JP2949155B2 - Shift control device for automatic transmission for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to an improvement in a shift control device for an automatic transmission for a vehicle configured to increase an engine torque during a shift that is performed while an engine brake is acting.

[Conventional improvement]

A gear shift mechanism and a plurality of friction engagement devices are provided, and the engagement of the friction engagement devices is selectively switched by operating a hydraulic control device, so that any one of a plurality of shift speeds is achieved. An automatic transmission for a vehicle configured as described above is conventionally widely known. Conventionally, in a downshift when the throttle opening of such an automatic transmission is fully closed, a technique has been proposed in which the shift torque is reduced by increasing the output torque of the engine during shifting (Japanese Patent Laid-Open No. 58-1983). 77138).

[Problems to be solved by the invention]

However, Japanese Patent Application Laid-Open No. 58-77138 describes a technique when the drive range is fully closed, that is, when the one-way clutch is idling (when the engine brake is not acting). No specific technique is disclosed for increasing the engine torque during a downshift when the vehicle is operating. However, in the case of a so-called clutch-to-clutch shift in which one friction is achieved by the simultaneous operation of two friction engagement devices, the rotation member of the automatic transmission is subject to variations in the operation of both friction engagement devices. In order to prevent the vehicle from becoming rigid (unrotatable), a neutral state of the engine is temporarily established during the shifting. Therefore, in such a neutral state, if the engine torque is increased carelessly, the engine will blow up more than necessary,
Various problems arise. In the case of a downshift in a state in which the engine brake is applied, a clutch-to-clutch shift is very often performed. SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and has been made in consideration of a conventional automatic vehicular system configured to increase an engine torque during a clutch-to-clutch shift performed while an engine brake is applied. In a shift control device for a transmission, even if there is a period in which a neutral state occurs during the shift, the operation of the friction engagement device that operates during the shift can be quickly terminated, and the automatic transmission during the shift can be stopped. It is an object of the present invention to provide a shift control device for an automatic transmission for a vehicle that can reduce fluctuations in output torque.

[Means for achieving the object]

The present invention relates to a shift control device for an automatic transmission for a vehicle configured to increase an engine torque during a clutch-to-clutch shift performed while an engine brake is applied, wherein the automatic transmission is in a neutral state. Means for detecting whether the automatic transmission is in the inertia phase, means for increasing the engine torque when the automatic transmission is in the neutral state, and Means for further increasing the engine torque in the inertia phase state achieves the above object. Note that the inertia phase is a period in which the rotation member changes the rotation speed for shifting by engagement of a friction engagement device that engages during shifting.

[Action]

