Vehicle control device

Abstract

To achieve suppression of reduction in regenerative brake force, suppression of fade occurrence in a brake gear, and suppression of reduction in friction brake force due to overcooling of the brake gear.SOLUTION: A control device 1 for a vehicle 2 is provided with: a motor device 4 which applies regenerative brake force to a wheel W by regenerative power generation; a brake gear 5 which applies friction brake force to the wheel W; a battery 3 which charges electric power generated by regenerative power generation; and a cooler 6 which cools the brake gear 5. The control device comprises: a first determination part which performs first determination as to whether or not an upper limit value P of acceptable power P for the battery 3 is a prescribed first determination threshold Pth or less; a second determination part which performs second determination as to whether or not a variable value Q related to a temperature of the brake gear 5 is a prescribed second determination threshold Qth or more; and a control part which performs cooling control for driving the cooler 6 by power generated by regenerative power generation and cooling the brake gear 5 when both of the first determination and the second determination are established.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle equipped with a motor device, a brake device, and a battery. [Background technology]

[0002] A conventional technique is known in which, when an on-board motor device generates electricity regeneratively, an auxiliary device electrically connected to the on-board battery is driven to consume the regenerated power generated by the regenerative power generation, thereby ensuring regenerative braking force applied to the wheels from the motor device. For example, Patent Document 1 discloses a control device that drives a cooling device to cool a mechanical brake device when the battery's charging rate is equal to or higher than a predetermined charging rate. Patent Document 1 states that by driving the cooling device when the battery's charging rate is equal to or higher than a predetermined charging rate, regenerative braking force can be ensured, and by cooling the brake device with the cooling device, brake device fade can be prevented. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-076636 Summary of the Invention [Problem to be solved by the invention]

[0004] In mechanical brake systems, an increase in the amount of heat generated on the friction surfaces between the pads and rotor can cause fade, resulting in a decrease in braking effectiveness. On the other hand, if the temperature of the brake system is too low, the frictional resistance between the pads and rotor can decrease, potentially reducing braking force (frictional braking force). In control systems such as those disclosed in Patent Document 1, only the battery's state of charge is taken into account when cooling the brake system using a cooling device. Therefore, there is room for improvement in preventing a decrease in frictional braking force due to overcooling of the brake system.

[0005] The present invention has been devised in view of the above-mentioned problems, and has as one of its objectives to suppress the reduction in regenerative braking force, the occurrence of brake fade, and the reduction in friction braking force due to excessive cooling of the brake device. However, in addition to these objectives, another objective of the present invention is to achieve effects that cannot be obtained by conventional techniques, which are derived from the configurations shown in the below-described embodiments of the invention. [Means for solving the problem]

[0006] The disclosed vehicle control device can be realized as the following disclosed aspects (application examples), which solve at least part of the above-mentioned problems. Each of the aspects from aspect 2 onwards is an aspect that can be selected as an additional option, and each of the aspects from aspect 2 onwards is an aspect that can be omitted. None of the aspects from aspect 2 onwards discloses an aspect or configuration that is essential to the present invention.

[0007] Aspect 1. The disclosed vehicle control device is a vehicle control device provided with a motor device that applies regenerative braking force to wheels by regenerative power generation, a brake device that applies frictional braking force to the wheels, and a battery that charges with electric power generated by the regenerative power generation. The vehicle is provided with a cooling device that cools the brake device. The control device includes a first determination unit that makes a first determination as to whether an upper limit value of electric power that can be accepted by the battery is equal to or less than a predetermined first determination threshold, a second determination unit that makes a second determination as to whether a variable value related to the temperature of the brake device is equal to or greater than a predetermined second determination threshold, and a control unit that, when both the first determination and the second determination are true, performs cooling control to drive the cooling device with electric power generated by the regenerative power generation to cool the brake device.

[0008] Aspect 2. In an aspect including the above aspect 1, the variable value is preferably a duration of a state in which the hydraulic pressure of the fluid in the brake device is equal to or greater than a predetermined third determination threshold value. Aspect 3. In any aspect including Aspect 1 above, the vehicle is preferably provided with a temperature sensor that detects the temperature of an element of the brake device that heats up when the friction braking force is applied to the wheel. In this case, the variable value is preferably the temperature of the element.

[0009] Aspect 4. In an aspect including aspect 1 above, if the second judgment becomes invalid after the start of the cooling control, it is preferable that the control unit continue the cooling control until a predetermined time has elapsed from the point at which the second judgment becomes invalid.

