JP6661529B2 - Trochoid pump - Google Patents

Description

  The present invention relates to a trochoid pump used as various pumps such as an oil pump for an industrial diesel engine.

  The trochoid pump rotates the inner rotor and the outer rotor simultaneously while the outer teeth of the inner rotor and the inner teeth of the outer rotor are in mesh with each other. (Pressure fluid). The inner rotor and the outer rotor have different axes, and are pumps that can change the volume thereof, and are known, for example, from Patent Document 1.

  The inner rotor and the outer rotor are eccentric to each other and have different numbers of teeth, so that a volume change between each rotor due to a compression change and an expansion change is enabled. Due to the volume change, the pump target fluid sucked from the suction port is compressed, and the high pressure pump target fluid is discharged from the discharge port.

  The loss in the trochoid pump is dominated by frictional resistance as friction, and when applied to an engine, tends to be consumed to a considerable extent with respect to the torque generated by the engine. For example, in a conventional trochoid pump, there is a portion where the inner rotor and the outer rotor are in direct sliding contact (metal touch) with the pump casing.

  Therefore, when making a new trochoid pump, it was an important issue how to reduce the frictional resistance at the sliding portion.

JP 2006-250104 A

  An object of the present invention is to provide a trochoid pump in which attention is paid to a sliding portion between an inner rotor or an outer rotor and a pump casing, and the frictional resistance at the sliding portion is further reduced.

The invention according to claim 1 is a trochoid pump,
A pump casing 1 in which a cylindrical housing space 2 is formed;
An outer rotor 3 having internal teeth 4 and rotatably fitted in the housing space 2;
An inner rotor 5 having outer teeth 6 meshing with the inner teeth 4 and rotatably disposed in the outer rotor 3;
A suction port 7 and a discharge port 8 formed in the pump casing 1 so as to open into the housing space 2;
The pump casing 1 includes a main casing 1A in which the outer rotor 3 is rotatably accommodated, and a cover casing 1B that covers an opening 1a of the main casing 1A, and is relatively fixed.
The suction port 7 and the discharge port 8 are formed in the cover casing 1B,
A pump shaft 9 pivotally supported by the pump casing 1 to drive and rotate the inner rotor 5;
The inner rotor 5 is configured to be pressed against the cover casing 1B due to a structure in which the pump shaft 9 is driven to rotate,
A groove or recess m in which the lower side in the relative rotation direction is open is formed on the rotor side surface 5S on the cover casing side of the inner rotor 5 or the case inner surface 18a in contact with the rotor side surface 5S on the cover casing 1B. Features.

The invention according to claim 2 is the trochoid pump according to claim 1,
The width h of the groove or the concave portion m is formed to be wider toward the lower side in the relative rotation direction of the rotor side surface 5S or the case inner surface 18a where the groove or the concave portion m is formed.

The invention according to claim 3 is the trochoid pump according to claim 1 or 2,
The depth t of the groove or the recess m is formed to be deeper toward the lower side in the relative rotation direction of the rotor side surface 5S or the case inner surface 18a where the groove or the recess m is formed.

The invention according to claim 4, Te trochoid pump smell according to any one of claims 1 to 3,
The groove or the recess m is formed on a rotor side surface 5S of the inner rotor 5.

The invention according to claim 5 is a trochoid pump according to any one of claims 1 to 4,
A groove or recess 1m is formed in a portion between the suction port 7 and the discharge port 8 on the inner surface 18a of the case where the suction port 7 and the discharge port 8 are formed so as to open to the suction port 7. It is characterized by having been done.

The invention according to claim 6 provides the trochoid pump according to any one of claims 1 to 5,
The groove or recess m, 1m is formed in a state where the upper side in the relative rotation direction is closed.

According to the present invention, since the groove or the concave portion in which the lower side in the relative rotation direction is opened is provided on the rotor side surface on the cover casing side of the inner rotor or the case inner surface of the cover casing , the housing is rotated by the pump drive. The pump target fluid taken into the groove or the recess from the space, the suction, and the discharge ports is smoothly supplied between the rotor side surface and the case inner surface.
As a result, a trochoid pump is provided which focuses on the sliding portion between the inner rotor or the outer rotor and the pump casing, and is provided with a groove or a concave portion by simple modification to further reduce the frictional resistance at the sliding portion. be able to.

Back view of trochoid pump AA sectional drawing of FIG. 1 which shows the structure of a trochoid pump. Rear view showing main casing Front view showing cover casing FIG. 5A is a cross-sectional view taken along the line BB of FIG. 5A showing the cross-sectional shape of the groove of the inner rotor. EE sectional view of FIG. 4 showing the groove of the cover casing.

