JP2014233157A - Road surface gradient estimation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate road surface gradient accurately in detail even if output variation occurs to a motor.SOLUTION: When calculating a road gradient θ on the basis of forward-reverse acceleration generated in a vehicle, in the vehicle at least including a motor that outputs drive force for traveling, a change amount ΔTm that is temporal change in motor torque Tm substantially affecting the forward-reverse acceleration is detected. In a case where the change amount ΔTm in the motor torque is equal to or more than a threshold ΔTc, variation in an input value of the forward-reverse acceleration used for calculating a road gradient θ is suppressed, and a road gradient θ is calculated on the basis of the input value with the variation suppressed.

Description

  The present invention relates to a road surface gradient estimation device for a vehicle that generates a travel driving force by at least an electric motor.

  Conventionally, the driving force generated by a vehicle is affected by the road gradient, and various technologies for controlling the driving force in consideration of the influence of the road gradient have been proposed for hybrid vehicles and electric vehicles that have been put into practical use in recent years. Has been. As a technique for increasing / decreasing the driving force in accordance with the road gradient, for example, in Japanese Unexamined Patent Application Publication No. 2009-290963 (hereinafter referred to as Patent Document 1), in a vehicle equipped with a drive motor for driving the vehicle, the road surface gradient is braked. A technology of a motor control device that estimates an uphill road, a downhill road, and a flat road based on the amount and an operation system response speed and determines a torque response of a drive motor according to a road gradient when the vehicle starts is disclosed.

JP 2009-290963 A

  By the way, in the electric vehicle disclosed in Patent Document 1 described above, the road surface gradient can only be roughly determined as an uphill road, a downhill road, and a flat road based on the brake depression amount and the operation system response speed. As a parameter, there is a problem that precise vehicle control such as driving force control cannot be performed. Further, in a hybrid vehicle having an engine and an electric motor, the value of the road surface gradient is often used as a threshold value for engine stop / restart conditions. However, the calculation of the road gradient is greatly influenced by the longitudinal acceleration of the vehicle. If the longitudinal acceleration of the vehicle fluctuates due to the output torque of the electric motor, a large error occurs in the detection of the road gradient. For this reason, for example, if it is erroneously determined that the road surface gradient is steep even though it is a flat road, there is a possibility that the engine is restarted and fuel consumption and riding comfort are deteriorated. Conversely, if it is erroneously determined that the road surface slope is a flat road despite the steep slope, the engine may be stopped and the driving force may be insufficient, causing the vehicle to slide down. There is also.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle road surface gradient estimation device capable of estimating the road surface gradient finely and accurately even if the output fluctuation of the electric motor occurs.

  A road surface gradient estimation device for a vehicle according to an aspect of the present invention calculates a road surface gradient by inputting an electric motor that outputs a driving force for traveling and a parameter generated in the vehicle by the driving force output by the electric motor. An apparatus for estimating a road surface gradient of a vehicle, comprising: a gradient calculating means; an output fluctuation detecting means for detecting temporal fluctuations in the output of the electric motor; and the above-mentioned in accordance with temporal fluctuations in the output of the electric motor. And fluctuation suppressing means for suppressing parameter fluctuations occurring in the vehicle and inputting the parameter to the road surface gradient calculating means.

  According to the vehicle road surface gradient estimation apparatus of the present invention, it is possible to estimate the road surface gradient finely and accurately even if the output fluctuation of the electric motor occurs.

1 is a system configuration diagram of a hybrid vehicle including a vehicle road surface gradient estimation device according to an embodiment of the present invention. It is a flowchart of the road surface gradient estimation which concerns on one Embodiment of this invention. FIG. 3 shows an example of a time chart of variation of each parameter relating to road surface slope estimation according to an embodiment of the present invention, FIG. 3A shows motor torque, FIG. 3B shows vehicle longitudinal acceleration, 3 (c) represents the calculated road gradient. It is explanatory drawing which shows an example of the time constant of the filter variably set according to the motor torque which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The power unit 1 of the hybrid vehicle provided with the vehicle road surface gradient estimation device according to the present embodiment is configured in, for example, a series / parallel system in which an engine 2 and an electric motor (hereinafter referred to as a motor) 3 are used together as a driving force source. The power unit 1 includes an automatic transmission 5 having a built-in motor 3 connected to the engine 2. The engine 2 is also provided with an integrated starter generator (ISG) 4 having a function as a starter and a function as a generator. Connected through.

