JP2016152638A - In-wheel motor drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-wheel motor drive device which cools a stator coil in a state where the stator coil is heated after regenerative operation is conducted and a vehicle is stopped.SOLUTION: An in-wheel motor drive device includes: a wheel bearing 5; an electric motor 1; and an oil supply mechanism Jk which cools the electric motor 1 with a lubrication oil. The oil supply mechanism Jk has an accumulation tank Ta for accumulating the lubrication oil. The accumulation tank Ta is provided with at least part thereof positioned above the stator coil 9b. In the accumulation tank Ta, the lubrication oil jetted from a rotor 10 and the lubrication oil dropped from an oil hole 26 provided in the middle of an oil passage 32 positioned at an upper part of the motor housing 8 are accumulated in the accumulation tank Ta. The accumulation tank Ta is provided with dropping means which drops the lubrication oil accumulated in the accumulation tank Ta to the stator coil 9ba.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an in-wheel motor drive device, and more particularly to a technique capable of cooling a stator when a regenerative operation is performed and the vehicle stops.

Various techniques for cooling the stator of a vehicle drive motor have been proposed.
(1) Rotating electric machine In this rotating electric machine, a structure for cooling a stator coil is proposed, a groove is formed in a circumferential direction facing the coil end, and air or oil is supplied to the groove to cool the coil end (patent) Reference 1). This is an application example of a drive motor for a hybrid vehicle. A reservoir is provided at the top to store the oil pumped up by the gear, and the oil is dropped onto the coil end through a flow path led from this reservoir to the coil end. To do.

(2) Motor drive device In this motor drive device, the guide oil that guides the lubricant oil that is axially lubricated and jetted from the rotor hits the inner wall surface of the motor housing and guides the lubricant oil adhering to the inner wall surface of the motor housing to the coil end. It is formed on the inner wall surface of the housing (Patent Document 2).

(3) In-wheel motor drive device Conventionally, as a technique for cooling the stator of the motor, as shown in FIG. 12, the lubricating oil supplied from the motor rotor shaft center passes from the rotor end surface via the flow path of the rotor 100. It was ejected radially and sprayed onto the stator coil to cool the coil end 101. Since the axial lengths of the stator 102 and the rotor 100 are substantially the same, the lubricating oil ejected from the rotor end surface intensively cools the inner diameter surface of the coil end 101 and cools the outer diameter surface of the coil end 101. There was a problem that it was difficult.
Therefore, the applicant of the present invention forms a cooling oil hole located directly above the coil end of the stator in communication with the oil passage at the top of the housing and forms a structure for cooling the outer diameter surface of the coil end. It has been proposed (Japanese Patent Application No. 2014-216886).

JP 2005-229671 A JP 2010-172069 A

In the prior art of (1), there is a problem that the stirring resistance is large because the scraping effect by the gear is used.
In the prior art of (2), since the lubricating oil pump operates in synchronization with the rotation of the output shaft, there is a problem that the lubricating oil cannot be supplied in a low rotation range or when stopped.
Similarly, in the prior art of (3), the lubricating oil pump operates in synchronization with the rotation of the output shaft, and the cooling effect in the low rotation range is less than that of the prior art of (2). Although it has a structure that can supply a large amount, the cooling effect is large, but there is still a problem that the lubricating oil cannot be supplied when stopped.

  In addition, when a vehicle equipped with an in-wheel motor drive device performs a power regeneration operation using a motor, a power regeneration operation in a middle rotation region or a low rotation region is required. Since the conventional in-wheel motor drive device has a pump characteristic synchronized with the rotation of the output shaft, the discharge flow rate is small in the low rotation range. When the regenerative operation is performed in the low rotation range, there is a problem that a large current flows through the coil in a state where the cooling lubricant is not sufficiently lubricated and the stator coil generates excessive heat.

  An object of the present invention is to provide an in-wheel motor drive device that can cool a stator coil in a state in which the stator coil has generated heat after performing a regenerative operation.

An in-wheel motor drive device according to the present invention includes a wheel bearing that supports a wheel, an electric motor that rotates a rotating wheel of the wheel bearing, and an oil supply mechanism that cools the electric motor with lubricating oil. A motor drive device,
The electric motor has a motor housing, a stator provided with a stator coil on the inner periphery of the motor housing away from the inner peripheral surface of the motor housing, and a rotor rotatable with respect to the stator,
The oil supply mechanism includes an oil passage for lubricating oil provided in each of the motor housing and the rotor shaft, and an oil passage for the motor housing and an oil passage for the rotor shaft driven by the electric motor. A pump for injecting lubricating oil from the rotor and guiding it to the stator;
The oil supply mechanism has a storage tank that stores lubricating oil, and the storage tank is provided at least partially above the stator coil, and the lubricating oil ejected from the rotor or the motor housing Lubricating oil dropped from an oil hole provided in the middle of the oil passage located in the upper part is stored, and a dropping means for dropping the lubricating oil stored in the storage tank onto the stator coil is provided in the storage tank. It is provided.

