JP2014126157A - Control device of automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain an excessive load from being imposed on a driving system component by the occurrence of a phenomenon in which slip and grip are repeated, without causing an increase in the weight and cost of the driving system component.SOLUTION: It is determined whether or not a phenomenon of repetition of slip and grip of a drive wheel occurs during backward movement. When it is determined that the phenomenon occurs, a brake 15 serving as a fastened friction element is slid.

Description

  The present invention relates to a control device for an automatic transmission mounted on a vehicle. In particular, the present invention relates to a technique for preventing an excessive load from being applied to drive system components due to a phenomenon in which slip and grip are repeated during reverse travel.

  In vehicles where the center of gravity of the vehicle body is located in the front, for example, an FR-driven light truck with no load loaded, if the accelerator pedal is depressed to drive backwards, the vehicle will drive depending on the friction between the road surface and the drive wheels. A phenomenon may occur in which the wheel repeats slipping and gripping.

Japanese Utility Model Publication No. 7-42415

  When such a phenomenon occurs, a large load is applied to a drive system component such as a differential gear. Therefore, the strength of the drive system component must be increased in anticipation of the load. As a result, the weight and cost increase.

  Patent Document 1 discloses a control method for reducing driving force during reverse travel, but cannot cope with the phenomenon that the drive wheel repeats slipping and gripping during reverse travel as described above.

  The present invention was devised in view of such problems, and an excessive load is applied to the drive system parts due to the occurrence of the phenomenon of repeating slip and grip without increasing the weight and cost of the drive system parts. It is an object of the present invention to provide a control device for an automatic transmission that can suppress the above-described problem.

  The control device for an automatic transmission according to the present invention determines whether or not a phenomenon of repeating slip and grip occurs on the drive wheel during reverse travel, and determines that the phenomenon has occurred by the means. And a means for sliding the frictional elements that are fastened.

  According to the control device for an automatic transmission having such a configuration, when the phenomenon that the driving wheel repeats slipping and gripping occurs when the vehicle moves backward, the friction element in the engaged state shifts to the sliding state. The phenomenon converges quickly.

  According to the present invention, it is possible to prevent an excessive load from being applied to a drive system component due to the occurrence of a phenomenon of repeating slip and grip without increasing the weight and cost of the drive system component.

1 is a schematic view of an FR drive type vehicle equipped with an automatic transmission according to an embodiment of the present invention. It is a figure which shows the control system of the control apparatus of the automatic transmission which concerns on embodiment of this invention. It is a time chart which shows R signal, a driving wheel rotation speed, and an accelerator opening. It is the map which set the relationship between engine torque and brake pressure fall amount.

  Hereinafter, a control apparatus for an automatic transmission according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an FR drive type vehicle 1 equipped with a control device for an automatic transmission according to this embodiment. In FIG. 1, 2 is an internal combustion engine, 3 is an automatic transmission (hereinafter referred to as “transmission 3”), 4 is a propeller shaft, 5 is a differential gear, 6 is a rear wheel as a drive wheel, and 7 is an output of the differential gear 5. A drive shaft 8 for transmitting to the drive wheel 6 is a front wheel as a driven wheel. Although not shown in FIG. 1, an ECU (electronic control unit) that controls the entire drive system is also mounted on the vehicle 1.

  As the transmission 3, for example, a 4-speed AT for a FR vehicle, which is a well-known transmission that achieves forward 4th speed and reverse 1st speed by a combination of a planetary gear (not shown), a clutch and a brake, is applied.

  FIG. 2 is a diagram showing a control system in the present embodiment. The ECU 11 is composed mainly of a microcomputer, and receives signals from various sensors, performs calculations based on the input signals, information stored in advance and a program, and calculates the calculation. Depending on the result, command signals are output to various solenoid valves.

  As shown in FIG. 2, the ECU 11 receives an output signal of a rotation speed detection sensor 10 that detects the rotation speed of the transmission 3. The ECU 11 acquires the rotational speed of the drive wheel 6 from the output signal of the rotational speed detection sensor 10.

  Further, the ECU 11 receives an output signal of the shift position sensor 12 provided on the shift lever, and the ECU 11 determines the current shift range from the output signal. The shift lever can be moved to at least an R (reverse) position for moving the vehicle backward and a D (drive) position for moving the vehicle forward. The shift position sensor 12 has the shift lever at the R position. In some cases, an "R signal" is output to the ECU 11, and when the shift lever is in the D position, a "D signal" is output to the ECU 11.

