JP2014101097A - Vehicle mass estimation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle mass estimation device capable of improving estimation accuracy of a vehicle mass.SOLUTION: Braking ECU does not adopt, for computation of an estimation value of a vehicle mass, drive force F or front-rear direction acceleration A obtained in a braking period TB that includes a brake operation detection period TB1 and a given period TB2, where the former period (TB1) is from a temporal point (a third timing t3) when a brake pedal operation start is detected to a temporal point (a fifth timing t5) when a brake pedal operation end is detected, while the latter period (TB2) is from a temporal point (the fifth timing t5) when the brake operation detection period TB1 ends to a temporal point (a seventh timing t7) when a counter determination value Cnt_th elapses.

Description

  The present invention relates to a vehicle mass estimation device that estimates vehicle mass.

  As vehicle behavior control using the vehicle mass as one of input variables, control for suppressing rollover of the vehicle during turning is known. In particular, in a large vehicle such as a truck or a bus, the vehicle mass may greatly change due to a change in the cargo load amount or the number of passengers. Therefore, in order to appropriately perform the behavior control described above with such a vehicle, it is preferable to update the vehicle mass as appropriate.

  Patent Document 1 discloses an example of an apparatus that periodically updates the vehicle mass when the vehicle is traveling. In this device, the driving force and acceleration before the shift and the acceleration during the shift are acquired, and the estimated value of the vehicle mass is obtained by dividing the driving force before the shift by the value obtained by subtracting the acceleration during the shift from the acceleration before the shift. By calculating, the estimation error of the vehicle mass is reduced.

Japanese Patent Laid-Open No. 2002-13620

However, even in the above-described vehicle mass estimation device, the estimation accuracy of the vehicle mass is not sufficient.
The present invention has been made in view of such circumstances. The object is to provide a vehicle mass estimation device capable of improving the estimation accuracy of the vehicle mass.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
The vehicle mass estimation device is a mass calculation unit (30, S20) that calculates an estimated value (M) of a vehicle mass based on a driving force (F) transmitted to a vehicle wheel (10) and an acceleration (A) of the vehicle. Assuming that And the vehicle mass estimation apparatus is further provided with the monitoring part (30, S13) which monitors the operation condition of a brake operation member (21), and a mass calculating part (30, S20) is a monitoring part (30, S13). The brake operation detection period (TB1) from the time when the operation start of the brake operation member (21) is detected to the time when the operation end of the brake operation member (21) is detected, and the brake operation detection period (TB1) The driving force (F) and acceleration (A) acquired during the braking period (TB) including the predetermined period (TB2) from the time when the predetermined time (Cnt_th) elapses to the estimated value of the vehicle mass It was not adopted for the calculation of (M).

  The braking force applied to the wheel (10) may remain for a while even after the driver changes from the operating state in which the brake operating member (21) is operated to the non-operating state. This is because the response delay of the mechanism for applying the braking force to the wheel (10) is not a little with respect to the change in the brake operation amount by the driver. Therefore, in the above configuration, the brake operation detection period (TB1) from when the start of the brake operation by the driver is detected until the end of the brake operation is detected, and when the brake operation detection period (TB1) ends. And a predetermined period (TB2) from when the predetermined time (Cnt_th) elapses to a braking period (TB), and the driving force (F) and acceleration (A) acquired during this braking period (TB) The calculation of the estimated value (M) of the vehicle mass was not adopted. As a result, the estimated value (M) of the vehicle mass is calculated based on the driving force (F) and acceleration (A) acquired when it is not the braking period (TB). Can be improved.

  During the braking period (TB), the driving force (F) and the acceleration (A) may be acquired periodically or irregularly, or the driving force (F) and the acceleration (A) are not acquired. You may do it.

  In addition, when the monitoring unit (30, S13) detects that the operation amount of the brake operation member (21) is decreasing, the vehicle mass estimation device described above decreases the operation amount (ΔPmc). It is preferable to further include a setting unit (30, S17) that sets the predetermined time (Cnt_th) to a larger value as the speed increases.