[0010] Aspect 5. In an aspect including the above aspect 1, it is preferable that the control unit intermittently cools the brake device in the cooling control. Aspect 6. In an aspect including the aspect 5 above, it is preferable that the control unit sets the on / off ratio of cooling the brake device based on at least one of the weather, the season, and the time of day when the vehicle is traveling. [Effects of the Invention]

[0011] The disclosed vehicle control device can suppress a decrease in regenerative braking force, suppress the occurrence of brake device fade, and suppress a decrease in friction braking force due to overcooling of the brake device. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a front part of a vehicle to which a control device according to an embodiment is applied; [Figure 2] FIG. 2 is a block diagram of the control device of FIG. [Figure 3] 2 is a flowchart illustrating the control contents executed by the control device of FIG. 1; DETAILED DESCRIPTION OF THE INVENTION

[0013] A vehicle control device according to an embodiment will be described with reference to the drawings. The embodiment described below is merely an example, and is not intended to exclude various modifications or applications of techniques not explicitly described in the embodiment. The configurations of the present embodiment can be modified in various ways without departing from the spirit of the invention. Furthermore, they can be selected or combined as needed.

[0014] In the following description, the forward direction of the vehicle is referred to as the forward direction (front of the vehicle), and the opposite direction is referred to as the rearward direction (rear of the vehicle). The forward direction of the vehicle is referred to as the forward direction when the vehicle is moving forward, and as the rearward direction when the vehicle is moving backward. Furthermore, left and right are defined based on the state in which the vehicle is facing forward. The left and right directions are perpendicular to the front-to-rear direction of the vehicle.

[0015] [1. Overall structure] FIG. 1 is a schematic diagram showing the front part of a vehicle 2 to which a control device 1 of this embodiment is applied. As shown in FIG. 1, the vehicle 2 is provided with a battery 3, a motor 4 (motor device), a brake device 5, and a cooling device 6. The control device 1 is an electronic control device that controls the cooling device 6. The control device 1 may be mounted on the vehicle 2 as shown in FIG. 1, or may be provided outside the vehicle 2 and remotely control the cooling device 6.

[0016] The battery 3 is, for example, a lithium ion secondary battery or a nickel-metal hydride secondary battery, and is a secondary battery capable of supplying a high-voltage direct current of several hundred volts. The state of the battery 3 is detected by a Battery Management Unit 21 (hereinafter also referred to as "BMU21") and output to the control device 1. The BMU21 detects (calculates) the state of the battery 3, for example, SOC (State Of Charge, charging rate), battery temperature, and degradation level (SOH, State of Health).

[0017] The motor 4 is a generator that applies a regenerative braking force to the wheels W by regenerating power using the inertial rotation of the wheels W, and charges the battery 3 with the regenerated power. The motor 4 is electrically connected to the battery 3 via an inverter 7. The inverter 7 is a converter (DC-AC inverter) that converts between the power of the DC circuit on the battery 3 side (DC power) and the power of the AC circuit on the motor 4 side (AC power), and is controlled by a motor control unit (MCU) (not shown). During regenerative power generation by the motor 4, the power generated by the motor 4 is converted into DC power by the inverter 7 and charged into the battery 3 as regenerative power.

[0018] The motor 4 may be a motor / generator that also has the function of driving the wheels W using power from the battery 3. In other words, the vehicle 2 may be an electric vehicle (EV) or hybrid electric vehicle (HEV) that has the motor 4 as a drive source, or a plug-in hybrid electric vehicle (PHEV) that can be externally charged or externally fed. A plug-in hybrid vehicle is a hybrid vehicle that can externally charge the battery or feed power from the battery. A plug-in hybrid vehicle is provided with a charging port (inlet) for inserting a charging cable that supplies power from an external charging facility and a receptacle (outlet) for external power feeding. A transaxle 8 may be interposed between the motor 4 and the wheels W on the power transmission path from the motor 4 to the wheels W.

[0019] The brake device 5 is a hydraulic disc brake that applies a friction braking force to the wheels W. In the brake device 5, fluid (brake oil) is pushed out from a master cylinder 10 in response to depression of a brake pedal 9, and the hydraulic pressure of the fluid is adjusted and output by a brake actuator 11. The hydraulic pressure output from the brake actuator 11 is transmitted to a pad 13 through a hydraulic circuit 12. As a result, the pad 13 presses against a rotor 14 (brake disc) that rotates together with the wheels W, and frictional resistance between the pad 13 and the rotor 14 applies a friction braking force to the wheels W. Note that the pad 13 and the rotor 14 may be provided on each wheel W, or may also be provided on each of the left and right rear wheels (not shown) of the vehicle 2.

[0020] The brake actuator 11 is controlled by, for example, a brake control device (Hydraulic Unit, H / U) (not shown) to adjust the hydraulic pressure of the fluid. The brake control device controls the brake actuator 11 to apply a desired braking force (required braking force) corresponding to the depression amount of the brake pedal 9 to the wheels W of the vehicle 2 while the vehicle is running, by using frictional braking force to compensate for the braking force that is insufficient with regenerative braking force alone.