According to this configuration, the oil supply mechanism drives the pump by the rotation of the electric motor, and causes the lubricating oil to be ejected from the rotor through the oil passage of the motor housing and the oil passage of the shaft center of the rotor and led to the inner diameter surface of the stator. . Basically, the stator is cooled by the oil passage and the jet. In addition, lubricating oil is stored in the storage tank. The storage tank is provided so that at least a part thereof is positioned above the stator coil. The storage tank receives and stores the jetted lubricating oil or the lubricating oil dropped from the oil hole of the oil passage. The stored lubricating oil is dropped from the dropping means onto the stator coil.
Since the rotation of the electric motor is stopped when the vehicle is stopped, the lubricating oil cannot be guided to the stator by driving the pump. However, the lubricating oil is stored in the storage tank as described above during driving of the vehicle, and the dropping of the lubricating oil from the dropping means to the stator coil continues even after the vehicle stops. The dropped lubricating oil directly cools the stator coil, which is a heat source. Therefore, cooling continues for a while after the vehicle stops. Therefore, the stator coil can be cooled in a state in which the stator coil generates heat after performing the regenerative operation.

In general, as a use situation of a vehicle using an electric motor as a driving source, in a low speed and high torque region, a main heat generating source is a stator coil. For example, in the case of a pump rotating in synchronization with an electric motor, Lubricating oil discharge is small. For this reason, there is a possibility that a flow rate sufficient to cool the stator coil cannot be obtained.
In particular, in the regenerative operation performed when the vehicle is decelerated, the stator coil may be in a heated state when the vehicle is stopped because current flows through the stator coil at a low speed, that is, to a region where the lubricant discharge amount is small. If it does so, it will become the temperature upper limit vicinity set in order to avoid the abnormality of a stator coil. As a result, the difference between the detected value of the stator coil and the set temperature upper limit value when the vehicle restarts after stopping is reduced, and the possibility of shifting to a fail-safe operation that avoids motor abnormality increases. If the operation shifts to the fail-safe operation, the driver may feel uncomfortable as the starting characteristic of the vehicle.

  Therefore, dropping means for dropping the stored lubricating oil onto the stator coil is provided in the storage tank. When the vehicle is stopped, the lubricating oil dripped from the storage tank can reliably cool the stator coil. Thereby, for example, it can be prevented that the electric motor is determined to be abnormal, and the transition to the fail-safe operation such as limiting the output of the electric motor can be avoided.

The dripping means may be a dripping hole formed in the storage tank. The flow rate of the lubricating oil changes according to the diameter and number of the dropping holes, the oil level of the lubricating oil stored in the storage tank, and the like. The flow rate of the lubricating oil dripped from the storage tank can be determined by setting the hole diameter of the dropping hole to an appropriate hole diameter and setting the volume of the storage tank that can store the lubricating oil to the maximum. Immediately after the vehicle stops, the lubricating oil filled in the storage tank flows out of the dripping hole vigorously, so that it is possible to prevent the stator coil from rapidly rising in temperature immediately after the vehicle stops. After the vehicle stops, the oil level of the storage tank decreases with the passage of time, so that the flow rate of the lubricating oil dripping from the dripping hole decreases, but the necessary and sufficient lubricating oil does not exceed the predetermined temperature of the stator coil. Can be dripped. Immediately after the vehicle stops, for example, the stator coil can be cooled over several seconds to several minutes. In this way, it is possible to prevent the stator coil from rising sharply immediately after the vehicle stops, and to prevent the stator coil from reaching a predetermined temperature thereafter.
The appropriate hole diameter and the determined temperature are set according to the results of tests and simulations, respectively.
A plurality of dropping holes may be formed. In this case, the entire stator coil can be cooled.

  The dripping means may include an opening provided at an upper portion of the storage tank and overflowing the stored lubricating oil. In this case, the lubricating oil overflowed from the opening of the storage tank can be dropped on the outer diameter surface of the stator coil to cool the stator coil.

The storage tank may be fixed to the stator or the motor housing. In this case, the storage tank can be easily installed.
It is good also as what contains the reduction gear which decelerates rotation of the said electric motor and transmits to the said rotation wheel of the said wheel bearing.
The oil supply mechanism may be a mechanism that guides lubricating oil from an oil passage of an axis of the rotor to the speed reducer. In this case, the required amount of lubricating oil to be supplied to the stator coil when the vehicle is stopped is secured through the dripping means of the storage tank, and the lubricating oil is ejected from the rotor through the oil passage in the rotor shaft center during vehicle operation. It is possible to cool the stator and secure a necessary amount of lubricating oil necessary for lubricating the reduction gear from the oil passage in the axial center of the rotor.

