JP2011230543A - Vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle that can change in proper timing, a driving force distribution ratio of the vehicle corresponding to a road surface change on the road while reducing energy consumption.SOLUTION: A main ECU3 of a vehicle, when a first friction coefficient μ1 which is the friction coefficient of a first position (A point) derived from a first piece of information obtained by a first information acquisition unit 4A is larger than a second friction coefficient μ2 which is the friction coefficient of a second position (B point) derived from a second piece of information obtained by a second information acquisition unit 4B, determines a driving force change point (C point) to become the nearer side of the second position (B point) on the road, when the size |Δμ| of the deviation Δu is larger.

Description

  The present invention provides a first driving force for driving one of a front wheel or a rear wheel of a vehicle as a first driving wheel and driving the first driving wheel by one or both of an engine and a motor, and the other as a second driving wheel. The present invention relates to a vehicle including a driving force control means for controlling the second driving force when the second driving wheel is driven by a motor as needed.

  Conventionally, in this type of vehicle, as shown in Patent Document 1 below, it is predicted whether or not the driving of the second driving wheel is necessary, and it is predicted that the driving of the second driving wheel by the motor is necessary. A configuration for driving the second drive wheel is known. Here, the case where it is predicted that the driving of the second drive wheel is necessary corresponds to the case where it is determined that the vehicle is starting, running on a low μ road, running in a snow mode, running on a slope, or the like (Patent Document 1 below). Paragraph [0052]).

JP 2000-127790 A

  However, in the conventional vehicle, when it is predicted that the driving of the second drive wheel is necessary, the vehicle is already in the low μ road running, the snow mode running, and the slope running. In other words, this is not a prediction, but only when the vehicle is running on a low μ road, running in a snow mode, or running on a slope, this is detected and the second drive wheel is driven.

  Therefore, there is a problem that the second drive wheel is not driven until it is necessary to drive the second drive wheel until the second drive wheel is driven after detection.

  On the other hand, it is conceivable to drive the second drive wheel in advance, but the second drive wheel is driven even when it is not necessary, and there is a concern about an increase in energy consumption.

  Furthermore, when the driving of the second driving wheel is left to the driver's operation, the driver does not perform the operation in time because the driver will perform this operation only after he can see the change in the road surface condition ahead. In addition, there is a problem that energy consumption increases because a brake operation is required to keep the operation in time.

  In view of the above circumstances, an object of the present invention is to provide a vehicle capable of changing the driving force distribution ratio corresponding to a change in the road surface on the course of the vehicle at an appropriate timing while reducing energy consumption. And

In order to achieve the above object, the vehicle of the first invention is:
A first drive wheel that is one of the front wheels or the rear wheels and is driven by one or both of the engine and the first motor, and a second wheel that is a wheel other than the first drive wheels and is driven by the second motor. A vehicle comprising: a driving wheel; and a driving force control means for controlling a driving force distribution ratio between a first driving force for driving the first driving wheel and a second driving force for driving the second driving wheel,
First acquisition means for acquiring a first friction coefficient that is a road surface friction coefficient of a first position that is a current position of the vehicle;
A second acquisition means for acquiring a second friction coefficient that is a road surface friction coefficient at a second position on the path of the vehicle;
When the first friction coefficient acquired by the first acquisition means is greater than the second friction coefficient acquired by the second acquisition means, the driving force control means 2 The larger the deviation of the friction coefficient, the more the driving force change point for changing the driving force distribution ratio corresponding to the first friction coefficient to the driving force distribution ratio corresponding to the second friction coefficient is on the path. The driving force change point is determined so as to be in front of the second position.

  According to the vehicle of the first invention, when the first friction coefficient is larger than the second friction coefficient as in the case where the second position is a low μ road, the first friction coefficient and the second friction coefficient The larger the deviation is, the more the driving force distribution ratio is changed before the second position.

  Here, when the driving force distribution ratio is changed immediately from the first position, the optimal driving force distribution ratio according to the current traveling road surface (high μ road) condition is impaired, and there is a concern about an increase in energy consumption. The However, according to the present invention, when the deviation between the first friction coefficient and the second friction coefficient is small, the driving force distribution ratio is changed at a position close to the second position, thereby suppressing an increase in energy consumption. Can do.

  On the other hand, when the deviation between the first friction coefficient and the second friction coefficient is large, there is a possibility that the road surface friction coefficient suddenly changes (to a low μ road) between the first position and the second position. is there. In such a case, if the driving force distribution ratio is changed after approaching the second position, the change of the driving force distribution ratio becomes ad hoc, such as the road surface state has already changed to the second friction coefficient. Is concerned. However, according to the present invention, when the deviation between the first friction coefficient and the second friction coefficient is large, the driving force distribution ratio is changed closer to the second position. The driving force distribution ratio can be changed in advance.

