JP5583484B2 - Control apparatus and control method - Google Patents

Description

  The present invention relates to a control device and a control method, and more particularly to a control device and a control method for an automobile and various industrial vehicles that use a drive shaft and transmit power from an electric motor to drive wheels.

  Conventionally, there are devices described in Patent Literature 1, Patent Literature 2, and the like as vehicle control devices. In Patent Document 1, when the operating angle of the constant velocity universal joint is in a large angle range, the thickness of the portion that may be damaged only when a large torque is input and the depth of the ball groove (track groove) are increased. It can be secured to the extent that it can withstand torque, and can contribute to downsizing of the constant velocity universal joint.

  That is, in the device described in Patent Document 1, when it is determined that the intersection angle of the constant velocity universal joint is included in a preset large angle region, the driving force transmitted to the drive shaft is set to a predetermined value. The driving force is variably controlled so as not to exceed the value. For this reason, when the condition prescribed | regulated by the crossing angle of a constant velocity universal joint is materialized, it sets so that the driving force exceeding a predetermined value may not be input into a constant velocity universal joint via a drive shaft.

  The thing of the said patent document 2 guarantees the intensity | strength of drive system components, such as a drive shaft and a constant velocity universal joint. That is, the one described in Patent Document 2 is a joint angle determination means for determining whether or not the drive shaft joint angle is a predetermined angle or more from the vehicle state, and the intention of sudden start or rapid acceleration to the driver from the vehicle state. If the drive shaft joint angle is equal to or greater than a predetermined angle and the driver intends to suddenly start or accelerate, the drive transmitted to the wheels is determined. Driving force suppressing means for suppressing force. For this reason, in a vehicle state where the drive shaft joint angle is equal to or greater than a predetermined angle and the driver intends to start or accelerate suddenly, the drive source transmits the drive wheel via the transmission, drive shaft, etc. Since the driving force (driving torque) is suppressed, sudden start or acceleration in such a vehicle state can be avoided. And the torque transmitted to drive system components can be reduced. Therefore, the load applied to the drive system component can be reduced, and damage to the drive system component is difficult to accumulate. Therefore, the durability of the drive system component can be improved, and the strength of the drive system component can be guaranteed. . In this case, it is possible to ensure sufficient strength of the drive system component without increasing the size of the drive system component or replacing the material of the drive system component with a material having excellent strength. Cost can also be reduced.

Japanese Patent Laid-Open No. 2004-19632 JP 2008-207723 A

  In Patent Document 1, a steering angle threshold value τs determined to be a large angle region of an intersection angle is determined, and when the threshold value τs is exceeded, a preset engine torque Ter (an engine torque that does not damage the constant velocity universal joint) is set. It is controlled not to exceed. That is, the relationship between the engine to be controlled and the turning angle is as shown in FIG.

  Further, Patent Document 2 is different from Patent Document 1 in that the driving force is suppressed when the driver intends to suddenly start and accelerate. However, if the sudden start / acceleration determining means is simply regarded as the accelerator opening, the configuration is similar to that of Patent Document 1. For this reason, the torque control is the same as in Patent Document 1.

  By the way, the constant velocity universal joint (fixed type constant velocity universal joint using a ball as a torque transmission member) used on the drive wheel side of the drive shaft shows the relationship between the operating angle and the torsional strength in the graph of FIG. become that way.

  FIG. 4A shows characteristics of the fixed type constant velocity universal joint. In other words, in general, the torsional strength of a fixed type constant velocity universal joint has the weakest shaft connected to the fixed type constant velocity universal joint when the operating angle is not large. The outer joint member and internal parts (inner joint member, ball, cage, etc.) are damaged, and their strength decreases with the operating angle.