  An in-wheel motor drive device according to the present invention includes a wheel bearing that supports a wheel, an electric motor that rotates a rotating wheel of the wheel bearing, and an oil supply mechanism that cools the electric motor with lubricating oil. A motor drive device, wherein the electric motor includes a motor housing, a stator having an inner periphery of the motor housing with a stator coil provided away from an inner peripheral surface of the motor housing, and rotatable with respect to the stator And the oil supply mechanism includes an oil passage of lubricating oil provided in each of the motor housing and the shaft center of the rotor, and an oil passage of the motor housing and a shaft of the rotor driven by the electric motor. And a pump for injecting lubricating oil from the rotor and guiding the stator to the stator through a central oil passage. The oil supply mechanism has a storage tank that stores lubricating oil, and the storage tank is provided at least partially above the stator coil, and the lubricating oil ejected from the rotor or the motor housing Lubricating oil dropped from an oil hole provided in the middle of the oil passage located in the upper part is stored, and a dropping means for dropping the lubricating oil stored in the storage tank onto the stator coil is provided in the storage tank. Since it is provided, the stator coil can be cooled in a state where the stator coil generates heat after performing a regenerative operation.

It is sectional drawing of the in-wheel motor drive device which concerns on embodiment of this invention. It is sectional drawing of the reduction gear part used as the II-II line cross section of FIG. FIG. 3 is a partially enlarged view of FIG. 2. It is the figure which looked at the pump of FIG. 1 from the axial direction. It is an enlarged view of the storage tank etc. of FIG. It is the VI-VI sectional view taken on the line of FIG. It is the VII-VII sectional view taken on the line of FIG. It is a perspective view of the storage tank of the in-wheel motor drive device. It is sectional drawing of the principal part of the in-wheel motor drive device which concerns on other embodiment of this invention. It is an expanded sectional view of the storage tank of the in-wheel motor drive concerning the further another embodiment of this invention. It is sectional drawing of the in-wheel motor drive device which concerns on other embodiment of this invention. It is sectional drawing of the in-wheel motor drive device of a prior art example.

  An in-wheel motor drive device according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the in-wheel motor drive device includes an electric motor 1 that drives wheels, a speed reducer 2 that decelerates the rotation of the electric motor 1, and an input shaft 3 (speed reducer input shaft) of the speed reducer 2. 3) and a wheel bearing 5 rotated by a coaxial output member 4 and an oil supply mechanism Jk. The reduction gear 2 is interposed between the wheel bearing 5 and the electric motor 1, and the wheel hub, which is a driving wheel supported by the wheel bearing 5, and the motor rotating shaft 6 of the electric motor 1 are coaxially arranged. It is connected. This in-wheel motor drive device is partially or entirely disposed in the wheel.

  A suspension (not shown) in the vehicle is connected to the reduction gear housing 7 that houses the reduction gear 2. In this specification, the side closer to the outer side in the vehicle width direction of the vehicle with the in-wheel motor drive device provided in the vehicle is referred to as the outboard side, and the side closer to the center of the vehicle is referred to as the inboard side. .

  The electric motor 1 is an IPM motor (so-called embedded magnet type synchronous motor) in which a radial gap is provided between a stator 9 fixed to a motor housing 8 and a rotor 10 attached to the motor rotating shaft 6. The stator 9 is formed by winding a stator coil 9b (sometimes simply referred to as a coil 9b) around a stator core 9a. The stator 9 is fitted to the inner peripheral surface of the motor housing 8 and is tightened in the axial direction with a bolt (not shown). It is fixed. A fixing portion for fixing the stator 9 in the motor housing 8 is a housing step portion 8a. The folded portion when the coil 9b is wound around the stator core 9a is referred to as a coil end 9ba. The coil end 9ba slightly protrudes on both sides in the axial direction from the stator core 9a.

  The housing step portion 8a is an annular step portion facing the outer diameter side portion of the axial end surface of the stator 9, and female threads 37 (FIG. 7) are formed at regular intervals in the circumferential direction. The housing end 8a is brought into contact with the axial end surface on the outboard side of the stator 9 and is screwed into the female screw 37 (FIG. 7) from the inboard side of the stator 9 through a plurality of bolts (not shown). The stator 9 is fixed.

  Roller bearings 11 and 12 are provided in the motor housing 8 so as to be separated from each other in the axial direction, and a motor rotation shaft 6 that is a main shaft is rotatably supported by the rolling bearings 11 and 12. A flange portion 6a extending radially outward is provided in the vicinity of the middle portion of the motor rotating shaft 6 in the axial direction, and the rotor 10 is attached to a rotor fixing member 13 extending radially outward from the flange portion 6a.

