JP6649906B2 - Oil pump - Google Patents

Description

  The present invention relates to an oil pump for feeding oil supplied from a suction port to a discharge port.

  As an oil pump for pressure-feeding oil supplied from an inlet to an outlet, there is an oil pump described in Patent Document 1, for example. The oil pump described in Patent Literature 1 has a pump gear, a pump housing including a pump body and a body cover that house the pump gear, and a pump shaft that is fitted into the pump gear and rotates the pump gear. In such an oil pump, a bearing is provided between the pump shaft and the pump housing to reduce friction between the pump shaft and the pump housing.

JP 2008-267236 A

  However, the bearing is not pressed against one of the pump shaft and the pump housing. The reason for this is to make the pump shaft, the pump housing and the bearing easier to assemble, and to prevent excessive stress between the bearing and the pump shaft and the pump housing during the assembling. It is for good reason. Therefore, when transporting the oil pump, it is difficult to transport the pump shaft, the pump housing, and the bearing integrally. That is, in the oil pump as described above, the pump shaft may fall off the bearing during transportation, or the pump shaft and the bearing may fall off the pump housing. Therefore, it is difficult to transport the pump shaft, the pump housing, and the bearing as a single unit, which may increase the transportation cost of the oil pump.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide an oil pump that can easily reduce transportation costs.

One embodiment of the present invention is an oil pump that pressure-feeds oil supplied from an intake port to a discharge port,
A pump gear,
A pump housing having a housing chamber for housing the pump gear, and a through hole communicating with the housing chamber and opening forward in one of the axial directions;
A pump shaft disposed inside the housing chamber and the through hole and fitted into the pump gear;
A bearing disposed between the pump shaft and the pump housing in a radial direction,
The pump shaft has a male screw portion on an outer peripheral surface of the pump shaft,
The through hole is formed on the inner peripheral surface of the through hole, and has a female screw portion that can be screwed with the male screw portion,
In the oil pump, the male screw portion of the pump shaft is formed at a position further away from the female screw portion in the axial direction and on the opposite side from the front side in the axial direction.

  In the oil pump, the pump shaft has a male screw portion, and the through hole has a female screw portion that can be screwed into the male screw portion. The male screw portion of the pump shaft is formed at a position further away in the axial direction than the female screw portion of the through hole. Therefore, at the time of transportation of the oil pump, the male screw part of the pump shaft is screwed into the female screw part of the through hole, or the screwing is further advanced from this state, so that the male screw part is moved from the female screw part. Also, the pump shaft can be prevented from falling forward from the through hole by setting the pump shaft at the rear. That is, in this case, since the male screw portion of the pump shaft interferes with the female screw portion of the through hole, it is possible to prevent the pump shaft from moving forward with respect to the through hole and dropping out of the through hole.

  As described above, according to the above aspect, it is possible to provide an oil pump that can easily reduce the transportation cost.

FIG. 2 is a cross-sectional view of the oil pump according to the first embodiment. FIG. 2 is a sectional view taken along line II-II of FIG. 1. FIG. 2 is an exploded cross-sectional view of the oil pump according to the first embodiment. FIG. 2 is a view of the pump shaft according to the first embodiment as viewed from the rear. The figure which looked at the pump cover in Embodiment 1 from the front. FIG. 2 is a cross-sectional view illustrating a state in which the oil pump is attached to a transaxle cover in the first embodiment. FIG. 2 is a sectional view of a pump housing, a pump body, and a bearing according to the first embodiment. FIG. 4 is a cross-sectional view illustrating a state in which a rear shaft portion of the pump shaft is inserted into a front end of a shaft insertion hole of the pump gear in the first embodiment. FIG. 4 is a cross-sectional view showing a state in which a male screw part of the pump shaft abuts on a female screw part of a through hole of the pump housing in the first embodiment. FIG. 3 is a cross-sectional view showing a state in which a male screw part of a pump shaft and a female screw part of a through-hole of the pump housing are screwed in the first embodiment.

(Embodiment 1)
An embodiment of an oil pump will be described with reference to FIGS.
As shown in FIG. 1, the oil pump 1 of this embodiment is for pumping oil supplied from an inlet 211 to an outlet 212 under pressure.