  When the driver performs the brake operation to cancel the brake operation, the wheel (10) is actually applied to the decrease in the required braking force required by the driver (that is, the decrease in the operation amount of the brake operation member (21)). The delay of the actual braking force decrease increases as the operation amount decrease rate (ΔPmc) of the brake operation member (21) increases. Therefore, by setting the predetermined time (Cnt_th) to a larger value as the decrease rate (ΔPmc) of the operation amount of the brake operation member (21) is faster, the braking force on the wheel (10) still remains. The possibility that the estimated value (M) of the vehicle mass is calculated based on the acquired driving force (F) and acceleration (A) is further reduced. As a result, the estimation accuracy of the vehicle mass can be improved.

  By the way, the vehicle is connected to the master cylinder (22) that generates a hydraulic pressure corresponding to the operating state of the brake operating member (21), and is connected to the master cylinder (22) and corresponds to the hydraulic pressure generated inside. A braking device comprising a wheel cylinder (25) for applying a braking force to the wheel (10), and a hydraulic pressure sensor (SE3) for detecting a master pressure (Pmc) which is a hydraulic pressure in the master cylinder (22). 20) may be mounted. In this case, when the master pressure (Pmc) detected by the hydraulic pressure sensor (SE3) becomes less than the end determination hydraulic pressure (Pmc_th), the monitoring unit (30, S13) It is preferable to detect the end of the operation.

  In the above configuration, the master pressure (Pmc), which is the hydraulic pressure in the master cylinder (22) connected to the wheel cylinder (25), is detected based on the signal output from the hydraulic pressure sensor (SE3). When the master pressure (Pmc) becomes less than the end determination hydraulic pressure (Pmc_th), the end of the operation of the brake operation member (21) by the driver is detected. Thus, by monitoring the operation state of the brake operating member (21) using the master pressure (Pmc) highly related to the hydraulic pressure in the wheel cylinder (25), the wheel cylinder against the decrease in the master pressure (Pmc). (25) The driving force (F) and acceleration (A) acquired when the braking force on the wheel (10) still remains due to the delay in the response of the hydraulic pressure in (25) is the estimated value (M) of the vehicle mass. It is possible to further reduce the possibility of being adopted in the calculation.

The schematic block diagram which shows the vehicle by which ECU for brakes which is one Embodiment of a vehicle mass estimation apparatus is mounted. A map for setting the counter judgment value according to the decrease rate of the master pressure. The flowchart explaining the process routine which ECU for brakes performs in order to calculate the estimated value of vehicle mass. (A)-(e) is a timing chart which shows an example of the timing which acquires a driving force and acceleration at the time of vehicle travel.

Hereinafter, a vehicle equipped with a brake ECU, which is an embodiment of a vehicle mass estimation device, will be described with reference to the drawings.
As shown in FIG. 1, the vehicle is provided with a power transmission mechanism 12 that transmits driving force generated by the engine 11 to a plurality of (for example, four) wheels 10. The power transmission mechanism 12 includes a clutch 121, a transmission 122, and a differential gear 123 that are disposed along the power transmission path. The clutch 121 operates to permit or prohibit power transmission by the operation of a clutch pedal (not shown) by the driver. Further, the transmission 122 is set to a gear position according to the operation mode of a shift lever (not shown) by the driver.

  Further, the vehicle is provided with an engine ECU 14 (also referred to as an “engine electronic control device”) that controls the engine 11 based on the operation mode of the accelerator pedal 13 by the driver. The engine ECU 14 includes an accelerator opening sensor SE1 for detecting an operation amount of the accelerator pedal 13, that is, an accelerator opening, and a rotation speed detection sensor SE2 for detecting the rotation speed of the output shaft 124 of the transmission 122. And are electrically connected. Then, the engine ECU 14 calculates the accelerator opening based on the detection signal from the accelerator opening sensor SE1, and controls the engine 11 based on the calculated accelerator opening. Further, the engine ECU 14 calculates the rotational speed of the output shaft 124 of the transmission 122 based on the detection signal from the rotational speed detection sensor SE2, and calculates the driving force F transmitted to the wheels 10 based on the calculated rotational speed. To do.