[0021] The brake actuator 11 is provided with a hydraulic sensor 22 that detects the hydraulic pressure R of the fluid output from the brake actuator 11. The brake device 5 is also provided with a temperature sensor 23 that detects the temperature of heating elements (e.g., fluid, pad 13, rotor 14) that are heated by applying frictional braking force to the wheel W, among the elements that make up the brake device 5. Here, the temperature sensor 23 that is attached to the hydraulic circuit 12 and detects the temperature FT of the fluid is shown as an example. However, the temperature sensor 23 may be attached to the pad 13 to detect the temperature of the pad 13, or may be attached to the rotor 14 to detect the temperature of the rotor 14. Alternatively, the temperature sensor 23 may be attached to multiple heating elements to detect the respective temperatures.

[0022] The cooling device 6 cools the brake device 5 by cooling air taken in from inside or outside the vehicle and sending the cooled air to the brake device 5. More precisely, the cooling device 6 cools at least one of the above-mentioned temperature-raising elements. A conventional heating, ventilation and air conditioning (HVAC) system may be used as the cooling device 6.

[0023] The cooling device 6 is provided with a cooling unit 15, a vehicle interior communication passage 16, an element communication passage 17, and a valve 18. The cooling unit 15 is driven by power from the battery 3 and / or regenerative power from the motor 4, and cools air taken in from inside or outside the vehicle. As shown in the figure, the cooling unit 15 is electrically connected in parallel with the inverter 7 and the battery 3. The operating state of the cooling unit 15 is controlled by the control device 1.

[0024] The cabin communication passage 16 is a passage that sends cooling air into the cabin of the vehicle 2. One end of the cabin communication passage 16 is connected to the cooling unit 15, and the other end opens toward the cabin. The element communication passage 17 is a passage that sends cooling air to the heating element. For example, one end of the element communication passage 17 is connected to the cabin communication passage 16 (branches off from the cabin communication passage 16), and the other end opens toward the heating element. The other end of the element communication passage 17 is provided, for example, near the pad 13, as shown in the figure.

[0025] The valve 18 is a valve (for example, a three-way valve or a flow path control valve) provided at a branching position where the element communication passage 17 branches off from the vehicle interior communication passage 16, and switches the element communication passage 17 between a communication state and a non-communication state with the cooling unit 15. The valve 18 may switch between sending the cooling air into the vehicle interior through the vehicle interior communication passage 16 and sending the cooling air to the heating element through the element communication passage 17. The valve 18 is controlled by the control device 1.

[0026] The vehicle 2 of this embodiment is further provided with a positioning device 24 and a wiper sensor 25. The positioning device 24 measures the current position information (latitude, longitude, and altitude) of the vehicle 2 and acquires the current date and time via communication with a GNSS (Global Navigation Satellite System). The wiper sensor 25 is a sensor that detects whether or not wipers (neither of which is shown) attached to the windshield of the vehicle 2 are operating.

[0027] The control device 1 is an electronic control device configured as, for example, an LSI device or an embedded electronic device that integrates a microprocessor, ROM, RAM, etc., and is connected to a communication line of a network of the vehicle 2. The control device 1 may be an integrated control device (Electronic Control Unit, ECU) that controls various on-board devices in an integrated manner. As shown in FIG. 2, the input side of the control device 1 is connected to the above-mentioned BMU 21, oil pressure sensor 22, temperature sensor 23, positioning device 24, and wiper sensor 25. The output side of the control device 1 is connected to the cooling unit 15 and valve 18 of the cooling device 6.

[0028] [2. Control Overview] When both the following first and second determinations are met, the control device 1 performs cooling control to drive the cooling device 6 with regenerative power to cool the brake device 5. By performing this cooling control, the control device 1 achieves three functions: suppressing a decrease in regenerative braking force, suppressing the occurrence of fade in the brake device 5, and suppressing a decrease in friction braking force due to overcooling of the brake device 5.

[0029] First determination: whether the upper limit value P of the power that the battery 3 can accept is equal to or less than a predetermined first determination threshold value Pth. Second determination: whether or not the variable value Q related to the temperature of the brake device 5 is equal to or greater than a predetermined second determination threshold value Qth

[0030] Here, the upper limit P of the power that can be received by the battery 3 means the upper limit of the power that the battery 3 can receive within a range in which the battery 3 can be used normally, and can also be said as the upper limit of the power that can be charged to the battery 3 (the available capacity of the battery 3). The upper limit P is not a fixed value, but varies depending on the state of the battery 3.