  The oil pump 1 has a pump gear 41, a pump housing 2, a pump shaft 3, and a bearing 11. The pump housing 2 has a housing chamber 210 for housing the pump gear 41, and a through hole 221 that communicates with the housing chamber 210 and that is opened forward in one of the axial directions X. The pump shaft 3 is disposed inside the accommodation room 210 and the through hole 221. Further, the pump shaft 3 is fitted into the pump gear 41. The bearing 11 is disposed between the pump shaft 3 and the pump housing 2 in the radial direction.

  The pump shaft 3 has a male screw portion 311 on the outer peripheral surface of the pump shaft 3. The through hole 221 is formed on the inner peripheral surface of the through hole 221, and has a female screw part 222 that can be screwed with the male screw part 311. The male screw portion 311 of the pump shaft 3 is formed at a position further away from the female screw portion 222 in the axial direction X and on the opposite side to the rear side. Note that the axial direction X is a direction in which the axis of the pump shaft 3 extends. Further, the term "radial direction" means the radial direction of the pump shaft 3 unless otherwise specified.

  In the present embodiment, the oil pump 1 is used by being arranged in a transaxle. The oil pump 1 is used to circulate oil stored in a transaxle case. Oil is used as a lubricant for various gears and various bearings in the transaxle. However, the oil pump 1 is not limited to one disposed inside the transaxle.

  As shown in FIGS. 1 and 3, the pump housing 2 has a pump body 21 and a pump cover 22. The pump body 21 has a housing chamber 210 and is open forward. As shown in FIG. 1, the pump cover 22 has a through hole 221 and covers an opening 213 of the pump body 21. The bearing 11 is arranged between the pump shaft 3 and the pump cover 22. The pump body 21 and the pump cover 22 are both made of aluminum.

  As shown in FIGS. 1 and 3, the accommodation chamber 210 of the pump body 21 is formed such that the front surface of the pump body 21 is recessed rearward. Further, the pump body 21 has a suction through-hole 214 and a discharge through-hole 215 communicating with the storage chamber 210. One end of each of the suction through-hole 214 and the discharge through-hole 215 communicates with the storage chamber 210, and the other end opens toward the outside of the pump body 21. The end of the suction through-hole 214 on the side opposite to the storage chamber 210 opens toward one side in a direction orthogonal to the axial direction X. An end of the suction through hole 214 on the opposite side to the storage chamber 210 is a suction port 211. The end of the discharge through-hole 215 opposite to the storage chamber 210 is open rearward. The end of the discharge through hole 215 on the opposite side to the storage chamber 210 is the discharge port 212. Note that the opening direction of the end of the suction through-hole 214 opposite to the storage chamber 210 is not limited to the above-described direction. Similarly, the opening direction of the end of the discharge through-hole 215 opposite to the storage chamber 210 is not limited to the above-described direction.

  As shown in FIGS. 1 and 2, the pump body 4 having the pump gear 41 is inserted and arranged in the storage chamber 210. In the present embodiment, the pump body 4 is an internal gear type pump which is a kind of a positive displacement pump. The pump body 4 has an annular outer rotor 42 and a pump gear 41 disposed inside the outer rotor 42. As shown in FIG. 2, the outer rotor 42 has a plurality of internal teeth 421 formed on an inner peripheral portion thereof. The pump gear 41 is housed inside the outer rotor 42. The pump gear 41 has a smaller number of outer teeth 411 than the inner teeth 421 of the outer rotor 42 on the outer peripheral side. Further, the pump gear 41 has a shaft insertion hole 410 penetrating in the axial direction X at the center thereof.

  The pump body 4 rotates the outer rotor 42 and the pump gear 41 relatively to each other and also rotates the outer body 42 and the pump gear 41 relatively to the pump body 21. With the rotation, the volume of the gap formed between the internal teeth 421 of the outer rotor 42 and the external teeth 411 of the pump gear 41 is increased or decreased, and oil is supplied from the suction port 211 of the pump body 21 through the suction through hole 214. The ink is sucked and discharged from the discharge port 212 through the discharge through hole 215.