  The reduction gear input shaft 3 has one end in the axial direction extending into the motor rotation shaft 6 and is spline-fitted with the motor rotation shaft 6 (including serration fitting; the same applies hereinafter). A rolling bearing 14a is fitted in the cup portion of the output member 4, and the rolling bearing 14b is fitted in a cylindrical connecting member 4a connected via an inner pin 22 fixed to the cup portion. The reduction gear input shaft 3 and the motor rotating shaft 6 are supported by the rolling bearings 11, 12, 14a, and 14b so as to be rotatable integrally and concentrically. Eccentric portions 15 and 16 are provided on the outer peripheral surface of the speed reducer input shaft 3. These eccentric portions 15 and 16 are provided with a 180 ° phase shift so that the centrifugal force due to the eccentric motion cancels each other. The speed reducer 2 is a cycloid speed reducer having curved plates 17 and 18, a plurality of outer pins 19, and a counterweight 21.

  2 is a cross-sectional view of the speed reducer portion taken along line II-II in FIG. In the speed reducer 2, two curved plates 17 and 18, each of which is formed by a wavy trochoid curve having a gentle outer shape, are mounted on the eccentric portions 15 and 16 via rolling bearings 85, respectively. A plurality of outer pins 19 for guiding the eccentric movements of the curved plates 17 and 18 on the outer peripheral side are provided inside the reduction gear housing 7, and a plurality of inner pins 22 are provided inside the curved plates 17 and 18. The plurality of circular through holes 89 are engaged in the inserted state.

  As shown in an enlarged view in FIG. 3, needle roller bearings 92 and 93 are attached to each outer pin 19 and each inner pin 22. Each outer pin 19 is supported at both ends by needle roller bearings 92 (see FIG. 1). The outer ring 92a of the needle roller bearing 92 is fixed to the speed reducer housing 7 and the outer pin 19 is rotatably supported, and is in rolling contact with the outer peripheral surfaces of the curved plates 17 and 18. Further, each inner pin 22 reduces the contact resistance between the outer ring 93a of the needle roller bearing 93 and the outer periphery of each curved plate 17, 18 and the contact resistance between each inner pin 22 and the inner periphery of each through hole 89. To do.

  Therefore, as shown in FIG. 1, the eccentric motion of the curved plates 17 and 18 can be smoothly transmitted to the inner member (rotating wheel) 5a of the wheel bearing 5 as a rotational motion. When the motor rotating shaft 6 rotates, the curved plates 17 and 18 provided on the speed reducer input shaft 3 rotating integrally with the motor rotating shaft 6 perform an eccentric motion. At this time, the outer pin 19 is engaged so as to be in rolling contact with the outer peripheral surfaces of the curved plates 17 and 18 that are eccentrically moved. At the same time, the curved plates 17 and 18 are engaged with the inner pins 22 and the through-holes 89 (FIG. 3), so that only the rotational movement of the curved plates 17 and 18 is inward of the output member 4 and the wheel bearing 5. This is transmitted as a rotational motion to the member 5a. The rotation of the inner member 5a is decelerated with respect to the rotation of the motor rotating shaft 6.

  The wheel bearing 5 is a double-row angular contact ball bearing in which a ball is incorporated between the inner member 5a and the outer member 5b. The outer member 5b is bolted to the speed reducer housing 7 of the speed reducer 2 by a flange 5c. Yes. The inner member 5a is spline-fitted (including serration fitting) to the output member 4. The rotational motion transmitted to the inner member 5a is transmitted to the tire from a wheel mounting flange 5d provided on the inner member 5a.

The oil supply mechanism Jk will be described.
The oil supply mechanism Jk is a so-called shaft center oil supply mechanism that supplies lubricating oil used for cooling of the electric motor 1 and lubrication and cooling of the speed reducer 2 from the inside of the motor rotating shaft 6. The oil supply mechanism Jk includes oil passages 23, 24, 25, an oil hole 26, a pump 27, a storage tank Ta, and a lubricating oil storage unit 29. An oil passage 23 is provided in the motor housing 8, and the oil passage 23 communicates with a pump 27 and an oil passage 24.

FIG. 4 is a view of the pump 27 of FIG. 1 viewed from the axial direction.
As shown in FIGS. 1 and 4, the pump 27 sucks up the lubricating oil stored in the lubricating oil reservoir 29 from the suction port in the lubricating oil reservoir 29 and circulates it through the oil passages 23, 24, 25. The pump 27 includes, for example, an inner rotor 40 that rotates as the output member 4 rotates, an outer rotor 41 that rotates following the rotation of the inner rotor 40, a pump chamber 42, a suction port 43, and a discharge port 44. Is a cycloid pump. The inner rotor 40 is fixed to the connecting member 4 a and is configured to be rotated by the rotation of the output member 4.