[0031] For example, when the battery 3 is at an extremely low temperature, the battery capacity decreases compared to when it is at room temperature, so the upper limit value P decreases even if the SOC is constant (when comparing an SOC of 50% at room temperature with an SOC of 50% at an extremely low temperature, the latter is greater). Also, when the SOH is low (deterioration is progressing), the battery capacity decreases compared to when the SOH is 100% (when new), so the upper limit value P decreases even if the SOC and battery temperature are constant. Furthermore, even when the battery capacity is constant, the upper limit value P is smaller when the SOC is relatively high (when close to full charge, i.e., when the SOC is close to 100%) than when the SOC is relatively low (when the SOC is close to 0%).

[0032] The first determination threshold Pth is set to a value that is at least smaller than the upper limit P in normal times. Here, normal times means when the battery 3 is not nearly fully charged and the battery capacity is appropriate (when the battery 3 is not deteriorating and is at room temperature). The first determination threshold Pth is preferably set to a value that corresponds to the upper limit P when the battery 3 is nearly fully charged or when the battery capacity is low.

[0033] In other words, when the upper limit value P is equal to or less than the first determination threshold value Pth, it can be said that the upper limit value P at that time (when P≦Pth) is lower than the upper limit value P under normal conditions. Here, there is a positive correlation between the magnitude of the regenerative braking force and the magnitude of the regenerative power. In other words, by increasing the regenerative power (the amount of power generated by regeneration), a large regenerative braking force can be obtained. Furthermore, the upper limit value of the regenerative power (the maximum power that can be generated by regeneration) is determined by the upper limit value P of the battery 3 and the power consumption of the auxiliary equipment, including the cooling unit 15, which is connected in parallel with the motor 4 to the battery 3.

[0034] Therefore, when the first condition is met and the power consumption of the auxiliary equipment is constant, the upper limit of the regenerative power becomes lower than usual, and the regenerative braking force becomes more limited than usual. This may result in a longer operating time of the brake device 5 or a larger frictional braking force being applied by the brake device 5 to compensate for the limited regenerative braking force, which may increase the temperature of the brake device 5 and cause brake fade.

[0035] Therefore, the control device 1 performs cooling control when the first condition is met. By performing cooling control, the cooling device 6 is driven. This increases the power consumption of the auxiliary equipment and raises the upper limit of regenerative power, thereby suppressing a decrease in regenerative braking force. Furthermore, by performing cooling control, the brake device 5 is cooled by the cooling device 6. This suppresses an increase in the temperature of the brake device 5 and suppresses the occurrence of fade.

[0036] As described above, brake fade occurs when the temperature of the brake device 5 rises. However, if the temperature of the brake device 5 has not yet reached a temperature at which fade can occur, there is no problem if cooling control is not performed. In other words, if fade of the brake device 5 is not likely to occur, the brake device 5 can be operated without cooling, and the limited regenerative braking force can be compensated for by friction braking force. Furthermore, if the temperature of the brake device 5 is too low, sufficient frictional resistance cannot be obtained, and the friction braking force may decrease. Therefore, when performing cooling control, the control device 1 performs not only the first determination but also the second determination described above.

[0037] Here, the variable value Q in the second determination is a value that has a positive correlation with the temperature of the braking device 5. Strictly speaking, the temperature of the braking device 5 means the temperature of the temperature-raising element. The second determination threshold Qth is set to, for example, a value corresponding to the lowest temperature of the braking device 5 at which fade may occur.

[0038] For example, the control device 1 may use, as the variable value Q, the duration FD of the pressurized state during which the fluid oil pressure R is equal to or greater than a predetermined third determination threshold value Rth. The third determination threshold value Rth is set to a value that is at least greater than the value of the fluid oil pressure R when the brake device 5 begins to apply frictional braking force to the wheel W (when the brake device 5 begins to operate). The third determination threshold value Rth is preferably set to the value of the fluid oil pressure R when a medium level of frictional braking force (for example, approximately half of the maximum frictional braking force that the brake device 5 can apply) is applied. Since the temperature of the brake device 5 increases the longer the operating time of the brake device 5 (i.e., the duration FD), using the duration FD as the variable value Q makes it possible to make the second determination, i.e., determine whether or not there is a possibility of brake fade occurring.

[0039] The control device 1 may also use the temperature of the heating element itself as the variable value Q. For example, the control device 1 may use the fluid temperature FT detected by the temperature sensor 23 as the variable value Q. Alternatively, if temperature sensors 23 are attached to multiple heating elements, the average or median of the temperatures detected by the temperature sensors 23 may be used as the variable value Q.