  The automatic transmission 5 includes a torque converter 6 that is connected to the engine 2, and a continuously variable transmission (CVT) 8 as an automatic transmission is connected to the torque converter 6 via a forward / reverse switching device 7. Has been.

  The torque converter 6 includes a pump impeller 6a connected to the output shaft 2a of the engine 2 and a turbine runner 6b facing the pump impeller 6a. A hollow pump shaft 6c is connected to the pump impeller 6a, and a turbine shaft 6d connected to the turbine runner 6b is inserted into the pump shaft 6c.

  A drive sprocket 15 is attached to the pump shaft 6c of the torque converter 6 via a one-way clutch 15a. The driven sprocket 15 is connected to a driven sprocket 20 b attached to one end of a rotating shaft 20 a of the mechanical oil pump 20 via a chain 16. As a result, the mechanical oil pump (machine O / P) 20 is rotationally driven by the engine driving force input via the pump shaft 6c, and the generated hydraulic pressure is transmitted to the clutches of the automatic transmission 5 and the CVT 8 It can be supplied to the control valve unit (C / V) 21 for setting the gear ratio.

  Further, the turbine shaft 6d of the torque converter 6 is arranged coaxially with a primary shaft 9a of a CVT 8 described later, and a forward / reverse switching device 7 is interposed between the turbine shaft 6d and the primary shaft 9a. The forward / reverse switching device 7 includes, for example, a double pinion planetary gear train 7a, a forward clutch 7b, and a reverse brake 7c. The forward / reverse switching device 7 is in a neutral state when both the forward clutch 7b and the reverse brake 7c are in an open state, and disconnects between the turbine shaft 6d and the primary shaft 9a. Further, when only the forward clutch 7b is engaged, the forward / reverse switching device 7 rotates the turbine shaft 6d and the primary shaft 9a integrally via the planetary gear train 7a, and transmits power between the shafts 6d and 9a. On the other hand, when the forward clutch 7b is released and the reverse brake 7c is engaged, the forward / reverse switching device 7 reversely rotates the turbine shaft 6d and the primary shaft 9a via the planetary gear train 7a, and both shafts 6d, 9a. The power is transmitted with the power reversed.

  The CVT 8 has a primary shaft 9a connected to the forward / reverse switching device 7 and a secondary shaft 10a parallel to the primary shaft 9a. The primary pulley 9 and the secondary pulley 10 are respectively connected to the shafts 9a and 10a. It is worn. Further, a winding type driving force transmission member 11 made of a belt or a chain is wound around the pulleys 9 and 10. The CVT 8 can be arbitrarily set between the primary shaft 9a and the secondary shaft 10a by changing the winding radius of the driving force transmission member 11 with respect to the pulleys 9 and 10 (that is, by changing the pulley ratio). Thus, it is possible to transmit the driving force that has been shifted at a gear ratio of 1 to 5.

  The shaft end of the primary shaft 9a extends to the opposite side of the forward / reverse switching device 7 with the primary pulley 9 interposed therebetween, and the rotor shaft 3a of the motor 3 is directly connected to the shaft end of the primary shaft 9a. Has been. The motor 3 is connected to a battery (BATT) 23 constituting a main power source of the vehicle via an inverter (INV) 22. The inverter 22 converts DC power from the battery 23 into AC power and drives the motor 3. Further, at the time of regeneration or the like, the inverter 22 uses the motor 3 as a generator, converts AC power generated by the motor 3 into DC power, and charges the battery 23.

  Further, between the primary pulley 9 and the forward / reverse switching device 7, a drive sprocket 17 is attached to the middle of the primary shaft 9a via a one-way clutch 17a. The drive sprocket 17 is connected to a driven sprocket 20 c that is attached to the other end of the rotating shaft 20 a of the mechanical oil pump 20 via a chain 18. As a result, the mechanical oil pump (machine O / P) 20 is rotationally driven not only by the engine driving force but also by the motor driving force input via the primary shaft 9a, and the generated hydraulic pressure is supplied to the control valve unit 21. It is possible to supply.

