Vehicle control system

Abstract

To provide a vehicle control device capable of improving responsiveness when switching from a non-power transmission range to a power transmission range while suppressing deterioration in fuel efficiency.SOLUTION: A vehicle 10 includes an automatic transmission 20 provided in a power transmission route PT between an engine 12, which is a drive source, and a pair of driving wheels 24, in which when a predetermined number of engagement devices CB for speed change of a plurality of engagement devices for speed change are brought into an engagement state in a power transmission range, a predetermined shift stage is selectively formed out of a plurality of shift stages. In a case where a part (a clutch C2 and a brake B2) of the predetermined number of engagement devices CB for speed change brought into the engagement state in the power transmission range is brought into the engagement state in an N range or a P range, an electronic control device 90 maintains the part in the engagement state if a rotational speed difference ΔNin(=|Nin-Ne|), which is a drag amount in the automatic transmission 20, is less than a speed difference determination value ΔNin_jdg, and, if not, returns it in a release state.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle including an automatic transmission provided in a power transmission path between a drive source and a pair of drive wheels, wherein a predetermined number of a plurality of shift engagement devices are engaged in a power transmission range to selectively form a predetermined gear stage from among a plurality of gear stages.

Background Art

[0002] A control device for a vehicle including an automatic transmission provided in a power transmission path between an engine and a pair of drive wheels, wherein a predetermined number of a plurality of shift engagement devices are engaged in a power transmission range to selectively form a predetermined gear stage from among a plurality of gear stages is known. For example, the one described in Patent Document 1 is such a device. In the vehicle described in Patent Document 1, the connection / disconnection state (engagement state or release state) of the shift engagement device is controlled according to a predetermined engagement operation table according to the shift range (power transmission range or non-power transmission range) of the automatic transmission. For example, in the case of a non-power transmission range, all the shift engagement devices are in the release state. On the other hand, in the case of a power transmission range, a predetermined number of the shift engagement devices are engaged so that a predetermined gear stage is selectively formed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in order to improve responsiveness when switching from a non-power transmission range to a power transmission range, such as during garage operation, it is conceivable that some of the predetermined number of transmission engagement devices that are engaged in the power transmission range are engaged even when the transmission is in a non-power transmission range. However, in such a configuration, if drag occurs within the automatic transmission for any reason, fuel efficiency may decrease.

[0005] The present invention was made against the above circumstances, and its objective is to provide a vehicle control device that suppresses the decrease in fuel consumption and improves responsiveness when switching from a non-power transmission range to a power transmission range. [Means for solving the problem]

[0006] The gist of the present invention is a control device for a vehicle comprising a drive source and an automatic transmission provided in a power transmission path between the drive source and a pair of drive wheels, wherein a predetermined number of a plurality of gear shifting engagement devices are engaged in a power transmission range, thereby selectively forming a predetermined gear from a plurality of gear steps, wherein in a non-power transmission range, when some of the predetermined number of gear shifting engagement devices that are engaged in the power transmission range are engaged, the control device maintains the engaged portion in the automatic transmission when the amount of drag within the automatic transmission is less than a predetermined determination value, and returns the portion to a disengaged state otherwise. [Effects of the Invention]

[0007] According to the vehicle control device of the present invention, in a non-power transmission range, when some of the predetermined number of transmission engagement devices that are engaged in the power transmission range are engaged, if the amount of drag within the automatic transmission is less than a predetermined determination value, the part is maintained in the engaged state; otherwise, the part is returned to the disengaged state. This ensures responsiveness when switching from a non-power transmission range to a power transmission range while suppressing the deterioration of fuel efficiency due to drag within the automatic transmission. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of a vehicle equipped with an electronic control device according to an embodiment of the present invention, wherein (a) is a basic diagram of the vehicle and a functional block diagram showing the main parts of the control functions for various controls in the vehicle, and (b) is an engagement operation table that explains the relationship between the gear shift operation of the automatic transmission and the combination of the engagement and disengagement states of the gear shift engagement device used therefor. [Figure 2] Figure 1 shows an example of a flowchart illustrating the control operation of the electronic control unit. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the embodiments, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily depicted accurately. [Examples]

[0010] Figure 1 is a schematic diagram of a vehicle 10 equipped with an electronic control device 90 according to an embodiment of the present invention, where (a) is a schematic diagram of the vehicle 10 and a functional block diagram showing the main parts of the control functions for various controls in the vehicle 10, and (b) is an engagement operation table that explains the relationship between the gear shift operation of the automatic transmission 20 and the combination of the engagement and disengagement states of the gear shift engagement device CB used therefor.

