29 that restricts the rotation of the protruding portion 82 is formed in the case 201 in the suction pressure chamber 25 so as to protrude in the circumferential direction opposite to the low pressure receiving surface portion 84, that is, the rotation direction Rb. The stopper portion 29 abuts on the protruding portion 82 when the protruding portion 82 rotates, and restricts the rotation of the protruding portion 82.

  The lower communication hole 27 is formed below the bearing member 8 in the case 201 and communicates with the case hole 21 at a lower position near the suction port 11. The discharge pressure chamber 26 communicates with the discharge port 32 via the discharge chamber 31 via the upper communication hole 28 (see FIG. 2) formed above the bearing member 8 in the case 201. The differential pressure chamber 24 shares a part of the bearing housing portion 23.

  Next, the radial force (hereinafter referred to as “radial force”) generated when the screw pump 101 is pumping fuel will be described. As shown in FIG. 4, in the meshing portion 50 of the male screw 4 and the female screw 5, the lower side of the figure is the front in the rotational direction and the upper side of the figure is the rear of the rotational direction with respect to the reference plane V. At the same height in the axial direction, the pressure of the fuel flowing in the groove portion at the rear in the rotational direction becomes higher than the pressure of the fuel flowing in the groove portion at the front in the rotational direction, and the meshing portion 50 is radial from the rear in the rotational direction to the front. A force Fr is generated.

  Further, since the pressure on the suction side is relatively low and the pressure on the discharge side is relatively high during fuel pumping, the radial force Fr increases as it approaches the discharge port 32 side. Due to such pressure distribution, the male screw 4 tends to move in a direction in which the male screw 4 is pressed from the near side to the far side in FIG. Similarly, the female screw 5 also tries to move in a direction in which the female screw 5 is pressed from the near side to the far side in FIG. The force acting on the male screw 4 is transmitted to the journal 7 and is mainly supported by the bearing member 8.

  Next, a general principle of the slide bearing will be described with reference to FIGS. Since the journal 7 has an integral structure with the male screw 4, the force acting on the male screw 4 acts on the journal 7 in the same manner. In FIG. 6, the outer diameter of the bearing member 8 is omitted. As the journal 7 rotates in the rotation direction Rm within the bearing member 8, a wedge-shaped oil film is formed over the minimum oil film portion 70 as shown in FIG. The oil film reaction force F1 is generated by the oil film pressure. This is the same magnitude as the force F2 acting on the journal 7 and in the opposite direction. Further, the journal 7 moves in the rotational direction Rm while moving in the direction of the acting force F1, and is eccentric by the eccentric angle Φ.

  The wedge-shaped oil film pressure can be illustrated as shown in FIG. In FIG. 7, the oil film up to an angle of 360 degrees in the rotational direction Rm is defined with the base point where the straight line connecting the center Ob of the bearing member 8 and the center Oj of the journal 7 in FIG. The magnitude of the pressure is schematically illustrated. The angle 180 degrees coincides with the minimum oil film portion 70, and the oil film reaction force becomes zero in a region where the angle is greater than 180 degrees. This pressure distribution is based on Gümbel boundary conditions.

  The “direction in which the journal tries to move when the journal receives a radial force” described in “Claims” is the direction indicated by the arrow A in FIG. The bearing member 8 at the time of pumping is configured to be eccentric to the arrow B side opposite to the arrow A. As shown in FIG. 3, the position where the bearing member 8 is eccentrically arranged on the arrow B side corresponds to the “eccentric position” described in “Claims”.

[effect]
(1) In the first embodiment, at the time of pressure feeding, the bearing member 8 rotates about the support pin 10 in the rotation direction Rb shown in FIG. 3 due to the differential pressure between the suction pressure and the discharge pressure, and the journal 7 is the bearing. It becomes an eccentric state with respect to the member 8, and a sufficient oil film supporting action as a slide bearing is obtained. Further, since the journal 7 is eccentric with respect to the bearing member 8 but the screws 4 and 5 and the case hole 21 are coaxial, for example, in a conventional screw pump, the sliding loss due to the eccentricity of the screw with respect to the case hole. And wear is reduced. Thereby, the reliability of a sliding part can be improved.

  (2) In the first embodiment, when no differential pressure is generated at the time of stopping and starting, the bearing member 8 can be rotated around the support pin 10, and therefore, between the bearing member 8 and the journal 7, the screw and the case. A gap between the holes 21 is secured. That is, since the bearing member 8 is in a free state, the sliding resistance can be reduced and the bearing member 8 can be started with light torque.

  (3) In the first embodiment, since the stopper portion 29 is formed, the suction pressure chamber 25 can be reliably communicated with the suction port 11 of the low-pressure side pressure even after the bearing member 8 rotates during the pressure feeding. . As a result, a sufficient differential pressure can always be maintained, and a force capable of rotating the bearing member 8 can be easily obtained, so that the bearing member 8 can be made compact.