  As described above, according to the vehicle of the first invention, it is possible to change the driving force distribution ratio corresponding to the road surface change on the course of the vehicle at an appropriate timing while reducing energy consumption.

The vehicle of the second invention is the vehicle according to the first invention,
Comprising speed acquisition means for acquiring the traveling speed of the vehicle;
In accordance with the traveling speed acquired by the speed acquiring means, the driving force control means increases the driving speed so that the driving force change point is closer to the second position on the route. The driving force change point is determined.

  According to the vehicle of the second aspect of the invention, even when the driving force change point is the same, the time required to reach the second position from the driving force change point differs depending on the vehicle traveling speed. That is, when the traveling speed is high, the time required to reach the second position from the driving force change point is shorter than when the traveling speed is low.

  Therefore, by increasing the driving speed so that the driving force change point is in front of the second position, the time from the driving force change point to the second position can be secured. In addition, it is possible to avoid a situation where the driver performs a braking operation and the energy consumption increases by changing the driving force immediately before the second position.

The vehicle of the third invention is the vehicle according to the first or second invention,
The drive force control means increases the distribution ratio of the drive force of the second drive wheel to the first drive force at the drive force change point.

  According to the vehicle of the third aspect of the present invention, when the second friction coefficient is smaller than the first friction coefficient as in the case where the second position is a low μ road, the first drive wheel at the driving force change point. The ratio of the second driving force acting on the second driving wheel to the first driving force is increased.

  That is, before the driving force change point, by reducing the ratio of the first driving force to the first driving force, it is possible to reduce the energy consumed by driving the second driving wheel. Further, after the driving force change point, by increasing the ratio of the second driving force to the first driving force, the driving force distribution ratio is increased before the road surface state changes from the first friction coefficient to the second friction coefficient. Can be changed to one corresponding to the second friction coefficient.

  Thereby, it is possible to change the driving force distribution ratio corresponding to the road surface change on the course of the vehicle at an appropriate timing while reducing energy consumption.

The vehicle of the fourth invention is
A first drive wheel that is one of the front wheels or the rear wheels and is driven by one or both of the engine and the first motor, and a second wheel that is a wheel other than the first drive wheels and is driven by the second motor. A vehicle comprising: a driving wheel; and a driving force control means for controlling a driving force distribution ratio between a first driving force for driving the first driving wheel and a second driving force for driving the second driving wheel,
First acquisition means for acquiring a first friction coefficient that is a road surface friction coefficient of a first position that is a current position of the vehicle;
A second acquisition means for acquiring a second friction coefficient that is a road surface friction coefficient at a second position on the path of the vehicle;
The driving force control means, when the first friction coefficient acquired by the first acquisition means is smaller than the second friction coefficient acquired by the second acquisition means, 2 The larger the deviation of the friction coefficient, the more the driving force change point for changing the driving force distribution ratio corresponding to the first friction coefficient to the driving force distribution ratio corresponding to the second friction coefficient is on the path. The driving force change point is determined so as to be close to the second position.

  According to the vehicle of the fourth invention, when the first friction coefficient is smaller than the second friction coefficient as in the case where the first position is a low μ road, the first friction coefficient and the second friction coefficient The larger the deviation is, the more the driving force distribution ratio is changed at a position closer to the second position.

  Here, when the driving force distribution ratio corresponding to the second friction coefficient (high μ road) is changed immediately from the first position, energy consumption can be reduced, but the road surface is still in the first friction state. There is a concern that the driving force distribution ratio may be changed despite the coefficient (low μ road). However, according to the present invention, when the deviation between the first friction coefficient and the second friction coefficient is large, the driving force distribution ratio is changed at a position closer to the second position, so that the road surface is still in the first friction state. It is possible to avoid changing the driving force distribution ratio in spite of the coefficient (low μ road).

  On the other hand, when the deviation between the first friction coefficient and the second friction coefficient is small, the change in the road surface friction coefficient between the first position and the second position is often small and gradual, reducing energy consumption. It is necessary to change the driving force distribution ratio. According to the present invention, the smaller the deviation between the first friction coefficient and the second friction coefficient, the more the driving force distribution ratio is changed before the second position, so that it is possible to reduce energy consumption.