  The vehicle is also equipped with a braking device 20 that applies a braking force to the wheels 10. The braking device 20 includes a hydraulic pressure generating device 23 and a brake actuator 24. The hydraulic pressure generating device 23 is provided with a master cylinder 22 that generates a hydraulic pressure corresponding to the operation amount when the driver operates a brake pedal 21 which is an example of a brake operation member. Is connected to a hydraulic pressure sensor SE3 for detecting the hydraulic pressure, that is, the master pressure Pmc.

  When the driver operates the brake pedal 21, a master pressure Pmc corresponding to the operation amount is generated in the master cylinder 22. Then, the brake fluid of the amount corresponding to the master pressure Pmc flows into the wheel cylinder 25 provided for each wheel 10 via the hydraulic pressure circuit (not shown) of the brake actuator 24, and the hydraulic pressure in the wheel cylinder 25 is increased. Get higher. Thereby, the braking force according to the hydraulic pressure in the corresponding wheel cylinder 25 is given to the wheel 10.

  The brake actuator 24 of the present embodiment is configured so that the braking force for each wheel 10 can be individually adjusted even when the driver does not operate the brake pedal 21. For example, the brake actuator 24 is used to supply a brake fluid into the wheel cylinder 25 and a differential pressure adjusting valve that generates a differential pressure between the hydraulic pressure in the master cylinder 22 and the hydraulic pressure in the wheel cylinder 25. And an electric pump. The brake actuator 24 is provided with various valves for individually adjusting the hydraulic pressure in each wheel cylinder 25.

  Further, the vehicle is provided with a brake ECU 30 (also referred to as “brake electronic control device”) that controls the brake actuator 24. In the present embodiment, the brake ECU 30 corresponds to a vehicle mass estimation device. The brake ECU 30 is electrically provided with a brake switch SW1 for detecting whether or not the driver operates the brake pedal 21, a hydraulic pressure sensor SE3, and a wheel speed sensor SE4 for detecting the wheel speed of the wheel 10. It is connected to the. The brake ECU 30 is electrically provided with a longitudinal acceleration sensor SE5 for detecting the longitudinal acceleration (vehicle acceleration) A of the vehicle and a lateral acceleration sensor SE6 for detecting the lateral acceleration of the vehicle. It is connected. Further, the brake ECU 30 can receive information about the driving force F from the engine ECU 14 via the bus 40. The brake ECU 30 appropriately controls the brake actuator 24 based on information detected by various switches and sensors, information received from the engine ECU 14, and the like.

  The brake ECU 30 of this embodiment estimates the vehicle mass based on the longitudinal acceleration A detected by the longitudinal acceleration sensor SE5 and the driving force F transmitted to the wheels 10 calculated by the engine ECU 14. The value M can be calculated. In the present embodiment, the “vehicle mass” is a concept including at least a mass of the vehicle itself, a mass of cargo loaded on the vehicle, and a mass based on a passenger on the vehicle.

  In calculating the estimated value M of the vehicle mass, if the longitudinal acceleration A and the driving force F detected and calculated when the braking force is applied to the wheel 10 are used, the calculation accuracy is lowered. Therefore, in order to increase the calculation accuracy of the estimated value M of the vehicle mass, the braking period in which the braking force is actually applied to the wheels 10 is specified, and the longitudinal acceleration A detected and calculated in this braking period and It is preferable not to employ the driving force F in the calculation of the estimated value M of the vehicle mass.

  Therefore, in the present embodiment, the master pressure Pmc detected by the hydraulic pressure sensor SE3 is monitored. Then, when the master pressure Pmc is lower than the predetermined hydraulic pressure Pmc_th (ie, the non-operation state), which is an example of the start determination hydraulic pressure, the master pressure Pmc is changed to a state higher than the predetermined hydraulic pressure Pmc_th (that is, the operation state). In addition, the start of operation of the brake pedal 21 is detected. Further, when the master pressure Pmc is less than the predetermined hydraulic pressure Pmc_th from the state where the master pressure Pmc is equal to or higher than the predetermined hydraulic pressure Pmc_th, which is an example of the end determination hydraulic pressure, the end of the operation of the brake pedal 21 is detected.