In the case where one shift is achieved by simultaneously engaging or disengaging two friction engagement devices (so-called clutch-to-clutch shift), a neutral state is formed during the shift. You. For example, in a case where two friction engagement devices are operated during one gear shift, and one rotating member in an automatic transmission,
If one of the friction engagement devices is a clutch that engages the engine and the rotating member, and the other friction engagement device is a brake between the housing of the automatic transmission and the rotating member, the shift is interrupted. Therefore, it is necessary to avoid that these two friction engagement devices are engaged together. This is because, when these two friction engagement devices are brought into the engaged state, the engine and the housing are connected. Therefore, in general, in a shift operation in which such two friction engagement devices are operated, even if there is a variation, at least the rotating member is generally prevented from forming a rigid (unrotatable) state. It is designed so that a neutral state is formed. In the shift of the automatic transmission, the gear ratio changes before and after the shift, so that the engine rotation speed is changed during the shift process. In a downshift during the operation of the engine brake, the engine speed increases during this shift process. In this shifting process, a torque is generated that resists an increase in the engine speed. In other words, in the present invention, the inertia torque is absorbed in the present invention by increasing the engine torque at the time of gear shifting, and the shift shock is reduced. However, when the automatic transmission is in the neutral state for the reason described above, the problem of occurrence of inertia torque of the engine due to the downshift does not occur. Accordingly, it is not necessary to increase the engine torque for canceling the inertia torque, but rather, various problems arise if the engine torque is inappropriately increased. For example, now
A case is considered where the engine rotation speed has increased to near the engine rotation speed after shifting due to an increase in engine torque. In this case, immediately after the shift, a state where the torque from the engine and the torque from the wheels are balanced, that is, a state where the engine brake is not effective at all is formed. The downshift in the engine braking state is generally performed manually when it is desired to change from a certain level of the engine braking state to a larger engine braking state. By passing)
It is not preferable that the engine brake is not effective. In view of the above, the present invention detects the start of the inertia phase, and increases the engine torque for absorbing the inertia torque by detecting the start of the inertia phase. As a result, the inertia torque can be effectively canceled without causing a problem caused by excessively increasing the engine torque in the neutral state, and the shift shock can be reduced. In the neutral state where the throttle is fully closed, the rotation speed of the engine drops to the idling rotation speed. The engine rotation speed must rise to a predetermined rotation speed at the end of the shift, so if the engine rotation speed is low during the neutral state, the shift time will be long as in the embodiment described later. The problem arises. In the present invention, even during such a neutral state, the engine torque is appropriately increased (less than during the inertia phase), so that it is effective in reducing the shift shock and shortening the shift time.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 shows an overall outline of an automatic transmission for a vehicle to which the present invention is applied. This automatic transmission has a torque converter 20 as a transmission unit thereof, a second transmission unit 40, three forward speeds,
And a first transmission section 60 of one reverse speed. The torque converter 20 includes a pump 21, a turbine 22,
It includes a stator 23 and a lock-up clutch 24. The pump 21 is connected to the crankshaft 10 of the engine 1, and the turbine 22 is connected to a carrier 41 of a planetary gear set in the second transmission section 40. In the second transmission section 40, a planetary pinion 42 rotatably supported by the carrier 41 meshes with a sun gear 43 and a ring gear 44. Also, sun gear
Between the 43 and the carrier 41, clutch C ₀ and has the one-way clutch F ₀ is provided, between the sun gear 43 and the housing H _U, brake B ₀ is provided. The first transmission unit 60 is provided with two front and rear rows of planetary gear units. This planetary gear device has a common sun gear 61, ring gear 62, 6
3. It consists of planetary pinions 64 and 65 and carriers 66 and 67. A ring gear 44 of the second transmission unit 40 is connected to the ring gear 62 via the clutch C _1. Also, the clutch C ₂ is provided between the ring gear 44 and sun gear 61. Further, the carrier 66 is connected to the ring gear 63, and the carrier 66 and the ring gear 63 are connected to an output shaft 70. On the other hand, it is provided with a brake B ₃ and the one-way clutch F ₂ is between the carrier 67 and the housing H _U, also, between the sun gear 61 and the housing H _U, via a one-way clutch F ₁ brake B ₂ is provided Te, further, between the sun gear 61 and the housing H _U, the brake B ₁ is provided. The automatic transmission includes a transmission unit as described above, and receives a signal from a throttle sensor 100 that detects a throttle opening reflecting a load state of the engine 1 and a vehicle speed sensor 102 that detects a vehicle speed. by the processing unit (ECT-ECU) 104, solenoid valves S ₁ to S ₄ of the hydraulic control circuit 106 is driven and controlled according to a preset shift pattern, as shown in FIG. 3 B portion, the clutch The combination of engagement of brakes and the like is performed to perform shift control. In FIG. 3, the circles indicate the engaged state. The electromagnetic solenoid valves S ₁ and S ₂ are connected to the first transmission unit 60.
The electromagnetic solenoid valve S ₃ controls the high-speed side and the low-speed side of the second transmission unit 40, and the electromagnetic solenoid valve S ₄ controls the lock-up clutch 24 of the torque converter 20. To do each. In FIG. 2, reference numeral 110 denotes a shift position sensor which detects the position of N, D, R, etc. operated by the driver, and 112 denotes a pattern select switch.
