JP2012231658A - Lubrication control device for in-wheel motor unit for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubrication control device that can evade deterioration of the running stability caused by generation of driving force difference due to the difference of the stirring resistance between right and left in-wheel motors in transition from the low vehicle speed to the high vehicle speed.SOLUTION: In a low vehicle speed range of less than the set vehicle speed VSP1 (VSP<VSP1) in which the oil stirring resistance in the in-wheel motor case does not exceed an acceptable level, noise is prevented by controlling the rotation speed including stop of an oil pump by gradually increasing the oil pumping quantity Q from the oil pump according to the increase of the vehicle speed. When the vehicle speed VSP has reached the set vehicle speed VSP1, and transiting to the high vehicle speed range (VSP≥VSP1) in which the oil stirring resistance exceeds the acceptable level, driving control of the oil pump is carried out so that the oil pumping quantity Q becomes the prescribed quantity Qconst in which the oil levels of the right and left in wheel-motor cases are the same. Therefore, when transiting to the high vehicle speed range (VSP≥VSP1), the right and left oil levels are the same, and the deterioration of the travel stability can be avoided without causing the difference in driving force between the right and left wheels.

Description

  The present invention relates to a lubrication control device useful for a drive unit for each wheel (hereinafter, referred to as an in-wheel motor unit) used in an electric vehicle that can travel by driving wheels with individual electric motors.

The in-wheel motor unit includes a reduction gear mechanism such as a planetary gear set in addition to the electric motor as described in Patent Document 1, for example.
The rotational power from the electric motor is transmitted to the wheel under deceleration by the reduction gear mechanism, and the wheel is driven.

Therefore, the in-wheel motor unit needs to lubricate the reduction gear mechanism.
However, the oil agitation resistance increases the power consumption of the in-wheel motor unit (electric motor) and is the most important issue for an electric vehicle, because the lubrication for that purpose depends on the scraped oil from the rotating body in the in-wheel motor unit. Electricity costs will deteriorate.

  Therefore, conventionally, as described in Patent Document 1, using an oil pump that consumes much less power compared to the power consumed by oil agitation resistance, the oil in the lower part in the in-wheel motor unit is sucked. In many cases, predetermined lubrication is performed by supplying oil toward a lubrication-required portion.

  In this lubrication, the lubrication control technology described in Patent Document 1 uses the amount of lubricating oil in the high-temperature side in-wheel motor unit when the oil temperature in the in-wheel motor unit of the pair of wheels on the left and right is different from each other. The suction amount) is made larger than the lubricating oil amount (oil suction amount by the oil pump) of the low-temperature side in-wheel motor unit so as to eliminate the oil temperature difference between the left and right in-wheel motor units.

  According to such in-wheel motor unit lubrication control technology, the difference between the left and right wheel drive force due to the oil temperature difference between the left and right in-wheel motor units is alleviated, and the in-wheel motor-driven electric vehicle (in-wheel motor drive vehicle) travels. Stability can be improved.

JP 2008-195233 A

By the way, since the in-wheel motor unit is directly coupled to the wheel, it is usually arranged inside the vehicle body that can take measures against sound insulation, but it is usually arranged to be exposed outside the vehicle, and it is difficult to take measures against sound insulation. .
Therefore, in a low vehicle speed range where the in-wheel motor drive vehicle is in a silent running state, the operating sound of the oil pump becomes a noise that is uncomfortable not only for the passengers but also for people around the vehicle.

For example, in order to cope with such noise or from the viewpoint of saving power consumption, when the rotation speed of the oil pump is made as low as possible in the low vehicle speed range, or when the oil pump is deactivated as much as possible, the low At the time of transition from the vehicle speed range to the high vehicle speed range, the oil pumps of the left and right in-wheel motor units may have different oil suction amounts due to a difference in rotational speed.
In this case, the oil levels in the lower parts in the left and right in-wheel motor units are different, resulting in the following problems.

That is, the electric motor in the in-wheel motor unit has a larger diameter than the reduction gear mechanism, as illustrated in Patent Document 1.
Considering that the radial dimensions of the in-wheel motor unit must be as small as possible to ensure the required mountability, a large gap cannot be set between the electric motor and the in-wheel motor unit case. .

On the other hand, the oil pump needs to suck in oil in the lower part of the in-wheel motor unit case even when the vehicle vibrates or tilts, so that the oil pump can inhale oil during these vibrations and tilts. The oil level in the lower part of the motor unit case must be increased considerably.
For these reasons, it is inevitable that a large-diameter electric motor (rotary rotor) is immersed in the oil in the lower part of the in-wheel motor unit.

However, as described above, if the oil level in the lower part of the left and right in-wheel motor units is different during the transition from the low vehicle speed range to the high vehicle speed range, the oil immersion amount of the electric motor (rotating rotor) is different between the left and right in-wheel motor units. Will be.
Moreover, during high revolutions that have shifted from the low vehicle speed range to the high vehicle speed range, the oil agitation resistance by the electric motor (rotary rotor) exceeds the allowable level. A problem arises that the running stability of the in-wheel motor driven vehicle deteriorates due to the generation of the driving force difference.

  However, the lubrication control technology described in Patent Document 1 is merely to vary the oil suction amount of the oil pump between the in-wheel motor units according to the oil temperature difference between the left and right in-wheel motor units. It is not possible to solve problems related to running stability.