  By the way, the braking force with respect to the wheel 10 may remain for a while even when the brake pedal 21 changes from the operating state to the non-operating state. This is because the hydraulic pressure is transmitted from the master cylinder 22 to the wheel cylinder 25 by the brake fluid having viscosity, so that the hydraulic pressure in the wheel cylinder 25 is decreased relative to the decrease in the hydraulic pressure in the master cylinder 22. This is because a delay occurs.

  Therefore, in the present embodiment, the elapsed time is measured from the time when the brake operation detection period from the time when the brake pedal 21 changes from the non-operating state to the time when the brake pedal 21 changes from the operating state to the non-operating state ends. Is done. Then, a period of the brake operation detection period and a predetermined period from when the brake operation detection period ends to when the elapsed time reaches a predetermined time is applied to the wheel 10 by a brake operation by the driver. A braking period in which there is a high possibility that a braking force is actually applied. Then, the longitudinal acceleration A and the driving force F detected and calculated during the braking period are not employed in the calculation of the estimated value M of the vehicle mass.

  The predetermined time is set to a value corresponding to the response delay of the hydraulic pressure in the wheel cylinder 25 with respect to the decrease in the master pressure Pmc in the master cylinder 22. However, such a response delay varies somewhat depending on the brake operation mode by the driver. That is, when the operation amount of the brake pedal 21 is gradually reduced when the brake operation is canceled, the response delay of the hydraulic pressure in the wheel cylinder 25 with respect to the decrease in the master pressure Pmc is slight. On the other hand, when the operation amount of the brake pedal 21 when the brake operation is canceled is sharply reduced, the response delay of the hydraulic pressure in the wheel cylinder 25 with respect to the decrease in the master pressure Pmc is increased. Therefore, in the present embodiment, the predetermined time is variable according to the operation amount when the brake operation is canceled.

Next, a map for setting the counter determination value Cnt_th corresponding to the predetermined time will be described with reference to FIG.
The map shown in FIG. 2 shows the relationship between the master pressure decrease rate ΔPmc and the counter determination value Cnt_th. As shown in FIG. 2, the counter determination value Cnt_th is set to a larger value as the master pressure decrease rate ΔPmc increases.

  Next, a processing routine executed by the brake ECU 30 of this embodiment in order to calculate the estimated value M of the vehicle mass will be described with reference to the flowchart shown in FIG. This processing routine is a processing routine that is executed every predetermined cycle set in advance.

  As shown in FIG. 3, in this processing routine, the brake ECU 30 acquires the master pressure Pmc of the master cylinder 22 calculated based on the detection signal from the hydraulic pressure sensor SE3 (step S11). Subsequently, the brake ECU 30 acquires a master pressure decrease rate ΔPmc (step S12). For example, the decrease rate ΔPmc is obtained by dividing a deviation obtained by subtracting the master pressure Pmc (n) acquired in the current cycle from the master pressure Pmc (n−1) acquired in the previous cycle by the time corresponding to the cycle. Value.

  Then, the brake ECU 30 determines whether or not the master pressure Pmc acquired in step S11 is lower than a predetermined hydraulic pressure Pmc_th (step S13). In this regard, in the present embodiment, the brake ECU 30 also functions as a “monitoring unit” that monitors the operation state of the brake pedal 21 with the master pressure Pmc. When the master pressure Pmc is equal to or higher than the predetermined hydraulic pressure Pmc_th (step S13: NO), it can be determined that the driver is operating the brake. Therefore, the brake ECU 30 sets a flag FLG and a counter value Cnt described later to “0 (zero). ”) (Step S14). Thereafter, the brake ECU 30 ends this processing routine.

  On the other hand, when the master pressure Pmc is lower than the predetermined hydraulic pressure Pmc_th (step S13: YES), it can be determined that the brake pedal 21 is in a non-operating state, so the brake ECU 30 adds one counter value Cnt ( Step S15). That is, the counter value Cnt corresponds to the elapsed time from the time when the brake pedal 21 is changed from the operating state to the non-operating state.