  In FIG. 2, 16 is an oil pump driven by the engine 2. The hydraulic pressure discharged and supplied from the oil pump 16 is regulated to a line pressure by a regulator valve 17, and the hydraulic pressure of the transmission 3 is constituted by a number of valves such as a switching valve, a pressure regulating valve, and a solenoid valve. It is supplied to the circuit 9.

  The ECU 11 transmits an instruction current to a solenoid valve or the like in the hydraulic circuit 9 of the transmission 3 to supply an appropriate hydraulic pressure to each clutch and each brake, thereby individually setting the clutch to the engaged state or the released state. The required gear stage is formed. Reference numeral 15 denotes a brake (friction element), which is a friction element that is tightened by supplying hydraulic pressure when the reverse gear is formed.

  The ECU 11 determines from the rotational speed of the drive wheel 6 obtained from the output signal of the rotational speed detection sensor 10 whether or not a phenomenon of repeating slip and grip occurs in the drive wheel 6 during reverse travel. That is, as shown in FIG. 3, at time t0, when the driver switches the shift lever from the N and P ranges to the R range and the ECU 11 detects that the “R signal” is output from the shift position sensor 12, An FFT (Fast Fourier Transform) process is performed on the rotational speed change of the driving wheel 6 obtained based on the output signal of the number detection sensor 10 to perform frequency analysis of the rotational speed change of the driving wheel 6. If the frequency obtained above a certain level is a predetermined frequency, it is determined that a phenomenon occurs in which the driving wheel 6 repeats slipping and gripping. Note that, since the optimum value varies depending on the vehicle, the predetermined frequency is obtained by experiment or simulation for each vehicle. It is a well-known fact that the fluctuation frequency of the rotational speed of the drive wheel 6 becomes a predetermined frequency when the phenomenon of repeating slip and grip occurs on the drive wheel 6 during reverse travel.

  When the ECU 11 determines that the phenomenon that the drive wheel 6 repeats slipping and gripping occurs when the vehicle is moving backward, the ECU 11 transmits a command signal to a solenoid valve or the like in the hydraulic circuit 9 and brakes that are fastened friction elements. 15 is controlled to slide (decrease the torque transmission amount). The control for sliding the brake 15 is performed, for example, according to a map as shown in FIG. That is, the hydraulic pressure Pd of the brake 15 to be reduced is determined according to the engine torque, and the hydraulic pressure Pd is reduced from the engagement hydraulic pressure of the brake 15. When the brake 15 starts to slide, the phenomenon in which the driving wheel 6 repeats slipping and gripping quickly converges. In the example shown in FIG. 4, the hydraulic pressure Pd to be reduced is smaller as the engine torque is larger.

  As described above, according to the control apparatus for an automatic transmission according to the embodiment of the present invention, when the phenomenon that the driving wheel repeats slipping and gripping occurs when the vehicle moves backward, the ECU 11 slides the B2 brake 15. Therefore, the phenomenon converges quickly, and an excessive load is not applied to the drive system components such as the differential gear 5. As a result, the strength of the drive system component can be set low, and the weight and cost of the drive system component can be reduced.

  It is known that the phenomenon that the driving wheel repeats slipping and gripping is converged by forcibly reducing the output of the engine 2 by the ECU, but this technology uses an electronically controlled throttle in the vehicle. It is assumed that However, according to the control apparatus for an automatic transmission according to the embodiment of the present invention, the phenomenon that the driving wheel repeats slipping and gripping can be quickly converged regardless of whether or not an electronically controlled throttle is employed. Can do.

  In the above-described embodiment, the control for sliding the brake 15 is determined according to the map as shown in FIG. 4, but the control for sliding the brake 15 is not limited to this, and various methods are possible. Is feasible. For example, the ECU 11 may perform control such that an appropriate slip is obtained based on the differential rotation between the input side and the output side of the brake 15 of the transmission 3.

  The present invention can be applied to, for example, a control device for an automatic transmission mounted on an automobile.

3 Automatic transmission (automatic transmission)
5 Differential gear (drive system parts)
6 Driving wheel 9 Hydraulic circuit 10 Rotation speed detection sensor 11 ECU
12 Shift position sensor 15 Brake (friction element)

Claims (1)

  A determination means for determining whether or not a phenomenon of repeating slip and grip occurs on the drive wheel during reverse travel, and when it is determined that the phenomenon has occurred, the friction element that is fastened is slipped. And a control device for the automatic transmission.

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