  The present invention controls the oil pump so that the oil level in the lower parts of the left and right in-wheel motor unit cases is the same when shifting from the low vehicle speed range to the high vehicle speed range, thereby causing the above problem of running stability. An object of the present invention is to provide a lubrication control device for an in-wheel motor unit for a vehicle that can eliminate the above-mentioned problem.

For this purpose, the in-wheel motor unit lubrication control device of the present invention is configured as follows.
First, an in-wheel motor drive vehicle that is a premise of the present invention, and a lubrication control device for an in-wheel motor unit used therefor will be described.
The in-wheel motor drive vehicle is capable of traveling by driving at least a pair of left and right wheels by individual in-wheel motor units,
The lubrication control device for an in-wheel motor unit used in this vehicle lubricates the inside of the in-wheel motor unit that is paired on the left and right with the oil sucked from the lower part inside the in-wheel motor unit case by each oil pump. is there.

The present invention is characterized by a configuration in which the following oil pump drive control means is provided for such a lubrication control device for an in-wheel motor unit.
The oil pump drive control means adjusts the oil pump to the oil from the oil pump as the vehicle speed increases in a low vehicle speed region below a set vehicle speed at which the agitation resistance due to oil in the lower part of the in-wheel motor unit case does not exceed an allowable level. The drive control is performed so that the suction amount gradually increases, and the oil suction amount becomes a predetermined amount that equals the oil level in the lower part in the case of the left and right in-wheel motor unit when the vehicle speed increases to the set vehicle speed. The oil pump is driven and controlled.

In the above-described lubrication control device for a vehicle in-wheel motor unit according to the present invention,
In order to control the oil pump so that the oil suction amount gradually increases as the vehicle speed rises in the low vehicle speed range below the set vehicle speed where the stirring resistance due to oil in the lower part of the in-wheel motor unit case does not exceed the allowable level,
It is possible to suppress unnecessary oil pump driving in a low vehicle speed region, and to perform, for example, the above-described noise countermeasures and power consumption savings.

Further, when the vehicle speed rises to the set vehicle speed, the oil suction amount becomes a predetermined amount that makes the oil level in the lower part in the case of the left and right in-wheel motor units the same when the transition is made from the low vehicle speed region to the high vehicle speed region. So that the oil pump is driven and controlled
It is possible to ensure that the oil level in the lower part in the case of the left and right in-wheel motor units is the same at the transition from the low vehicle speed region to the high vehicle speed region.

  For this reason, at the time of transition from the low vehicle speed region to the high vehicle speed region, the oil immersion amount of the large-diameter rotating member in the in-wheel motor unit can be made the same between the left and right in-wheel motor units. The resistance can be the same between the left and right in-wheel motor units.

  Therefore, even when shifting to a high vehicle speed range where the oil stirring resistance by the large-diameter rotating member cannot be allowed, a driving force difference is not generated between the left and right in-wheel motor units. The above problem that the running stability of the vehicle is deteriorated can be solved.

It is a vertical side view which shows the in-wheel motor unit provided with the lubrication control apparatus which becomes one Example of this invention. Fig. 1 shows the oil guide installed in the oil gallery of the in-wheel motor unit in Fig. 1, (a) is a detailed longitudinal section of the oil guide as seen in the direction of the arrow, taken along the line II-II in Fig. 2 (b) Side view (b) is a detailed front view of the oil guide as seen from the right side of FIG. 2 (a). 2 is a flowchart showing a lubrication control program executed by an oil pump controller in FIG. FIG. 4 is a characteristic diagram showing an oil suction amount control characteristic of an oil pump driven and controlled by the lubrication control program of FIG. 2 is a time chart showing the oil temperature change characteristic of the in-wheel motor unit in FIG. 1 for each oil immersion amount of the rotor. FIG. 5 is a characteristic diagram showing a change characteristic of an oil pump target rotational speed necessary for realizing the constant flow rate shown in FIG. 4 in the constant flow rate control region of FIG. FIG. 5 is a change characteristic diagram showing a change characteristic related to a reduction allowance ΔVSP0 of the oil pump starting vehicle speed VSP0 in FIG. 4 using an integral value of a required drive torque as a parameter. FIG. 5 is a change characteristic diagram showing a change characteristic related to a decrease allowance ΔVSP0 of the oil pump starting vehicle speed VSP0 in FIG. 4 with a travel distance in a state where the oil pump is stopped as a parameter.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
<Configuration of Example>
FIG. 1 is a vertical side view showing an in-wheel motor unit including a lubrication control device according to an embodiment of the present invention.
In this figure, 1 is a case main body of the in-wheel motor unit, and 2 is a rear cover of the case main body 1. A unit case 3 of the in-wheel motor unit is constituted by the combination of the case main body 1 and the rear cover 2.

The in-wheel motor unit shown in FIG. 1 is configured by housing an electric motor 4 and a planetary gear type reduction gear set 5 (hereinafter simply referred to as “reduction gear set”) in a unit case 3.
The electric motor 4 includes an annular stator 6 fitted and fixed to the inner periphery of the case body 1, and a rotor 7 arranged concentrically with a radial gap on the inner periphery of the annular stator 6. To do.

The reduction gear set 5 is used to drive-couple between the input shaft 8 and the output shaft 9 which are disposed so as to face each other coaxially,
A sun gear 11, a fixed ring gear 12 arranged concentrically with respect to the sun gear 11 in the axial direction approaching the output shaft 9, a stepped planetary pinion (stepped pinion) 13 meshing with the sun gear 11 and the ring gear 12, The stepped planetary pinion 13 is constituted by a pinion shaft 14 that rotatably supports the carrier, and carriers 15a and 15b that support the pinion shaft 14.