  On the other hand, a drive shaft 24 is connected to the secondary shaft 10 a through a reduction gear train 25. A drive pinion 24 a is provided at the tip of the drive shaft 24, and the drive pinion 24 a is engaged with the final reduction gear 27. Here, an output clutch 26 is interposed between the reduction gear train 25 and the drive shaft 24 of the present embodiment. When the output clutch 26 is in the connected state, the secondary shaft 10a and the drive shaft 24 Power transmission between them is possible.

  The engine 2, the motor 3, the battery 23, and the control valve unit 21 are respectively an engine control unit (engine ECU) 31, a motor control unit (motor ECU) 32, a battery management unit (battery ECU) 33, and a transmission control unit (transmission ECU). ) 34.

  The control units such as the ECUs 31 to 34 described above and various sensors / switches 35 are connected to a central hybrid control unit (hybrid ECU) 30 that performs overall control of the entire system. Each of the ECUs 30 to 34 including the hybrid ECU 30 is configured to include various interfaces, peripheral devices, and the like centering on a microcomputer, and is connected to be capable of bidirectional communication via a communication line such as a CAN (Controller Area Network). Control information and sensing information related to the operating state of the controlled object are communicated with each other.

  When the functions of the ECUs 31 to 34 are outlined, the engine ECU 31 receives a control command from the hybrid ECU 30, and based on signals from sensors provided in the engine 2, the throttle opening, ignition timing, fuel injection amount, etc. Calculate the parameters. Then, the actuators are driven by the control signals of these parameters, and the operation state of the engine 2 is controlled so that the output of the engine 2 matches the control command value. Further, the hybrid ECU 30 calculates the required driving force from the driver's accelerator pedal depression amount, the road resistance such as the road surface gradient θ (estimated value described later), and other loads, and when the road surface gradient θ is small and close to a flat road When the driving force is low, a signal is output to the motor ECU 32 to output the driving force by the motor 3 alone. However, when the road surface gradient θ is steep or the required driving force is large, in addition to the motor 3, The engine 2 is restarted by outputting a signal, and the required driving force can be realized by the driving force of the engine 2 and the motor 3.

  The motor ECU 32 receives a control command from the hybrid ECU 30 and controls the motor 3 via the inverter 22. Based on information such as the rotation speed of the motor 3, voltage / current, and the like, A voltage command is output and the motor 3 is controlled so that the output of the motor 3 matches the control command value.

  The battery ECU 33 determines the battery state based on the remaining capacity indicated by the state of charge (SOC) of the battery 23, the input / output possible power amount indicated by the maximum input / output power in the battery 23, the degree of deterioration of the battery 23, and the like. It manages the control of cooling and charging of the battery 23 after grasping this battery state, detecting the abnormality, the protection operation at the time of detecting the abnormality, and the like.

  The transmission ECU 34 receives a control command from the hybrid ECU 30, determines the gear ratio of the CVT 8, and controls the gear ratio to an appropriate gear ratio according to the driving state. Further, for example, the transmission ECU 34 receives the control command from the hybrid ECU 30 and controls the forward clutch 7b, the reverse brake 7c, the output clutch 26, and the like to switch the traveling mode.

  Here, each traveling mode will be described below. Since the hybrid vehicle according to the present embodiment includes the engine 2 and the motor 3 as described above, the engine traveling mode in which the vehicle travels using only the driving force (engine torque) Te of the engine 2 and the driving force (motor torque) of the motor 3 are used. ) Motor travel modes that travel using only Tm and hybrid travel modes that travel using the driving force of the engine 2 and the driving force of the motor 3 are possible. In the present embodiment, as described above, when the road surface gradient θ is small and the road surface is flat or when the required driving force is low, the driving force is output only by the motor 3, but when the road surface gradient θ is large and steep If the required driving force is large, the engine 2 is restarted in addition to the motor 3, and the required driving force can be realized by the driving force of the engine 2 and the motor 3.

  Specifically, in the engine travel mode, the forward clutch 7b is engaged, the output clutch 26 is engaged, and the motor 3 is controlled so that unnecessary motor torque Tm is not applied from the motor 3, and the driving force of the engine 2 is controlled. Drive on.

  The hybrid travel mode can be realized by supplying electricity to the motor 3 from the battery 23 and adding the driving force of the motor 3 to the driving force of the engine 2 in the engaged state of the clutch. Further, by rotating the rotor 3a of the motor 3 with the driving force of the engine 2 in the engaged state of the clutch, it is possible to generate and charge with the driving force of the engine 2 even during traveling.

