JP4161369B2 - Vehicle driving force distribution control device - Google Patents

Description

  The present invention relates to a vehicle driving force distribution control device for a four-wheel drive vehicle.

  The vehicle driving force distribution control device transmits torque transmitted from the engine to one rotating shaft to the other rotating shaft, and the driving force transmitting device is provided between the driving shaft and the driven shaft of a four-wheel drive vehicle. The torque transmitted from the engine to the drive shaft is transmitted to the driven shaft, and the vehicle is brought into a four-wheel drive state. For four-wheel drive vehicles, in addition to the part-time method that switches between four-wheel drive and two-wheel drive as appropriate, and the full-time method that always drives the four-wheel drive, it is possible to switch between the four-wheel drive state and the two-wheel drive state as necessary. There is a standby method to transition.

  In the standby system, in general, a transaxle including a transmission and a transfer transmits the driving force of the engine to the front wheels via a pair of left and right front axles. The transaxle transmits the driving force of the engine to the driving force transmission device via the propeller shaft. The driving force transmission device is connected to the rear differential via a drive pinion shaft, and the rear differential is connected to the rear wheels via a pair of left and right rear axles.

  In general, a driving force transmission device includes a wet multi-plate electromagnetic clutch mechanism, and by energizing and controlling an electromagnetic coil built in the clutch mechanism, the clutch plates are frictionally engaged with each other and transmitted via a propeller shaft. The driving force of the engine is transmitted to the rear differential. The driving force transmitted to the rear differential is transmitted to the rear wheels through a pair of left and right front axles. The frictional engagement force of the clutch plate is determined by the current value supplied to the electromagnetic coil, and the greater the frictional engagement force, the greater the transmission of driving force to the rear wheels. That is, in the standby system, the driving force transmission device selects either the four-wheel driving state or the two-wheel driving state by controlling the frictional engagement force, and between the front wheels and the rear wheels in the four-wheel driving state. To control the driving force distribution ratio.

  When the driving force distribution ratio for the rear wheels increases, the frictional engagement force of the clutch plate increases, and the temperature of the lubricating oil in the driving force transmission device rises due to the generated frictional heat. Lubricating oil has the property that the viscosity decreases as the temperature rises, and the transmitted driving force also decreases. At this time, in order to transmit the required driving force, it is necessary to further increase the frictional engagement force of the clutch plate. However, if the frictional engagement force of the clutch plate is increased, the oil temperature further increases. Therefore, a rise in the temperature of the lubricating oil leads to damage to the driving force transmission device. For this reason, a temperature sensor for measuring the oil temperature is provided, and when the oil temperature exceeds a certain value, a driving force transmission device has been devised that reduces the friction engagement force of the clutch plate by lowering the transmission ratio of the driving force to reduce the oil temperature. (See Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 2003-136989 JP 2003-136990 A

  In the examples of Patent Documents 1 and 2, an electronic control device that controls the driving force transmission device (hereinafter also referred to as ECU = Electronic Control Unit) is attached to a place that is not easily affected by water or dust. It is often located at a location away from the driving force transmission device. For this reason, it is necessary to attach a temperature sensor in the housing of the driving force transmission device and to draw out a lead wire extending from the output terminal of the temperature sensor to the outside of the housing. And it is necessary to seal between the lead wire and the housing in order to prevent moisture and the like from entering the inside of the housing. Therefore, the conventional driving force transmission device has a problem that it takes time to install the temperature sensor and the cost is high.

  Also, instead of placing a temperature sensor in the housing of the driving force transmission device, for example, a temperature sensor is attached at a location slightly away from the driving force transmission device of the vehicle body, and the temperature of the driving force transmission device is adjusted by this temperature sensor. A configuration is conceivable in which the temperature of the lubricating oil is calculated based on the detected temperature and the current supplied to the electromagnetic coil. However, in this configuration, in order to protect the temperature sensor from moisture and the like, for example, a case with a sealed structure must be attached to the vehicle body, and the temperature sensor must be attached in this case. End up.

  Further, when a thermal resistance element whose resistance value varies with temperature is used as a temperature sensor, there is a possibility that a correct resistance value (that is, temperature) cannot be measured due to the influence of the resistance contained in the lead wire itself. Also, depending on the length of the lead wire or the wiring position, there is a possibility that the correct temperature cannot be measured due to the influence of noise.

  When the temperature sensor is connected to the ECU via a lead wire, a connector is generally used, and a waterproof one is essential. When a connector is connected, there is a possibility that the correct resistance value cannot be measured due to the influence of the contact resistance at the connector pin. Further, when the connector is assembled, it may be in a semi-fitted state, resulting in an assembly failure.