  If the conventional control method (operation angle-torque control that does not damage the constant velocity universal joint) is applied to the constant velocity universal joint having such characteristics, the result is as shown in FIG. In such a case, the constant velocity universal joint torque to be controlled by the steering angle threshold is set based on the allowable torque of the constant velocity universal joint at the maximum steering angle, so in the operating angle region between the steering threshold and the maximum steering angle. A region H in which the performance of the constant velocity universal joint is not effectively used occurs. In FIG. 4B, θjmax is the maximum operating angle of the fixed type constant velocity universal joint, θsmax is the operating angle of the fixed type constant velocity universal joint at the time of maximum steering, and θs is fixed at the steering angle threshold τs. KJ is the torque that causes damage to the fixed constant velocity universal joint, KEmax is the fixed constant velocity universal joint input torque (maximum input torque) at the maximum engine torque, KEer is a fixed type constant velocity universal joint input torque controlled by the steering angle threshold τs.

  For this reason, in a situation where the steering angle threshold is crossed, an engine torque change (change in torque transmitted to the drive shaft) occurs before and after that, and the behavior of the vehicle may change.

  The problem of the present invention is that it is possible to prevent the constant velocity universal joint from being damaged by excessive input from the motor in the entire operating angle of the constant velocity universal joint, and in the region where the operating angle of the constant velocity universal joint is large. A control device and a control method capable of effectively utilizing constant velocity universal joint performance are proposed.

The control device of the present invention is a control device in a vehicle that uses an electric motor as a power source and transmits the power from the electric motor to the drive wheels via the drive shaft, and is a constant velocity universal joint used for the drive shaft. Control means for limiting the drive shaft input torque below the drive shaft limit torque over the entire operating angle is provided , and the limit torque of the constant velocity universal joint with respect to the operation angle of the constant velocity universal joint is experimentally determined in advance, and based on this The drive shaft limit torque is defined by an approximate expression that is a function of the relationship between the operating angle and the limit torque .

  According to the control device of the present invention, the drive shaft input torque can be limited below the drive shaft limit torque over the entire operating angle of the constant velocity universal joint, and the shaft, the outer joint member, and the internal parts (inner joint member, Ball, cage, etc.) can be prevented.

  A limit torque of the constant velocity universal joint with respect to the operating angle of the constant velocity universal joint is experimentally obtained in advance, and an approximate expression that is a function of a relationship between the operating angle and the limit torque derived based on the limit torque is used to determine the drive shaft limit Torque can be defined.

  The control means can control the drive shaft input torque by controlling the output torque of the electric motor. The electric motor can be controlled with high accuracy such as current and voltage by motor control, and the output torque of the electric motor can be accurately controlled.

  The vehicle may have no transmission, or may have a transmission and no transmission torque increase / decrease mechanism. In such a vehicle, the torque of the motor is directly transmitted as drive torque.

  The control means can limit the drive shaft input torque by a signal from the steering device, or can limit the drive shaft input torque by a signal from the suspension device.

  Even if the drive shaft has a fixed constant velocity universal joint connected to one end and a sliding constant velocity universal joint connected to the other end, the first sliding constant velocity universal is connected to one end. The joint may be connected, and the second sliding type constant velocity universal joint may be connected to the other end side.

  In the present invention, it is possible to effectively prevent damage to the constant velocity universal joint due to excessive input from the motor over the entire operating angle of the constant velocity universal joint. Further, the constant velocity universal joint performance can be effectively utilized in a region where the operating angle of the constant velocity universal joint is large. In addition, the change in the stepwise driving torque unlike the conventional case is hardly generated, and the drivability (ease of driving and maneuverability) of the vehicle is improved.

  By the way, the above-mentioned prior art is only the torque control of the high operating angle of the constant velocity universal joint, and the maximum input torque to the drive shaft from the assumed engine (power source) so that the drive shaft is not damaged in the uncontrolled operating angle region. A drive shaft having the above allowable load torque was required. On the other hand, in the present invention, since the input torque is controlled over the entire operating angle, if the vehicle performance is satisfactory, it becomes possible to select a drive shaft having an allowable load torque less than the maximum output torque. Can be realized.

  Experimentally obtained for the applicable constant velocity universal joint, and using an approximation formula for the operating angle of the constant velocity universal joint, it is possible to cope with different limit torques depending on the design of the constant velocity universal joint and the assumed failure mode. Highly accurate control is possible.

