JP2008114818A - Four-wheel drive controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a four-wheel drive controller which estimates a friction value of a clutch, applies the optimum torque to driving wheels and prevents 4WD performance such as startability and power performance from lowering by estimating a temperature of lubricating oil. <P>SOLUTION: An e×4WD C/U6 for controlling a motor 10 and the reducer clutch 17 for applying torque of the motor 10 to a motor driving wheel 12, stores a deferential gear oil temperature °C and characteristics of a deferential gear friction value Nm of the reducer clutch 17, and estimates a deferential gear friction value Nm from the characteristics and the estimated deferential gear oil temperature °C. The optimum torque of the motor 10 is calculated from the estimated deferential gear friction value Nm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a four-wheel drive control device for a four-wheel drive vehicle driven by a motor.

Conventionally, a four-wheel drive vehicle in which front wheels are driven by an engine and rear wheels are driven by a motor has been proposed. The four-wheel drive vehicle further includes a generator that receives the driving force of the engine via a belt and converts it into electric energy, connection means that supplies the electric energy converted by the generator to the motor, and And a rear wheel drive unit for driving the rear wheel based on the driving force of the motor (see Patent Document 1).
Japanese Patent Laid-Open No. 7-231508

  However, in the clutch used in the motor described above, if the temperature of the lubricating oil filled between the metal plates is low, the friction of the clutch increases, and even if the motor torque is applied to the driving wheel according to the required value, the required driven wheel There is a problem that the driving force is not applied and the 4WD performance such as startability and power performance is deteriorated.

  The present invention has been made in view of these problems, and by estimating the temperature of the lubricating oil, it is possible to estimate the friction value of the clutch, and to apply an optimum torque to the drive wheels. An object of the present invention is to provide a four-wheel drive control device capable of preventing a decrease in 4WD performance such as performance.

  In order to achieve the above object, the four-wheel drive control device according to the present invention stores in advance the clutch lubricating oil temperature and the friction characteristic, and estimates the friction value from the characteristic and the estimated lubricating oil temperature. Further, the motor torque is calculated from the estimated friction value.

  According to the present invention, the friction value of the clutch can be estimated by estimating the lubricating oil temperature of the clutch. From this, it is possible to apply an optimum torque to the drive wheels, and it is possible to prevent a decrease in 4WD performance such as startability and power performance.

  As a four-wheel drive vehicle including the four-wheel drive control device according to the present invention, a four-wheel drive vehicle in which front wheels are driven by an engine and rear wheels are driven by a motor will be described as an example. Hereinafter, a four-wheel drive control device according to first to third embodiments of the present invention and a four-wheel drive vehicle including the four-wheel drive control device will be described with reference to FIGS. 1 to 11.

(First embodiment)
A four-wheel drive control device according to a first embodiment of the present invention and a four-wheel drive vehicle including the four-wheel drive control device will be described with reference to FIGS.

(Configuration of four-wheel drive vehicle)
FIG. 1 is a diagram illustrating a system configuration of a four-wheel drive vehicle including a four-wheel drive control device according to a first embodiment of the present invention. In FIG. 1, an engine 1 that is a driving force source arranged in front of a four-wheel drive vehicle, a transmission 3 that changes the rotation of the engine 1, engine drive wheels 11 that are driven by the engine 1, and the engine 1 A generator 4 that is driven via the belt 2 to generate electric power, a motor 10 that is driven by the electric power generated by the generator 4, a power cable 8 that supplies AC electric power to the motor 10 via the relay BOX 15; A reduction gear 9 that is a reduction gear that reduces the rotation of the motor 10 and motor drive wheels 12 that are driven by the motor 10 are shown. The reduction gear 9 is configured by overlapping dozens of metal plates and includes a reduction gear clutch 17 including a pilot clutch (electromagnetic coil) 16. The space between the metal plates is filled with lubricating oil.