  Thus, according to the vehicle of the fourth aspect of the invention, it is possible to change the driving force distribution ratio corresponding to the road surface change on the course of the vehicle at an appropriate timing while reducing energy consumption.

The vehicle of the fifth invention is
The driving force control means reduces the distribution ratio of the driving force of the second driving wheel to the first driving force at the driving force change point.

  According to the vehicle of the fifth aspect of the present invention, when the second friction coefficient is larger than the first friction coefficient, as in the case where the first position is a low μ road, the first drive wheel at the driving force change point. The ratio of the second driving force acting on the second driving wheel to the first driving force is reduced.

  That is, before the driving force change point, when the ratio of the first driving force to the first driving force is increased, the road surface state may be the first friction coefficient (low μ road). The driving force distribution ratio can correspond to the first friction coefficient. Furthermore, after the driving force change point, the energy consumption by driving the second driving wheel can be reduced by reducing the ratio of the second driving force to the first driving force.

  Thereby, it is possible to change the driving force distribution ratio corresponding to the road surface change on the course of the vehicle at an appropriate timing while reducing energy consumption.

A vehicle according to a sixth aspect of the invention is any one of the first to fifth aspects of the invention.
The second acquisition means includes map information of a navigation device mounted on the vehicle, travel history information of a vehicle other than the vehicle on the route, and a road surface that is installed on the route and detects a road surface state. The second friction coefficient is obtained from a part or all of the output information of the detection device.

  According to the vehicle of the sixth invention, the map information of the navigation mounted on the vehicle, the travel history information of the vehicle other than the vehicle on the route, and the road surface that is installed on the route and detects the state of the road surface The second friction coefficient at the second position can be accurately recognized and acquired from a part or all of the output information of the detection device. By determining the driving force change point based on the second friction coefficient, it is possible to change the driving force distribution ratio corresponding to the road surface change on the course of the vehicle at an appropriate timing while reducing energy consumption. it can.

A vehicle according to a seventh aspect of the invention is any one of the first to sixth aspects of the invention.
The driving force control means includes notifying means for notifying the change of the driving force before the determined driving force change point.

  According to the vehicle of the seventh aspect of the invention, the driver can be made aware that the driving force is changed by notifying in advance that the driving force is changed via the notification means. As a result, it is possible to give the driver a sense of security and improve drivability, and to avoid a situation in which the driver performs a braking operation and energy consumption increases.

1 is an overall configuration diagram of a vehicle according to an embodiment. The flowchart which shows the process by main ECU in this Embodiment. The flowchart which shows the process of STEP19 of FIG. The time chart which shows the processing content by main ECU. Explanatory drawing which shows the processing content by main ECU.

  As shown in FIG. 1, the vehicle according to the present embodiment is, for example, a four-wheel drive hybrid vehicle, and includes an engine 1 that is an internal combustion engine, a first motor 11 that rotates by electric power supplied from a battery 2, and It has the 2nd motor 12, and main ECU3 (Electric Control Unit, equivalent to the driving force control means of this invention) which manages and controls these engines 1, the 1st motor 11, the 2nd motor 12, etc. intensively. . The main ECU 3 performs processing based on information acquired through the information acquisition unit 4 connected to the information acquisition unit 4.

  Supplementally, the main ECU 3 is a microcomputer (not shown) including a RAM (Random Access Memory), a ROM (Read Only Memory), a CPU (Central Processing Unit), an input / output interface, a timer, etc., and is recorded in the ROM. The processing is performed in accordance with the programmed program and data.

  Further, the hybrid vehicle includes a front wheel 6 (corresponding to the first drive wheel of the present invention) driven by the engine 1 and the first motor 11 and a rear wheel 7 driven by the second motor 12 (second of the present invention). Corresponding to drive wheels).

  The engine 1 and the first motor 11 are connected to a common drive shaft, and drive the front wheels 6 via a gear mechanism, a differential gear, and the like (both not shown). Similarly, the second motor 12 drives the rear wheel 7 via a gear mechanism, a differential gear, and the like (both not shown).

  Further, the hybrid vehicle includes a first PDU (Power Drive Unit having an inverter function and performing current control) 21 that performs power control of the first motor 11 and a second PDU (Power Drive Unit) 22 that performs power control of the second motor 12. The first motor 11 and the second motor 12 also function as a generator under the control of the first PDU 21 and the second PDU 22. That is, the first motor 11 can generate power or regenerate by receiving driving force from the engine 1 or the front wheel 6 and charge the battery 2, and the second motor 12 can regenerate by receiving driving force from the rear wheel 7. To charge the battery 2.