[0011] The vehicle 10 has a power transmission path PT between the engine 12, which is the drive source for driving, and a pair of drive wheels 24. In the power transmission path PT between the engine 12 and the vehicle, the components are arranged in order from the engine 12 side, in a case 16, including an engine connecting shaft 30, a torque converter 14, an input shaft 32, an automatic transmission 20, an output shaft 34, and a differential 22, as well as a pair of axles 36 connected to the differential 22. All of these components are well-known. A lock-up clutch LU is provided between the pump impeller and the turbine impeller of the torque converter 14. The vehicle 10 also includes a hydraulic control circuit 40, a shift lever 50, and an electronic control device 90.

[0012] Vehicle 10 has shift ranges, for example, P range, R range, N range, and D range. The shift lever 50 is an operator for operating to each of the following operating positions POSsh: "P", "R", "N", and "D". "P" is the operating position that sets the automatic transmission 20 to the P range (= a parking range that is set to neutral and in which the pair of drive wheels 24 are mechanically fixed so that they cannot rotate). "R" is the operating position that sets the automatic transmission 20 to the R range (= a range that enables vehicle 10 to move in reverse). "N" is the operating position that sets the automatic transmission 20 to the N range (= a range that is set to neutral). "D" is the operating position that sets the automatic transmission 20 to the D range (= a range that enables forward driving by executing the shift control of the automatic transmission 20). The R range and D range are "power transmission ranges" in which the automatic transmission 20 transmits power transmitted from the engine 12 to the pair of drive wheels 24. The P range and N range are "non-power transmission ranges" in which the automatic transmission 20 cuts off the power transmitted from the engine 12 to the pair of drive wheels 24.

[0013] The automatic transmission 20 is a planetary gear type multi-stage transmission that has, for example, a plurality of hydraulic friction engagement devices (hereinafter referred to as "shifting engagement devices CB") and performs so-called clutch-to-clutch shifting by changing the grip of any of the plurality of shifting engagement devices CB. In the automatic transmission 20, predetermined gears are formed according to the shift range and, for example, the accelerator opening θacc[%] or the vehicle speed V[km / h].

[0014] The gear shifting engagement device CB includes, for example, clutches C1-C4 and brakes B1-B2. In the engagement operation table shown in Figure 1(b), "○" indicates the engaged state, "blank" indicates the released state, and "△" indicates a state where both the engaged and released states are possible. In the D range and R range, the automatic transmission 20 selectively engages three of the multiple gear shifting engagement devices CB to form a predetermined gear from among 11 gears with different gear ratios γ (10 gears for the D range and 1 gear for the R range). The gear ratio γ is the ratio of the input shaft rotation speed Nin [rpm] to the output shaft rotation speed Nout [rpm] (= Nin / Nout). The input shaft rotation speed Nin is the rotation speed of the input shaft 32, and the output shaft rotation speed Nout is the rotation speed of the output shaft 34. These "three" that are selectively engaged correspond to the "determined number" in this invention. In D range, the gear ratio γ is largest for the lowest gear (1st gear), and the gear ratio γ decreases as the gears move towards the higher gears.

[0015] The hydraulic control circuit 40 uses, for example, the hydraulic fluid discharged by the oil pump 18 as the source pressure and supplies regulated hydraulic pressure to actuators that control the engagement and disengagement states of the lock-up clutch LU of the torque converter 14 and the transmission engagement device CB.