[0040] In this way, the control device 1 performs cooling control only when both the first determination and the second determination are satisfied, thereby preventing the brake device 5 from being excessively cooled when the temperature of the brake device 5 has not yet reached a temperature at which fade may occur. This prevents a decrease in frictional braking force due to overcooling of the brake device 5.

[0041] As described above, when applying a desired braking force to the wheels W of the vehicle 2 while the vehicle 2 is traveling, the brake device 5 operates when the regenerative braking force alone is insufficient, and applies the insufficient braking force (friction braking force) to the wheels W. Therefore, when the vehicle 2 is traveling and no regenerative braking force is being applied to the wheels W (i.e., the motor 4 is not generating regenerative power), the brake device 5 does not operate, and the second determination is made when regenerative braking force is being applied to the wheels W.

[0042] The control device 1 may terminate the cooling control if either the first determination or the second determination becomes invalid after the cooling control is started. Alternatively, the control device 1 may provide hysteresis to the cooling control. This suppresses chattering between the execution and non-execution of the cooling control.

[0043] For example, even if the second determination becomes false after the start of the cooling control, the control device 1 may continue the cooling control until a predetermined time T (for example, several tens of seconds to several minutes) has elapsed since the second determination became false, and may end the cooling control after the predetermined time T has elapsed. Note that if regenerative power generation by the motor 4 is no longer performed before the predetermined time T has elapsed, the control device 1 may drive the cooling device 6 with the power of the battery 3 to cool the brake device 5.

[0044] [3. Control configuration] 2, the control device 1 is provided with a first determination unit 1A, a second determination unit 1B, and a control unit 1C as functional elements that perform cooling control. These elements may be realized by electronic circuits (hardware), or may be programmed as software, or some of these functions may be provided as hardware and the other parts may be software.

[0045] The first determination unit 1A performs a first determination and transmits the determination result to the control unit 1C. The first determination unit 1A acquires, for example, an upper limit value P from the BMU 21 and identifies (determines) whether the first determination is successful. The first determination unit 1A may acquire information on the state of the battery 3 (SOC, battery temperature, SOH, current value, voltage value, etc.) from the BMU 21, calculate the upper limit value P from the acquired information, and identify (determine) whether the first determination is successful.

[0046] The second determination unit 1B performs the second determination and transmits the determination result to the control unit 1C. When the duration FD is used as the variable value Q, the second determination unit 1B acquires the fluid oil pressure R from the oil pressure sensor 22 and determines whether the acquired fluid oil pressure R is equal to or greater than the third determination threshold Rth (i.e., whether the fluid is in a pressurized state). When the second determination unit 1B determines that the fluid oil pressure R is equal to or greater than the third determination threshold Rth, it calculates the duration FD of the pressurized state from that point in time and determines whether the second determination is successful. When the fluid temperature FT is used as the variable value Q, the second determination unit 1B acquires the fluid temperature FT from the temperature sensor 23 and determines whether the second determination is successful.

[0047] The control unit 1C performs cooling control based on information transmitted from the first determination unit 1A and the second determination unit 1B. Specifically, the control unit 1C performs (starts) cooling control when it receives a signal indicating that the first determination is made from the first determination unit 1A and a signal indicating that the second determination is made from the second determination unit 1B.

[0048] In the cooling control, the control unit 1C may cool the brake device 5 continuously or intermittently. When intermittently cooling the brake device 5, the control unit 1C may, for example, drive the cooling unit 15 intermittently. Alternatively, the control unit 1C may control the opening and closing of the valve 18 while driving the cooling unit 15, thereby intermittently switching the element communication passage 17 between a connected state and a disconnected state with respect to the cooling unit 15. In this case, the cooling air may be supplied into the vehicle cabin via the vehicle cabin communication passage 16, or may be discharged outside the vehicle via another communication passage (not shown). When the brake device 5 is intermittently cooled by controlling the valve 18, the cooling unit 15 continues to be driven, thereby further suppressing a decrease in regenerative braking force.

[0049] When cooling the brake devices 5 intermittently, the control unit 1C may set an intermittent cooling ratio C for the brake devices 5 based on at least one of the weather, season, and time of day at the current location of the vehicle 2 while the vehicle 2 is traveling. Here, the intermittent ratio C refers to the ratio between the time during which cooling of the brake devices 5 is performed and the time during which cooling of the brake devices 5 is stopped, and can also be expressed as the proportion of the time during which cooling of the brake devices 5 occupies a certain period of time. In other words, the intermittent ratio C can also be expressed as the duty ratio of a signal transmitted to the cooling unit 15 or the valve 18.

[0050] When setting the on-off ratio C based on the weather, the control unit 1C may, for example, acquire information from the wiper sensor 25 and determine that it is sunny when the wipers are not operating, and determine that it is raining or snowing when the wipers are operating. For example, the control unit 1C may set the on-off ratio C to be smaller when the weather is raining or snowing than when it is sunny.