  The main ECU 3 includes a target driving force calculation unit 3A, a front and rear wheel distribution ratio determination unit 3B, and a driving force change point determination unit 3C.

  The target driving force calculation unit 3 </ b> A is based on the information (road surface information) acquired via the information acquisition unit 4 connected to the information acquisition unit 4 and the target driving force of the entire vehicle (first driving of the front wheels 6, 6). The upper limit threshold value of the force and the second driving force of the rear wheels 7 and 7) is set, and the vehicle is based on the output values of an accelerator opening sensor and a vehicle speed sensor (not shown) within the set upper limit threshold range. The target driving force (instantaneous value) is sequentially calculated.

  The front and rear wheel distribution ratio determining unit 3B determines the target driving force calculated by the target driving force calculating unit 3A based on information (road surface information) acquired via the information acquiring unit 4 connected to the information acquiring unit 4. The distribution ratio to be distributed to the first driving force of the front wheels 6 and 6 and the second driving force of the rear wheels 7 and 7 is determined.

  The driving force change point determination unit 3C determines whether or not to drive the second motor 12 based on information (road surface information) acquired via the information acquisition unit 4 connected to the information acquisition unit 4. The timing for driving is determined.

  Details of the processing by the main ECU 3 will be described later.

  The main ECU 3 is connected to the engine ECU 30, the first motor ECU 31, the second motor ECU 32, and the battery ECU 33. The engine ECU 30 controls the engine 1, and the battery ECU 33 controls the charging / discharging of the battery 2. Is executed. Further, the first motor ECU 31 controls the first motor 11 via the first PDU 21, and the second motor ECU 32 controls the second motor 12 via the second PDU 22.

  The information acquisition unit 4 includes a first information acquisition unit 4A (corresponding to a first acquisition unit of the present invention) and a second information acquisition unit 4B (corresponding to a second acquisition unit of the present invention).

  4A of 1st information acquisition parts acquire the 1st information about the 1st position which is the current run road surface of vehicles. Here, the first information is the first friction coefficient μ1, which is the road surface friction coefficient at the first position, or information from which this can be derived.

  In this embodiment, as the first information, output values (first friction coefficient μ1) of various road surface friction coefficient calculation units that estimate the first friction coefficient μ1 included in the host vehicle are acquired.

  The configuration of the road surface friction coefficient calculation unit is described in the prior art document (Japanese Patent Laid-Open No. 2009-274582, paragraph [0019]) by the applicant of the present application, and a detailed description thereof is omitted here. The outline of the processing of the road surface friction coefficient calculating section is as follows. The speed V and the brake torque T of the front wheels 6 and 6 and the rear wheels 7 and 7 are detected by a wheel speed sensor and a brake torque sensor (not shown), respectively, The first friction coefficient μ1 is calculated from the equation.

μ1 = [T + (I × (dw / dt)) / R] / W
Here, I is a wheel inertia moment, R is a wheel radius, w is a wheel rotational speed, W is a wheel ground load, and a relationship of V = R · w is established.

  Next, the 2nd information acquisition part 4B acquires the 2nd information regarding the 2nd position on the course of vehicles. Here, the second information is the second friction coefficient μ2, which is the road surface friction coefficient at the second position, or information from which this can be derived.

  The second information corresponds to a measurement value obtained by measuring the road surface state at the second position by the outside device. As an out-of-vehicle device, a road surface friction coefficient calculation unit provided in another vehicle on the course of the host vehicle, an information server in which information (second friction coefficient μ2) provided from the other vehicle is stored, information transmission such as a beacon Applicable means.

  Further, as the second information, the output value (second friction coefficient μ2) of the road surface friction coefficient calculation unit of the other vehicle, information that can be acquired from the information server, and road surface information (second friction coefficient) provided by the other vehicle μ2), information on the road surface state on the route that can be acquired from information transmitting means such as a beacon (for example, information on a road surface frozen, wet, dry, etc.).

  Furthermore, the hybrid vehicle includes a notification unit 8 connected to the main ECU. The notification means 8 is, for example, a sound device such as a display device or a speaker provided in the meter panel, and changes the driving force prior to the driving force change timing determined by the driving force change point determination unit 3C. The notice is notified visually or audibly to the driver who is the user.

  Next, details of the processing by the main ECU 3 will be described with reference to the flowchart shown in FIG.

  First, the main ECU 3 acquires the first friction coefficient μ1 that is the friction coefficient of the first position where the host vehicle is currently traveling through the first information acquisition unit 4A of the information acquisition unit 4 (FIG. 2 / STEP 11). .