  Here, e · 4WD C / U6, which is a four-wheel drive control device, detects the detection signal of the accelerator opening sensor 5, the detection signal of the 4WD switch 13, the detection signal of the shift position switch 14, the engine drive wheels 11 and A torque command value is output to the motor 10 based on the speed of the motor drive wheel 12. The motor 10 is driven with a torque based on the torque command value. Further, the occurrence of a failure due to a component failure or the like is detected, and various warning lights 7 are turned on. Further, when four-wheel drive is performed by the engine 1 and the motor 10, a clutch ON / OFF command is output to the pilot clutch (electromagnetic coil) 16, and the pilot clutch (electromagnetic coil) 16 is engaged (hereinafter referred to as ON). To do. As a result, the reduction gear clutch 17 is turned on, and the torque of the motor 10 is applied to the motor drive wheels 12. Further, during four-wheel drive, the e · 4WD C / U 6 monitors the state of the motor 10 based on an Nmot sensor signal from a sensor (not shown) that detects the motor rotation speed Nmot [rpm]. Similarly, the pilot clutch (electromagnetic coil) 16 is based on Icl and Vcl sensor signals from sensors (not shown) that detect the clutch current Icl [A] and the clutch voltage Vcl [V] of the pilot clutch (electromagnetic coil) 16. Monitor the status of The e · 4WD C / U 6 includes storage means for preliminarily storing the lubricating oil temperature and friction characteristics of the reduction gear clutch 17, the resistance value of the pilot clutch (electromagnetic coil) 16 of the reduction gear clutch 17, and the lubricating oil temperature. The characteristic is stored in advance, the resistance value of the pilot clutch (electromagnetic coil) 16 is calculated from the current and voltage flowing through the pilot clutch (electromagnetic coil) 16, and the characteristic of the resistance value and the lubricant temperature is calculated from the calculated resistance value. First lubricating oil temperature estimating means for estimating the lubricating oil temperature, friction value estimating means for estimating the friction value from the lubricating oil temperature and the characteristics of the friction, and the estimated lubricating oil temperature, and the estimated friction Torque calculating means for calculating torque from the value.

  As described above, the reduction gear clutch 17 includes a plurality of metal plates and the lubricating oil filled between the metal plates, and therefore the temperature of the lubricating oil (hereinafter referred to as differential oil temperature) [° C.]. If it is low, the friction value (hereinafter referred to as the differential friction value) [Nm] of the reduction gear clutch 17 becomes large. When the differential friction value [Nm] increases, the e · 4WD C / U 6 outputs a torque command value to the motor 10, and even if the motor 10 applies the torque based on the torque command value to the reduction gear 9, the motor drive wheel 12 The required driving force cannot be applied to the. Therefore, the e · 4WD C / U 6 executes the optimum torque calculation method, outputs a torque command value based on the optimum torque (hereinafter referred to as the optimum torque command value) to the motor 10, and sends the torque from the motor 10 to the reduction gear 9. Optimal torque is applied, and a required driving force is applied to the motor drive wheels 12.

(Optimum torque calculation method)
FIG. 2 is a diagram for explaining the characteristics of the differential friction [Nm] and the differential oil temperature [° C.] of the reduction gear clutch 17 shown in FIG. In the optimum torque calculation method executed by the e · 4WD C / U6 according to the first embodiment, the diffractive friction value [Nm] is estimated from the characteristics shown in FIG. 2, and the optimum from the estimated diffractive friction value [Nm]. Torque is calculated. Specifically, first, in the reduction gear clutch 17, the differential friction value [Nm] and the differential oil temperature [° C.] are measured in advance. From the measurement results, the characteristics of differential friction [Nm] and differential oil temperature [° C.] as shown in FIG. 2 are obtained in advance. Next, an estimated value [° C.] of the differential oil temperature is obtained by a differential oil temperature estimation method described later. Accordingly, the differential friction value [Nm] can be estimated from the estimated value [° C.] of the differential oil temperature and the characteristics shown in FIG. Next, the optimum torque is calculated from the relationship between the driving force required for the motor driving wheel 12, the torque of the motor 10, and the differential friction value [Nm]. In addition, said relationship is represented by the following relational expression.
Torque = (required driving force × tire dynamic radius + diffractive friction value) / reduction gear ratio The reduction gear ratio is a gear ratio of the reduction gear 9. From the above relational expression, it can be seen that as the differential friction value [Nm] increases, a larger torque is required to apply the necessary driving force to the motor drive wheels 12. Therefore, the optimum torque can be calculated by substituting the estimated differential friction value [Nm] into the relational expression. From this, the e · 4WD C / U 6 executes the optimum torque calculation method step by step to calculate the optimum torque. Then, feedback control for controlling the optimum torque command value is executed one by one.