  Therefore, the problem of the present invention is to solve the above technical problem and reduce the time and effort required for mounting temperature detecting means such as a temperature sensor, thereby reducing the cost and reducing the temperature of the driving force transmission device. It is an object of the present invention to provide a vehicle driving force distribution control device capable of accurately measuring.

Means for Solving the Problems and Effects of the Invention

The present invention provides a vehicle driving force distribution control device for solving the above-described problems. That is ,
In a vehicle driving force distribution control device that distributes driving force from a driving source to a plurality of wheels via a driving force transmission unit,
A resin housing provided separately from the driving force transmission unit, a temperature sensor that is mounted inside the housing and measures the temperature of the driving force transmission unit, and is stored in the housing, and processes temperature information from the temperature sensor A sensor signal processing circuit, a resin bracket integrally molded with the housing for fixing the housing to the driving force transmission portion, and heat generated in the driving force transmission portion provided on the bracket to the temperature sensor and a heat-conducting portion tell, only including,
The heat conduction part is composed of a metal heat conduction member, and is integrated with the resin bracket by insert molding,
The temperature sensor is mounted in the housing so as to be able to conduct heat between one end of the heat conducting member,
When the resin bracket is closely fixed to the driving force transmitting portion, one end of the heat conducting member is fixed together, thereby transferring heat generated in the driving force transmitting portion to the temperature sensor .

  In the present invention, since the temperature sensor is built in the ECU without being assembled in the driving force transmission unit (the above-described driving force transmission device), the lead wire extending from the output terminal of the temperature sensor is provided outside the housing of the driving force transmission device. There is no need to pull it out. Therefore, there is no need to make a hole for attaching the temperature sensor in the housing, and there is no need to use a sealing material between the lead wire and the housing in order to prevent moisture and the like from entering the motor inside the housing. Therefore, the structure of the housing of the driving force transmission unit is simplified and the manufacturing cost can be reduced.

  According to the present invention, a cable for connecting the temperature sensor and the ECU becomes unnecessary, and it is possible to reduce the cost of parts of the cable and the cost required for assembly.

  In addition, since the cable for connecting the temperature sensor and the ECU, which has conventionally been installed in the driving force transmission unit, is no longer necessary, the number of pins of the connector of the cable connecting the driving force transmission unit and the ECU can be reduced. As a result, the connector can be miniaturized and the cost can be reduced. Further, the influence of the resistance value of the cable itself on the temperature sensor (thermal resistance element) and the contact resistance generated between the connectors is eliminated, and the reliability of the measured value of the temperature sensor is improved.

  Further, since the driving force transmission unit and the temperature sensor are connected by a heat conduction path, the problem that noise during connection of a conventional cable affects temperature measurement is also solved. In addition, since the temperature sensor is in the ECU, even if noise countermeasures are taken, it can be handled simply by examining the wiring on the printed circuit board of the ECU or the arrangement of components, as in the case of a shielded cable that causes a cost increase as in the past. It is not necessary to use a cable with high noise resistance or to consider the cable routing. Since the noise resistance test can be performed only by the ECU alone without preparing a vehicle, the degree of freedom in the ECU development / evaluation schedule is increased, leading to a shortened development period or a reduced development cost.

  The heat conducting part of the present invention is thicker and stronger than the cable. That is, since the probability that the heat conducting part is disconnected is lower than that of the cable, the failure rate is also low. When a failure occurs in the conventional configuration, all of the temperature sensor, the cable, and the ECU had to be examined. However, in the present invention, the temperature sensor is built in the ECU, and the heat conduction unit is integrated with the ECU, so only the ECU. By examining the above, it becomes possible to investigate the cause of the failure. Therefore, the time required for failure cause analysis is also shortened.

  In addition, since the metal heat conduction member is integrated with the bracket by insert molding, the heat conduction part of the present invention does not significantly affect the manufacturing process of the ECU. Further, when the ECU is assembled to the vehicle body, the heat conduction part is also fixed to the vehicle body at the same time, so that the work load at the time of assembling the ECU does not increase.

Further , the vehicle driving force distribution control device of the present invention can be configured to control the driving force transmission unit based on a signal after processing by the sensor signal processing circuit.