  Next, the main ECU 3 determines whether or not the second information as the road surface information of the second position, which is the road surface on the course of the host vehicle, can be acquired via the second information acquisition unit 4B of the information acquisition unit 4. (FIG. 2 / STEP 12).

  Then, the main ECU 3 repeats this determination until the second information can be acquired (NO in FIG. 2 / STEP 12), and from the acquired second information at the timing when the second information can be acquired (YES in FIG. 2 / STEP 12). A second friction coefficient μ2 that is a friction coefficient at the second position is derived.

  Here, in order to derive the second friction coefficient μ2, when the second information itself includes the second friction coefficient μ2, the included second friction coefficient μ2 is used as it is. For example, when the second information provided by another vehicle includes the second friction coefficient μ2 as the second information, the second friction coefficient μ2 is used as it is.

  On the other hand, when the second friction coefficient μ2 is not included, the second friction coefficient μ2 is estimated from the second information. For example, when the second information is road surface condition information (for example, a frozen road surface, a wet state of water, a dry state, etc.) on a route that can be acquired from information transmitting means such as a beacon, the road surface The corresponding second friction coefficient μ2 is estimated from the state information by referring to a map, table, relational expression, etc. (hereinafter referred to as a map or the like) stored in advance in a memory or the like.

  In addition, although the information acquired as 2nd information may be acquired about all the road surfaces on the course of the own vehicle, the range acquired based on map information, such as a navigation apparatus which is not illustrated, is according to the distance with the own vehicle. It is preferable to be limited (for example, a range of 5 km ahead of the host vehicle). Thereby, it is possible to avoid changing the driving force distribution ratio based on the second friction coefficient μ2 at the second position on the path away from the present.

  Next, the main ECU 3 calculates a deviation Δμ between the first friction coefficient μ1 acquired in STEP 11 and the second friction coefficient μ2 derived in STEP 13 (FIG. 2 / STEP 14).

  Next, the main ECU 3 determines the first driving force for the front wheels 6 and 6 and the rear wheel based on whether or not the magnitude | Δμ | of the deviation Δμ calculated in STEP 14 is equal to or larger than a predetermined threshold value. It is determined whether or not it is necessary to change the driving force distribution ratio with the second driving force of the wheels 7 and 7 (FIG. 2 / STEP 15).

  For example, as shown in FIG. 4A, when the road surface friction coefficient changes from a high μ road to a low μ road (when μ1> μ2), the first friction coefficient μ1 at point A in the first position is dry. When the second friction coefficient μ2 at point B in the second position is a snowy road surface on the asphalt road surface, the main ECU 3 determines that | Δμ | = | μ1-μ2 | It is determined that the driving force distribution ratio between the first driving force and the second driving force of the rear wheels 7, 7 (usually 0 on a dry asphalt road surface) needs to be changed.

  If the main ECU 3 determines that it is not necessary to change the driving force distribution ratio (NO in STEP 2 in FIG. 2), the main ECU 3 ends the series of processes. On the other hand, if the main ECU 3 determines that the driving force distribution ratio needs to be changed (YES in STEP 15 in FIG. 2), the target driving force calculation unit 3A has a target driving force corresponding to the second friction coefficient μ2. Is set (FIG. 2 / STEP 16).

  Here, the upper limit threshold value of the target driving force is determined by referring to a map that defines the relationship between the road surface friction coefficient μ and the upper limit threshold value stored in advance in a memory (not shown) or the like.

  Next, the front and rear wheel distribution ratio determination unit 3B of the main ECU 3 determines the drive force distribution ratio between the first driving force of the front wheels 6 and 6 and the second driving force of the rear wheels 7 and 7 corresponding to the second friction coefficient μ2. Determine (FIG. 2 / STEP 17).

  Here, the driving force distribution ratio is determined by referring to a map or the like that defines the relationship between the road surface friction coefficient μ and the driving force distribution ratio stored in advance in a memory or the like (not shown).

  Next, the driving force change point determination unit 3C of the main ECU 3 refers to map information such as a navigation device (not shown), and the current position (first position) of the host vehicle and the position (second position) related to the second information. ) Is calculated (FIG. 2 / STEP 18).

  For example, as illustrated in FIG. 4A, the driving force change point determination unit 3C determines the distance between the point A (first position) related to the first information and the point B (second position) related to the second information. D is calculated.

  Next, the driving force change point determination unit 3C executes a driving force change point determination process (FIG. 2 / STEP 19).

  In the driving force change point determination process, the driving force change point for changing the driving force is determined from | Δμ | calculated in STEP 14 according to the flowchart shown in FIG.