  When the inner rotor 40 is rotated by the rotation of the output member 4 driven by the electric motor 1, the outer rotor 41 is driven to rotate. At this time, the inner rotor 40 and the outer rotor 41 rotate about different rotation centers c1 and c2, respectively, so that the volume of the pump chamber 42 changes continuously. As a result, the lubricating oil stored in the lubricating oil reservoir 29 is sucked up, flows in from the suction port, and is pumped from the discharge port to the oil passages 23, 24, and 25 (see FIG. 1).

  As shown in FIG. 1, an oil passage 24 is provided in the shaft center of the rotor 10, that is, in the motor rotation shaft 6. A radial oil passage 28 communicating with the oil passage 24 is provided inside the flange portion 6a. An axial groove δ 1 is formed between the bottom surface of the rotor fixing member 13 and the inner peripheral surface of the rotor 10, and the axial groove δ 1 communicates with the oil passage 28 in the radial direction. Further, a substantially radial annular gap (not shown) communicating with the axial groove δ1 is formed on the flange of the rotor fixing member 13.

  During operation of the vehicle, a part of the lubricating oil is guided radially outward from the oil passage 24 of the motor rotating shaft 6 and the radial oil passage 28 of the flange portion 6a by the centrifugal force of the rotor 10 and the pressure of the pump 27. . Further, the lubricant is guided to the axial groove δ1 and the annular gap in the substantially radial direction, thereby cooling the rotor 10. Furthermore, the coil 9b is cooled by injecting lubricating oil into the inner peripheral surface of each coil end 9ba from the annular gap in the substantially radial direction.

  Further, when the vehicle is in operation, the lubricating oil guided to the oil passage 25 lubricates and cools each part in the speed reducer 2 via the oil supply port 45. The oil passage 25 communicates with the oil passage 24 and extends in the axial direction from the inboard side end inside the reduction gear input shaft 3 to the outboard side. The oil supply port 45 extends radially outward from an axial position where the eccentric portions 15 and 16 are provided in the oil passage 25. In the speed reducer 2, the lubricating oil is supplied radially outward by the centrifugal force from the oil supply port 45 and the pressure of the pump 27, thereby lubricating and cooling each part in the speed reducer 2. The lubricating oil provided for the lubrication or the like moves downward due to gravity and is stored in the lubricating oil storage portion 29 provided at the lower portion of the reduction gear housing 7 via the oil discharge port 46.

  The oil passage 23 of the motor housing 8 sequentially passes through the first oil passage 30, the second oil passage 31, the third oil passage 32, and the fourth oil passage 33 from the upstream side to the downstream side in the lubricating oil flow direction. Including. First and second oil passages 30 and 31 are respectively provided on the outboard side in the motor housing 8. The first oil passage 30 extends from the suction port in the lubricating oil reservoir 29 substantially outward in the radial direction to the suction port 43 (see FIG. 4) of the pump 27. The second oil passage 31 extends substantially outward in the radial direction from the discharge port 44 (see FIG. 4) of the pump 27 and is provided to the outboard side end of the third oil passage 32. The third oil passage 32 extends in the axial direction from the outboard side to the inboard side in the upper part in the motor housing 8. The fourth oil passage 33 communicates with the inboard side end of the third oil passage 32 and the oil passage 24 of the motor rotating shaft 6.

  FIG. 5 is an enlarged view of the storage tank Ta and the like of FIG. Of the third oil passage 32 extending in the axial direction, oil holes 26 are provided above the storage tank Ta and the coil end 9ba. Part of the lubricating oil passing through the third oil passage 32 is discharged from the oil holes 26 and 26 and stored in the storage tank Ta, and the lubricating oil is dropped from the storage tank Ta to the stator 9 and supplied. These oil holes 26, 26 are formed so as to penetrate in the radial direction at the axial position where the storage tank Ta and the coil end 9ba are arranged, among the bottom surface of the third oil passage 32.

  The storage tank Ta stores lubricating oil in the motor housing 8. At least a part of the storage tank Ta is provided above the stator coil 9b. In this example, storage tanks Ta and Ta are provided at predetermined intervals above coil ends 9ba projecting on both axial sides from stator core 9a. The storage tanks Ta, Ta on both sides in the axial direction have the same structure and are arranged symmetrically with respect to a plane perpendicular to the axial direction.