  The driving force transmission unit controls the frictional engagement force of the clutch plate by driving the electromagnetic coil. When the temperature of the lubricating oil that fills the driving force transmitting portion increases due to the temperature rise of the electromagnetic coil and the frictional engagement force, the viscosity of the lubricating oil decreases (the viscosity becomes weak). Then, the torque transmission force between the clutch plates is also reduced. That is, since the driving force of the wheels becomes weak, the driver feels uncomfortable and further depresses the accelerator to obtain a desired driving force. As a result, fuel consumption may deteriorate, or the oil temperature may rise abnormally and the driving force transmission unit may be damaged. Therefore, in this configuration, since the lubricating oil temperature is constantly monitored, the driving force control according to the driver's request can be performed, and the driving force transmission unit can be prevented from being damaged.

  In order to accurately measure the oil temperature in the driving force transmission unit, a temperature sensor is built in the ECU, and the ECU is fixed to the driving force transmission unit via a bus bar or the like that conducts heat.

  Embodiments of the present invention embodied in a front wheel drive-based four-wheel drive vehicle will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a four-wheel drive vehicle in the present embodiment. In FIG. 1, a four-wheel drive vehicle 1 includes an engine 2 and a transaxle 3 which are internal combustion engines. The transaxle 3 includes a transmission 3a, a front differential 3b, a transfer 3c, and the like. The front differential 3b is connected to a pair of left and right front axles 4a and 4b, and front wheels 5a and 5b are connected to the pair of front axles 4a and 4b, respectively. Accordingly, the driving force of the engine 2 is transmitted to the front wheels 5a and 5b via the transmission 3a, the front differential 3b and the pair of left and right front axles 4a and 4b, respectively.

  The transfer 3c is connected to a propeller shaft 6, and the propeller shaft 6 is drivingly connected to a driving force transmission device 7 (a driving force transmission unit in the present invention). Therefore, the driving force of the engine 2 is transmitted to the driving force transmission device 7 via the transmission 3a, the transfer 3c, and the propeller shaft 6. The driving force transmission device 7 is connected to a rear differential 9 via a drive pinion shaft 8, and the rear differential 9 is connected to a pair of left and right rear axles 10a and 10b. Rear wheels 11a and 11b are connected to the rear axles 10a and 10b, respectively.

  The driving force transmission device 7 includes a wet multi-plate electromagnetic clutch mechanism (not shown), and the electromagnetic clutch mechanism includes a plurality of clutch plates that can contact and separate from the electromagnetic coil 7a (see FIG. 2). Then, the clutch plates are frictionally engaged with each other in accordance with a current value supplied based on a control signal (command value) from the driving force distribution electronic control unit 21 which will be described later to the electromagnetic coil 7a, and the drive pinion shaft 8 Torque is transmitted to the driving force of the propeller shaft 6 via the lubricating oil filled in the driving force transmission device 7.

  More specifically, the driving force transmitted from the propeller shaft 6 (that is, the engine 2) to the drive pinion shaft 8 (that is, the rear wheels 11a and 11b) is determined by the frictional engagement force of the clutch plate. large. The frictional engagement force is determined by the current value supplied to the electromagnetic coil 7a. That is, the driving force transmission device 7 selects either the four-wheel driving state or the two-wheel driving state by controlling the friction engagement force, and in the four-wheel driving state, the front wheels 5a and 5b and the rear wheels 11a and 11b To control the driving force distribution ratio between.

  Next, the electrical configuration of the driving force transmission control circuit that controls the driving force transmission device 7 will be described with reference to FIG. The driving force transmission control circuit includes a driving force distribution electronic control unit (hereinafter referred to as a driving force distribution ECU) 21. The driving force distribution ECU 21 includes a CPU 22, a ROM 23, a RAM 24, an input / output circuit 25, a driving circuit 35, and a bus line 26 for connecting these components. The CPU 22 executes various arithmetic processes for driving control of the driving force transmission device 7 according to various programs stored in the ROM 23, that is, energization control of the electromagnetic coil 7a. The ROM 23 stores various programs for controlling energization of the electromagnetic coil 7a of the driving force transmission device 7, various data, and various map data. The RAM 24 temporarily stores the arithmetic processing result of the CPU 22 and stores various data.

  The CPU 22 is connected to a throttle opening sensor 32 provided on the throttle valve via an input / output circuit 25. The CPU 22 calculates the throttle valve opening (throttle opening) based on the detection signal from the throttle opening sensor 32.