  Hereinafter, an embodiment of a trochoid pump according to the present invention will be described with reference to the drawings as an oil pump mounted on an industrial diesel engine such as an agricultural machine or a construction machine.

  FIGS. 1 and 2 show an oil pump P composed of a trochoid pump. The oil pump P includes a pump casing 1 in which a cylindrical housing space 2 is formed, an outer rotor 3 having internal teeth 4 and rotatably fitted in the housing space 2, and external teeth 6 meshing with the internal teeth 4. It has an inner rotor 5 provided rotatably in the outer rotor 3, and a suction port 7 and a discharge port 8 formed in the pump casing 1 so as to open into the accommodation space 2.

  As shown in FIGS. 1 to 3, the outer rotor 3 is rotatably accommodated in the accommodation space 2 in a state where the outer peripheral surface 3 a is fitted inside the inner peripheral surface 10 </ b> A (described later). It is configured to be able to rotate to the center. Five inner teeth 4 protruding toward the outer rotor axis X and five inward tooth valleys 4a formed between the circumferentially adjacent inner teeth 4 are formed radially inward of the outer rotor 3. Have been. The internal teeth 4 and the inward tooth valleys 4a are formed at equal intervals around the outer rotor axis X.

  As shown in FIGS. 1 to 3, a pump shaft (drive shaft) 9 rotatably supported by the pump casing 1 is provided in a center hole 5 a of the inner rotor 5, for example, a connection pin 15 (see FIG. 2). It is equipped with an inner fitting in an integrally rotating state by using. On the radially outer side of the inner rotor 5, four external teeth 6 protruding radially outward with respect to the pump axis Y, and outward tooth valleys 6a formed between the external teeth 6, 6 adjacent in the circumferential direction. Four are formed. The external teeth 6 and the outward tooth valleys 6a are formed at equal intervals around the pump axis Y.

  As shown in FIGS. 1 to 3, in a state where the five internal teeth 4 of the outer rotor 3 and the four external teeth 6 of the inner rotor 5 are engaged with each other, the inner rotor 5 is provided in the outer rotor 3 and Is housed. The outer rotor 3 and the inner rotor 5 having different axes X and Y have the same width (thickness).

  Here, the movement of the oil pump P will be briefly described. When the pump shaft 9 is driven and rotated to rotate the inner rotor 5 around the pump axis Y in the direction of arrow Z (see FIG. 1), the outer rotor 3 meshing with this 5 is also rotated. It is rotated around the outer rotor axis X. Then, engine oil (an example of a fluid to be pumped) is sucked into the expansion space a between the outer rotor 3 and the inner rotor 5 from the suction port 7. The sucked engine oil is discharged from the compression space b between the outer rotor 3 and the inner rotor 5 to the discharge port 8 this time.

  As shown in FIGS. 1 to 4, the pump casing 1 includes an outer rotor insertion opening 1 a and a main casing 1 A in which the outer rotor 3 is rotatably accommodated, and covers the opening 1 a of the main casing 1 A. The cover casing 1B, which can be assembled to the main casing 1A in this state, is relatively fixed in a spigot fitting state.

  As shown in FIGS. 1 to 3, the main casing 1 </ b> A has an outer peripheral wall 10 having an inner peripheral surface 10 </ b> A having the outer rotor axis X as a virtual axis, and a shaft support hole 12 centering on the pump axis Y. And a side wall 11 having an inner side surface 11a, and is made of a metal material such as an aluminum alloy or a casting. The inner peripheral surface 10A of the outer peripheral wall 10 has a depth that is slightly longer than the width (thickness) of the outer rotor 3, and the distal end thereof is formed in the outer spigot portion 13 forming the opening 1a. Further, an outer side surface 14 having a side peripheral surface shape is formed at a tip of the outer peripheral wall 10.

  As shown in FIGS. 1, 2, and 4, the cover casing 1 </ b> B includes an aluminum alloy including a shaft support hole 19 centered on the pump axis Y and a protruding cylindrical portion 18 centered on the outer rotor axis X. And a metal material such as a steel plate. The protruding cylindrical portion 18 includes a circular side surface 18 a that forms the accommodation space 2, and an inner spigot portion 16 that is a fitting outer peripheral surface that fits inside the outer spigot portion 13. A bonding surface 17 that contacts the outer surface 14 is formed on the radially outer side of the protruding cylindrical portion 18.