  6 is a cross-sectional view taken along line VI-VI in FIG. 7 is a sectional view taken along line VII-VII in FIG. FIG. 8 is a perspective view of the storage tank Ta. As shown in FIGS. 6 to 8, each storage tank Ta has four side plates 47 to 50 each having a rectangular frame shape with an open top, and a bottom plate 51 that closes the lower portions of these side plates 47 to 50. The bottom plate 51 has a curved surface shape substantially along the circumferential direction, and is arranged so that the top of the bottom plate 51 is positioned below the oil hole 26. The bottom plate 51 is formed in a rectangular shape in a plan view when the bottom plate 51 is viewed from above. Each storage tank Ta receives and stores the lubricating oil dropped from the oil holes 26, 26, and a part of the lubricating oil injected radially outward via the radial oil passage 28 (FIG. 5) and the like. Is stored (described later).

  As shown in FIGS. 5 and 8, a plurality of (two in this example) fixing holes ha for fixing the storage tank Ta are formed in one side plate 48 of the storage tank Ta. The storage tank Ta is fixed using a plurality of bolts that fix the stator 9 to the housing step 8a. Each storage tank Ta is fixed to the housing step 8 a together with the stator 9. Specifically, as shown in FIG. 7, among the plurality of female screws 37 formed in the housing step portion 8a at regular intervals in the circumferential direction, in accordance with the pitch of the two female screws 37, 37 located at the upper part, Two fixing holes ha, ha of the side plate 48 are formed.

  5 and 8, a side plate 48 of one storage tank Ta (on the left side in FIG. 5) is interposed between the housing step portion 8a and the axial end surface of the stator 9 on the outboard side. Yes. A side plate 48 of the other storage tank Ta is disposed on the axial end surface of the stator 9 on the inboard side. The fixing holes ha and ha of the side plate 48 of the other storage tank Ta and the fixing holes ha and ha of the side plate 48 of the one storage tank Ta are screwed into the female screw 37 (FIG. 7) of the housing step 8a. Thereby, each storage tank Ta is fixed to the housing step 8 a together with the stator 9.

  The storage tank Ta is provided with a dropping hole hb as a dropping means for dropping the lubricating oil stored in the storage tank Ta onto the outer diameter surface of the coil end 9ba. The dropping hole hb is a through hole made of, for example, a round hole. A plurality (five in this example) of dripping holes hb are formed in the bottom plate 51 of the storage tank Ta at appropriate intervals in the circumferential direction. Since a plurality of dripping holes hb are provided in this way, the lubricating oil dropped into the storage tank Ta from each oil hole 26 and the like is dispersed along the outer peripheral surface of the bottom plate 51, and each of the plurality of dripping holes hb of the bottom plate 51 is provided. It can be dropped on the coil end 9ba. Therefore, the entire coil end can be cooled.

  The oil hole diameter of each dropping hole hb may be, for example, about φ0.1 mm to φ5.0 mm, and particularly preferably about φ1 mm to φ2 mm. With such an oil hole diameter, the lubricating oil stored in the storage tank Ta can cool the coil end 9ba, for example, over several seconds to several minutes after the vehicle stops. Moreover, the time which can cool coil end 9ba also changes with the quantity of the lubricating oil stored in the storage tank Ta. The lubricating oil stored in the storage tank Ta flows out from each drip hole hb vigorously when the vehicle stops, but the momentum decreases as the oil level decreases.

  As shown in FIG. 5, in the motor housing 8, the housing inner surface 52 on the outboard side located above the rotor 10 has an inclined surface 52 a and a curved surface 52 b in order toward the upper side. The inclined surface 52 a is formed in the vicinity of the second oil passage 31. The inclined surface 52a is formed in a cross-sectional shape that is inclined so as to reach the outer side in the radial direction toward the outboard side. The curved surface 52 b is formed in the vicinity of the third oil passage 32. The inner diameter edge of the curved surface 52b is smoothly connected to the outer diameter edge of the inclined surface 52a without a step. The curved surface 52b is formed in a curved shape that is recessed outward. It arrange | positions so that the outer-diameter edge part of this curved surface 52b may be located above the storage tank Ta by the side of an outboard.

  The housing inner surface 52 on the inboard side positioned above the rotor 10 also has an inclined surface 52a and a curved surface 52b, and has the same configuration as the housing inner surface 52 on the outboard side.

  As shown in FIGS. 1 and 5, when the vehicle is in operation, the lubricating oil is directed radially outward through the radial oil passage 28 and the like by the centrifugal force of the rotor 10 and the pressure of the pump 27. It sprays on the inner peripheral surface. Part of the injected lubricating oil is stored in the storage tank Ta through the inclined surface 52a and the curved surface 52b of each housing inner surface 52. Further, when the vehicle is in operation, the lubricating oil falls from the respective oil holes 26 into the storage tank Ta and is stored as described above.