(Differential oil temperature estimation method)
Hereinafter, a differential oil temperature estimation method executed in the e · 4WD C / U6 according to the first embodiment will be described. FIG. 3 is a diagram for explaining the characteristics of the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.] of the electromagnetic coil 16 shown in FIG. In the differential oil temperature estimation method executed by the e · 4WD C / U6, the differential oil temperature [° C.] is estimated from the characteristics shown in FIG. Specifically, first, the clutch current Icl [A] and the clutch voltage Vcl [V] required when turning on the pilot clutch (electromagnetic coil) 16 are measured in advance based on the Icl and Vcl sensor signals. Further, the differential oil temperature [° C.] of the reduction gear clutch 17 is measured in advance. Based on the measurement result, a resistance value (hereinafter referred to as a clutch coil resistance value) Rcl [Ω] of the pilot clutch (electromagnetic coil) 16 is calculated. The clutch coil resistance value Rcl [Ω] is calculated from the clutch current Icl [A] and the clutch voltage Vcl [V] by Rcl = Vcl / Icl. Next, from the calculated clutch coil resistance value Rcl [Ω] and the measured differential oil temperature [° C.], the characteristics of the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.] as shown in FIG. Find in advance. In FIG. 3, the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.] are proportional. Next, the e · 4WD C / U 6 measures the clutch current Icl [A] and the clutch voltage Vcl [V] one by one based on the Icl and Vcl sensor signals during four-wheel drive. Then, the clutch coil resistance value Rcl [Ω] is calculated one by one. Next, an estimated value [° C.] of the differential oil temperature is obtained from the calculated clutch coil resistance value Rcl [Ω] and the characteristics shown in FIG. From this, e · 4WD C / U 6 executes the above-described differential oil temperature estimation method one by one in order to execute the feedback control by the optimum torque calculation method, and continuously obtains the estimated value [° C.] of the differential oil temperature.

(Control processing by differential oil temperature estimation method)
4 is a flowchart for obtaining the characteristics of the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.] shown in FIG. 3, and FIG. 5 is a flowchart for estimating the differential oil temperature [° C.] from the characteristics shown in FIG. is there. Here, FIGS. 4 and 5 show the flow of automatic control processing by the differential oil temperature estimation method executed by the first lubricating oil temperature estimation means of e · 4WD C / U6.

  Hereinafter, the automatic control process will be described. As shown in FIG. 4, a control process for obtaining the characteristics of the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.] is executed. First, it is determined whether or not the reduction gear clutch 17 is ON, that is, whether or not a clutch ON / OFF command is output from the e · 4WD C / U 6 to the pilot clutch (electromagnetic coil) 16 (step S101). If the reduction gear clutch 17 is OFF (No in step S101), the automatic control process is terminated. On the other hand, when the reduction gear clutch 17 is ON (Yes in step S101), the clutch current Icl [A] and the clutch voltage Vcl [V] are measured based on the Icl and Vcl sensor signals (step S102). Next, the differential oil temperature [° C.] of the reduction gear clutch 17 is measured (step S103). Next, an equation Rcl = Vcl / Icl stored in advance in e · 4WD C / U6 is read, and a clutch coil resistance value Rcl [Ω] is calculated from the measured clutch current Icl [A] and clutch voltage Vcl [V] ( Step S104). Next, the characteristics of the calculated clutch coil resistance value Rcl [Ω] and the measured differential oil temperature [° C.] are obtained, stored in e · 4WD C / U 6 (step S105), and this automatic control process is terminated. . From this, the characteristics of the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.] can be automatically obtained in advance.

  Thereafter, the e · 4WD C / U 6 executes a control process for estimating the differential oil temperature [° C.] as shown in FIG. 5 during the four-wheel drive. First, the e · 4WD C / U 6 determines whether or not the reduction gear clutch 17 is ON (step S111). When the reduction gear clutch 17 is OFF (No in step S111), the motor drive wheel 12 is not driven by the torque of the motor 10, and therefore it is necessary to estimate the differential oil temperature [° C.] necessary for calculating the optimum torque. This automatic control process is terminated. On the other hand, when the reduction gear clutch 17 is ON (Yes in step S111), the clutch current Icl [A] and the clutch voltage Vcl [V] are measured one by one during the four-wheel drive based on the Icl and Vcl sensor signals ( Step S112). Next, the equation Rcl = Vcl / Icl previously stored in e · 4WD C / U6 is read, and the clutch coil resistance value Rcl [Ω] is calculated one by one from the measured clutch current Icl [A] and clutch voltage Vcl [V]. (Step S113). Next, the characteristics of the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.] stored in advance in the e · 4WD C / U6 are read, and the value corresponding to the calculated clutch coil resistance value Rcl [Ω] is read out. The estimated value of oil temperature [° C.] is set (step S114), and the automatic control process is terminated. From this, the differential oil temperature [° C.] can be automatically estimated one by one during the four-wheel drive.

(Control processing for calculating optimum torque)
FIG. 6 is a flowchart for calculating the optimum torque from the estimated value [° C.] of the differential oil temperature. Here, FIG. 6 shows the optimum value based on the estimated value [° C.] of the differential oil temperature obtained by the control process of step S114 shown in FIG. 5, which is executed in the friction value estimating means and torque calculating means of e · 4WD C / U6. The flow of the automatic control process which calculates a torque is shown.