  The CPU 22 is connected to wheel speed sensors 33a to 33d that detect the rotation of the wheels of the front wheels 5a and 5b and the rear wheels 11a and 11b via the input / output circuit 25. The CPU 22 receives detection signals from the wheel speed sensors 33a to 33d, and calculates the wheels of the front wheels 5a and 5b and the rear wheels 11a and 11b based on the detection signals. Further, the CPU 22 obtains the average front wheel speed from both wheel speeds of the front wheels 5a and 5b and calculates the average rear wheel speed from both wheel speeds of the rear wheels 11a and 11b. Further, the CPU 22 calculates a differential rotational speed that is an absolute value of a difference between the front wheel average wheel speed and the rear wheel average wheel speed.

  The CPU 22 is connected to a temperature sensor 34 built in the ECU via an input / output circuit 25. The CPU 22 receives the detection signal from the temperature sensor 34 and estimates the oil temperature of the lubricating oil charged in the driving force transmission device 7 based on the result of processing the detection signal by the sensor signal processing circuit 37. It is supposed to be.

  The CPU 22 is connected to a drive circuit 35 that supplies current to the electromagnetic coil 7 a of the drive force transmission device 7 via the input / output circuit 25. The CPU 22 outputs a duty ratio control signal for feeding the current value calculated by the CPU 22 to the electromagnetic coil 7 a to the drive circuit 35. The drive circuit 35 is driven based on the duty ratio control signal and feeds the current value calculated by the CPU 22 to the electromagnetic coil 7a.

  Among the various programs stored in the ROM 23, an energization control program is included. In the two-wheel drive mode and the four-wheel drive mode, the energization control program calculates a current value to be supplied to the electromagnetic coil 7a with respect to the traveling state at that time, and uses the calculated current value to connect the electromagnetic coil 7a via the input / output circuit 25. This program controls energization.

  That is, when the driver sets the mode selection switch 31 to the four-wheel drive mode, the CPU 22 determines the electromagnetic wave from the map data for the four-wheel drive mode based on the calculated throttle opening, differential rotation speed, vehicle speed, and oil temperature. A target current value to be supplied to the coil 7a is obtained as a duty ratio. Then, the CPU 22 outputs a duty ratio control signal corresponding to the obtained duty ratio to the drive circuit 35 via the input / output circuit 25.

  When the driver sets the mode selection switch 31 to the two-wheel drive mode, the CPU 22 enters the two-wheel drive mode, cuts off the energization to the electromagnetic coil 7a and sets the friction engagement force to “0”, and the driving force based on the two-wheel drive mode. Control allocation rate.

  Next, a method for attaching the driving force distribution ECU 21 to the driving force transmission device 7 will be described. First, the driving force distribution ECU 21 will be described.

  FIG. 3 shows an appearance of the driving force distribution ECU 21. FIG. 3A is a view as seen from above, and FIG. 3B is a view as seen from the side where the connectors 43 and 44 are located. The resin casing 51 of the driving force distribution ECU 21 is formed integrally with the brackets 41a and 41b as shown in FIG. The lid 50 may be made of resin or metal.

  FIG. 4 is a diagram showing an example of the internal configuration of the driving force distribution ECU 21. A temperature sensor 34 is mounted on a printed circuit board 48 together with circuit elements necessary for driving control of the driving force transmission device 7 and other controls.

  FIG. 5 is a diagram illustrating an example in which the driving force distribution ECU 21 is attached to the driving force transmission device 7. The driving force distribution ECU 21 is attached to the housing 36 containing the driving force transmission device 7 by means of brackets 41a and 41b using mounting screws 46a and 46b and collars 45a and 45b.

  FIG. 6A is an enlarged view of a cross section taken along the line X-X ′ of FIG. 4 of the driving force distribution ECU 21 for explaining the details. A metal collar 45a (heat conducting portion of the present invention) and a bus bar 47 (heat conducting portion of the present invention) are insert-molded on the bracket 41a. At this time, the collar 45a and the bus bar 47 are in contact with each other so as to conduct heat. Further, the collar 45a and the bus bar 47 may be manufactured as an integral part. The bus bar 47 is disposed so as to be sandwiched between the temperature sensor 34 and the side wall portion of the casing 51 of the driving force distribution ECU 21, and is in contact with the temperature sensor 34.

  When the characteristics (temperature measurement possible range) of the temperature sensor 34 and the heat information transmitted from the bus bar 47 cannot be matched, that is, when the heat transmitted from the bus bar 47 exceeds the upper limit of the measurement range of the temperature sensor 34, the temperature sensor 34 A member for attenuating the heat conduction effect such as a resin plate may be inserted between the bus bar 47 and the oil temperature may be measured accurately. Further, when the exposed area of the bus bar 47 in the casing 51 is large and the temperature in the casing 51 rises more than necessary, the exposed area of the bus bar 47 in the casing 51 is reduced to the minimum necessary. Then, the heat radiation of the bus bar 47 may be suppressed.