  According to the in-wheel motor drive device described above, the oil supply mechanism Jk drives the pump 27 when the vehicle is operated, that is, when the electric motor 1 is rotated, and the lubricating oil is supplied to the oil passage 23 of the motor housing 8 and the oil passage of the motor rotating shaft 6. Injected from the rotor 10 through 24 etc., it guide | induces to the internal diameter surface of coil end 9ba. Furthermore, the lubricating oil guided to the oil passage 25 lubricates and cools each part in the speed reducer 2 via the oil supply port 45. The lubricating oil used for the lubrication or the like moves downward and is stored in the lubricating oil storage unit 29 via the oil discharge port 46. Basically, the pump 27 is driven in this way, and the stator 9 is cooled by the oil passage 24 and jetting.

  Further, as shown in FIG. 5, the storage tank Ta receives and stores the lubricating oil dropped from the oil holes 26 and 26 when the vehicle is operated. At the same time, a part of the lubricating oil injected radially outward from the rotor 10 is stored in the storage tank Ta through the inclined surface 52a and the curved surface 52b of each housing inner surface 52. Even when the vehicle is in operation, the lubricating oil is dropped from the respective dripping holes hb of the storage tank Ta onto the outer diameter surface of the coil end 9ba. Even when the lubricating oil is dripped from the storage tank Ta during vehicle operation, the lubricating oil is always supplied to the storage tank Ta by the rotation of the electric motor 1 from the oil hole 26 or the like, so that the amount of the lubricating oil is less than the dripping amount. The supply amount exceeds and the lubricating oil to be stored in the storage tank Ta does not run out.

  When the vehicle is stopped, that is, when the rotation of the electric motor 1 is stopped, the lubricating oil cannot be guided to the stator 9 by driving the pump 27. However, as described above, the lubricating oil is stored in the storage tank Ta while the vehicle is being driven, and the lubricating oil continues to be dropped from the dropping hole hb to the stator coil 9b even after the vehicle is stopped. The dropped lubricating oil directly cools the stator coil 9b as a heat source. Therefore, cooling continues for a while after the vehicle stops. In particular, the stator coil 9b can be cooled in a state where the stator coil 9b has generated heat after performing a regenerative operation. Thereby, for example, it can be prevented that the electric motor 1 is determined to be abnormal, and the transition to a fail-safe operation such as limiting the output of the electric motor 1 can be avoided.

  A dropping hole hb formed in the storage tank Ta was applied as dropping means. The flow rate of the lubricating oil changes according to the diameter of the dropping hole hb, the number of holes, and the oil level of the stored lubricating oil. The flow diameter of the lubricating oil dropped from the storage tank Ta is determined by setting the hole diameter of the dropping hole hb to an appropriate hole diameter and setting the volume of the storage tank Ta that can store the lubricating oil to the maximum extent. Immediately after the vehicle stops, the lubricating oil filled in the storage tank Ta flows out of the dripping hole hb, so that the temperature of the stator coil 9b can be prevented from rising sharply immediately after the vehicle stops. Since the oil level of the storage tank Ta decreases with time after the vehicle stops, the flow rate of the lubricating oil dripping from the dripping hole hb is reduced, but the stator coil 9b does not become more than a predetermined temperature. A suitable lubricating oil can be dripped. Immediately after the vehicle stops, for example, the stator coil 9b can be cooled over several seconds to several minutes. In this way, it is possible to prevent the stator coil 9b from rising sharply immediately after the vehicle stops, and to prevent the stator coil 9b from exceeding a predetermined temperature thereafter. Since the plurality of dropping holes hb of the storage tank Ta are formed, the entire coil end can be cooled.

  In addition, a necessary amount of lubricating oil to be supplied to the coil end 9ba when the vehicle is stopped is secured through the dropping hole hb which is a dropping means of the storage tank Ta, and the lubricating oil is supplied via the oil passage 24 of the motor rotating shaft 6 when the vehicle is operated. Can be ejected from the rotor 10 to cool the stator 9 and the required amount of lubricating oil for lubricating the speed reducer 2 can be secured from the oil passages 24 and 25.

Another embodiment will be described.
In the following description, the same reference numerals are assigned to the portions corresponding to the matters described in the preceding forms in each embodiment, and overlapping descriptions are omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in advance unless otherwise specified. The same effect is obtained from the same configuration. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

  In the above-described embodiment, the storage tank Ta is fixed to the motor housing 8 together with the stator 9, but is not limited to this example. As shown in FIG. 9, the storage tank Tb may be directly fixed to the motor housing 8 without the stator 9 interposed. In the motor housing 8, each storage tank Tb is fixed to each storage tank Tb by being screwed into a female screw of the motor housing 8 through bolts in the fixing holes ha and ha (FIG. 8) of the side plate 48. However, the upper part of each storage tank Tb is not opened, and the lubricating oil transmitted through each housing inner surface 52 does not enter the storage tank Tb. Each storage tank Tb stores only the lubricating oil dropped from the oil holes 26 and 26.