  Hereinafter, the automatic control process will be described. First, as shown in FIG. 6, it is determined whether or not the differential oil temperature [Ω] has been estimated (step S121). That is, it is determined whether or not there is an estimated value [° C.] of the differential oil temperature by the automatic control process using the differential oil temperature estimation method shown in FIGS. If there is no estimated differential oil temperature value [° C.] (No in step S121), the differential friction value [Nm] cannot be estimated, and the optimum torque cannot be calculated, so this automatic control process is terminated. On the other hand, if there is an estimated value [° C.] of the differential oil temperature (Yes in step S121), the differential friction value [Nm] is estimated from the estimated value [° C.] of the differential oil temperature (step S122). That is, the characteristics of the differential friction [Nm] and the differential oil temperature [° C.] stored in advance in the storage unit of the e · 4WD C / U 6 are read, and the value corresponding to the estimated differential oil temperature [° C.] is used as the differential friction value. The estimated value [Nm]. Next, the relational expression of the driving force necessary for the motor driving wheel 12, the torque of the motor 10 and the diffractive friction value stored in advance in the e · 4WD C / U6 is read, and the optimum value is estimated from the estimated value [Nm] of the diffractive friction value. Torque is calculated (step S123), and this automatic control process is terminated. Thus, as long as there is an estimated value [° C.] of the differential oil temperature by the differential oil temperature estimation method during the four-wheel drive, the optimum torque can be automatically calculated. Thereafter, in order to apply the calculated optimum torque to the reduction gear 9, the e · 4WD C / U 6 outputs an optimum torque command value to the motor 10 based on the calculated optimum torque. From this, the e · 4WD C / U 6 executes automatic control processing by the optimum torque calculation method one by one, and executes feedback control for controlling the optimum torque command value based on the calculated optimum torque.

  As described above, the differential oil temperature [° C.] can be automatically estimated by the automatic control process using the differential oil temperature estimation method. Furthermore, by the automatic control processing by the optimum torque calculation method, the differential friction value [Nm] can be automatically estimated from the estimated value [° C.] of the differential oil temperature, and the optimal torque can be automatically calculated. Therefore, the optimum torque can be applied to the reduction gear 9, and the necessary driving force can be reliably applied to the motor drive wheels 12. As a result, stable startability and power performance can be realized at all times, and deterioration of 4WD performance due to increase of the differential friction value [Nm] when the differential temperature [° C.] is low can be prevented.

(Second Embodiment)
Next, the e · 4WD C / U according to the second embodiment will be described with reference to FIGS. 7 to 9 with a focus on differences from the e · 4WD C / U6 of the first embodiment. Moreover, about 2nd Embodiment, the same number is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted. The configuration of the four-wheel drive vehicle including the e · 4WD C / U of the second embodiment is the same as that of the four-wheel drive vehicle including the e · 4WD C / U6 of the first embodiment. The only difference between the e · 4WD C / U according to the second embodiment and the e · 4WD C / U6 according to the first embodiment is that the lubricating oil temperature estimation means is different. That is, the e · 4WD C / U according to the second embodiment has a motor rotational speed increase change rate calculated from a temporal change of the rotational speed when the motor 10 is independently driven with a predetermined torque for a predetermined time, and the lubricating oil. Temperature characteristics are stored in advance, and the motor rotation speed increase change rate is calculated from the time change of the rotation speed when the motor 10 is independently driven with a predetermined torque for a predetermined time, and the motor rotation speed increase change rate and the lubricating oil are calculated. Second lubricating oil temperature estimating means for estimating the lubricating oil temperature from the temperature characteristic and the calculated rate of change in the motor rotation speed is provided.