  First, the driving force change point determination unit 3C determines whether there is a change in the first friction coefficient μ1 and the second friction coefficient μ2 (FIG. 3 / STEP20). Here, the case where there is no change between the first friction coefficient μ1 and the second friction coefficient μ2 is not only when μ1 = μ2, but also when the change is very small (| Δμ | ≈0). including.

  When there is no change between the first friction coefficient μ1 and the second friction coefficient μ2 (YES in STEP 3 / STEP 20), the driving force change point determination unit 3C ends this process, and the first friction coefficient μ1 And the second friction coefficient μ2 (NO in FIG. 3 / STEP 20), it is determined whether or not the first friction coefficient μ1 is larger than the second friction coefficient μ2 (FIG. 3 / STEP 21). That is, it is determined whether or not the road surface state has changed from a high μ road to a low μ road.

  When the first friction coefficient μ1 is greater than the second friction coefficient μ2 (YES in FIG. 3 / STEP 21), the driving force change point determination unit 3C drives in this case as shown in FIG. The point C, which is a force change point, is determined as follows using the distance X from the point B (second position) according to the second information on the course of the host vehicle (FIG. 3 / STEP 22). That is, based on a map or the like that defines the relationship between | Δμ | and the distance X from the second position shown in FIG. 5A, the driving force is changed so that the greater the | Δμ | A point (point C) is determined.

  For example, in FIG. 5A, | Δμ in the case where the first friction coefficient μ1 at the point A at the first position is a dry asphalt road surface and the second friction coefficient μ2 at the point B at the second position is a snowy road. In |, the driving force change point C is determined as the position of the distance X1 from the point B.

  On the other hand, when the first friction coefficient μ1 at the point A in the first position is a dry asphalt road surface, and the second friction coefficient μ2 ′ at the point B in the second position is a wet asphalt road surface wet with water | Δμ ′ In |, the driving force change point C ′ is determined at a position of a distance X2 from the point B. At this time, from | Δμ ′ | <| Δμ |, a relationship of X2 <X1 is established.

  By determining the driving force change point (C point, C ′ point) in this way, when | Δμ | is small, the distribution of the driving force is changed near the second position, and the consumption energy increases. When | Δμ | is large, the driving force distribution ratio is changed before the second position, so that the situation where the vehicle reaches the second position during the change or the driver It is possible to avoid the situation where the energy consumption increases due to the brake operation.

  Here, as shown in FIG. 4 (a), the driving force distribution ratio changed at the driving force change point is first on the front wheels 6 and 6 before the driving force change point (C point, C 'point). Only the driving force is applied, and after the driving force change point (C point, C ′ point), in addition to the first driving force acting on the front wheels 6, 6, the second driving force is applied to the rear wheels 7, 7. Act. Further, the ratio of the second driving force acting on the rear wheels 7 and 7 is determined according to the second friction coefficients μ2 and μ2 ′ such that the smaller the second friction coefficient is, the larger the ratio of the second driving force is. .

  From the above, in front of the driving force change point (C point, C ′ point), it is possible to maintain the optimum driving force distribution ratio according to the current traveling road surface condition and reduce the energy consumption, and to reduce the road surface. Before the state changes, the driving force distribution ratio can correspond to the second friction coefficient μ2.

  Further, when the driving force change point is small (when ΔΔμ | is small) (when the driving force change point is C ′), the current driving force distribution ratio is maintained long, and the driving force distribution ratio with an emphasis on reduction of energy consumption is Changes can be realized. On the other hand, when | Δμ | is large (when the driving force change point is C), a change to the driving force distribution ratio corresponding to a large change in the road surface friction coefficient can be realized.

  Next, the driving force change point determination unit 3C corrects the distance X calculated in STEP 22 (FIG. 3 / STEP 23), and ends the series of processes. As the correction processing here, a part or all of the following first to third aspects can be adopted.

  As a first mode of the correction process, the distance X is corrected according to the distance D between the first point and the second point calculated in STEP18. For example, when the distance D between the first point and the second point is less than a predetermined lower limit threshold, the host vehicle is positioned immediately before the second point, so that the distance X is corrected so as to increase. As a result, the driving force distribution ratio can be changed at an early stage.

  Further, as a second aspect of the correction process, the distance X may be corrected according to the vehicle speed. Specifically, as shown in FIG. 5B, the driving force change point (C point) is corrected to be closer to the second position as the vehicle speed increases.