The input shaft 8 includes the sun gear 11 integrally formed at the inner end near the output shaft 9 and extends the input shaft 8 rearward from the sun gear 11 toward the rear cover 2.
The output shaft 9 extends in the opposite direction (forward) from the reduction gear set 5 and protrudes from the opening of the front end (right side of the figure) of the case body 1, and a wheel 16 is attached to the output shaft 9 at the protruding portion as described later. Join.

The input shaft 8 and the output shaft 9 are formed by inserting the coaxial butted ends of the two into a mutually rotatable manner, and interposing a bearing 17 that enables a ball bearing between the two, thereby providing an input / output shaft bearing. Set the fitting part.
The portions of the input shaft 8 and the output shaft 9 that are spaced apart from the bearing 17 in the axial direction are respectively supported on the unit case 3 by a bearing 18 that allows a ball bearing and a bearing 19 that allows a double-row angular bearing.

  The bearing 19 is interposed between the inner periphery of the end lid 20 that closes the front end opening of the case body 1 and the outer periphery of the wheel hub 21 that is fitted to the protruding portion of the output shaft 9 that protrudes from the front end opening of the case body 1. Let

  In the electric motor 4, the rotor 7 is coupled to the input shaft 8, and this coupling position is defined as the axial position between the reduction gear set 5 and the bearing 18.

The ring gear 12 is prevented from turning in the front end opening of the case main body 1 and is fixed so as not to come off.In order to prevent this, the ring gear 12 is prevented from coming off by a seal adapter 22 that closes the front end opening of the case main body 1. Do.
The seal adapter 22 is attached to the front end of the case body 1 with a bolt 22a, and the end cover 20 is attached to the seal adapter 22 with the bolt 20a.

The stepped planetary pinion 13 includes a large-diameter gear portion 13a that meshes with the sun gear 11 on the input shaft 8, and a small-diameter gear portion 13b that meshes with the ring gear 12 and rolls the stepped planetary pinion 13 along the inner periphery of the ring gear 12. Is a stepped pinion (planetary gear).
The stepped planetary pinion 13 is arranged so that the large-diameter gear portion 13a is located on the side far from the output shaft 9 and the small-diameter gear portion 13b is located on the side close to the output shaft 9.

The stepped planetary pinions 13 are, for example, arranged as a set of four at equal intervals in the circumferential direction, and the stepped planetary pinions 13 are held via the pinion shaft 14 by a common carrier 15a, 15b while maintaining this circumferentially equal interval arrangement. Support for rotation.
The carriers 15a and 15b function as output rotating members of the reduction gear set 5, and are provided at the inner end of the output shaft 9 close to the input shaft 8 so as to be integrated therewith.
Therefore, the carriers 15a and 15b and the stepped planetary pinion 13 (pinion shaft 14) project from the output shaft 9 toward the input shaft 8 and are attached to the output shaft 9.

Next, how to connect the wheel 16 to the output shaft 9 will be described in detail.
A brake drum 25 is provided concentrically with the wheel hub 21, and a plurality of wheel bolts 26 are implanted so as to penetrate the wheel hub 21 and the brake drum 25 and protrude in the axial direction.
When mounting the wheel 16, the wheel disc is brought into close contact with the bottom surface of the brake drum 25 so that the wheel bolt 26 penetrates into the bolt hole made in the wheel disc, and in this state, the wheel nut 27 is tightened and screwed. By doing so, the wheel 16 is attached to the output shaft 9.

<Operation of in-wheel motor unit>
When the stator 6 of the electric motor 4 is energized, the rotor 7 of the electric motor 4 is rotationally driven by the electromagnetic force from now on, and the rotational driving force is transmitted to the sun gear 11 of the reduction gear set 5 via the input shaft 8.
As a result, the sun gear 11 rotates the stepped planetary pinion 13 via the large-diameter gear portion 13a. At this time, since the fixed ring gear 12 functions as a reaction force receiver, the stepped planetary pinion 13 has a small-diameter gear portion 13b. Performs a planetary motion that rolls along the ring gear 12.
The planetary motion of the stepped planetary pinion 13 is transmitted to the output shaft 9 via the carriers 15a and 15b, and the output shaft 9 is rotated in the same direction as the input shaft 8.

Due to the above transmission operation, the reduction gear set 5 decelerates the rotation from the electric motor 4 to the input shaft 8 at a ratio determined by the number of teeth of the sun gear 11 and the number of teeth of the ring gear 12, and transmits it to the output shaft 9.
The rotation to the output shaft 9 is transmitted to the wheel 16 via the wheel hub 21 and the wheel bolt 26 coupled thereto, and the wheel 16 can be driven to rotate.

A wheel (not shown) on the opposite side in the left-right direction that forms a pair with the wheel 16 is also rotated in the same manner by an in-wheel motor unit of the same specification as in FIG. The vehicle can be driven by rotational driving with force.
When braking the vehicle, the brake shoe 27 is pressed against the inner peripheral surface of the brake drum 25 to frictionally brake the wheels 16.

<Lubrication oil path for in-wheel motor unit>
In the in-wheel motor unit described above, it is necessary to lubricate the reduction gear set 5 between the input shaft 8 and the output shaft 9.