(Differential oil temperature estimation method)
FIG. 7 is a diagram for explaining a differential oil temperature estimation method executed in the e · 4WD C / U according to the second embodiment. As shown in FIG. 7, in the differential oil temperature estimation method executed in the e · 4WD C / U according to the second embodiment, the motor rotational speed increase rate of change [1 / (dNmot / dt)] and differential oil The estimated differential oil temperature [° C.] is obtained from the temperature [° C.] characteristic. Specifically, first, the e · 4WD C / U preliminarily changes the motor rotation speed Nmot [rpm] for a certain period of time when the motor 10 is independently driven at a certain torque based on the above Nmot sensor signal. measure. Further, the differential oil temperature [° C.] of the reduction gear clutch 17 is measured in advance. Based on the measurement result, the motor rotation speed increase change rate [1 / (dNmot / dt)] is calculated. This utilizes the property that when the motor 10 is driven at a constant torque, the amount of swelling of the motor rotation speed Nmot [rpm] per unit time changes. Next, from the calculated motor rotation speed increase change rate [1 / (dNmot / dt)] and the measured differential oil temperature [° C.], the motor rotation speed increase change rate [1 / (dNmot] as shown in FIG. / Dt)] and differential oil temperature [° C.] characteristics. Next, e · 4WD C / U is the number of rotations Nmot [rpm] of the motor 10 when the reduction gear clutch 17 is OFF, that is, when the motor 10 is rotated at a constant torque for a fixed time. Measure changes one by one. Specifically, measurement is performed by driving the motor 10 alone for a certain period of time before the four-wheel drive. From the measurement result, the rate of change in motor rotation speed increase [1 / (dNmot / dt)] is calculated. From the calculated rate of change in motor rotation speed [1 / (dNmot / dt)] and the characteristics shown in FIG. 7, an estimated value [° C.] of the differential oil temperature can be obtained. From this, e · 4WD C / U can calculate the optimum torque from the estimated value [° C.] of the differential oil temperature, as in the first embodiment. Therefore, as in the first embodiment, the e · 4WD C / U executes the optimum torque calculation method and performs feedback control for controlling the optimum torque command value based on the calculated optimum torque.

(Control processing by differential oil temperature estimation method)
FIG. 8 is a flowchart for obtaining the characteristics of the motor rotational speed increase rate of change [1 / (dNmot / dt)] and the differential oil temperature [° C.] shown in FIG. 7, and FIG. [° C.]. Here, FIGS. 8 and 9 show the flow of automatic control processing by the differential oil temperature estimation method executed by the second lubricating oil temperature estimation means of e · 4WD C / U.

  Hereinafter, the automatic control process will be described. As shown in FIG. 8, a control process for obtaining the characteristics of the motor rotational speed increase change rate [1 / (dNmot / dt)] and the differential oil temperature [° C.] is executed. First, it is determined whether or not the motor 10 is in a single drive state, that is, whether or not the speed reducer clutch 17 is OFF (step S201). If the motor 10 is not in the single drive state (No in step S201), the automatic control process is terminated. On the other hand, when the motor 10 is in the single drive state (Yes in step S201), the motor 10 is driven alone at a constant torque for a fixed time. In this case, the change in the motor rotation speed Nmot [rpm] is measured in advance based on the Nmot sensor signal (step S202). Next, the differential oil temperature [° C.] of the reduction gear clutch 17 is measured in advance (step S203). Next, the motor rotation speed increase rate of change [1 / (dNmot / dt)] is calculated from the measured motor rotation speed Nmot [rpm] (step S204). Next, the calculated characteristics of the motor rotational speed increase change rate [1 / (dNmot / dt)] and the measured differential oil temperature [° C.] are obtained and stored in e · 4WD C / U (step S205). The automatic control process ends. From this, the characteristics of the motor rotational speed increase rate of change [1 / (dNmot / dt)] and the differential oil temperature [° C.] can be automatically obtained in advance.

  Thereafter, the e · 4WD C / U executes a control process for estimating the differential oil temperature [° C.] shown in FIG. 9 before the four-wheel drive. First, it is determined whether or not the motor 10 is in a single drive state (step S211). If the motor 10 is not in the single drive state (No in step S211), the automatic control process is terminated. On the other hand, when the motor 10 is in the single drive state (Yes in step S211), the motor 10 is driven alone at a constant torque for a fixed time. In this case, the change in the motor rotation speed Nmot [rpm] is measured based on the Nmot sensor signal (step S212). Next, the motor rotational speed increase rate of change [1 / (dNmot / dt)] is calculated from the measured motor rotational speed Nmot [rpm] (step S213). Next, the characteristics of the motor rotational speed increase change rate [1 / (dNmot / dt)] and the differential oil temperature [° C.] stored in advance in e · 4WD C / U are read out, and the calculated motor rotational speed increase change rate [ The value corresponding to 1 / (dNmot / dt)] is set as the estimated differential oil temperature [° C.] (step S214), and the automatic control process is terminated. From this, the differential oil temperature [° C.] can be automatically estimated.

  Furthermore, also in the second embodiment, the optimum torque is calculated from the estimated value [° C.] of the differential oil temperature. A torque command value based on the calculated optimum torque is output to the motor 10 and the speed reducer clutch 17 is turned on. From this, the optimum torque of the motor 10 is applied to the reduction gear 9 and the required driving force is applied to the motor drive wheels 12. Therefore, also in the second embodiment, the same effect as that of the first embodiment can be obtained.