  In what controls the output torque of an electric motor, highly accurate control is attained. When the motor torque is directly transmitted as the drive torque, the controllability and responsiveness are excellent.

  The drive shaft may be one in which a fixed type constant velocity universal joint is connected to one end side and a sliding type constant velocity universal joint is connected to the other end side. Even if it is connected, it can respond to various types.

It is a simplified diagram of a vehicle using a control device of the present invention. The relation between the operating angle of the constant velocity universal joint and the limit torque of the constant velocity universal joint is shown, (a) is a graph not showing the drive shaft input torque range, and (b) is the drive shaft input torque range. It is the displayed graph figure. It is a graph which shows the relationship between the rolling angle used for the conventional control, and an engine torque. The relationship between the operating angle of a constant velocity universal joint and the torsional strength of a constant velocity universal joint is shown, (a) is a graph which does not display the controlled torque, (b) is the torque controlled by the prior art. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a simplified diagram of a vehicle (electric vehicle) using the control device of the present invention. That is, the electric vehicle includes a battery 1 that accumulates and generates electric energy, a drive motor (electric motor) 2 that is driven by the electric energy of the battery 1, a motor controller 3 that controls the electric motor 2, and the like.

  An output shaft of the electric motor 2 is connected to a pair of drive shafts 6 and 6 via a differential (front differential) 5. The drive shaft 6 is connected to the differential 5 via a sliding constant velocity universal joint, and is connected to the drive wheel (front wheel) 7 via a fixed constant velocity universal joint. An accelerator pedal 4 is connected to the motor controller 3, and the motor controller 3 controls the number of revolutions of the motor 2 based on the depression amount of the accelerator pedal 4. In addition, rear wheels 10 and 10 are disposed behind the vehicle body.

  Various types of sliding constant velocity universal joints such as double offset type, tripod type, cross groove type can be used, and fixed constant velocity universal joints can also be used as barfield type, undercut free type Various types such as can be used.

  The double offset type constant velocity universal joint includes an outer joint member having a plurality of track grooves formed on the inner peripheral surface, an inner joint member having a plurality of track grooves formed on the outer peripheral surface, and a track groove of the outer joint member. And a cage having a pocket for accommodating the ball, wherein the center of the outer peripheral surface of the cage and the center of the inner peripheral surface are the joints. It is offset in the opposite direction in the axial direction with respect to the center.

  The tripod type constant velocity universal joint includes an outer joint member in which three track grooves having roller guide surfaces arranged in the circumferential direction are formed in the axial direction, and three leg shafts projecting in the radial direction. A tripod member and a roller member fitted on the leg shaft.

  The cross groove type constant velocity universal joint has an inner joint member having an outer peripheral surface in which ball grooves inclined in opposite directions with respect to the axis are alternately formed in the circumferential direction, and inclined in directions opposite to each other with respect to the axis. An outer joint member having an inner peripheral surface in which track grooves are alternately formed in the circumferential direction, a torque transmission ball incorporated at the intersection of the track groove of the inner joint member and the track groove of the outer ring, and the torque transmission ball are held It is equipped with a cage.

  The Barfield type fixed constant velocity universal joint includes an outer joint member in which a plurality of track grooves are formed on the inner diameter surface along the axial direction at equal intervals in the circumferential direction, and a track groove of the outer joint member on the outer diameter surface. A ball in which a plurality of paired track grooves are formed along the axial direction at equal intervals in the circumferential direction, and the track groove of the outer joint member and the track groove of the inner joint member are formed in cooperation. A torque transmission ball disposed on each track and a cage for holding the ball are provided.

  Undercut-free fixed constant velocity universal joints are different from barfield fixed fixed constant velocity universal joints where the track groove bottom is only an arc portion, while the track groove bottom is formed from an arc portion and a straight portion. It will be.

  In this motor vehicle, the control means for limiting the drive shaft input torque below the drive shaft limit torque over the entire operating angle of the constant velocity universal joint (fixed constant velocity universal joint) on the drive wheel 7 (tire) side is the motor. The controller 3 is provided.