  Subsequently, the brake ECU 30 determines whether or not the flag FLG is “0 (zero)” (step S16). When the flag FLG is “0 (zero)” (step S16: YES), the brake ECU 30 uses the map shown in FIG. 2 to set the counter determination value Cnt_th according to the decrease speed ΔPmc obtained in the previous step S12. A value is set (step S17). In this regard, in this embodiment, the brake ECU 30 sets the counter determination value Cnt_th to a larger value as the master pressure decrease rate ΔPmc increases as the operation amount of the brake pedal 21 decreases. Also works. Then, the brake ECU 30 substitutes “1”, which means that the counter determination value Cnt_th has been set, into the flag FLG (step S18), and the process proceeds to step S19 described later.

  On the other hand, if the flag FLG is 1 in the previous step S16 (step S16: NO), since the counter determination value Cnt_th has already been set, the brake ECU 30 performs the processes in steps S17 and S18. Without performing this process, the process proceeds to the next step S19.

  In step S19, the brake ECU 30 determines whether or not the counter value Cnt updated in step S15 exceeds the counter determination value Cnt_th set in step S17. When the counter value Cnt is equal to or smaller than the counter determination value Cnt_th (step S19: NO), the brake ECU 30 once ends this processing routine because the braking force may still be applied to the wheel 10. . On the other hand, when the counter value Cnt exceeds the counter determination value Cnt_th (step S19: YES), it can be determined that no braking force is applied to the wheel 10, so the brake ECU 30 determines the vehicle mass estimated value M. Arithmetic processing is performed (step S20). In this regard, in the present embodiment, the brake ECU 30 also functions as a “mass calculation unit” that calculates the estimated value M of the vehicle mass based on the driving force F transmitted to the wheels 10 and the longitudinal acceleration A of the vehicle. To do. Thereafter, the brake ECU 30 once ends this processing routine.

Next, an example of the calculation process of the estimated value M of the vehicle mass in step S20 will be described.
The brake ECU 30 acquires the driving force F1 (F) and the longitudinal acceleration A1 (A) of the vehicle when the clutch 121 is disconnected and the driving force from the engine 11 is not transmitted to the wheels 10. At this time, the relationship between the driving force F1 and the longitudinal acceleration A1 can be expressed by a known equation of motion “F1 = M · A1”.

  Further, the brake ECU 30 acquires the driving force F2 (F) and the vehicle longitudinal acceleration A2 (A) when the clutch 121 is connected and the driving force from the engine 11 is transmitted to the wheels 10. . At this time, the relationship between the driving force F2 and the longitudinal acceleration A2 can be expressed by a known equation of motion “F2 = M · A2”.

  When the driving force F1 and the longitudinal acceleration A1 during the disengagement of the clutch 121, the driving force F2 during the engagement of the clutch 121 and the longitudinal acceleration A2 of the vehicle are acquired, the brake ECU 30 obtains the following relational expression ( The estimated value M of the vehicle mass is calculated using Equation 2).

M = (F2-F1) / (A2-A1) (Formula 1)
Next, an example of the operation of the brake ECU 30 when the driver starts a brake operation while the vehicle is running and then cancels the brake operation will be described with reference to the timing chart shown in FIG. In FIG. 4A, the master pressure Pmc that is the brake fluid pressure of the master cylinder 22 is indicated by a solid line, and the hydraulic pressure in the wheel cylinder 25 is indicated by a two-dot chain line.

  As shown in FIGS. 4A and 4B, at the first timing t1, the master pressure Pmc is lower than the predetermined hydraulic pressure Pmc_th and the counter value Cnt updated every predetermined cycle is the counter at that time. It is larger than the determination value Cnt_th. In other words, it can be estimated that the braking force is not applied to the wheel 10 at the first timing t1.

  Then, when the driver starts operating the brake pedal 21 at the second timing t2, the master pressure Pmc of the master cylinder 22 increases. However, immediately after the start of the brake operation, since the master pressure Pmc is less than the predetermined hydraulic pressure Pmc_th, the start of the brake operation has not yet been detected.