Since the electric motor 4 does not need to be lubricated, a partition wall is provided in the case body 1 between the electric motor 4 and the reduction gear set 5, and the housing for the electric motor 4 and the reduction gear set 5 are provided. It may be possible to partition the storage room,
In this case, the electric motor 4 and the reduction gear set 5 cannot be arranged close to each other so as to overlap in the radial direction as shown in FIG. 1, and the in-wheel motor unit becomes easier to mount due to its longer axial direction. descend.

  Therefore, in the present embodiment, as shown in FIG. 1, the storage chamber of the electric motor 4 and the storage chamber of the reduction gear set 5 are made common, and the electric motor 4 and the reduction gear set 5 are placed in the case body 1 in the radial overlap state. By placing close to the same room and shortening the axial direction dimension of the in-wheel motor unit, the mountability is improved.

  In this embodiment, the lubrication of the reduction gear set 5, the lubrication of the bearing 17 between the input / output shafts 8 and 9, and the lubrication of the bearing 18 between the input shaft 8 and the unit case 3 are as follows. This is done by a simple lubrication control device.

First, a lubricating oil path for this purpose will be described with reference to FIG. 1. Lubricating oil 31 is stored in the lower part of the unit case 3 as shown in FIG. 1, and an electric oil pump 32 is provided in the lower part.
The oil pump 32 has a suction port 32a and a discharge port 32b, and the suction port 32a is opened through the oil filter 33 to a storage portion for the oil 31 in the lower part in the unit case 3.

The amount of oil 31 stored is such that the level 31a does not become lower than the suction port 32a even when the vehicle is vibrated or tilted, and the oil pump 32 is removed from the suction port 32a even when the vehicle is vibrated or tilted. So that the oil 31 can be inhaled,
The amount of oil 31 stored for all in-wheel motor driven wheels is such that the static oil level 31a at the lower part in the in-wheel motor unit is the same.

In the rear cover 2, a concentric circular oil gallery 34 is formed on the input shaft 8, and the oil gallery 34 is passed through a discharge port 32 b of the oil pump 32.
The oil gallery 34 is defined between the end face of the input shaft 8 far from the output shaft 9 and the end face of the bearing 18 and an oil cap 35 fitted to the rear cover 2 so as to face both the end faces. Form.

An oil guide 38 is interposed between the end face of the input shaft 8 far from the output shaft 9 and the end face of the bearing 18 and the oil cap 35.
2A and 2B, the oil guide 38 has a disk shape as a whole, a guide cylinder 38a is projected from the center thereof, and a guide hole 38b is formed in the peripheral portion.

  The oil guide 38 is installed by inserting a guide cylinder 38a into a corresponding end of a hollow hole 8a provided at the center of the input shaft 8 as shown in FIG. , 9 open in the interengagement cavity.

A radial oil hole 42 extending radially outward is provided in the carrier 15a, and a radial oil hole 8b is also provided in the input shaft 8 in alignment with the radial oil hole 42.
The radially outer end of the radial oil hole 42 provided in the carrier 15a is communicated with the hollow hole 43 at the center of the pinion shaft 14.
The pinion shaft 14 is further provided with an oil ejection hole 44 extending radially outward from the hollow hole 43, and oil can be supplied from the oil ejection hole 44 to a lubrication required portion of the reduction gear set 5 by centrifugal force. Do it like this.

  The input shaft 8 is further provided with a radial oil hole 8c extending from the hollow hole 8a toward the bearing 17 interposed in the mutual fitting portion of the input / output shafts 8 and 9, from here to the bearing 17 as well. Be able to supply oil.

The operation of the lubricating oil passage described above with reference to FIGS.
When the in-wheel motor unit is in operation, if the bearings 17 and 18 and the reduction gear set 5 need to be lubricated, the oil pump 32 is driven.
When the oil pump 32 is driven, the lubricating oil 31 at the lower part in the in-wheel motor unit case 3 is sucked through the port 32a and discharged from the port 32b as shown by the arrow in FIG. Go to Gallery 34.

While the wheel 16 is driven to rotate by the in-wheel motor unit, the oil in the hollow hole 43 and the oil ejection hole 44 of the pinion shaft 14 receives centrifugal force and is ejected from the oil ejection hole 44 as shown by the arrow in FIG. , And supplied to the lubrication required portion of the reduction gear set 5.
As shown by the arrows in FIG. 1, the oil jetted from the jet holes 44 includes a guide cylinder 38a from the oil gallery 34 to the oil guide 38, a hollow hole 8a in the input shaft 8, a radial oil hole 8b, and a radial oil hole. The oil is replenished by the oil directed to the pinion shaft hollow hole 43 through 42, and the oil supply to the reduction gear set 5 can be continuously performed.

On the other hand, the stored oil in the oil gallery 34 passes through the peripheral guide hole 38b provided in the oil guide 38, goes to the bearing 18 as indicated by an arrow in FIG.
The oil that has reached the hollow hole 8a of the input shaft 8 from the oil gallery 34 through the guide cylinder 38a of the oil guide 38 simultaneously passes through the radial oil hole 8c as shown by the arrow in FIG. It reaches the bearing 17 and is also used for lubrication of the bearing 17.

Incidentally, since the reduction gear set 5 is a mechanical element, metal powder is generated during transmission, and this metal powder is mixed in the circulating oil as described above.
Thus, the oil mixed with the metal powder reaches the lower oil reservoir in the housing 3 through the input shaft hollow hole 8a, the reduction gear set 5, and the electric motor 4 from the pump 32, and is sucked and circulated again by the pump 32.