  As shown in FIG. 3, the pump cover 22 is separate from the pump body 21. As shown in FIG. 1, the pump cover 22 covers the opening 213 of the pump body 21 from the front of the opening 213. The through-hole 221 formed in the pump cover 22 has a front hole 221f and a rear hole 221b communicating with the front hole 221f and formed behind the front hole 221f. As shown in FIGS. 3 and 5, the front hole 221f is formed to have a larger diameter than the rear hole 221b.

  And the female screw part 222 is formed in the back hole part 221b. As shown in FIG. 3, the female screw part 222 is formed from the front end of the rear hole part 221b. In the present embodiment, the female screw part 222 is formed by two or more round threads.

  The pump body 21 and the pump cover 22 are fastened and fixed in the axial direction X by bolts (not shown). The bolt is inserted into a bolt insertion hole (not shown) formed in the pump cover 22 from the front of the pump cover 22 and screwed into a bolt screw hole (not shown) formed in the pump body 21. Thus, the pump body 21 and the pump cover 22 are integrated with each other.

  As shown in FIG. 1, the pump shaft 3 is inserted and arranged inside the accommodation room 210 and the through hole 221. Further, the pump shaft 3 is fitted into a shaft insertion hole 410 of the pump gear 41, and when the pump shaft 3 rotates, the pump gear 41 rotates similarly. In the present embodiment, the pump shaft 3 includes a rear shaft part 31, a rear bearing arrangement part 32, a rear contact part 33, an external gear 34, a front contact part 35, and a front bearing arrangement part 36 which will be described later. Have in order. The pump shaft 3 is made of a steel material.

  The rear shaft portion 31 is arranged at least inside the accommodation room 210 and the rear hole portion 221b, and is fitted into the shaft insertion hole 410. A male screw portion 311 is formed in front of the portion of the rear shaft portion 31 fitted into the shaft insertion hole 410. The male screw portion 311 is formed by two or more turns of a screw thread. As described above, the male screw portion 311 is formed at a position further away from the female screw portion 222 formed in the through hole 221 of the pump cover 22. That is, when the oil pump 1 is completed or used, the male screw portion 311 and the female screw portion 222 are not engaged.

  As shown in FIG. 1, in the axial direction X, the length L1 between the rear end of the male screw portion 311 and the rear end of the pump shaft 3 is equal to the front end of the female screw portion 222 and the pump gear 41. Is longer than the length L2 between the front end and the front end. This makes it easy to assemble the pump shaft 3 in the oil pump 1 as described later.

  As shown in FIGS. 1 and 2, the rear shaft portion 31 has a substantially bar shape. As shown in FIGS. 2 and 4, the rear shaft portion 31 has a pair of engagement surfaces 312 chamfered in parallel in the axial direction X. The pair of engagement surfaces 312 are formed parallel to each other. Then, as shown in FIG. 2, the shaft insertion hole 410 of the pump gear 41 into which the rear shaft 31 is fitted also has a shape along the rear shaft 31. That is, the shaft insertion hole 410 has a substantially circular shape when viewed from the axial direction X, and has an engaged surface 412 facing the engagement surface 312 of the rear shaft portion 31.

  As shown in FIGS. 1 and 3, the rear bearing arrangement portion 32 is formed to have a larger diameter than the rear shaft portion 31. The annular bearing 11 is arranged so as to cover the outer peripheral surface of the rear bearing arrangement portion 32. In the present embodiment, the inner peripheral surface of the bearing 11 is not pressed against the pump shaft 3. On the other hand, in the present embodiment, the bearing 11 is in pressure contact with the inner peripheral surface of the through hole 221. The bearing 11 is press-fitted into a front hole 221f of the through hole 221.

  The rear contact portion 33 has a larger diameter than the rear bearing arrangement portion 32. The front surface of the bearing 11 is in contact with the rear surface of the rear contact portion 33. Thus, the pump shaft 3 in the oil pump 1 is positioned in the axial direction X.