  For example, when the distance X1 is 60 [km / h] per hour and the vehicle speed is 80 [km / h] per hour and 100 [km / h] per hour, the distance X1 is corrected to the distances X11 and X12. Is preferable (where X12> X11> X1). Similarly, when the vehicle speed is 40 [km / h], it is preferable to correct the distance X1 to the distance X13 (where X13 <X1).

  Thus, even when the driving force change point (C point) is the same, when the vehicle speed is high, the time required to reach the second position B from the driving force change point is shorter than when the vehicle speed is low. However, as the vehicle speed increases, the driving force change point (C point) becomes closer to the second point (B point) before the driving force change point (C point) to the second position (B point). ) Can be secured for a certain period of time, and it is possible to avoid a situation where the driver performs a brake operation and increases energy consumption.

  Furthermore, as a third aspect of the correction process, the distance X may be corrected according to the slope of the second position (point B). Specifically, height difference information is added to the map information of the navigation device provided in the vehicle, and when the second position has an inclination, the driving force change point is positioned closer to the second position. It may be corrected. Furthermore, the correction amount may be changed depending on whether the slope is an upward slope or a downward slope. For example, even when the second friction coefficient at the second position is the same, when the second position is a downward slope, it is possible to cope with a decrease in the limit driving force due to a decrease in the shaft weight on the rear wheels 7 and 7 side. The driving force distribution ratio can be changed at an appropriate timing in response to a substantial road surface change on the vehicle path.

  On the other hand, when the first friction coefficient μ1 is smaller than the second friction coefficient μ2 in STEP 21 (NO in FIG. 3 / STEP 21), the driving force change point determination unit 3C, as shown in FIG. The point C which is the driving force change point in this case is determined as follows using the distance Y from the point B (second position) according to the second information on the course of the host vehicle (FIG. 3 / STEP 26). . That is, the driving force change point (point C) is determined so that the distance Y becomes smaller as | Δμ | becomes larger, using a map or the like (not shown) corresponding to FIG.

  Accordingly, when the first friction coefficient is smaller than the second friction coefficient as in the case where the first position is a low μ road, the road surface state is still the first friction coefficient (low μ road). Nevertheless, there is a concern that the driving force distribution ratio is changed, but when the deviation between the first friction coefficient and the second friction coefficient is large, the driving force distribution ratio is closer to the second position. Therefore, it is possible to avoid changing the driving force distribution ratio even though the road surface state is still the first friction coefficient (low μ road).

  Furthermore, when the deviation between the first friction coefficient and the second friction coefficient is small, the change in the road surface friction coefficient between the first position and the second position is often small and gradual, reducing energy consumption. Changes in the driving force distribution ratio that are emphasized are required. However, the smaller the deviation between the first friction coefficient and the second friction coefficient, the more the driving force distribution ratio is changed in front of the second position. You can plan.

  Next, the driving force change point determination unit 3C corrects the distance Y calculated in STEP 26 (FIG. 3 / STEP 27) and ends the series of processes. The correction process here corresponds to the correction process of the distance X in STEP23.

  As a first mode of the correction process, the distance Y is corrected according to the distance D between the first point and the second point calculated in STEP18. For example, when the distance D between the first point and the second point is less than a predetermined lower limit threshold, the host vehicle is positioned immediately before the second point, so that the distance Y is corrected so as to increase. As a result, the driving force distribution ratio can be changed at an early stage.

  As a second mode of the correction process, the correction is performed so that the distance Y increases as the vehicle speed increases, that is, the driving force change point (C point) is closer to the second position. Thereby, the driving force distribution corresponding to the first friction coefficient can be maintained for a long time, and a sense of security can be given to the driver.

  Furthermore, as a third aspect of the correction process, the distance Y may be corrected according to the slope of the first position (point A). Specifically, when there is an inclination at the first position, the driving force change point may be corrected so as to be closer to the second position. Furthermore, the correction amount may be changed depending on whether the slope is an upward slope or a downward slope. For example, even if the first friction coefficient at the first position is the same, when the first position is a downward slope, it is possible to cope with a decrease in the limit driving force due to a decrease in the shaft weight on the rear wheels 7 and 7 side. The driving force distribution ratio can be changed at an appropriate timing in response to a substantial road surface change on the vehicle path.

  The main ECU 3 notifies the driving force change point in advance (precisely in terms of time or distance) prior to this in accordance with the driving force change point (point C) corrected in STEP23 or STEP27. To the driver who is the user visually or audibly via the notification means 8 (see point D in FIG. 4A), to allow the driver to recognize in advance that the driving force is changed. Can do. As a result, it is possible to give the driver a sense of security and improve drivability, and to avoid a situation where the driver performs a braking operation and increases energy consumption.