During this circulation, a part of the metal powder mixed in the oil is adsorbed by the permanent magnet in the electric motor 4, and the amount of metal powder adhering to the electric motor 4 increases with time.
Thus, when the adhesion amount of the metal powder to the electric motor 4 increases, the performance of the electric motor 4 is lowered, and the power performance of the in-wheel motor type electric vehicle is lowered.

In order to solve this problem, the following measures are taken for the in-wheel motor unit shown in FIG.
An axial groove 47 is provided in the housing inner peripheral surface 3a to which the lower portion 6a of the stator 6 immersed in the oil reservoir is fitted, and both ends 47a and 47b of the axial groove 47 are spaces 45 on both axial sides of the electric motor 4, respectively. Open to 46,
The oil 31 is transported between the housing space 45 on the side where the reduction gear set 5 is located and the housing space 46 on the opposite side through the axial groove 47.

Further, a permanent magnet 48 is fixed in the housing 3 so as to approach the opening end 47a of the axial groove 47 close to the housing space 45 on the side where the reduction gear set 5 is located.
The stator 6 is preferably molded so that at least the lower part 6a does not penetrate oil.

Thus, the metal powder mixed in when the oil passes through the reduction gear set 5 is adsorbed by the permanent magnet 37 when entering the open end 47a of the axial groove 47 from the oil reservoir in the reduction gear housing space 45, and the oil Can be removed from within.
As a result, the metal powder can be prevented from adhering to the electric motor 4, and the electric motor 4 is deteriorated in performance due to the adhesion of the metal powder, and the power performance of the in-wheel motor type electric vehicle is reduced. The problem can be avoided.

<Lubrication control of in-wheel motor unit>
In the above-described lubrication of the in-wheel motor unit (the reduction gear set 5 and the bearings 17 and 18), the oil pump controller 51 in FIG. 1 controls the lubrication as described below through the drive control of the oil pump 32.

  Therefore, the oil pump controller 51 is required to calculate a signal from the oil temperature sensor 52 that detects the oil temperature Temp of the lubricating oil 31, a signal from the vehicle speed sensor 53 that detects the vehicle speed VSP, and a required driving torque Td of the vehicle. A signal from the drive torque calculator 54 and a signal from the odometer 55 that measures the vehicle mileage L while the oil pump 32 is in a stopped state are input.

The required drive torque calculator 54 can calculate the required drive torque Td by a known calculation from the accelerator opening operated by the driver and the rotational speed information such as the vehicle speed VSP.
The odometer 55 is reset to 0 when the vehicle is stopped, and can measure the mileage L by integrating the vehicle mileage when the oil pump is stopped.

  The oil pump controller 51 executes the control program shown in FIG. 3 based on the above input information, and drives the oil pump 32 so that the oil suction amount by the oil pump 32 is as shown in FIG. Control.

In step S11 in FIG. 3, it is checked whether or not the vehicle speed VSP is equal to or higher than the set vehicle speed VSP1 in FIG.
Since the rotor 7 has a large diameter, the set vehicle speed VSP1 is a high value in which the oil stirring resistance to the rotor 7 immersed in the oil 31 exceeds an allowable level (a level that can be almost ignored) as indicated by D in FIG. This is the lower limit vehicle speed (for example, 30 km / h) in the vehicle speed range.
In this high vehicle speed range, if the oil level 31a in the lower part of the in-wheel motor unit case is different between the left and right wheels, the oil immersion amount D of the rotor 7 between the left and right wheels, that is, the oil stirring resistance to the rotor 7 is large. On the other hand, a large driving force difference is generated between the left and right wheels, which causes a problem that the running stability of the vehicle deteriorates.

As will be further described with reference to FIG. 5, FIG. 5 shows how the oil temperature Temp in the in-wheel motor unit varies depending on the oil immersion amount D of the rotor 7 under a certain vehicle speed VSP of the set vehicle speed VSP1 or higher. It is the characteristic view which showed how it changed.
The larger the oil immersion amount D of the rotor 7 is, the more rapidly the rate of change in the oil temperature Temp is, and this is because the greater the oil immersion amount D of the rotor 7, the greater the oil stirring resistance to the rotor 7, It means that the wheel driving force is greatly reduced due to power loss.

  Therefore, in a high vehicle speed range (VSP ≧ VSP1) where the oil stirring resistance to the rotor 7 exceeds the allowable level, if the oil level 31a of the left and right in-wheel motor units is different, the oil immersion amount D of the rotor 7 between the left and right wheels D As a result, the difference in oil agitation resistance to the rotor 7 due to the difference between the two causes a large driving force difference between the left and right wheels, resulting in a problem that the running stability of the vehicle deteriorates.

Therefore, in this embodiment, when it is determined in step S11 that the vehicle speed VSP is equal to or higher than the set vehicle speed VSP1, in step S12 in FIG. 3, the oil pump 32 of each of the left and right in-wheel motor units has an oil suction amount Q. Drive control is performed so that the constant flow rate Qconst in FIG. 4 is maintained.
Therefore, step S12 corresponds to the oil pump drive control means in the present invention.

In this drive control, the oil pump controller 51 has a constant flow rate (for example, a constant flow rate (see FIG. 6) considering this characteristic because the oil suction amount Q varies depending on the oil temperature Temp even at the same rotational speed of the oil pump 32. Qconst) Based on the realization characteristic, the oil pump target rotational speed Nop is obtained from the oil temperature Temp, and this is instructed to the oil pump 32 as shown in FIG. 1, and the oil pump 32 is driven and controlled to become the target rotational speed Nop.
According to such drive control, the oil pump 32 can control the oil pump suction amount Q to the constant flow rate Qconst shown in FIG. 4 in the high vehicle speed range (VSP ≧ VSP1) under any oil temperature Temp. it can.