  In this embodiment, the bus bar 47 is formed by bending a plate-like conductor into a shape that can be insert-molded into the bracket 41a. Therefore, the shape of the bus bar 47 depends on the shape of the bracket 41a. The shape of the conductor used for the bus bar 47 is not limited as long as it does not hinder the insert molding of the bracket 41a and can transmit heat information effective to the temperature sensor 34 (for example, a rod shape).

  The collar 45a is formed by bending a metal plate into a cylindrical shape as shown in FIG. 6B, and a screw 46a is inserted and fixed to the driving force transmission device 7. In addition, there is no restriction | limiting in particular about the processing method of a metal plate.

  Next, the state of heat conduction from the driving force transmission device 7 to the temperature sensor 34 will be described. In FIG. 2, in the two-wheel drive mode and the four-wheel drive mode, the current value supplied to the electromagnetic coil 7a for the running state at that time is calculated by the energization control program stored in the ROM 23, and the electromagnetic coil is calculated with the calculated current value. When energization control of 7a is performed, the driving force transmission device 7 controls the friction engagement force of the clutch plate. Due to this frictional engagement force, the temperature of the lubricating oil that fills the driving force transmission device 7 rises, and accordingly, the temperature of the housing 36 also rises.

  The heat of the housing 36 is transmitted to the collar 45 a and is transmitted to the temperature sensor 34 via the bus bar 47. The temperature sensor 34 estimates the temperature of the lubricating oil of the driving force transmission device 7 based on the temperature of the bus bar 47.

  The temperature of the lubricating oil measured by the temperature sensor 34 (that is, the temperature of the bus bar 47) is different from the actual temperature of the lubricating oil. This is due to conduction loss (heat radiation) in the housing 36, the collar 45a, and the bus bar 47. This is because the correlation between the actual temperature of the lubricating oil and the temperature measured by the temperature sensor 34 is obtained by actual measurement, stored in the ROM 23 as map data, and this data map is stored when the lubricating oil temperature measurement program is executed. It may be used to estimate the actual temperature of the lubricating oil. The correlation can also be theoretically obtained from the thermal characteristics of the materials constituting the housing 36, the collar 45a, and the bus bar 47.

  In the above embodiment, the driving force transmission device 7 is housed in the same case as the rear differential 9. However, the driving force transmission device 7 may be disposed in the center of the propeller shaft 6 or housed in the same case as the transfer 3 c. May be.

  Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed schematic structure of the four-wheel drive vehicle which is one Example of this invention. The figure for demonstrating a driving force transmission control circuit. The external view of ECU for driving force distribution. The figure which shows an example of the internal structure of ECU for driving force distribution. The figure for demonstrating the attachment method of ECU for driving force distribution. The figure for demonstrating the detail of the heat conduction method to a temperature sensor.

Explanation of symbols

1 Four-wheel drive vehicle 6 Propeller shaft 7 Drive force transmission device (drive force transmission part)
7a Electromagnetic coil 21 Driving force distribution electronic control unit (ECU)
34 Temperature sensor 36 Housing 37 Sensor signal processing circuit 41a Bracket 45a Color (heat conduction part)
46a Mounting screw 47 Bus bar (heat conduction part)

Claims (2)

In a vehicle driving force distribution control device that distributes driving force from a driving source to a plurality of wheels via a driving force transmission unit,
A resin-made housing provided separately from the driving force transmission unit;
A temperature sensor attached to the inside of the housing and measuring the temperature of the driving force transmission unit;
A sensor signal processing circuit that is stored in the housing and processes temperature information from the temperature sensor;
A resin-made bracket integrally molded with the housing for fixing the housing to the driving force transmission unit;
A heat conduction unit provided on the bracket and transmitting heat generated by the driving force transmission unit to the temperature sensor;
Only including,
The heat conduction part is composed of a metal heat conduction member, and is integrated with the resin bracket by insert molding,
The temperature sensor is mounted in the housing so as to be capable of conducting heat between one end of the heat conducting member,
When the resin bracket is firmly fixed to the driving force transmitting portion, one end of the heat conducting member is fixed together, thereby transferring heat generated in the driving force transmitting portion to the temperature sensor. A vehicle driving force distribution control device.   The vehicle driving force distribution control device according to claim 1, wherein the driving force transmission unit is controlled based on a signal after processing by the sensor signal processing circuit.

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