  When the third timing t3 is reached, the master pressure Pmc of the master cylinder 22 becomes equal to or higher than the predetermined hydraulic pressure Pmc_th, so that the start of the brake operation is detected. That is, since the master pressure Pmc is equal to or higher than the predetermined hydraulic pressure Pmc_th from the third timing t3 to a fifth timing t5 described later, it can be said that the brake pedal 21 is in an operating state. The counter value Cnt is initialized to “0 (zero)” at the third timing t3.

  From the third timing t3 to the fifth timing t5, the master pressure Pmc of the master cylinder 22 increases due to the brake operation by the driver, and decreases after taking the maximum value.

  As shown in FIG. 4C, the clutch 121 is disengaged at a fourth timing t4 that is a timing between the third timing t3 and the fifth timing t5. Therefore, in the period from the fourth timing t4 to the eighth timing t8 when the clutch 121 is connected, the driving force from the engine 11 is not transmitted to the wheels 10, so the vehicle travels with inertia.

  As shown in FIG. 4A, at the fifth timing t5 when the master pressure Pmc of the master cylinder 22 is decreasing, the master pressure Pmc falls below the predetermined hydraulic pressure Pmc_th, and the driver operates the brake pedal 21. Termination is detected. That is, since the brake pedal 21 is changed from the operation state to the non-operation state at the fifth timing t5, in this embodiment, the period from the third timing t3 to the fifth timing t5 is set as the brake operation detection period TB1. The

  Then, as shown in FIG. 4B, at the fifth timing t5, the counter determination value Cnt_th is set according to the master pressure decrease rate ΔPmc obtained at this timing, and the counter value Cnt Addition is started.

  As indicated by a two-dot chain line in FIG. 4A, at the fifth timing t5, the response of the decrease in the hydraulic pressure in the wheel cylinder 25 to the decrease in the hydraulic pressure in the master cylinder 22 causes a delay in the wheel cylinder 25. The hydraulic pressure is higher than a predetermined hydraulic pressure Pmc_th. Therefore, braking force is still applied to the wheel 10. However, since the hydraulic pressure in the wheel cylinder 25 gradually decreases even after the fifth timing t5, the braking force on the wheel 10 decreases with time. Then, at the sixth timing t6 before the seventh timing t7 when the counter value Cnt exceeds the counter determination value Cnt_th, the hydraulic pressure in the wheel cylinder 25 becomes lower than the predetermined hydraulic pressure Pmc_th.

  When the seventh timing t7 is reached, the hydraulic pressure in the wheel cylinder 25 decreases to the same level as the master pressure Pmc, and no braking force is applied to the wheel 10. Further, at the seventh timing t7, since the counter value Cnt exceeds the counter determination value Cnt_th, execution of the calculation process of the estimated value M of the vehicle mass is permitted. That is, in the present embodiment, the period from the fifth timing t5 to the seventh timing t7 is the predetermined period TB2 in which the braking force for the wheel 10 may still be applied. A braking period TB is a period obtained by combining a brake operation detection period TB1 from the third timing t3 to the fifth timing t5 and a predetermined period TB2 from the fifth timing t5 to the seventh timing t7. . The driving force F and the longitudinal acceleration A calculated and detected during the braking period TB are not employed in the vehicle mass estimation calculation.

  Since the clutch 121 is disengaged at the seventh timing t7, the driving force F and the longitudinal acceleration A acquired at this timing are the driving force F1 and the longitudinal acceleration A1 when the clutch 121 is disengaged. Is done.

  Then, at the ninth timing t9 after the eighth timing t8 at which the clutch 121 is engaged, the driving force F and the longitudinal acceleration A are the driving force F (F1) acquired at the seventh timing t7. And it is larger than the longitudinal acceleration A (A1). The driving force F and the longitudinal acceleration A at this timing are set as the driving force F2 and the longitudinal acceleration A2 in the connected state of the clutch 121. Then, the estimated value M of the vehicle mass is calculated using the above relational expression (Expression 1).

  When calculating the estimated value M of the vehicle mass, if the difference between the longitudinal accelerations A1 and A2 is small and the acquired longitudinal accelerations A1 and A2 include a detection error, The estimated value M of the vehicle mass may be calculated with an error with respect to the vehicle mass. For this reason, it is more preferable that the driving force F2 and the longitudinal acceleration A2 are acquired after sufficiently increasing with respect to the driving force F1 and the longitudinal acceleration A1.