[0051] Furthermore, when setting the on-off ratio C based on the season, the control unit 1C may, for example, acquire a date from the positioning device 24 and determine the season (spring, summer, autumn, or winter) from the acquired date. For example, when the season is winter, the control unit 1C may set the on-off ratio C to be smaller than when the season is other seasons (spring, summer, or autumn).

[0052] When setting the on-off ratio C based on the time period, the control unit 1C may, for example, obtain the time from the positioning device 24 and determine the time period (day or night) from the obtained time. For example, the control unit 1C may set the on-off ratio C to a smaller value when the time period is night than when it is day. In this way, the control unit 1C sets the on-off ratio C to a smaller value when the temperature outside the vehicle is likely to be relatively low, thereby preventing excessive cooling of the brake device 5.

[0053] The control unit 1C may set the on-off ratio C based on two or three of the weather, season, and time period. For example, a reference on-off ratio C' may be set, and coefficients may be set for each of the weather, season, and time period. The on-off ratio C may be set by multiplying the reference on-off ratio C' by the coefficient. For example, the weather coefficient may be 1.0 for clear weather (when the wipers are not operating), 0.8 for rain (0.7 for snow if rain and snow can be distinguished), the season coefficient may be 0.7 for winter, and 1.0 for other seasons. The time period coefficient may be 0.9 for night, and 1.0 for other seasons. In this case, the on-off ratio C when it is raining on a winter night (when the temperature outside the vehicle is likely to be relatively low) is calculated as the reference on-off ratio C' x 0.8 x 0.7 x 0.9 (= 0.504), which prevents excessive cooling of the brake device 5.

[0054] The control unit 1C may adjust the temperature of the cooling air that cools the brake device 5 based on at least one of the weather, season, and time of day at the current location of the vehicle 2 while the vehicle 2 is traveling.

[0055] [4. Flowchart] Fig. 3 is a flowchart illustrating the contents of the control performed by the control device 1. In the flowchart of Fig. 3, a flag F for identifying whether or not cooling control is being performed has an initial value of 0 (cooling control is not being performed). Also, a timer t for counting the elapsed time from the point in time when the second determination becomes false after the start of cooling control has an initial value of 0.

[0056] This flow may be started, for example, when the vehicle 2 starts traveling (when the vehicle speed of the vehicle 2 is no longer 0), repeatedly executed at a predetermined calculation cycle, and forcibly terminated when the vehicle 2 stops. In this case, the flag F and the timer t may be reset to their initial values ​​when this flow ends. Alternatively, after this flow is started when the vehicle 2 starts traveling, even if the vehicle 2 stops, if the flag F is 1 (cooling control is being performed), the end of this flow may be postponed and the flow may be terminated when the flag F becomes 0.

[0057] In step S1, it is determined whether the upper limit value P is equal to or less than the first determination threshold value Pth, i.e., a first determination is made. If it is determined in step S1 that the upper limit value P is equal to or less than the first determination threshold value Pth, the process proceeds to step S2. Note that the result of step S1 may be true, for example, when the vehicle 2 is traveling with the battery 3 nearly fully charged, or when the battery capacity is low in an extremely low temperature environment and / or when the battery 3 is deteriorated.

[0058] In the following step S2, it is determined whether or not the variable value Q is equal to or greater than the second determination threshold Qth, i.e., a second determination is made. If it is determined in step S2 that the variable value Q is not equal to or greater than the second determination threshold Qth, the process proceeds to step S5, where it is determined whether or not the flag F is 1. Since the flag F is initially set to 0, if it is determined in step S5 that the flag F is not 1, steps S9 and S10 are performed as initialization processing while cooling control is not being performed. Specifically, in step S9, the timer t is reset (t remains at 0), and in step S10, the flag F is set to 0 (the setting state of flag F=0 continues). In the following step S11, the valve 18 is controlled to a closed state, so that the element communication passage 17 is not connected to the cooling unit 15, and the flow returns.

[0059] As described above, the temperature of the brake device 5 increases the longer the operation time of the brake device 5. Therefore, for example, immediately after the start of operation of the brake device 5, the temperature of the brake device 5 has not yet reached the temperature at which fade occurs, and the second determination using the variable value Q related to that temperature may not be established. For this reason, after the processes of steps S2, S5, and S10, the valve 18 is controlled to a closed state in step S11. This prohibits the delivery of cooling air to the element communication passage 17, thereby preventing excessive cooling of the brake device 5 when the temperature of the brake device 5 has not yet reached the temperature at which fade occurs. Note that in step S11, the operation of the cooling unit 15 may be stopped, or if a conventional air conditioning device is used as the cooling device 6, it may be operated in accordance with the temperature in the vehicle cabin.