(Second Embodiment)
Next, the screw pump 102 of 2nd Embodiment of this invention is demonstrated with reference to FIG. 8, FIG. The screw pump 102 of the second embodiment is mainly different from the first embodiment in that the differential pressure chamber 24 is not provided. Accordingly, neither the lower communication hole 27 nor the upper communication hole 28 is provided. Further, the bearing member 80 of the second embodiment has a normal cylindrical shape, and does not have the protruding portion 82 as in the first embodiment.

  As shown in FIG. 9, a compression coil spring 71 as an urging member is provided at a position that is substantially point-symmetric with respect to the support pin 10 and the center Oj in the bearing housing portion 232 of the case 202. By this compression coil spring 71, the bearing member 80 is biased so as to be in an eccentric position eccentric from the center Oj of the journal 7.

  In the second embodiment, the journal 7 is always eccentric with respect to the bearing member 80. At the time of pressure feeding, as in the first embodiment, a sufficient oil film supporting action as a slide bearing can be obtained while ensuring the coaxiality between the screws 4 and 5 and the case hole 21.

(Third embodiment)
Next, the screw pump of 3rd Embodiment of this invention is demonstrated with reference to FIG. The third embodiment is different from the first embodiment in that the means for rotating the bearing member 8 is not based on the pressure difference between the discharge pressure and the suction pressure, and the electromagnet 72 and the permanent magnet 73 are used to turn the bearing on and off. The difference is that the member 8 is rotationally controlled by electromagnetic force.

  As shown in FIG. 10, an electromagnet 72 is provided in the housing portion 231 in which the protruding portion 82 is housed in the bearing housing portion 233 of the case 203. A permanent magnet 73 is provided at a position that is the protruding portion 82 and faces the electromagnet 72. The electromagnet 72 and the permanent magnet 73 are provided on the rotation direction Rb side of the protrusion 82. Since the differential pressure chamber 24 does not need to be provided, an overall view of the screw pump 103 is omitted, but the lower communication hole 27 and the upper communication hole 28 are unnecessary.

  In the third embodiment, at the time of stopping and starting up, the current of the electromagnet 72 is turned off, so that the bearing member 8 can be rotated freely. On the other hand, at the time of pumping, by turning on the current, the permanent magnet 73 is attracted to the electromagnet 72, and the bearing member 8 is rotated in the rotation direction Rb to be an eccentric position. As described above, the effects (1) and (2) of the first embodiment are exhibited in common. The electromagnet 72 and the permanent magnet 73 of the present embodiment correspond to the “biasing member” described in “Claims”.

(Fourth embodiment)
Next, the screw pump 104 of 4th Embodiment of this invention is demonstrated with reference to FIG. 11, FIG. The fourth embodiment is different from the second embodiment in that the screws 4, 5, the journal 7, the inner surface of the case hole 214 of the case 204, and the inner surface of the bearing member 804 are inclined. The point that the bearing member 804 is eccentric with respect to the journal 7 is the same as in the second embodiment.

  As shown in FIG. 12, when the horizontal plane of the receiving plate 12 is a reference plane S, the angle θb of the inner surface of the bearing member 804 with respect to the reference plane S, the angle θsc of the rotation axis P of the screw 4 with respect to the reference plane S, and the case hole 214 The angles θc with respect to the reference plane S of the inner surface are both less than 90 degrees and the same angle.

  When the differential pressure between the discharge pressure and the suction pressure is large and a downward thrust force acts from the discharge port 32 side toward the suction port 11 side, the male screw is shown with the tips 41 and 51 on the receiving plate 12 side as fulcrums. 11 on the rear side of the paper (direction of force F3 shown in FIG. 12). The fourth embodiment is characterized in that the inner surfaces of the screws 4 and 5, the journal 7, the case hole 214, and the bearing member 804 are inclined in advance toward the force F <b> 3 side where the male screw 4 tends to fall.

  For example, when the angle θb = θsc = θc = 90 degrees, there is a concern that the thickness of the oil film is not uniform in the axial direction, and the force for supporting the journal 7 by the oil film is smaller than when the oil film is uniform. Furthermore, there is a concern that leakage increases because the axial gap between the case hole 214 and the screws 4 and 5 is not uniform.

  In this respect, in the present embodiment, even when a thrust force is exerted greatly, the thickness of the oil film and the gap with the case hole 214 can be made uniform in the axial direction, thereby improving the reliability of the sliding portion. be able to. The configuration of the first embodiment or the third embodiment may be adopted as the configuration of the bearing member and the case hole for making the bearing member 804 eccentric with respect to the journal 7.

<Other embodiments>
In the first embodiment, the suction pressure chamber 25 communicates with the lower portion of the case hole 21 through the lower communication hole 27. However, the suction pressure chamber 25 may be directly communicated with the suction port 11 through the lower cover 1, for example. The point is that the suction pressure chamber 25 only needs to communicate with the location of the low-pressure side pressure, and the opening position of the lower communication hole 27 in the case hole 21 is slightly above that described in the first embodiment. Also good. Similarly, the discharge pressure chamber 26 only needs to communicate with the location of the high pressure side pressure, and the form of the upper communication hole 28 can be variously changed.