As described above, in the present embodiment, the following effects can be obtained.
(1) In this embodiment, the brake operation detection period TB1 from the time when the start of the brake operation by the driver is detected to the time when the end of the brake operation is detected and the time from when the brake operation detection period TB1 ends are predetermined. The predetermined period TB2 until the time (counter determination value Cnt_th) elapses is set as a braking period TB. The driving force F and the longitudinal acceleration A acquired during the braking period TB are not employed in the calculation of the estimated value M of the vehicle mass. As a result, the estimated value M of the vehicle mass is calculated based on the driving force F and the longitudinal acceleration A acquired during the braking period TB, so that the accuracy of estimating the vehicle mass can be improved. It becomes like this.

  (2) In the present embodiment, the counter determination value Cnt_th is set to a larger value as the operating speed of the brake pedal 21 decreases (the decreasing speed ΔPmc of the master pressure Pmc). This further reduces the possibility that the estimated value M of the vehicle mass is calculated based on the driving force F and the longitudinal acceleration A acquired when the braking force on the wheels 10 still remains. The estimation accuracy can be improved.

  (3) Further, when the brake operation is canceled, if the operation amount gradually decreases, the braking force is actually applied to the wheel 10 relatively early after the end of the brake operation is detected. Disappear. In the present embodiment, when the response delay of the hydraulic pressure in the wheel cylinder 25 with respect to the master pressure Pmc is small as described above, the calculation of the estimated value M of the vehicle mass is permitted immediately. Therefore, the estimated value M of the vehicle mass can be quickly calculated after the brake operation is completed.

  (4) In the present embodiment, when the master pressure Pmc in the master cylinder 22 is equal to or higher than the predetermined hydraulic pressure Pmc_th and the master pressure Pmc becomes lower than the predetermined hydraulic pressure Pmc_th, The end of operation is detected. In this way, by monitoring the operation state of the brake pedal 21 using the master pressure Pmc that is highly related to the hydraulic pressure in the wheel cylinder 25, the braking force on the wheel 10 due to a delay in the response of the hydraulic pressure in the wheel cylinder 25. The possibility that the estimated value M of the vehicle mass is calculated based on the driving force F and the longitudinal acceleration A acquired when the vehicle still remains can be further reduced.

The above embodiment may be changed to another embodiment as described below.
The vehicle braking device 20 may be configured to include a stroke sensor that can detect the depression amount of the brake pedal 21. In this case, the operating condition of the brake pedal 21 by the driver may be monitored based on the depression amount (stroke amount) detected by the stroke sensor. In this case, the counter determination value Cnt_th may be set to a larger value as the decrement speed of the depression amount is faster when the operation of the brake pedal 21 is canceled.

-The operation state of the brake pedal 21 by the driver may be monitored according to the on / off state of the brake switch SW1.
In addition, the end determination hydraulic pressure does not necessarily have the same value as the start determination hydraulic pressure. That is, the end determination hydraulic pressure may be a value smaller than the start determination hydraulic pressure.

  The counter determination value Cnt_th may be set according to a decrease rate ΔPmc at an arbitrary time point from when the master pressure Pmc becomes maximum until a predetermined time elapses. Further, the master pressure (hereinafter also referred to as “maximum master pressure”) when the master pressure Pmc is maximized by the brake operation by the driver, and the master pressure Pmc when the master pressure Pmc falls below the predetermined fluid pressure Pmc_th. The decrease speed ΔPmc may be obtained by dividing the hydraulic pressure difference by the elapsed time from when the maximum master pressure is detected until the master pressure Pmc falls below the predetermined hydraulic pressure Pmc_th. Then, the counter determination value Cnt_th may be set according to the decrease rate ΔPmc.