(Third embodiment)
Next, the e · 4WD C / U according to the third embodiment will be described with reference to FIGS. 10 and 11 with a focus on differences from the e · 4WD C / U of the first and second embodiments. . In the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted. The configuration of the four-wheel drive vehicle including the e · 4WD C / U of the third embodiment is the same as that of the four-wheel drive vehicle including the e · 4WD C / U of the first and second embodiments. The only difference between the e · 4WD C / U according to the third embodiment and the e · 4WD C / U according to the first and second embodiments is that the lubricating oil temperature estimation means is different. Specifically, the e · 4WD C / U according to the third embodiment has first and second lubricating oil temperature estimating means, and the lubricating oil estimated by the first lubricating oil temperature estimating means. The friction value is estimated using either the temperature or the lubricating oil temperature estimated by the second lubricating oil temperature estimating means. More specifically, when the lubricating oil temperature estimated by the second lubricating oil temperature estimating means exceeds a predetermined value, the friction value using the lubricating oil temperature estimated by the first lubricating oil temperature estimating means is used. Is estimated.

(Differential oil temperature estimation method)
FIG. 10 is a diagram for explaining a differential oil temperature estimation method executed in the e · 4WD C / U according to the third embodiment. In the characteristics of the motor rotational speed increase change rate [1 / (dNmot / dt)] and the differential oil temperature [° C.] shown in FIG. 10, the change width when the differential oil temperature [° C.] is high is y1, and the change width y1 The change width of the motor rotational speed increase change rate [1 / (dNmot / dt)] is assumed to be x1. Further, the change width when the differential oil temperature [° C.] is low is y2, and the change width of the motor rotation speed increase change rate [1 / (dNmot / dt)] with respect to the change width y2 is x2. Here, when the change width y1 is equal to the change width y2, it can be seen that the change width x2 is wider than the change width x1. That is, when the differential oil temperature [° C.] is low, even if an error is included in the rate of change in motor speed increase [1 / (dNmot / dt)], it has an effect on the estimated differential oil temperature [° C.]. Less. From this, it becomes possible to estimate the differential oil temperature [° C.] with high resolution and high accuracy. On the other hand, when the differential oil temperature [° C.] is high, if the motor rotational speed increase rate of change [1 / (dNmot / dt)] includes an error, the difference in the estimated differential oil temperature [° C.] is greatly affected. Become.

  Therefore, in the third embodiment, when the differential oil temperature [° C.] is high, a method for estimating the differential oil temperature [° C.] from the clutch coil resistance value [Ω], that is, the e · 4WD C of the first embodiment. A method for estimating the differential oil temperature [° C.] from the rate of change in the motor speed increase [1 / (dNmot / dt)] when the differential oil temperature [° C.] is low when the differential oil temperature estimation method similar to / U is employed. That is, the differential oil temperature estimation method similar to the e · 4WD C / U of the second embodiment is adopted. Specifically, a predetermined value A [° C.] is provided for the characteristics of the motor speed increase rate of change [1 / (dNmot / dt)] and the differential oil temperature [° C.] shown in FIG. Then, the differential oil temperature [° C.] is estimated by the differential oil temperature estimation method similar to the e · 4WD C / U of the second embodiment. When the estimated value [° C.] of the differential oil temperature is equal to or lower than the predetermined value A [° C.], the optimum torque is calculated based on the estimated value [° C.] of the differential oil temperature. On the other hand, when the estimated value [° C.] of the differential oil temperature exceeds the predetermined value A [° C.], the influence of the error included in the estimated value [° C.] of the differential oil temperature is large. And the differential oil temperature [° C.] is estimated again by the differential oil temperature estimation method similar to the e · 4WD C / U of the first embodiment. Then, the optimum torque is calculated based on the estimated value [° C.] of the differential oil temperature estimated again. Thereafter, as in the first and second embodiments, the e · 4WD C / U executes feedback control for controlling the optimum torque command value based on the calculated optimum torque.

(Control processing by differential oil temperature estimation method)
FIG. 11 is a flowchart for executing the switching method of the differential oil temperature estimation method shown in FIG. Here, FIG. 11 shows a flow of automatic control processing by the differential oil temperature estimation method executed in the e · 4WD C / U having the first and second lubricating oil temperature estimation means.

  Hereinafter, the automatic control process will be described. As in the first and second embodiments, the characteristics of the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.], the motor rotational speed increase rate [1 / (dNmot / dt)], and the differential oil The characteristic of temperature [° C.] is obtained in advance and stored in e · 4WD C / U. First, as shown in FIG. 11, the e · 4WD C / U determines whether or not the motor 10 is in a single drive state (step S311). If the motor 10 is not in the single drive state (No in step S311), the automatic control process is terminated. On the other hand, when the motor 10 is in the single drive state (Yes in step S311), the motor 10 is driven alone with a constant torque for a fixed time. In this case, the change in the motor rotation speed Nmot [rpm] is measured based on the Nmot sensor signal (step S312). Next, the motor rotational speed increase rate of change [1 / (dNmot / dt)] is calculated from the measured motor rotational speed Nmot [rpm] (step S313). Next, the characteristics of the motor rotational speed increase change rate [1 / (dNmot / dt)] and the differential oil temperature [° C.] stored in advance in e · 4WD C / U are read out, and the calculated motor rotational speed increase change rate [ The value corresponding to 1 / (dNmot / dt)] is set as the estimated differential oil temperature [° C.] (step S314).