  As shown in FIG. 1, the external gear 34 is formed in front of the through hole 221 in the axial direction X. The external gear 34 has a larger diameter than the through hole 221. The external gear 34 has a larger diameter than both the front hole 221f and the rear hole 221b of the through hole 221. The external gear 34 faces the front surface of the pump cover 22 in the axial direction X. The rotating force of an external motor is applied to the external gear 34. Thus, torque is transmitted from the motor to the pump shaft 3 and the pump gear 41 via the external gear 34. In FIG. 4, the shape of the teeth of the external gear 34 is omitted.

  The front bearing arrangement portion 36 is formed to have a larger diameter than the rear shaft portion 31. However, the present invention is not limited to this, and the diameter of the front bearing arrangement portion 36 may be smaller than the diameter of the rear shaft portion 31. When the oil pump 1 is attached to the transaxle, an annular front bearing 112 is arranged so as to cover the outer peripheral surface of the front bearing arrangement portion 36, as shown in FIG. The inner peripheral surface of the front bearing 112 is not pressed against the pump shaft 3. On the other hand, the outer peripheral side of the front bearing 112 is pressed against the transaxle case 10 to which the oil pump 1 is attached.

  As shown in FIG. 1, the front contact portion 35 has a larger diameter than the front bearing arrangement portion 36. As shown in FIG. 6, the rear surface of the front bearing 112 contacts the front surface of the front contact portion 35. Thereby, positioning in the axial direction X between the pump shaft 3 and the transaxle is performed.

  As shown in FIG. 6, the oil pump 1 is fastened to the transaxle case 10 by bolts 111 in the axial direction X before use. Then, by fastening the oil pump 1 to the transaxle case 10 by bolts, the front bearing 112 press-fitted into the case 10 holds the pump shaft 3 in the axial direction X. That is, when the oil pump 1 is fastened to the transaxle case 10 by the bolts 111, the positioning of the oil pump 1 in the axial direction X of the pump shaft 3 is maintained by the axial force of the bolts 111 in the axial direction X. You. Although not shown in FIG. 6, the space in the transaxle case 10 in which the external gear 34 of the oil pump 1 is housed communicates with the space in which gears that mesh with the external gear 34 are arranged.

Next, an example of how to assemble the oil pump 1 will be described with reference to FIGS. 1 and 7 to 10.
As shown in FIG. 7, the pump body 4 is inserted into the accommodation room 210 of the pump body 21. Then, the pump cover 22 is attached to the pump body 21 from the front of the pump body 21, and the pump body 21 and the pump cover 22 are fastened by the above-mentioned bolts (not shown). Then, the bearing 11 is pressed into the front hole 221f of the pump cover 22. This results in the state shown in FIG.

  Next, as shown in FIG. 8, the pump shaft 3 is inserted into the through hole 221 of the pump cover 22 in the axial direction X from the rear shaft portion 31 side. Here, as described above, in the axial direction X, the length L1 between the rear end of the male screw portion 311 and the rear end of the pump shaft 3 is equal to the front end of the female screw portion 222 and the pump gear. 41 is longer than the length L2 between the front end and the front end. Therefore, when the pump shaft 3 is inserted from the through hole 221 of the pump cover 22 in the axial direction X, as shown in FIG. First, first, the rear shaft portion 31 is inserted into the shaft insertion hole 410 of the pump gear 41.

  Here, as shown in FIG. 2, the rear shaft portion 31 has a pair of engagement surfaces 312, and the shaft insertion hole 410 of the pump gear 41 has a pair of engagement surfaces 412. Therefore, when the rear shaft 31 is inserted into the shaft insertion hole 410, the pump shaft 3 is rotated so that the engagement surface 312 of the rear shaft 31 is parallel to the engaged surface 412 of the shaft insertion hole 410. Then, the posture of the pump shaft 3 and the shaft insertion hole 410 is adjusted. Here, in the state in which the posture is adjusted by rotating the pump shaft 3, the male screw portion 311 does not interfere with the female screw portion 222 as described above. The posture of the shaft 31 can be adjusted, and the rear shaft 31 can be easily inserted into the shaft insertion hole 410.