  On the other hand, the forward travel clutch 7b is disconnected, the output clutch 26 is engaged, and only the motor 3 is driven to travel, so that the motor travel mode can be realized. Further, in this clutch state, regeneration is performed by rotating the rotor 3a of the motor 3 during deceleration or the like.

  Further, by connecting the forward clutch 7b and disengaging the output clutch 26, the rotor 2a of the motor 3 is rotated by the engine 2 while the vehicle is stopped, so that power generation / charging can be performed with the driving force of the engine 2. Yes.

  As described above, in the hybrid vehicle of the present embodiment, the driving force is set and the engine 2 is started and stopped based on the road surface gradient θ estimated (calculated) by the hybrid ECU 30. The estimation of the road surface gradient θ will be described with reference to the flowchart of FIG.

  First, in step (hereinafter abbreviated as “S”) 101, the electric motor torque Tm of the motor 3 is read from the motor ECU 32.

Next, the process proceeds to S102, and a change amount ΔTm that is a temporal variation of the electric motor torque Tm is calculated by, for example, the following equation (1).
ΔTm = (Tmp−Tmc) / t (1)
Here, Tmp is the electric motor torque t seconds ago, and Tmc is the current electric motor torque, and can be obtained by the following equations (2) and (3), for example.
Tmp = ΣTm (−tj · Δt) / (k + 1): where Σ is j = 0 to j = k (2)
Tmc = ΣTm (−j · Δt) / (k + 1): where Σ is from j = 0 to j = k (3)
Here, Tm is an instantaneous value and Δt is a sampling time. The electric motor torque change amount ΔTm may be obtained as a difference between the maximum value and the minimum value of the peak values of a plurality of electric motor torques sampled within a predetermined time, for example.

  Next, the process proceeds to S103, where it is determined whether or not the change amount ΔTm of the electric motor torque is equal to or greater than a threshold value ΔTc (ΔTm ≧ ΔTc) set in advance through experiments, calculations, etc. If ΔTm ≧ ΔTc, the process proceeds to S104. The filter time constant T with respect to the input value of the longitudinal acceleration Axr obtained by differentiating the longitudinal acceleration Axs from the longitudinal acceleration sensor and the vehicle speed value from the wheel speed sensor used for the calculation of the road surface gradient θ is slow. Change to be. Specifically, when a first-order lag filter is used for these input values, the filter time constant T is changed to a larger value set in advance. For example, as shown in FIG. 4, the filter time constant T may be changed so that the response delay is delayed as the change amount ΔTm of the electric motor torque increases.

  In S103, if the change amount ΔTm of the electric motor torque is less than the threshold value ΔTc (ΔTm <ΔTc) set in advance by experiment, calculation, etc., it is determined that the fluctuation of the change amount ΔTm of the electric motor torque has converged. In S105, the filter time constant T is returned to the initial value.

  After setting the filter time constant T in S104 or S105, the process proceeds to S106, and the longitudinal accelerations Axs and Axr are input through the filter in which the filter time constant T is set.

Then, the process proceeds to S107, where, for example, the road surface gradient θ is calculated and output by the following equation (4) to exit the program.
θ = sin ⁻¹ ((Axs−Axr) / g) (4)
Here, g is a gravitational acceleration.

  As is clear from the above processing, the hybrid ECU 30 is configured to have the functions of a road surface gradient calculating means, an output fluctuation detecting means, and a fluctuation suppressing means.

  As described above, according to the embodiment of the present invention, when the road surface gradient θ is calculated based on the longitudinal acceleration generated in the vehicle in the vehicle having the electric motor 3 that outputs at least the driving force for traveling, the longitudinal acceleration is calculated. When a change amount ΔTm, which is a temporal variation of the electric motor torque Tm that greatly affects the electric motor torque, is detected and the change amount ΔTm of the electric motor torque is greater than or equal to the threshold value ΔTc, the input value of the longitudinal acceleration used for calculating the road surface gradient θ The fluctuation is suppressed, and the road surface gradient θ is calculated based on the input value in which the fluctuation is suppressed.