  Next, it is determined whether or not the estimated value [° C.] of the differential oil temperature estimated by the control process in step S 314 exceeds a predetermined value A [° C.] (step S 315). When the estimated value [° C.] is equal to or lower than the predetermined value A [° C.] (No in step S315), the automatic control process is terminated. Thereafter, the optimum torque is calculated based on the estimated value [° C.] and the reduction gear clutch 17 is turned on. Specifically, a clutch ON / OFF command is output to the pilot clutch (electromagnetic coil) 16 as described above. In this way, the optimum torque of the motor 10 is applied to the reduction gear 9 and the required driving force is applied to the motor drive wheels 12. On the other hand, when the estimated value [° C.] exceeds the predetermined value A [° C.], the reduction gear clutch 17 is turned on (step S316). Next, the clutch current Icl [A] and the clutch voltage Vcl [V] are measured based on the Icl and Vcl sensor signals (step S317). Next, the equation Rcl = Vcl / Icl stored in advance in e · 4WD C / U is read, and the clutch coil resistance value Rcl [Ω] is calculated from the measured clutch current Icl [A] and clutch voltage Vcl [V] ( Step S318). Next, the characteristics of the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.] stored in advance in e · 4WD C / U are read, and the value corresponding to the calculated clutch coil resistance value Rcl [Ω] is Instead of the estimated value [° C.] of the differential oil temperature estimated in the control process of step S314, the estimated value [° C.] of the differential oil temperature is set (step S319), and this automatic control process is terminated. Thereafter, the optimum torque is calculated based on the estimated value [° C.] of the differential oil temperature estimated in the control process of step S319. In this way, the optimum torque of the motor 10 is applied to the reduction gear 9 and the required driving force is applied to the motor drive wheels 12.

  As described above, it is possible to estimate the differential oil temperature [° C.] with high resolution and high accuracy by switching the differential oil temperature estimation method based on the estimated differential oil temperature [° C.]. Therefore, the differential friction value [Nm] can be estimated with high accuracy. Thus, the optimum torque can be applied to the reduction gear clutch 17 with high accuracy, and the driving force can be applied to the motor drive wheels 12 with high accuracy. Also, the same effects as those of the first and second embodiments can be obtained.

  The embodiment described above is an example of the implementation of the present invention, and the scope of the present invention is not limited thereto, and other various embodiments are within the scope described in the claims. It is applicable to. For example, in the first embodiment, the characteristics of the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.] are obtained from the pilot clutch (electromagnetic coil) 16 provided in the four-wheel drive vehicle. It is not limited to this, and may be obtained from the same type of pilot clutch (electromagnetic coil). Similarly, in the second embodiment, the characteristics of the motor rotational speed increase rate of change [1 / (dNmot / dt)] and the differential oil temperature [° C.] are obtained from the motor 10 provided in the four-wheel drive vehicle. However, it is not particularly limited to this, and it may be obtained from the same type of motor.

  Further, in the e · 4WD C / U of the third embodiment, the estimated value [° C.] of the differential oil temperature estimated by the same differential oil temperature estimation method as that of the second embodiment is the predetermined value A [° C.]. In the case of exceeding, the differential oil temperature estimation method is switched to the differential oil temperature estimation method similar to that of the first embodiment, but is not particularly limited thereto, and the differential oil temperature similar to that of the second embodiment is used. Switching may be performed when the motor rotation speed increase rate [1 / (dNmot / dt)] calculated by the temperature estimation method is a predetermined value or less.

  In the first and third embodiments, the characteristics of the clutch coil resistance value Rcl [Ω] and the differential oil temperature [° C.] are obtained in advance by e · 4WD C / U provided in the four-wheel drive vehicle. However, it is not particularly limited to this, and may be obtained in advance by another control device. Similarly, in the second and third embodiments, the characteristics of the motor rotation speed increase rate change rate [1 / (dNmot / dt)] and the differential oil temperature [° C.] are set to e · 4WD provided in the four-wheel drive vehicle. Although it is obtained in advance by C / U, it is not particularly limited to this and may be obtained in advance by another control device.