[0016] The electronic control unit 90 is composed of a so-called microcomputer, for example, equipped with a CPU, RAM, ROM, input / output interface, etc. The CPU performs various controls on the vehicle 10 by performing signal processing according to a program pre-stored in ROM while utilizing the temporary storage function of RAM. The electronic control unit 90 corresponds to the "control device" in the present invention.

[0017] Various signals etc. (e.g., engine rotational speed Ne [rpm] which is the rotational speed of engine 12, input shaft rotational speed Nin, output shaft rotational speed Nout corresponding to vehicle speed V, accelerator opening θacc, operation position POSsh, oil temperature THoil [°C] which is the temperature of the working oil, etc.) based on the detection values by various sensors etc. (e.g., engine rotational speed sensor 70, input shaft rotational speed sensor 72, output shaft rotational speed sensor 74, accelerator opening sensor 76, operation position sensor 78, oil temperature sensor 80, etc.) provided in vehicle 10 are respectively input into electronic control device 90.

[0018] Various command signals (e.g., engine control signal Se for controlling engine 12, LU control signal Slu for controlling the engagement and disengagement of lock-up clutch LU, and shift control signal Sat for controlling the shift of automatic transmission 20, etc.) are respectively output from electronic control device 90 to various devices (e.g., engine 12, hydraulic control circuit 40, etc.) provided in vehicle 10.

[0019] Electronic control device 90 functionally includes range determination unit 92, condition determination unit 94, drag determination unit 96, and engagement control unit 98.

[0020] Range determination unit 92 determines whether it is in N range or P range based on operation position POSsh.

[0021] Condition determination unit 94 determines whether a predetermined condition for executing the "partial engagement control" described later is satisfied regardless of the presence or absence of drag within automatic transmission 20. The predetermined condition is: (a) vehicle speed V is greater than or equal to vehicle speed determination value V_jdg; (b) accelerator opening θacc is greater than or equal to opening determination value θacc_jdg; (c) oil temperature THoil is less than oil temperature determination value THoil_jdg; (d) the difference between engine rotational speed Ne and target idle rotational speed Nidl_tgt (=|Ne - Nidl_tgt|) is greater than or equal to rotational speed determination value Ne_jdg. If any of (a) to (d) is satisfied, it is determined that the predetermined condition is satisfied.

[0022] Condition (a) is met when, for example, the vehicle is set to N range while driving, and the responsiveness (hereinafter referred to as "drivability") when switching from N range to D range takes precedence. The vehicle speed determination value V_jdg is a predetermined value (for example, a value near zero) that is experimentally or design-defined in advance to determine whether or not the vehicle is in motion. Condition (b) is met when it is assumed that the driver intends to drive the vehicle 10, and therefore drivability takes precedence. The opening degree determination value θacc_jdg is a predetermined value (for example, a value near zero) that is experimentally or design-defined in advance to determine whether or not the driver intends to drive the vehicle 10. Condition (c) is met when, compared to the case where it is not met, a longer time is required to switch the transmission engagement device CB from the disengaged state to the engaged state, and therefore drivability takes precedence. The oil temperature determination value THoil_jdg is a predetermined value, either experimentally or by design, used to determine whether the time required to switch the transmission engagement device CB from the disengaged state to the engaged state is outside the acceptable range and has a significant impact on the deterioration of drivability. When the oil temperature THoil is low, the viscosity of the hydraulic fluid increases, making it more likely that the time required to switch the transmission engagement device CB from the disengaged state to the engaged state will be outside the acceptable range. The fulfillment of predetermined condition (d) means that the operation of the engine 12, which is the drive source, is unstable, and the judgment by the drag determination unit 96, described later, becomes inaccurate. The rotational speed determination value Ne_jdg is a predetermined value (for example, a value near zero) that is either experimentally or by design, used to determine whether the operation of the engine 12 is unstable. Therefore, if any of the predetermined conditions (a) to (c) are met, partial engagement control is performed in order to prioritize drivability over fuel efficiency. If the predetermined condition (d) is met, the drag determination unit 96 will make an inaccurate determination, so partial engagement control is performed to prioritize drivability.