As shown in FIG. 2, the main casing 1A and the cover casing 1B are relatively fixed by a plurality of bolts (not shown) in a spigot state in which the projecting cylindrical portion 18 and the inner peripheral surface 10A are fitted. More specifically, the fitting portion k in which the inner spigot portion 16 and the outer spigot portion 13 are spigot-fitted is assembled, and the accommodation space 2 is formed by such an uneven fitting structure. Is formed.
As shown by phantom lines in FIG. 2, a cover casing 1 </ b> B made of a flat plate having a uniform thickness at the protruding columnar portion 18 and an inner peripheral surface having the same depth as the width (thickness) of the outer rotor 3. The pump casing 1 may be composed of a main casing having 10A.

  As shown in FIG. 2, the pump shaft 9 has a mounting shaft portion 9a for externally fitting the inner rotor 5 with the connecting pin 15 so as to be integrally rotated, and a main bearing for rotatably supporting the shaft support hole 12 of the main casing 1A. A shaft portion 9b, a spline portion 9c at one end protruding outside from the pump casing 1, and the like are provided. The other end of the pump shaft 9 (corresponding to the end of the mounting shaft portion 9a) is formed in an end bearing shaft portion 9d rotatably supported by a shaft support hole 19 of the cover casing 1B. The pump shaft 9 has a pump shaft center Y, and rotational power is input by a spline portion 9c.

  As shown in FIGS. 1, 2, and 4, the suction port 7 and the discharge port 8 are formed radially inward of a fitting portion k into which the main casing 1 </ b> A and the cover casing 1 </ b> B fit. That is, the outer frame surfaces 7a, 8a of the suction port 7 opening to the expansion space a and the discharge port 8 opening to the compression space b are slightly smaller than the diameter Rk of the fitting portion k centered on the outer rotor axis X. It has diameters R7 and R8. Rk> R7, Rk> R8, and R7 = R8, but R7 ≠ R8 may be satisfied.

  As shown by phantom lines in FIGS. 1, 2, and 4, the suction port 7 and the discharge port 8 are arranged such that the outer frame surfaces 7a, 8a or their diameters R7, R8 are outside the diameter Rk of the fitting portion k. , A setting having a larger area may be adopted.

  Since the main casing 1A and the cover casing 1B are relatively fixed in the spigot fitting state including the fitting portion k, in addition to the outer surface 14 and the joining surface 17 being in surface contact, the inner and outer The parts 16 and 13 are configured to be fitted. Therefore, compared with the conventional structure in which only the outer surface 14 and the joint surface 17 are in contact with each other, the sealing performance of the joint between the main casing 1A and the cover casing 1B is improved, and the engine oil may leak from the joint. There is an effect of being suppressed or reduced.

  As shown in FIGS. 1 and 2, if the suction port 7 and the discharge port 8 are formed within the diameter of the fitting portion k, the fitting portion k is formed by the inner and outer spigot portions 16 and 13 all around. It becomes a structure to fit. Therefore, since the ports 7 and 8 are not formed so as to cross the joint portion between the main casing 1A and the cover casing 1B, the sealing property of the joint portion is further improved, and the above-described effect of suppressing engine oil leakage is reduced. The advantage is further enhanced.

The diameter of the fitting portion k is set to the same diameter as the inner peripheral surface 10A of the main casing 1A in which the outer rotor 3 is internally fitted, and the processing of the inner peripheral surface 10A can be extended. As compared with the case where the stepped structure is adopted, the structure can be simplified and the processing cost can be reduced, and the effect of promoting more rationalization can be obtained.
Further, it is also preferable that the suction port 7 and the discharge port 8 are formed in a cover casing 1B which is simple in shape and easy to process as compared with the main casing 1A.

Next, a friction reducing structure applied to the trochoid pump P will be described.
As shown in FIGS. 1 to 3, a groove (or concave portion) m in which the lower side in the relative rotation direction is open is formed on the rotor side surface 5 </ b> S on the cover case side of the inner rotor 5. The grooves m are formed at a total of four positions for each of the four external teeth 6 in a state where the upper side in the relative rotation direction is closed (recessed state). The groove m can facilitate the pump target fluid (engine oil) to enter between the inner rotor 5 and the cover casing 1B as lubricating oil.

  As shown in FIGS. 5A and 5B, the width h and the depth t of the groove m having a substantially triangular shape correspond to the lower side in the relative rotation direction of the rotor side surface 5S, that is, the inner rotor 5. The lower side in the rotation direction (arrow Z: see FIG. 1) is wider and deeper. The groove m is formed to have a concave shape in an arc shape or an elliptical shape, but may have a V shape, a U shape, or a rectangular shape. The groove m opens in the lower outer peripheral surface (lower outer peripheral edge) 6s in the rotation direction of the external teeth 6, and does not open in the upper outer peripheral surface (upper outer peripheral edge) 6k in the rotation direction.