  The above is the details of the processing by the main ECU 3. As described above, according to the vehicle of the present embodiment, the driving power distribution ratio corresponding to the road surface change on the course of the vehicle is reduced while reducing energy consumption. Can be changed at any time.

   In the present embodiment, the vehicle (electric 4WD) including the first motor 11 and the second motor 12 has been described as an example of the vehicle. However, the vehicle on which the power supply system is mounted is not limited to this. As long as the vehicle is propelled by the electric power supplied from the battery 2, it may be a fuel cell vehicle or an electric vehicle provided with power storage means, in addition to a series hybrid vehicle or a parallel hybrid vehicle.

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Battery, 3 ... Main ECU (driving force control means), 3A ... Target driving force calculation part, 3B ... Front-and-rear wheel distribution ratio determination part, 3C ... Driving force change point determination part, 4 ... Information acquisition part 4A ... 1st information acquisition part (1st acquisition means), 4B ... 2nd information acquisition part (2nd acquisition means), 6 ... Front wheel (1st drive wheel), 7 ... Rear wheel (2nd drive wheel), DESCRIPTION OF SYMBOLS 8 ... Notification means, 11 ... 1st motor, 12 ... 2nd motor, 21 ... 1st PDU, 22 ... 2nd PDU, 30 ... Engine ECU, 31 ... 1st motor ECU, 32 ... 2nd motor EUC, 33 ... Battery ECU .

Claims (7)

A first drive wheel that is one of the front wheels or the rear wheels and is driven by one or both of the engine and the first motor, and a second wheel that is a wheel other than the first drive wheels and is driven by the second motor. A vehicle comprising: a driving wheel; and a driving force control means for controlling a driving force distribution ratio between a first driving force for driving the first driving wheel and a second driving force for driving the second driving wheel,
First acquisition means for acquiring a first friction coefficient that is a road surface friction coefficient of a first position that is a current position of the vehicle;
A second acquisition means for acquiring a second friction coefficient that is a road surface friction coefficient at a second position on the path of the vehicle;
When the first friction coefficient acquired by the first acquisition means is greater than the second friction coefficient acquired by the second acquisition means, the driving force control means 2 The larger the deviation of the friction coefficient, the more the driving force change point for changing the driving force distribution ratio corresponding to the first friction coefficient to the driving force distribution ratio corresponding to the second friction coefficient is on the path. The driving force change point is determined so as to be in front of the second position. The vehicle according to claim 1,
Comprising speed acquisition means for acquiring the traveling speed of the vehicle;
In accordance with the traveling speed acquired by the speed acquiring means, the driving force control means increases the driving speed so that the driving force change point is closer to the second position on the route. A vehicle characterized in that the driving force change point is determined. The vehicle according to claim 1 or 2,
The vehicle, wherein the drive force control means increases a distribution ratio of the drive force of the second drive wheel to the first drive force at the drive force change point. A first drive wheel that is one of the front wheels or the rear wheels and is driven by one or both of the engine and the first motor, and a second wheel that is a wheel other than the first drive wheels and is driven by the second motor. A vehicle comprising: a driving wheel; and a driving force control means for controlling a driving force distribution ratio between a first driving force for driving the first driving wheel and a second driving force for driving the second driving wheel,
First acquisition means for acquiring a first friction coefficient that is a road surface friction coefficient of a first position that is a current position of the vehicle;
A second acquisition means for acquiring a second friction coefficient that is a road surface friction coefficient at a second position on the path of the vehicle;
The driving force control means, when the first friction coefficient acquired by the first acquisition means is smaller than the second friction coefficient acquired by the second acquisition means, 2 The larger the deviation of the friction coefficient, the more the driving force change point for changing the driving force distribution ratio corresponding to the first friction coefficient to the driving force distribution ratio corresponding to the second friction coefficient is on the path. The driving force change point is determined so as to be close to the second position. The vehicle according to claim 4, wherein
The vehicle, wherein the driving force control means reduces a distribution ratio of the driving force of the second driving wheel to the first driving force at the driving force change point. The vehicle according to any one of claims 1 to 5,
The second acquisition means includes map information of a navigation device mounted on the vehicle, travel history information of a vehicle other than the vehicle on the route, and a road surface that is installed on the route and detects a road surface state. A vehicle characterized in that the second friction coefficient is obtained from a part or all of output information of a detection device. The vehicle according to any one of claims 1 to 6,
The vehicle, wherein the driving force control means includes notifying means for notifying the change of the driving force before the determined driving force change point.

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