[0023] When the range determination unit 92 determines that it is in the N range or the P range and the condition determination unit 94 determines that a predetermined condition is not satisfied, the engagement control unit 98 executes partial engagement control. "Partial engagement control" is control in which, in a non-power transmission range, when switching to a power transmission range, a part of the three shift engagement devices CB that are to be in an engaged state is brought into an engaged state. In the present embodiment, for example, in the P range, it is control in which the clutch C2 and the brake B2, which are two of the three shift engagement devices CB that are in an engaged state in the first gear shift stage 1st of the D range or the R range, are brought into an engaged state. In partial engagement control, while maintaining the P range, two of the three shift engagement devices CB that are in an engaged state in the first gear shift stage 1st of the D range or the R range are brought into an engaged state in advance. As a result, compared with the case where partial engagement control is not executed, when switching from the P range to the D range or the R range, the three shift engagement devices CB are brought into an engaged state faster, so that drivability is improved.

[0024] When the engagement control unit 98 executes partial engagement control, the drag determination unit 96 determines whether the rotational speed difference ΔNin (=|Nin - Ne|) [rpm] is less than the speed difference determination value ΔNin_jdg. The speed difference determination value ΔNin_jdg is a predetermined value determined in advance experimentally or by design in order to determine whether drag within the automatic transmission 20 is within an allowable range. When there is no drag within the automatic transmission 20, the rotational speed difference ΔNin is determined by the difference between the rotational speed Np (=Ne) of the pump impeller and the rotational speed Nt (=Nin) of the turbine impeller. For example, the difference between the rotational speed Np and the rotational speed Nt when the lock-up clutch LU is in the released state is determined in advance by the performance of the torque converter 14. When there is drag within the automatic transmission 20, the rotational speed difference ΔNin becomes larger beyond the difference between the rotational speed Np and the rotational speed Nt determined in advance by the performance of the torque converter 14. Note that the "rotational speed difference ΔNin" and the "speed difference determination value ΔNin_jdg" respectively correspond to the "drag amount" and the "predetermined determination value" in the present invention.

[0025] If the engagement control unit 98 determines that the rotational speed difference ΔNin is less than the speed difference determination value ΔNin_jdg, the engagement control unit 98 maintains the engaged state of the clutch C2 and brake B2. If the engagement control unit 98 determines that the rotational speed difference ΔNin is greater than or equal to the speed difference determination value ΔNin_jdg, the engagement control unit 98 returns the clutch C2 and brake B2 from the engaged state to the released state.

[0026] Figure 2 is an example of a flowchart illustrating the control operation of the electronic control device 90 shown in Figure 1. The flowchart in Figure 2 is executed repeatedly.

[0027] First, in step S10 (steps omitted hereafter), it is determined whether the gear is in N range or P range. If the determination in S10 is YES, then in steps S20 to S50, it is sequentially determined whether predetermined conditions are met. If all of the determinations in S20 to S50 are NO, then in S60, partial engagement control is performed, and in S70, it is determined whether the rotational speed difference ΔNin is less than the speed difference determination value ΔNin_jdg. If any of the determinations in S20 to S50 is YES, then in S80, partial engagement control is performed. If the determination in S70 is YES, then in S90, the engagement state of clutch C2 and brake B2 is maintained. If the determination in S70 is NO, then in S100, clutch C2 and brake B2 are returned from the engaged state to the released state. If the determination in S10 is NO, then in S110, based on the engagement operation table, engagement and disengagement control of the gear shift engagement device CB is performed according to the shift range. After the execution of S80 to S110, all of these steps result in a return.

[0028] According to this embodiment, in the N range or P range, when two of the three transmission engagement devices CB, namely clutch C2 and brake B2, which are engaged in the first gear stage 1st of the D range or the R range, are engaged, if the rotational speed difference ΔNin is less than the speed difference determination value ΔNin_jdg, clutch C2 and brake B2 are maintained in the engaged state; otherwise, clutch C2 and brake B2 are returned to the released state. This ensures drivability while suppressing the deterioration of fuel efficiency due to drag within the automatic transmission 20.