[0060] In the next calculation cycle or later, if the variable value Q increases without the first determination being false in step S1 and it is determined in step S2 that the variable value Q is equal to or greater than the second determination threshold Qth, the process proceeds to step S3. In step S3, if both the first determination and the second determination are true, flag F is set to 1. In the following step S4, cooling control is performed, and the flow returns. Thereafter, the processes of steps S1 to S4 are repeated until either step S1 or step S2 is false.

[0061] In step S4, more specifically, the cooling unit 15 is driven (ON) by the regenerative power, and the valve 18 is controlled to be in an open state, thereby connecting the element communication passage 17 to the cooling unit 15. As a result, the regenerative power is consumed to drive the cooling unit 15, thereby suppressing a decrease in the regenerative braking force, and cooling the brake device 5 prevents the occurrence of fade.

[0062] If the upper limit value P exceeds the first determination threshold Pth during the execution of cooling control and step S1 is not established, the timer t is reset in step S9 and the flag F is set to 0 in step S10 as an initialization process (termination process of cooling control) during the non-execution of cooling control. In the following step S11, the valve 18 is controlled to a closed state, thereby prohibiting the delivery of cooling air to the temperature-raising element, and the flow returns. Note that in this step S11, the operation of the cooling unit 15 may also be stopped. By stopping the operation of the cooling unit 15, unnecessary consumption of regenerative power is suppressed.

[0063] On the other hand, if step S1 is not false and variable value Q falls below second determination threshold Qth while cooling control is being performed, step S2 is false and the process proceeds to step S5. In step S5, it is determined whether flag F is 1. Here, flag F is set to 1 while cooling control is being performed. Therefore, if it is determined in step S5 that flag F is 1, a process of providing hysteresis to cooling control (the processes of steps S6 to S8) is performed.

[0064] More specifically, in step S6, it is determined whether the value of timer t is 0. If it is determined in step S6 that the value of timer t is 0, that is, that counting of timer t has not started, the process proceeds to step S7, where counting of timer t is started. Subsequently, in step S8, it is determined whether the value (time) of timer t is equal to or greater than a predetermined time T. If it is determined in step S8 immediately after counting of timer t is started that the value of timer t is not equal to or greater than the predetermined time T, the process proceeds to step S4, where cooling control is performed (continued), and this flow returns.

[0065] In the next calculation cycle, if the process proceeds to step S6 via the Yes route of step S1, the No route of step S2, and the Yes route of step S5, the timer t has already started counting, so step S7 is skipped. Then, in step S8, it is determined whether the value (time) of the timer t is equal to or greater than a predetermined time T. Thereafter, the processes of steps S1, S2, S5, S8, and S4 are repeated in order until the result of step S8 is established. As a result, the cooling control continues until the predetermined time T has elapsed, thereby ensuring sufficient cooling of the brake device 5, which has risen to a temperature at which fade occurs.

[0066] If it is determined in step S8 that the value of the timer t is equal to or greater than the predetermined time T, the cooling control is terminated by resetting the timer t (t=0) in step S9 and setting the flag F to 0 in step S10. In the following step S11, the valve 18 is controlled to a closed state, thereby prohibiting the delivery of cooling air to the temperature-raising element, and the flow returns. Note that in step S11, the operation of the cooling unit 15 may also be stopped.

[0067] [5. Effects] (1) The control device 1 described above is provided with a first determination unit 1A that makes a first determination, a second determination unit 1B that makes a second determination, and a control unit 1C that performs cooling control to drive the cooling device 6 with regenerative power to cool the brake device 5 when both the first determination and the second determination are true. The first determination determines whether the upper limit value P of the power that can be received by the battery 3 is equal to or less than a first determination threshold value Pth. The second determination determines whether a variable value Q related to the temperature of the brake device 5 is equal to or greater than a second determination threshold value Qth.

[0068] In this way, in the control device 1 described above, when performing cooling control, not only the upper limit value P of the battery 3 but also the variable value Q related to the temperature of the brake device 5 is taken into consideration. Therefore, according to the control device 1 described above, by performing cooling control, it is possible to suppress a decrease in regenerative braking force and the occurrence of fade in the brake device 5. In addition, by not performing cooling control when the temperature of the brake device 5 has not reached a temperature at which fade may occur, it is possible to suppress a decrease in frictional braking force due to overcooling of the brake device 5.