  Then, the insertion of the rear shaft portion 31 into the shaft insertion hole 410 is advanced, and the male screw portion 311 of the rear shaft portion 31 is brought into contact with the female screw portion 222 of the through hole 221 as shown in FIG.

  Next, by rotating the pump shaft 3, the male screw 311 of the rear shaft 31 is screwed into the female screw 222 of the through hole 221 as shown in FIG. 10. At this time, the pump gear 41 into which the rear shaft portion 31 is fitted also rotates together with the pump shaft 3. Then, the screwing of the male screw 311 is advanced until the male screw 311 passes the female screw 222. That is, the male thread 311 is screwed into the female thread 222 until the front end of the male thread 311 is located at the rear end of the female thread 222 or behind it. Next, as shown in FIG. 1, the pump shaft 3 is inserted into the through hole 221 until the rear contact portion 33 of the pump shaft 3 contacts the bearing 11. Thereby, the positioning of the pump shaft 3 in the oil pump 1 is performed. The oil pump 1 is assembled as described above. As described above, after the oil pump 1 is mounted on the transaxle case 10, the positioning of the oil pump 1 in the axial direction X of the pump shaft 3 is performed by moving the oil pump 1 relative to the transaxle case 10. It is maintained by the axial force of the bolt 111 fastened in the axial direction X.

Next, the operation and effect of the present embodiment will be described.
In the oil pump 1, the pump shaft 3 has a male screw portion 311, and the through hole 221 has a female screw portion 222 that can be screwed into the male screw portion 311. The male screw portion 311 of the pump shaft 3 is formed at a position farther rearward in the axial direction X than the female screw portion 222 of the through hole 221. Therefore, when the oil pump 1 is transported, the male screw 311 of the pump shaft 3 is screwed into the female screw 222 of the through-hole 221 (that is, the state shown in FIG. 10), or the screw is further changed from this state. By proceeding with the engagement, the male screw portion 311 is located behind the female screw portion 222 (that is, the state shown in FIG. 1), so that the pump shaft 3 can be prevented from falling out of the through hole 221 forward. it can. That is, in this case, since the male screw portion 311 interferes with the female screw portion 222 of the through-hole 221, the pump shaft 3 moves forward with respect to the through-hole 221 and falls out of the through-hole 221. Can be prevented. In particular, when the oil pump 1 is transported, it is preferable that the male screw 311 of the pump shaft 3 is screwed into the female screw 222 of the through hole 221 (ie, the state shown in FIG. 10) from the viewpoint of preventing vibration. Is preferred. On the other hand, from the viewpoint of preventing the pump shaft 3 from dropping off from the oil pump 1, it is preferable that the male screw portion 311 of the pump shaft 3 is located behind the female screw portion 222 (ie, the state shown in FIG. 1). .

  The pump housing 2 has a pump body 21 and a pump cover 22. A through hole 221 is formed in the pump cover 22. Therefore, as compared with the case where the pump housing 2 is integrally formed, the member having the through hole 221 including the female screw portion 222, that is, the pump cover 22 can be easily formed smaller. Therefore, it is easy to form the through hole 221 including the female screw portion 222 in the pump housing 2. Thereby, the productivity of the oil pump 1 can be improved.

  In the axial direction X, the length L1 between the rear end of the male screw 311 and the rear end of the pump shaft 3 is equal to the front end of the female screw 222 and the front end of the pump gear 41. It is longer than the length L2 between the portions. Therefore, it is easy to insert the pump shaft 3 into the pump gear 41 as described above. Thus, the productivity of the oil pump 1 can be improved.

  The male screw part 311 and the female screw part 222 are each formed of two or more turns of thread. Therefore, it is easier to prevent the pump shaft 3 from falling off during transportation. In addition, the screw thread of the male screw part 311 and the female screw part 222 can be, for example, three turns or less. Accordingly, the thickness of the pump cover 22 does not become too large, and the size of the entire oil pump 1 can be reduced.