  Each storage tank Tc shown in FIG. 10 includes, as its dripping means, an opening 53 that causes the stored lubricating oil to overflow. The opening 53 is provided in the upper part of the storage tank Tc. In each storage tank Tc, a connecting portion 54 between the side plate 47 and the bottom plate 51 facing the side plate 48 that contacts the stator 9 among the four side plates having a rectangular frame shape is curved in a rounded shape. The lubricating oil overflowed from the storage tank Tc is finally dropped onto the outer diameter surface of the coil end 9ba through the surfaces of the side plate 47, the connecting portion 54, and the bottom surface 51. The dripping hole hb is not provided in each storage tank Tc. In addition, the configuration is the same as the configuration of FIG.

  According to the configuration of FIG. 10, the structure of the storage tank Tc can be simplified and the manufacturing cost can be reduced as compared with the configuration in which the dripping hole hb is provided in the storage tank Tc. Further, since the overflowing lubricating oil is routed through the connecting portion 54 that is curved in a rounded chamfered shape, the overflowing lubricating oil is not interrupted on the surface of the side plate 47 and finally travels outside the coil end 9ba. It can be dripped on the radial surface.

  It is good also as a structure of FIG. 11 which abbreviate | omitted the oil hole 26 from the structure of FIG. In this configuration, only a part of the lubricating oil injected from the rotor 10 is stored in the storage tank Tc along the inclined surface 52a and the curved surface 52b of each housing inner surface 52. According to the configuration of FIG. 11, the number of processing steps can be reduced as compared with the configuration of FIG. 10 and 11, the dropping hole hb is not provided, but the dropping portion 53 may be combined with the overflow opening 53 and the dropping hole hb.

In each embodiment, the pump 27 is built in the motor housing 8, but is not limited to this example. For example, the pump 27 may be provided in the reducer housing 7. Further, the pump 27 may be provided outside the in-wheel motor driving device and connected by piping.
The dripping hole hb of the storage tank is not limited to a round hole. For example, it may be a dripping hole hb composed of a slit along the circumferential direction. Drop holes hb may be formed not only on the bottom surface of the storage tank but also on other side surfaces. It is also possible to set the number of dripping holes at one place.
In an in-wheel motor drive device, a cycloid reducer, a planetary reducer, a two-axis parallel reducer, and other reducers can be applied, and even a so-called direct motor type that does not employ a reducer. Good.

  As mentioned above, although the form for implementing this invention based on embodiment was demonstrated, embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 ... Electric motor 2 ... Reduction gear 5 ... Wheel bearing 8 ... Motor housing 9 ... Stator 9b ... Stator coil 10 ... Rotor 23, 24 ... Oil path 27 ... Pump 53 ... Opening (dropping means)
hb ... Drip hole (Drip means)
Jk: Refueling mechanism Ta, Tb, Tc: Storage tank

Claims (5)

An in-wheel motor drive device comprising a wheel bearing that supports a wheel, an electric motor that rotates a rotating wheel of the wheel bearing, and an oil supply mechanism that cools the electric motor with lubricating oil,
The electric motor has a motor housing, a stator provided with a stator coil on the inner periphery of the motor housing away from the inner peripheral surface of the motor housing, and a rotor rotatable with respect to the stator,
The oil supply mechanism includes an oil passage for lubricating oil provided in each of the motor housing and the rotor shaft, and an oil passage for the motor housing and an oil passage for the rotor shaft driven by the electric motor. A pump for injecting lubricating oil from the rotor and guiding it to the stator;
The oil supply mechanism has a storage tank that stores lubricating oil, and the storage tank is provided at least partially above the stator coil, and the lubricating oil ejected from the rotor or the motor housing Lubricating oil dropped from an oil hole provided in the middle of the oil passage located in the upper part is stored, and dropping means for dropping the lubricating oil stored in this storage tank onto the outer diameter surface of the stator coil, An in-wheel motor drive device provided in the storage tank.   The in-wheel motor drive device of Claim 1 WHEREIN: The said dripping means is an in-wheel motor drive device which is a dripping hole formed in the said storage tank.   3. The in-wheel motor drive device according to claim 1, wherein the dripping means includes an opening that is provided at an upper portion of the storage tank and that overflows the stored lubricating oil. .   The in-wheel motor drive device according to any one of claims 1 to 3, wherein the storage tank is fixed to the stator or the motor housing.   The in-wheel motor drive device according to any one of claims 1 to 4, further comprising a reduction gear that decelerates the rotation of the electric motor and transmits the reduced speed to the rotating wheel of the wheel bearing. .

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