  In the first embodiment, the bearing member 8 is configured as a single body. However, after first forming the cylindrical main body 810 like the bearing member 800 shown in FIG. 13 and digging the groove 811 in the main body 810, It is good also as what is comprised by pushing in the protrusion part 820 as another member.

  In the second embodiment, the installation position of the compression coil spring 71 in the bearing housing portion 232 may be any other position as long as the bearing member 80 can be urged toward the eccentric position with the support pin 10 as a fulcrum.

  The screw pump of the said embodiment is provided with one drive side screw and one driven side screw. In another form, it is good also as a structure provided with several driven side screws around the circumference | surroundings of one driving side screw.

  Contrary to the above-described embodiment, the female screw 5 may be a driving screw and the male screw 4 may be a driven screw.

  In addition to the electric motor 6, the drive means may use a rotary actuator that uses hydraulic pressure, air pressure or the like as a power source. Further, the driving means may be provided outside the upper cover.

  Regarding the configuration of the screw pump other than the bearing member and the case, which is a characteristic part of the present invention, the shape, arrangement, quantity, and the like may be changed as appropriate with respect to the above embodiment.

  The fluid to which the screw pump of the present invention is applied is not limited to fuel, but may be applied to liquids other than fuel and gases such as air.

  As mentioned above, this invention is not limited to the said embodiment at all, In the range which does not deviate from the meaning of invention, it can implement with a various form.

101, 102, 103, 104 ... Screw pumps 201, 202, 203, 204 ... Case 4 ... Male screw (drive side screw)
5 ... Female screw (driven screw)
6 ... Motor (drive means)
7 ... Journal 8, 80, 804 ... Bearing member 12 ... Receiving plate 21, 214 ... Case hole (screw accommodating hole)
23, 232, 233, bearing housing 25, suction pressure chamber 26, discharge pressure chamber 71, spring (biasing member)
72 ... Electromagnet (biasing member)
73 ... Permanent magnet (biasing member)
81 ・ ・ ・ Body part 82 ・ ・ ・ Projecting part

Claims (5)

When one driving side screw constituted by one of the male screw (4) or the female screw (5) and one or more driven side screws constituted by the other of the male screw or the female screw rotate while meshing with each other. A screw pump for pumping fluid from the low pressure side suction port (11) to the high pressure side discharge port (32),
The drive side screw;
The driven screw;
Drive means (6) having an output shaft (64) through which torque is transmitted to the drive-side screw, and capable of rotationally driving the drive-side screw via the output shaft;
The drive side screw and the driven side screw are arranged so as to be orthogonal to the rotation shafts (P, Q) on the front end side of the driven side screw, and the front end (41) of the drive side screw and the front end (51) of the driven side screw are arranged. A backing plate (12) that is rotatably supported;
A journal (7) provided to be integrally rotatable between the output shaft of the drive means and the drive side screw;
A bearing member (8, 80, 804) having a cylindrical main body (81) for rotatably supporting the journal;
A case (201, 202, 203) having a screw accommodation hole (21, 214) for accommodating the drive side screw and the driven side screw, and a bearing accommodation portion (23, 232, 233) for accommodating the bearing member. 204)
With
At the time of fluid pressure feeding, the bearing member receives a radial force generated from the rear to the front in the rotational direction of the drive side screw in a plane perpendicular to the axial direction of the rotary shaft. A screw pump, wherein the screw pump is arranged at an eccentric position that is eccentric with respect to the journal, on a side opposite to a direction in which the journal is to move. The bearing member is
It is supported by the case so as to be rotatable in a plane perpendicular to the axial direction,
A seal part (83) which is formed to project outward in the diameter direction of the main body part and forms a seal with the case at the projecting tip, and a low pressure receiving surface part (84) on the eccentric position side among side parts extending in the projecting direction. ) And a high-pressure receiving surface portion (85) on the side opposite to the eccentric position among the side surface portions extending in the protruding direction, and the suction pressure communicating with the suction port between the low-pressure receiving surface portion and the case A protrusion (82) forming a chamber (25) and forming a discharge pressure chamber (26) communicating with the discharge port between the high pressure receiving surface portion and the case;
The screw pump according to claim 1, further comprising:   The screw pump according to claim 2, wherein the suction pressure chamber communicates with the suction port via a portion near the discharge port of the screw housing hole.   The suction pressure chamber further includes a stopper portion (29) that protrudes in the circumferential direction toward the low-pressure receiving surface portion and is formed in the case, and abuts against the protrusion when the protrusion rotates. The screw pump according to claim 2 or claim 3.   The screw pump according to claim 1, further comprising a biasing member (71, 72, 73) for biasing the bearing member toward the eccentric position.

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