  The bearing 11 is in pressure contact with the inner peripheral surface of the through hole 221. Therefore, it is possible to prevent the bearing 11 and the pump housing 2 from being worn when the oil pump 1 is transported or used. In particular, in the present embodiment, since the pump housing 2 is made of aluminum, which is relatively easily worn, the wear generated in the pump housing 2 is effectively suppressed by pressing the bearing 11 against the inner peripheral surface of the through hole 221. can do.

  Further, the pump shaft 3 has an external gear 34 formed in front of the through hole 221 in the axial direction X and having a larger diameter than the through hole 221. As described above, when the external gear 34 is provided, the pump shaft 3 cannot be inserted into the through hole 221 of the pump housing 2 from the external gear 34 side in the axial direction X. Therefore, the rear shaft portion 31 of the pump shaft 3 is inserted into the through hole 221 from the front of the through hole 221 with respect to the pump housing 2. In this case, some integration means is needed to integrate the pump housing 2 and the pump shaft 3. Therefore, as described above, by adopting the configuration of the present embodiment in which the male screw portion 311 of the pump shaft 3 and the female screw portion 222 of the through hole 221 are provided, a new member for the integration means is required. Without this, the pump shaft 3 and the pump housing 2 can be temporarily assembled and integrated. In this state, the pump shaft 3 in the oil pump 1 is prevented from dropping off, and handling such as transportation can be facilitated in a state before being mounted on a transaxle or the like.

  As described above, according to the present embodiment, it is possible to provide an oil pump whose transportation cost is easily reduced.

The present invention is not limited to the above embodiments, and can be applied to various embodiments without departing from the gist thereof.
For example, the bearing may be configured to be in pressure contact with the pump shaft but not in contact with the inner peripheral surface of the through hole of the pump housing. In this case, wear of the pump shaft and the bearing can be prevented.
Further, in the above embodiment, the pump body is an internal gear type pump, but other pumps are also possible.
Further, in the above-described embodiment, the form in which the accommodation chamber is provided in the pump body and the through-hole is provided in the pump cover has been described. However, the present invention is not limited thereto. For example, both the accommodation chamber and the through-hole may be formed in the pump cover. Is also possible.

DESCRIPTION OF SYMBOLS 1 Oil pump 11 Bearing 2 Pump housing 210 Storage room 211 Inlet 212 Outlet 221 Through hole 222 Female screw hole 3 Pump shaft 311 Male screw part X-axis direction

Claims (7)

An oil pump (1) for pumping oil supplied from an inlet (211) to an outlet (212),
A pump gear (41);
A pump housing (2) having a housing chamber (210) for housing the pump gear, and a through hole (221) communicating with the housing chamber and opening forward in one of the axial directions (X);
A pump shaft (3) disposed inside the housing chamber and the through hole and fitted into the pump gear;
A bearing (11) disposed between the pump shaft and the pump housing in a radial direction,
The pump shaft has a male screw portion (311) on an outer peripheral surface of the pump shaft,
The through hole is formed on an inner peripheral surface of the through hole, and has a female screw portion (222) that can be screwed with the male screw portion,
The oil pump, wherein the male screw portion of the pump shaft is formed at a position further away from the female screw portion than the female screw portion in the axial direction and on the opposite side of the front side.   The pump housing includes a pump body (21) provided with the housing chamber and opening forward, and a pump cover (22) provided with the through hole and covering an opening surface (213) of the pump body. The oil pump according to claim 1, wherein the bearing is provided between the pump shaft and the pump cover.   In the axial direction, the length (L1) between the rear end of the male screw and the rear end of the pump shaft is equal to the length of the front end of the female screw and the pump gear. The oil pump according to claim 1, wherein the length of the oil pump is longer than a length between the front end and the front end.   The oil pump according to any one of claims 1 to 3, wherein at least one of the male screw portion and the female screw portion is formed by two or more turns of a screw thread.   The oil pump according to claim 1, wherein the bearing is in pressure contact with an inner peripheral surface of the through hole.   The oil pump according to claim 1, wherein the bearing is in pressure contact with the pump shaft.   The oil pump according to any one of claims 1 to 6, wherein the pump shaft has an external gear (34) formed with a larger diameter than the through hole in the front of the through hole in the axial direction. .

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