  The groove m is formed in a narrowing on the upper side (recessed state) in which the cross-sectional area becomes gradually smaller and finally becomes zero, so that the rotation of the inner rotor 5 causes the accommodation space 2, the suction port 7, and the discharge The engine oil taken into the groove m from the port 8 or the like is pressure-fed between the rotor side surface 5S and the side surface 18a, and an effect of promoting lubricating oil supply is obtained. Although not shown, the external teeth 6 may be formed so as to penetrate the rotor side surface 5S in a state of being narrowed on the upper side so that the groove m is also opened on the upper side in the rotation direction.

  As shown in FIGS. 1 and 4, a concave portion (or a recessed portion) that opens to the suction port 7 is provided in a portion between the suction port 7 and the discharge port 8 on the circular side surface 18 a that is the inner surface of the case of the cover casing 1 </ b> B. (Groove) 1 m is formed. As shown in FIG. 6, the substantially triangular recess 1m is formed in a recessed state in which the width and depth are narrower and shallower toward the upper side in the relative rotation direction.

  The inner and outer rotors 5 and 3 actually rotate, but when the inner and outer rotors 5 and 3 are fixed and viewed, the pump casing 1 rotates in the direction opposite to the arrow Z (see FIGS. 1 and 3). Will do. Therefore, the upper side and the lower side in the rotation direction in the concave portion 1m of the pump casing 1 are opposite to the groove m of the inner rotor 5. Therefore, “relative rotation” is used to define the rotation direction for both the rotors 5 and 3 and the pump casing 1.

  As shown by an imaginary line in FIG. 2, when a structure in which the pump shaft 9 is driven and rotated by the helical gear mechanism 20 or the like is adopted, the pump shaft 9 has an axial force (a force pushed in the pump axis Y direction). ) Works. In the case of FIG. 2, since the pump shaft 9 is pressed against the cover casing 1B with the driving rotation, the groove m is provided on the rotor side surface 5S on the cover casing side on which the axial force acts, thereby reducing the friction on the easily worn side. Therefore, there is an advantage that durability can be improved, and friction conditions can be offset on the left and right rotor side surfaces 5S, 5S.

(Another embodiment)
The groove or the recess m may be provided on the rotor side surface 5S on the main casing side of the inner rotor 5, or may be provided on the inner side surface 11a of the main casing 1A (an example of the “rotor side surface”) or the side surface 18a of the cover casing 1B. . Further, grooves or recesses m may be provided on the left and right rotor side surfaces 3S of the outer rotor 3.

1 pump casing
1A Main casing
1B Cover casing
1a Opening 1m Groove (or recess)
2 Housing space 3 Outer rotor 4 Inner teeth 5 Inner rotor 5S Rotor side surface 6 Outer teeth 7 Suction port 8 Discharge port 9 Pump shaft 18a Case inner surface h Groove width m Groove (or recess)
t Groove depth

Claims (6)

A pump casing in which a cylindrical housing space is formed,
An outer rotor having internal teeth and rotatably fitted in the housing space;
An inner rotor rotatably provided in the outer rotor with external teeth meshing with the internal teeth,
A suction port and a discharge port formed in the pump casing so as to open to the accommodation space,
The pump casing is configured by a relative fixation of a main casing in which the outer rotor is rotatably housed, and a cover casing that covers an opening of the main casing,
The suction port and the discharge port are formed in the cover casing,
A pump shaft pivotally supported by the pump casing and driving and rotating the inner rotor is provided,
The inner rotor is configured to be pressed against the cover casing due to a structure in which the pump shaft is driven to rotate,
A trochoid pump in which a groove or a concave portion in which a lower side in a relative rotation direction is open is formed on a rotor side surface on a cover casing side of the inner rotor or an inner surface of a case in contact with the rotor side surface of the cover casing.

  2. The trochoid pump according to claim 1, wherein the width of the groove or the concave portion is formed such that the width of the groove or the concave portion increases toward the lower side in the relative rotation direction of the rotor side surface or the inner surface of the case where the groove or the concave portion is formed.   The trochoid pump according to claim 1, wherein the depth of the groove or the concave portion is formed to be deeper toward the lower side in the relative rotation direction of the rotor side surface or the inner surface of the case where the groove or the concave portion is formed. The trochoid pump according to any one of claims 1 to 3, wherein the groove or the concave portion is formed on a rotor side surface of the inner rotor.
  The groove or the concave portion is formed in a portion between the suction port and the discharge port on the inner surface of the case where the suction port and the discharge port are formed, so as to open to the suction port. The trochoid pump according to any one of claims 1 to 4.   The trochoid pump according to any one of claims 1 to 5, wherein the groove or the concave portion is formed in a state where an upper side in a relative rotation direction is closed.

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