The counter determination value Cnt_th may be changed stepwise in accordance with the master pressure decrease rate ΔPmc.
The counter determination value Cnt_th may be a constant value regardless of the master pressure decrease rate ΔPmc. In this case, it is preferable to set the counter determination value Cnt_th based on the maximum value of the response delay of the hydraulic pressure in the wheel cylinder 25 with respect to the decrease in the master pressure Pmc assumed in the braking device 20.

  The vehicle may be an electric vehicle that includes a motor as a drive source, or may be a hybrid vehicle that includes an engine 11 and a motor as drive sources. Moreover, the vehicle provided with the other drive source may be sufficient.

  Here, some electric vehicles and hybrid vehicles can apply a regenerative braking force to the wheels 10. In such a vehicle, depending on whether or not the regenerative braking force is applied to the wheel 10 at the end of the brake operation by the driver, the length from the end point to the time when the braking force on the wheel 10 actually becomes zero. May change. Therefore, the counter determination value Cnt_th may be set according to the ratio between the regenerative braking force and the braking force due to the hydraulic pressure at the end of the braking operation by the driver.

The estimated value M of the vehicle mass may be calculated only from the driving force F and the longitudinal acceleration A when the clutch 121 is connected.
If the driving force F and the longitudinal acceleration A are used, the estimated value M of the vehicle mass can be calculated by an equation of motion considering air resistance, road resistance, road gradient, etc. that can act on the vehicle. Good.

  The calculation of the estimated value M of the vehicle mass may be performed by the engine ECU 14 or a dedicated ECU.

  DESCRIPTION OF SYMBOLS 10 ... Wheel, 14 ... ECU for engines as an example of vehicle mass estimation apparatus, 20 ... Brake device, 21 ... Brake pedal as an example of brake operation member, 22 ... Master cylinder, 25 ... Wheel cylinder, 30 ... Vehicle mass estimation Brake ECU (mass calculation unit, monitoring unit, and setting unit) as an example of the device, F: driving force, A: longitudinal acceleration, M: estimated value of vehicle mass, TB1: brake operation detection period, TB2: predetermined Period, TB: braking period, Cnt_th: counter determination value corresponding to a predetermined time, SE3: hydraulic pressure sensor, Pmc: master pressure, Pmc_th: predetermined hydraulic pressure (start determination hydraulic pressure and end determination hydraulic pressure), ΔPmc: decrease rate .

Claims (3)

Vehicle mass estimation including a mass calculation unit (30, S20) that calculates an estimated value (M) of the vehicle mass based on the driving force (F) transmitted to the vehicle wheel (10) and the acceleration (A) of the vehicle. In the device
A monitoring unit (30, S13) for monitoring the operating status of the brake operating member (21);
The mass calculation unit (30, S20) detects the end of operation of the brake operation member (21) from the time when the monitoring unit (30, S13) detects the start of operation of the brake operation member (21). Within the braking period (TB) including the brake operation detection period (TB1) up to the time and the predetermined period (TB2) from the time when the brake operation detection period (TB1) ends to the time when the predetermined time (Cnt_th) elapses The vehicle mass estimation device is characterized in that the driving force (F) and acceleration (A) acquired in the above are not adopted in the calculation of the estimated value (M) of the vehicle mass. When it is detected by the monitoring unit (30, S13) that the operation amount of the brake operation member (21) is decreasing, the faster the decrease amount (ΔPmc) of the operation amount, the faster the predetermined time ( The vehicle mass estimation apparatus according to claim 1, further comprising: a setting unit (30, S17) that sets Cnt_th to a large value. The vehicle has a master cylinder (22) that generates a hydraulic pressure according to the operation status of the brake operating member (21), and is connected to the master cylinder (22) and corresponds to the hydraulic pressure generated inside. A braking device comprising a wheel cylinder (25) for applying a braking force to the wheel (10), and a hydraulic pressure sensor (SE3) for detecting a master pressure (Pmc) which is a hydraulic pressure in the master cylinder (22). 20) is installed,
The monitoring unit (30, S13) operates the brake operation member (21) when a master pressure (Pmc) detected by the hydraulic pressure sensor (SE3) becomes less than an end determination hydraulic pressure (Pmc_th). The vehicle mass estimation apparatus according to claim 1 or 2, wherein the end is detected.