  The above-mentioned constant flow rate Qconst is the minimum unit required oil amount necessary to lubricate the reduction gear set 5 in the in-wheel motor unit, for example, the oil amount at the vehicle speed at which this unit required oil amount is the largest. Set.

When the oil pump 32 is driven and controlled so that the oil suction amount Q by the oil pump 32 of the left and right in-wheel motor unit is maintained at the above constant flow rate Qconst,
As described above, the static oil level 31a in the lower part in the left and right in-wheel motor unit is the same, so that the oil level 31a in the lower part in the left and right in-wheel motor unit is kept the same during the operation of the oil pump 32.

  In this way, the oil level 31a in the lower part of the left and right in-wheel motor units is kept the same during the operation of the oil pump 32, so that the oil stirring resistance to the rotor 7 exceeds the permissible level (VSP ≧ VSP1) Even so, the oil agitation resistance to the rotor 7 in the left and right in-wheel motor units is kept the same, there is no drive force difference between the left and right wheels, and the running stability of the vehicle deteriorates. The problem can be avoided.

  In addition, since the above-described constant flow rate Qconst in FIG. 4 is set to the minimum amount of oil necessary for lubricating the reduction gear set 5 in the in-wheel motor unit, the reduction gear set 5 is set to the minimum oil (minimum The above problem can be solved while lubricating as required by the pump power consumption).

When it is determined in step S11 of FIG. 3 that the vehicle speed is low (VSP <VSP1), the control proceeds to step S13 corresponding to the oil pump drive control means in the present invention, and the oil pump 32 is set to a variable flow rate as follows. Control.
The reason is that when the vehicle speed is low (VSP <VSP1), the rotational speed of the rotor 7 is slow, the oil agitation resistance is below an allowable level, and the above-mentioned problems relating to running stability are not caused. This is because the demand is low and it is desirable to avoid the operation of the oil pump 32 as much as possible from the viewpoint of saving electricity costs and noise of the oil pump.

By the way, the oil pump 32 is not located inside the vehicle body where noise insulation measures can be taken, but because it is installed in the in-wheel motor unit exposed outside the vehicle, noise insulation measures are impossible,
In particular, in the low vehicle speed range (VSP <VSP1) where the in-wheel motor drive vehicle is in a silent running state, the operating sound of the oil pump 32 causes noise that is uncomfortable to the passengers and people around the vehicle. It is preferable to make the rotation speed of the pump 32 as low as possible, or to make the oil pump 32 inactive as much as possible, and it is good to do so from the viewpoint of saving power consumption.

Therefore, in the variable flow rate control of the oil pump 32 in the low vehicle speed range (VSP <VSP1) executed in step S13,
When the required drive torque Td is 0 and the travel distance L when the oil pump is stopped is 0, as shown by the solid line characteristics (basic characteristics) in the low vehicle speed range (VSP <VSP1) in FIG. Until the VSP rises to the oil pump starting vehicle speed VSP0, the oil suction amount Q by the oil pump 32 is set to 0 and the oil pump 32 is stopped.
While the vehicle speed VSP rises from the oil pump start vehicle speed VSP0 and reaches the set vehicle speed VSP1, the oil pump 32 is gradually quadratic from the oil suction amount Q to 0 to the constant flow rate Qconst. Drive control to increase.

  This constant flow rate Qconst is the oil suction amount (predetermined amount in the present invention) of the oil pump 32 to make the oil level 31a in the lower part in the left and right in-wheel motor units the same, as is apparent from the above-mentioned place. As described above, the minimum unit required oil amount necessary for lubricating the reduction gear set 5 in the in-wheel motor unit is made to correspond.

In the above-described drive control of the oil pump 32 in the low vehicle speed range (VSP <VSP1), the oil pump controller 51 is an oil pump for realizing the oil suction amount Q that varies between 0 and a constant flow rate Qconst as described above. The target rotational speed Nop is obtained according to the oil temperature Temp based on the same concept as described above with reference to FIG. 6, and this is instructed to the oil pump 32 as shown in FIG.
According to such drive control, under any oil temperature Temp, the oil pump 32 controls the oil pump suction amount Q so as to follow the characteristic indicated by the solid line in FIG. 4 in the low vehicle speed range (VSP <VSP1). be able to.

Here, the oil pump starting vehicle speed VSP0 is caused by the residual oil stored in the lubricating oil passage from the oil gallery 34 to the oil ejection hole 44 being ejected by centrifugal force due to the start of wheel driving by the in-wheel motor unit. The vehicle speed when all of the oil runs out, or the vehicle speed when the residual oil becomes less than a predetermined amount.
The reason is that if the oil pump 32 is kept stopped even after reaching the oil pump starting vehicle speed VSP0 determined in this way, the lubricating oil is not temporarily supplied to the reduction gear set 5, and the reduction gear set 5 This is because it is damaged by temporary lubrication failure.

Therefore, when the required drive torque Td becomes larger than 0, the required lubricating oil amount of the reduction gear set 5 increases, and the oil pump starting vehicle speed VSP0 decreases as shown by the wavy characteristics in FIG. It is necessary to start 32.
For example, at the time of so-called `` hill hold '' in which the vehicle is stopped by the torque of the electric motor 4 on an uphill road, the reduction gear set 5 is in a torque transmission state even if the vehicle speed VSP is 0, so it is necessary to lubricate this. Even when the vehicle speed VSP is 0, the required lubricating oil amount of the reduction gear set 5 is as illustrated by Qo in FIG.