  In the first to third embodiments, a four-wheel drive control device according to the first to third embodiments of the present invention is applied to a four-wheel drive vehicle in which front wheels are driven by an engine and rear wheels are driven by a motor. However, the present invention is not particularly limited thereto, and the four-wheel drive control device can also be applied to a four-wheel drive vehicle in which front and rear wheels are driven by motors.

  In the first to third embodiments, the control process for obtaining the estimated value [° C.] of the differential oil temperature and the control process for calculating the optimum torque are made independent independently, but the present invention is particularly limited to this. It is also possible to use one control process.

The figure explaining the system configuration | structure of the four-wheel drive vehicle containing e * 4WD C / U based on the 1st Embodiment of this invention. A diagram for explaining the characteristics of the differential friction and differential oil temperature of the reduction gear clutch shown in FIG. 1 is a diagram for explaining the characteristics of the clutch coil resistance value and differential oil temperature of the electromagnetic coil shown in FIG. Flowchart for obtaining characteristics of clutch coil resistance value and differential oil temperature shown in FIG. Flowchart for estimating differential oil temperature from characteristics shown in FIG. Flow chart for calculating optimum torque from estimated differential oil temperature The figure explaining the differential oil temperature estimation method performed in e * 4WD C / U which concerns on 2nd Embodiment. FIG. 7 is a flowchart for determining the characteristics of the motor rotational speed increase rate and the differential oil temperature. Flowchart for estimating differential oil temperature from characteristics shown in FIG. The figure explaining the differential oil temperature estimation method performed in e * 4WD C / U which concerns on 3rd Embodiment. The flowchart which performs the switching method of the differential oil temperature estimation method shown in FIG.

Explanation of symbols

1 engine, 2 belts, 3 transmissions, 4 generators,
5 accelerator opening sensor, e 4WD C / U which is 6 wheel drive control device,
7 Warning light, 8 Power cable, 9 Reduction gear as reduction gear, 10 Motor,
11 engine driving wheel, 12 motor driving wheel, 134 4WD switch,
14 shift position switch, 15 relay BOX,
16 pilot clutch (electromagnetic coil), 17 reducer clutch,
Icl clutch current, Vcl clutch voltage,
Rcl Clutch coil resistance value, Nmot motor speed,

Claims (5)

A four-wheel drive control device that controls a motor and a clutch that applies torque of the motor to drive wheels,
Prestore the clutch lubricant temperature and friction characteristics,
Estimating the lubricating oil temperature;
The friction value is estimated from the lubricating oil temperature, the characteristics of the friction, and the estimated lubricating oil temperature,
A four-wheel drive control device characterized in that the torque is calculated from the estimated friction value.   The resistance value of the coil of the clutch and the characteristic of the lubricating oil temperature are stored in advance, the resistance value of the coil is calculated from the current and voltage flowing through the coil, and the resistance value and the characteristic of the lubricating oil temperature are calculated. The four-wheel drive control device according to claim 1, further comprising first lubricating oil temperature estimating means for estimating the lubricating oil temperature from the calculated resistance value.   The motor speed increase rate calculated from the time change of the rotation speed when the motor is driven independently at a predetermined torque for a predetermined time and the characteristics of the lubricating oil temperature are stored in advance, and the motor is determined at a predetermined torque. The motor rotation speed increase rate of change is calculated from the time change of the rotation speed when driven alone, the motor rotation speed increase change rate, the characteristics of the lubricating oil temperature, and the calculated motor rotation speed increase. The four-wheel drive control device according to claim 1, further comprising second lubricating oil temperature estimating means for estimating the lubricating oil temperature from the rate of change. The motor speed increase rate calculated from the time change of the rotation speed when the motor is driven independently at a predetermined torque for a predetermined time and the characteristics of the lubricating oil temperature are stored in advance, and the motor is determined at a predetermined torque. The motor rotation speed increase rate of change is calculated from the time change of the rotation speed when driven alone, the motor rotation speed increase change rate, the characteristics of the lubricating oil temperature, and the calculated motor rotation speed increase. A second lubricating oil temperature estimating means for estimating the lubricating oil temperature from the rate of change;
Estimating the friction value using one of the lubricating oil temperature estimated by the first lubricating oil temperature estimating means and the lubricating oil temperature estimated by the second lubricating oil temperature estimating means. The four-wheel drive control device according to claim 2, wherein   When the lubricating oil temperature estimated by the second lubricating oil temperature estimating means exceeds a predetermined value, the friction value is calculated using the lubricating oil temperature estimated by the first lubricating oil temperature estimating means. The four-wheel drive control device according to claim 4, wherein the four-wheel drive control device is estimated.

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