  In this case, the limit torque of the constant velocity universal joint with respect to the operation angle of the constant velocity universal joint is experimentally obtained in advance, and an approximate expression that is a function of the relationship between the operation angle and the limit torque derived based on this is given by Defines drive shaft limit torque.

  The relationship between the operating angle of the fixed type constant velocity universal joint and the limit torque of the fixed type constant velocity universal joint is a graph shown in FIG. The allowable limit torque (diagram) varies with the operating angle depending on the design of the constant velocity universal joint. For this reason, it is difficult to obtain theoretically by calculation, and it is preferable to obtain experimentally.

  That is, when the allowable limit torque is based on the proof strength against a single excessive torque, the “static torsional strength” defined in the automobile engineering standard “Constant universal joint for driving shafts of automobiles” (JASO C304-89) Can be used.

  Change the operating angle to determine the static torsional strength. Specifically, in the case of a fixed type constant velocity universal joint having a maximum operating angle of 50 degrees, for example, static torsional strength at respective angles of 0 °, 10 °, 20 °, 30 °, 40 °, and 50 °. Ask for. In this case, the number of samples is plural (at least two) for each condition. The obtained data is graphed, and an empirical formula is derived based on the graph. If there is a lot of variation in the data, use statistical methods such as increasing the number of test samples.

  Therefore, the formula in the range A in FIG. 2A (the formula in the range 0 ° ≦ θ <θa) becomes the static torsional strength T (θ) = Ta, and the formula in the range B in FIG. (Θa ≦ θ ≦ θmax (50 °)) is static torsional strength T (θ) = Tb−Tc · θ. At this time, intensity variation is taken into consideration. When the variation in strength is 10%, the constant velocity universal joint limit torque is set as KJ (θ) = 0.9T (θ).

  In this way, the drive shaft input torque range as shown in FIG. 2B can be set by an approximate expression obtained experimentally. That is, the constant velocity universal joint limit torque can be determined with respect to the operating angle θ, but the limit torque with respect to the operating angle θ differs depending on the assumed failure mode of the constant velocity universal joint. For this reason, it calculates | requires experimentally with respect to the constant velocity universal joint to apply, and calculates | requires the approximate expression KJ ((theta)) with respect to the working angle (theta). The assumed failure mode is different depending on whether the vehicle is based on one strength close to static failure or on the assumption of repeated input. For this reason, in FIG. 2 (a), although it was a straight line in the range of A and the range of B, there may be a case where a curve or a combination of a plurality of lines / curves is combined depending on the design of the constant velocity universal joint and the assumed failure mode. is there.

As in this embodiment, when the configuration is one motor, differential 6 and left and right drive shafts 6, assuming that the motor torque is Tm, the differential reduction ratio is R, and the drive shaft input is Td, The formula is obtained. For this reason, by controlling the operation angle θ so that the following relational expression 2 is satisfied, that is, the relational expression expressed by the following expression 3, it is possible to prevent the constant velocity universal joint from being damaged due to excessive input and to operate. It is possible to effectively utilize the performance of the CVJ in a region having a large corner.

Here, assuming a shocking input, a safety factor A (A ≧ 1) may be considered. When this safety factor is taken into account, the following relational expression 4 is obtained. When the safety factor is added in this way, the drive shaft input torque range shown in FIG. 2B is obtained.

  Actually, the torque of the motor 2 is determined by the accelerator opening of the driver and the safety control of the vehicle. Therefore, in the control of the present invention, a limit value is set for the maximum torque of the motor that can be output at the operating angle θ.

  In the present invention, the drive shaft input torque can be limited below the drive shaft limit torque over the entire operating angle of the constant velocity universal joint, so that the shaft 6 is damaged and internal parts (inner joint members, balls, cages, etc.) are damaged. Can be prevented. The constant velocity universal joint performance can be effectively utilized in a region where the operating angle of the constant velocity universal joint is large. In addition, it is difficult for the conventional step-like drive torque to change, and the drivability (ease of driving and maneuverability) of the vehicle is improved.