Therefore, in the present embodiment, as a map relating to the reduction margin of the oil pump starting vehicle speed VSP0 indicated by ΔVSP0 in FIG. 4, the oil pump that increases as shown in FIG. 7, for example, as the integral value ΣTd of the required drive torque Td increases. A map related to the reduction allowance ΔVSP0 of the starting vehicle speed VSP0 is obtained in advance through experiments or the like and prepared.
Note that the decrease amount ΔVSP0 of the oil pump starting vehicle speed VSP0 is VSP0 as the maximum value α is apparent from FIG. 4, and the map of FIG. 7 shows that the integral value ΣTd of the required drive torque Td is greater than or equal to a certain value ΣTdm. This means that the oil pump starting vehicle speed VSP0 is set to 0 by ΔVSP0 = α, and the oil pump 32 is driven from the stopped state to satisfy, for example, the above-described requirements at the time of hill hold.

When the oil pump controller 51 executes step S13 of FIG. 3 in the low vehicle speed range (VSP <VSP1),
When the integral value ΣTd of the required drive torque Td is 0, the oil pump 32 is controlled by the above-described control so that the oil suction amount Q changes according to the solid line characteristic of FIG.
When the integral value ΣTd of the required drive torque Td exceeds 0, a reduction margin ΔVSP0 of the oil pump starting vehicle speed VSP0 corresponding to the integral value ΣTd of the required drive torque Td is obtained from the map of FIG. The oil pump 32 is driven and controlled so as to achieve the change characteristic of the oil suction amount Q as illustrated by the wavy line in FIG. 4 as the starting vehicle speed.

  On the other hand, if the mileage L when the oil pump is stopped becomes greater than 0 due to the start of the vehicle, the residual oil amount is reduced by the jetting due to the centrifugal force. It is necessary to start the oil pump 32 at an early stage by lowering as shown in FIG.

Therefore, in the present embodiment, a map related to the reduction allowance ΔVSP0 of the oil pump starting vehicle speed VSP0 that becomes large as shown in FIG. Have it ready.
The map in FIG. 8 means that when the travel distance L when the oil pump is stopped is equal to or greater than a certain value Lm, the oil pump start vehicle speed VSP0 is set to 0 by ΔVSP0 = α and the oil pump 32 is driven. ,
Even if the residual oil is lost or less than a predetermined amount due to L ≧ Lm, the oil pump 32 is kept in a stopped state so that a problem of poor lubrication does not occur.

When the oil pump controller 51 executes step S13 in FIG. 3 in the low vehicle speed range (VSP <VSP1),
When the travel distance L when the oil pump is stopped is 0, the oil pump 32 is controlled by the above-described control so that the oil suction amount Q changes according to the solid line characteristic of FIG.
When the travel distance L when the oil pump is stopped exceeds 0, a reduction allowance ΔVSP0 of the oil pump starting vehicle speed VSP0 corresponding to the travel distance L when the oil pump is stopped is obtained from the map of FIG. 8, and (VSP0−ΔVSP0) is obtained. The oil pump 32 is driven and controlled so that the change characteristic of the oil suction amount Q as exemplified by the wavy line in FIG. 4 is achieved as the oil pump starting vehicle speed.

<Effect of Example>
In the lubrication control of the in-wheel motor unit configured as described above,
In the high vehicle speed range (VSP ≧ VSP1) where the oil agitation resistance to the rotor 7 exceeds the permissible level, the oil pump 32 of the left and right in-wheel motor units is both kept at the constant flow rate Qconst in FIG. To control the drive so that
Since the static oil level 31a in the lower part in the left and right in-wheel motor unit is the same, the oil level 31a in the lower part in the left and right in-wheel motor unit is kept the same during the operation of the oil pump 32.

Therefore, even in the high vehicle speed range (VSP ≧ VSP1) where the oil agitation resistance to the rotor 7 exceeds the allowable level, the oil agitation resistance to the rotor 7 in the left and right in-wheel motor unit is kept the same, Thus, it is possible to avoid the problem that the running stability of the vehicle is deteriorated without generating a driving force difference.
Since this effect is achieved by simple constant flow rate control of the oil pump 32, the cost is significant.

  In addition, since the above-described constant flow rate Qconst in FIG. 4 is set to the minimum amount of oil necessary for lubricating the reduction gear set 5 in the in-wheel motor unit, the reduction gear set 5 is set to the minimum oil (minimum The above problem can be solved while lubricating as required by the pump power consumption).

Further, in the drive control of the oil pump 32, the oil pump target rotation speed Nop is obtained from the oil temperature Temp based on the constant flow rate (Qconst) realization characteristic of the oil pump 32 illustrated in FIG. In order to control the drive so that it becomes a few Nop,
Under any oil temperature Temp, the oil pump 32 can control the oil pump suction amount Q to the constant flow rate Qconst shown in Fig. 4 in the high vehicle speed range (VSP ≥ VSP1), ensuring the above effect Can play.

Further, in this embodiment, the constant flow rate control of the oil pump 32 is performed so that the oil agitation resistance to the rotor 7 exceeds an allowable level, and the high vehicle speed region (VSP ≥VSP1) only,
In the low vehicle speed range (VSP <VSP1) where the oil agitation resistance to the rotor 7 is less than the allowable level, the “running stability problem” does not occur, and the lubrication requirement of the reduction gear set 5 is low. Since the pump 32 is controlled at a variable flow rate so that the oil suction amount Q is smaller than the constant flow rate Qconst as shown in FIG. 4 and the vehicle speed VSP is lower, the oil suction amount becomes smaller, so the following effects can be obtained. it can.