[0029] The above-described examples are embodiments of the present invention, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art, without departing from its spirit.

[0030] In the above-described embodiment, the difference, such as the rotational speed difference ΔNin (=|Nin-Ne|), corresponds to the "amount of drag" in the present invention, but it is not limited to this. For example, the rotational speed ratio, such as |Nin / Ne|, may correspond to the "amount of drag" in the present invention. In this embodiment, the drag determination unit 96 determines whether |Nin / Ne| is less than a predetermined rotational speed ratio. For example, the predetermined rotational speed ratio is "1-ΔNin_jdg / Ne".

[0031] In the above-described embodiment, in "partial engagement control," two of the gear shift engagement device CB, the clutch C2 and the brake B2, were engaged, but this is not limited to this. For example, in an embodiment where only one of the gear shift engagement device CB, the clutch C2 or the brake B2, is engaged, this is also acceptable.

[0032] In the above embodiment, it was determined whether any of the predetermined conditions (a) to (d) that execute "partial engagement control" are met, regardless of whether or not there is drag within the automatic transmission 20, but it is not limited to this. For example, it is also possible to determine whether or not only some of the predetermined conditions (a) to (d) are met, or to determine whether or not all of the predetermined conditions (a) to (d) are met.

[0033] In the above-described embodiment, a torque converter 14 was provided between the engine 12, which is the drive source, and the automatic transmission 20, but the present invention is not limited to this. For example, the present invention is also applicable to an embodiment in which a starting clutch that disconnects and connects power transmission between the drive source and the automatic transmission 20 is provided instead of the torque converter 14.

[0034] For example, in an embodiment where a starting clutch is provided, if the starting clutch is engaged in the non-power transmission range, control substantially the same as in the above embodiment can be performed. Note that when the starting clutch is engaged, the input shaft rotational speed Nin is equal to the engine rotational speed Ne. Therefore, the method for determining whether or not the drag within the automatic transmission 20 is within the permissible range is different. For example, if the clutch C2 and brake B2 are engaged and there is drag, the determination is made by whether or not the rotational speed of the gears etc. rotated within the automatic transmission 20 is less than a predetermined rotational speed.

[0035] For example, in an embodiment where a starting clutch is provided, even when the starting clutch is disengaged in the non-power transmission range, control substantially the same as in the above embodiment can be performed, but the method for determining whether the drag within the automatic transmission 20 is within an acceptable range is different. For example, when the operating position POSsh is operated from "D" to "N" after the vehicle 10 has been brought from a driving state to a stopped state, the starting clutch is disengaged and the automatic transmission 20 is set to the N range. When the automatic transmission 20 is set to the N range, the gears and the like within the automatic transmission 20 maintain the rotation that it had when it was driving due to inertia. Therefore, when partial engagement control is performed, if the rate of decrease in the rotational speed of the gears and the like within the automatic transmission 20 (= amount of decrease in rotational speed per unit time) is smaller than a predetermined decrease determination value, it is determined that the drag within the automatic transmission 20 is within an acceptable range. [Explanation of Symbols]

[0036] 10: Vehicle, 12: Engine (drive source), 20: Automatic transmission, 24: Pair of drive wheels, 90: Electronic control unit (control device), CB: Transmission engagement device, PT: Power transmission path, ΔNin: Rotational speed difference (drag amount), ΔNin_jdg: Speed ​​difference judgment value (predetermined judgment value)

Claims

[Claim 1] A control device for a vehicle comprising a drive source and an automatic transmission provided in a power transmission path between the drive source and a pair of drive wheels, wherein a predetermined number of a plurality of gear shifting engagement devices are engaged in a power transmission range, thereby selectively forming a predetermined gear from a plurality of gear stages, In the non-power transmission range, when some of the predetermined number of gear shifting engagement devices that are engaged in the power transmission range are engaged, if the amount of drag within the automatic transmission is less than a predetermined determination value, the portion is maintained in the engaged state; otherwise, the portion is returned to the disengaged state. A vehicle control device characterized by the following features.

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