[0069] (2) When the duration FD is used as the variable Q, the second determination (i.e., determining whether or not there is a possibility of fade occurring) can be performed using a simple method. In addition, the fluid oil pressure R related to the calculation of the duration FD can also be detected by the brake system of a typical vehicle. Therefore, the second determination can be performed without providing any additional sensors for the second determination. (3) When the temperature of the temperature-raising element itself is used as the variable value Q, the second determination (that is, the determination of whether or not there is a possibility of fade occurring) can be made more appropriately.

[0070] (4) In the control device 1 described above, if the second determination becomes false after the start of cooling control, the cooling control continues to be performed until a predetermined time T has elapsed from the time the second determination becomes false. This prevents the second determination from becoming true again immediately after the second determination switches from true to false. Therefore, it is possible to suppress fluctuations in the execution and non-execution of cooling control.

[0071] (5) In the cooling control, when the brake device 5 is cooled intermittently, the reduction in the friction braking force due to the brake device 5 being overcooled can be further suppressed. (6) Furthermore, when the cooling on / off ratio C of the brake device 5 is set based on at least one of the weather, season, and time of day, it is possible to more appropriately suppress the decrease in friction braking force due to overcooling of the brake device 5.

[0072] [6. Other] The configurations of the control device 1 and the vehicle 2 described above are examples. Also, the control performed by the control device 1 described above is an example. For example, the calculation of the upper limit value P used in the first determination may take into account other information (values) indicating the state of the battery 3 in addition to the above-described SOC, battery temperature, and SOH. Also, the upper limit value P may be calculated based only on the SOC. The variable value Q used in the second determination may be any value that is positively correlated with at least the temperature of the brake device 5, and is not limited to the above-described duration FD or the temperature of the temperature-raising element.

[0073] When the duration FD is used as the variable value Q, the temperature sensor 23 may be omitted. When the fluid temperature FT is used as the variable value Q, the oil pressure sensor 22 may be omitted. The temperature of the heating element is not limited to the fluid temperature FT, but may also be the temperature of the pad 13 or the temperature of the rotor 14.

[0074] The cooling device 6 does not have to be an air conditioning device installed in a conventional vehicle. In other words, the vehicle 2 may be provided with a cooling device dedicated to cooling the brake device 5. The cooling device may be a device that cools at least the temperature-raising element. Furthermore, if control based on any one of weather, season, and time of day is not performed, the positioning device 24 and the wiper sensor 25 may be omitted. [Industrial Applicability]

[0075] The present invention is applicable to the manufacturing industry of vehicle control devices, and also applicable to the manufacturing industry of vehicles equipped with such control devices. [Explanation of symbols]

[0076] 1. Control device (vehicle control device) 1A First Judgment Department 1B Second judgment section 1C Control section 2 vehicles 3 Battery 4. Motor (motor device) 5 Brake system 6 Cooling device 13 Pads (elements) 14 rotor (element) 23 Temperature Sensor C Intermittent ratio FD duration FT Fluid temperature (element temperature) P Upper limit (upper limit of the battery's acceptable power) Pth first judgment threshold Q variable Qth Second judgment threshold R fluid oil pressure Rth Third decision threshold T predetermined time W wheels

Claims

1. A control device for a vehicle provided with a motor device that applies a regenerative braking force to a wheel by regenerative power generation, a brake device that applies a friction braking force to the wheel, and a battery that charges the electric power generated by the regenerative power generation, The vehicle is provided with a cooling device that cools the brake device, a first determination unit that performs a first determination as to whether an upper limit value of the power that can be received by the battery is equal to or less than a predetermined first determination threshold; a second determination unit that performs a second determination as to whether a variable value related to the temperature of the brake device is equal to or greater than a predetermined second determination threshold value; a control unit that, when both the first determination and the second determination are established, performs cooling control to drive the cooling device with electric power generated by the regenerative power generation and cool the brake device. A vehicle control device comprising:

2. The variable value is a duration of a state in which the hydraulic pressure of the fluid in the brake device is equal to or greater than a predetermined third determination threshold value.

2. The vehicle control device according to claim 1.

3. the vehicle is provided with a temperature sensor that detects the temperature of an element of the brake device that increases in temperature due to the application of the friction braking force to the wheel; The variable is the temperature of the element.

2. The vehicle control device according to claim 1.

4. When the second determination is not established after the start of the cooling control, the control unit continues the cooling control until a predetermined time has elapsed from the time when the second determination is not established.

4. The vehicle control device according to claim 1, wherein the vehicle control device is a control device for controlling a vehicle.

5. The control unit intermittently cools the brake device in the cooling control.

4. The vehicle control device according to claim 1, wherein the vehicle control device is a control device for controlling a vehicle.

6. The control unit sets an on / off ratio of cooling the brake device based on at least one of weather, season, and time period during which the vehicle is traveling.

6. The vehicle control device according to claim 5.

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