  That is, in such a low vehicle speed range (VSP <VSP1), especially in the extreme vehicle speed range of VSP <VSP0 including stopping, the in-wheel motor drive vehicle is in a silent running state, so the operating sound of the oil pump 32 is However, it is preferable for the number of revolutions of the oil pump 32 to be as low as possible, or to make the oil pump 32 inactive if possible, from the viewpoint of saving electricity costs. But it's better to do that.

In this embodiment, the oil pump 32 is operated in the low vehicle speed range (VSP <VSP1), and the oil suction amount is smaller as the oil suction amount Q is smaller than the constant flow rate Qconst as shown in FIG. 4 and the vehicle speed VSP is lower. Since the variable flow rate control is performed so as to satisfy the above requirement, the above requirement can be realized.
Especially in the extreme vehicle speed range of VSP <VSP0 including stopping, the oil pump 32 is stopped while the operation is unnecessary from the viewpoint of lubrication, so that the operation noise of the oil pump 32 is prevented from becoming "noise". In addition, the power consumption of the oil pump 32 can be prevented from increasing due to unnecessary operation.

Then, as the vehicle speed increases in the low vehicle speed range (VSP <VSP1) where the stirring resistance due to the oil 31 in the lower part of the in-wheel motor unit case does not exceed the permissible level, the oil pump 32 and the oil suction amount Q are When the drive control is performed so as to gradually increase as shown in FIG.
In order to drive and control the oil pump 32 so that the oil suction amount Q becomes the predetermined amount Qconst that makes the oil level in the lower part in the left and right in-wheel motor unit case the same when the vehicle speed rises when the vehicle speed VSP reaches the set vehicle speed VSP1,
At the time of transition from the low vehicle speed range (VSP <VSP1) to the high vehicle speed range (VSP ≧ VSP1), the oil level in the lower part of the case of the left and right in-wheel motor units can be made the same, and the high vehicle speed range (VSP ≧ VSP1) ), A problem that a large difference in driving force between the left and right wheels is generated and the running stability is deteriorated can be avoided.

1 Case body
2 Rear cover
3 In-wheel motor unit case
4 Electric motor
5 Reduction gear set
6 Stator
7 Rotor
8 Input shaft
9 Output shaft
11 Sungear
12 Ring gear
13 Stepped planetary pinion
14 Pinion shaft
15a, 15b career
16 wheels
17,18,19 Bearing
20 End lid
21 Wheel hub
22 Seal adapter
26 Wheel bolt
27 Wheel nut
31 Lubricating oil
31a Oil level
32 Oil pump
32a Suction port
32b Discharge port
33 Oil filter
34 Oil Gallery
35 Oil cap
38 Oil guide
38a Guide tube
38b Guide hole
42 radial oil hole
43 hollow holes
44 Oil outlet
51 Oil pump controller
52 Oil temperature sensor
53 Vehicle speed sensor
54 Required drive torque calculator
55 Odometer

Claims (5)

Used in an in-wheel motor drive vehicle capable of driving by driving at least a pair of left and right wheels by individual in-wheel motor units,
In the in-wheel motor unit lubrication control device for lubricating the inside of the in-wheel motor unit paired on the left and right with the oil sucked from the lower part in the in-wheel motor unit case by each oil pump,
As the vehicle speed rises in a low vehicle speed region where the agitation resistance due to oil in the lower part of the in-wheel motor unit case does not exceed the allowable level, the oil suction amount from the oil pump gradually increases as the vehicle speed increases. Oil that controls the oil pump so that when the vehicle speed increases to the set vehicle speed, the oil suction amount becomes a predetermined amount that equals the oil level in the lower part in the case of the left and right in-wheel motor unit. A lubrication control device for an in-wheel motor unit for a vehicle, comprising pump drive control means. In the vehicle in-wheel motor unit lubrication control device according to claim 1,
The oil pump drive control means controls the oil pump so that the oil suction amount from the oil pump is maintained at the predetermined amount in a high vehicle speed region higher than the set vehicle speed. The in-wheel motor unit lubrication control device for vehicles. In the lubrication control device for an in-wheel motor unit for a vehicle according to claim 1 or 2,
The lubrication control device for a vehicle in-wheel motor unit, wherein the predetermined amount related to the oil suction amount is a minimum amount of oil necessary for lubrication in the in-wheel motor unit. In the vehicle in-wheel motor unit lubrication control device according to claim 2 or 3,
The oil pump drive control means controls the oil pump according to the oil temperature so that the oil suction amount is maintained at the predetermined amount regardless of a temperature change in the high vehicle speed region. A lubrication control device for an in-wheel motor unit for vehicles, which is characterized. 5. The in-wheel motor for a vehicle according to claim 2, wherein the in-wheel motor for a vehicle according to claim 2 is used for an in-wheel motor-driven vehicle in which oil of the same oil level is stored in a lower part in the case of each of the left and right in-wheel motor units. In the unit lubrication control device,
The vehicle is characterized in that the oil pump drive control means drives and controls these oil pumps so that the oil suction amount by the oil pumps of the left and right in-wheel motor units is the same in the high vehicle speed region. In-wheel motor unit lubrication control device.

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