  For example, as shown in FIG. 3, when the electric motor torque Tm greatly fluctuates from time t1 as shown in FIG. 3A, the longitudinal acceleration Axs generated in the vehicle is also shown in FIG. 3B. , Detected with large fluctuations. For this reason, the value of the road surface gradient θ calculated using the fluctuating longitudinal acceleration Axs is as shown by the broken line in FIG. 3C, although the actual road surface gradient θ does not vary. The result will be fluctuating. If the driving force is set or the start / stop control of the engine 2 is performed with such a road surface gradient θ including an error, the driving force cannot be accurately set, and the road is flat. Nevertheless, if it is erroneously determined that the road surface gradient is steep, the engine 2 may be started, leading to deterioration in fuel consumption and ride comfort. On the other hand, if it is erroneously determined that the road surface gradient is a flat road despite the steep slope, the engine 2 is stopped and the driving force becomes insufficient, causing the vehicle to slide down. There is a fear. For this reason, when the change amount ΔTm of the electric motor torque is equal to or greater than the threshold value ΔTc (time t2 to t3 in the example of FIG. 3), the fluctuation of the input value of the longitudinal acceleration used for calculating the road surface gradient θ is suppressed, and the fluctuation By calculating the road surface gradient θ based on the suppressed input value (shown by the solid line in FIG. 3C), the road surface gradient θ is obtained with high accuracy, and the driving force is accurately set, and the engine 2 is started / stopped. To be able to Further, since the longitudinal acceleration generated in the vehicle is generated in the vehicle later than the value of the electric motor torque Tm, the fluctuation of the input value of the longitudinal acceleration is suppressed based on the change amount ΔTm of the electric motor torque. Thus, the road surface gradient θ can be obtained with good response and accuracy compared to a system that suppresses fluctuations in the longitudinal acceleration while observing the longitudinal acceleration values that have already occurred. Furthermore, since the road surface gradient θ can be calculated in detail using the longitudinal acceleration value, fine control based on the value of the road surface gradient θ is possible.

  Note that the configuration of the hybrid vehicle according to the present embodiment is merely an example, and may be the configuration of a hybrid vehicle with other configurations (such as a clutch and an automatic transmission). Needless to say, the present invention can be applied to an electric vehicle that generates a driving force only by an electric motor, without being limited to a hybrid vehicle that generates a driving force by an engine and an electric motor.

DESCRIPTION OF SYMBOLS 1 Power unit 2 Engine 3 Motor 4 Integrated starter generator 5 Automatic transmission 6 Torque converter 7 Forward / reverse switching device 7a Planetary gear train 7b Forward clutch 7c Reverse brake 8 CVT
DESCRIPTION OF SYMBOLS 9 Primary pulley 10 Secondary pulley 11 Driving force transmission member 21 Control valve unit 22 Inverter 23 Battery 24 Drive shaft 26 Output clutch 27 Final reduction device 30 Hybrid ECU (Road surface gradient calculation means, output fluctuation detection means, fluctuation suppression means)
31 Engine ECU
32 motor ECU
33 Battery ECU
34 Transmission ECU
35 Sensors and switches

Claims (4)

An apparatus for estimating a road surface gradient of a vehicle, comprising: an electric motor that outputs a driving force for traveling; and a road surface gradient calculating unit that calculates a road surface gradient by inputting a parameter generated in the vehicle by the driving force output by the electric motor. There,
Output fluctuation detection means for detecting temporal fluctuations in the output of the electric motor;
Fluctuation suppression means that suppresses fluctuations in parameters that occur in the vehicle in response to temporal fluctuations in the output of the electric motor and that is input to the road surface gradient calculation means;
An apparatus for estimating a road surface gradient of a vehicle.   The fluctuation suppressing means suppresses a fluctuation of a parameter generated in the vehicle and inputs it to the road surface slope calculating means when the temporal fluctuation of the output of the electric motor is equal to or greater than a preset threshold value. The road surface gradient estimation device for a vehicle according to claim 1.   The fluctuation suppressing means increases the parameter fluctuation generated in the vehicle as the temporal fluctuation of the output of the electric motor increases when the temporal fluctuation of the output of the electric motor is equal to or greater than a preset threshold value. 3. The road surface gradient estimating device for a vehicle according to claim 2, wherein the road surface gradient calculating device suppresses the input to the road surface gradient calculating means.   The vehicle road surface gradient estimation apparatus according to any one of claims 1 to 3, wherein the parameter generated in the vehicle is a longitudinal acceleration of the vehicle.

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