  In the present invention, since the input torque is controlled over the entire operating angle range, if the vehicle performance is satisfactory, it becomes possible to select the drive shaft 6 having an allowable load torque equal to or less than the maximum output torque from the motor to the drive shaft. Smaller and lighter can be achieved.

  Experimentally obtained for the applicable constant velocity universal joint, and using an approximation formula for the operating angle of the constant velocity universal joint, it is possible to cope with different limit torques depending on the design of the constant velocity universal joint and the assumed failure mode. Highly accurate control is possible.

  In the case of controlling the output torque of the electric motor 2, more accurate control is possible. The vehicle may have no transmission, or may have a transmission and no transmission torque increase / decrease mechanism. In such a vehicle, the torque of the motor 2 and the drive shaft input torque are in a one-to-one relationship if the transmission loss of the drive transmission element is ignored, and control is easy. For this reason, it becomes what was excellent in controllability and responsiveness.

  The drive shaft 6 may be one in which a fixed type constant velocity universal joint is connected to one end side and a sliding type constant velocity universal joint is connected to the other end side. Even if the joint is connected, various types can be supported.

  That is, in the above-described embodiment, the description has been made assuming the outboard constant velocity universal joint of the steered wheel drive shaft. However, the control of the present invention is the torque control for the drive shaft, for example, the inboard side slide type constant velocity universal. A constant velocity universal joint limit torque KJ (θ) can be provided for the joint, and the same control can be performed. In this case, it is reasonable to substitute the movement amount of the suspension for the operating angle of the constant velocity universal joint. The outboard side is a side that is on the outside of the vehicle when assembled on a vehicle such as an automobile, and a side that is on the inside of the vehicle when assembled on a vehicle such as an automobile is called an inboard side.

  In the present invention, it is difficult to directly measure the operating angle of the constant velocity universal joint, and it is reasonable to substitute information from the steering device such as the steering angle of the steering wheel or the position of the steering rack as the operating angle. It is. Further, a signal (information) from the suspension device, for example, the amount of contraction of the shock absorber of the suspension can be used.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, in the control of the present invention, both the outboard and inboard constant speeds are used. Torque control for the universal joint is also possible. As an electric motor to be used, various types such as DCM (DC motor), SM (permanent magnet synchronous motor), IM (induction motor), SRM (switched reluctance motor) can be used. Also, the battery 1 to be used may be any battery as long as it can supply energy to the motor according to the motor to be used and thereby drive the vehicle, and various batteries such as a lithium ion battery can be used. it can.

2 Electric motor 3 Motor controller 5 Differential 6 Drive shaft

Claims (8)

A control device in a vehicle that uses an electric motor as a power source and transmits power from the electric motor to drive wheels via a drive shaft,
Control means for limiting the drive shaft input torque below the drive shaft limit torque over the entire operating angle of the constant velocity universal joint used for the drive shaft, and the limit of the constant velocity universal joint relative to the operating angle of the constant velocity universal joint A control device characterized in that the drive shaft limit torque is defined by an approximate expression which is a function of a relationship between an operating angle and a limit torque derived based on the torque obtained experimentally in advance . The control device according to claim 1, wherein the control unit controls the drive shaft input torque by controlling an output torque of the electric motor . The control device according to claim 1, wherein the vehicle does not have a transmission . The vehicle as well as have a transmission control device according to claim 1 or claim 2, characterized in that no transmission torque fluctuation mechanism. The control device according to any one of claims 1 to 4, wherein the control means substitutes a steering angle of a steering wheel of a steering device or a position of a steering rack for the operating angle . The control device according to any one of claims 1 to 4, wherein the control means substitutes a contraction amount of a shock absorber of a suspension of a suspension device for the operating angle . 7. The drive shaft has a fixed type constant velocity universal joint connected to one end side and a sliding type constant velocity universal joint connected to the other end side. 8. The control device described in 1. The drive shaft has a first sliding type constant velocity universal joint connected to one end side and a second sliding type constant velocity universal joint connected to the other end side. Item 7. The control device according to any one of item 6.

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