E (economic running), P (power running) and the like are selected. Reference numeral 116 denotes a foot brake, and 118 denotes a brake switch for detecting operation of a side brake switch. In this embodiment, in addition to these input signals, a speed sensor 12 for detecting the rotation speed of the sun gear 61 of the first transmission unit 60 is provided to the central processing unit (ECT-ECU) 104 in this embodiment.
Speed sensor 115 for detecting the signal of 0 and the engine speed
Are also input. In FIG. 2, reference numeral 105 denotes an engine computer (EFI-ECU), and the central processing unit (ECT-ECU) 104
Control of the increase or decrease of the engine torque in accordance with the signal of the torque control request SG1 from the controller. Reference numeral 114 denotes a water temperature sensor for detecting the temperature of cooling water of the engine, and reference numeral ISC denotes an idle speed control valve. This idle speed control valve ISC is an engine computer (EFI-EC
U) The engine torque is controlled by the control of 105. FIG. 4 is a flowchart showing a control flow performed by the central processing unit (ECT-ECU) 104. In this figure, from the fifth gear in the D range to the third gear in the third range with the engine brake applied.
A control flow at the time of a manual downshift operation to a gear is shown. The downshift, clutch C ₂ is released, the clutch of the brake B ₁ is engaged --to-- a clutch. In this shift, in order to prevent these tie-up of the clutch C ₂ and the brake B _1, are designed to neutral period is formed during shifting. The flag F in steps 202a to 202d is a flag for controlling the flow. Since the flag F is initially reset to 0, the process proceeds to step 204. In step 204, manually enter the fifth gear to the third gear.
It is determined whether or not a downshift operation to the speed position has been performed. If this determination is not made, the process proceeds to reset after executing another shift control in step 238. When there is the judgment issues a supply command drain command and the brake B ₁ of the clutch C ₂ proceeds to step 206. While supply command at step 206 the drain command and the brake B ₁ of the thus clutch C ₂ is output at the same time, the release action clutch C ₂ is as a friction engagement device that is faster than the engaging operation of the brake B ₁ the characteristics, first, the engagement of the brake B ₁ after release of the clutch C ₂ is completed and the start is initiated. As a result, during the release operation end clutch C ₂ and the start of the engaging operation brake B ₂ is the duration of the neutral state. In this embodiment, it provided two timers T ₁ and T _2, step
Immediately after the clutch C ₂ and drain and brake B ₁ apply command output at 206, the counting of these two timers is started,
It detects the start neutral state by timeout of the timer T _1, the time-up of the timer T ₂ to detect the end i.e. the inertia phase start of the brake B ₁ of the neutral state, further, the sun gear 61 of the first transmission portion 60 Rotation speed N _C2
, The end of the inertia phase is detected. Perform the time-up detection step 208 the aforementioned timer T _1, if the timer T ₁ times out, i.e., performs an increase in the previously obtained amount of the engine torque in step 210 because it is neutral state start. This torque increase is smaller than the torque increase in step 214 described later, as shown in FIG. On the other hand, if the timeout of the timer T ₁ is not detected in step 208, the process proceeds to reset the flag F to 1 in step 230. Step 212 In detecting a time-up of the aforementioned timer T _2, if the timeout of the timer T _2, i.e., since the inertia phase state start, in step 214, the amount determined engine torque previously in step 210 Only increase. On the other hand, if the timeout of the timer T ₂ is not detected at step 212, the flag F in step 232
To 2 and proceed to reset. As the increase in engine torque will be described later in the step 210 is for maintaining a predetermined rotational speed a rotational speed N _C2 of the sun gear 61 in the neutral state in order to shorten the speed change time. Also, the increase in the engine torque in step 214 is for reducing shift shock by inertia torque reduction during the inertia phase state of the brake B _1. FIG. 5 shows the first-stage engine torque increase amount during the neutral state period in the present embodiment;
FIG. 10 is a diagram showing a second-stage engine torque increase amount during an inertia phase state. These engine torque increase amounts are determined depending on the vehicle speed, and the relationship shown in FIG. 5 is represented by a map as a central processing unit (ECT-ECU).
It is stored in 104. Note that the determination of the torque increase amount is not limited to this. For example, the torque increase amount may be increased or decreased according to the type of shift. From step 216, the inertia phase end process of returning the increased engine torque by comparing the predetermined constant N _C2 'with the rotation speed N _C2 of the sun gear 61 of the first transmission unit 60 is started. The timing is detected, and if it is the start time of the inertia phase end processing, the inertia phase end processing is performed in step 218. Immediately after the start time of the inertia phase end processing is detected, assuming that the increase amount of the engine torque is ΔTe and the rotation speed of the sun gear 61 of the first transmission unit 60 is N _C2 ′, the speed is reduced according to the end of the inertia phase. The rotation speed N
By outputting the value obtained by multiplying _C2 by the coefficient ΔTe / N _C2 ′ as the engine torque increase amount, the engine torque can be reduced in synchronization with the deceleration of the rotation speed N _C2 .
That is, in step 218, the output of ΔTe / N _C2 ′ × N _C2 is performed. In step 220, by the rotational speed of the rotational speed N _C2 of the sun gear 61 of the first transmission unit 60 performs a determination whether it is substantially zero, the transmission is terminated from the fifth speed to the third speed stage It is determined whether or not it has been done. Here, if it is determined that the shift is completed, the flag F is set to 0 in step 222 and the process proceeds to reset. If it is determined that the shift is not completed, the flag F is set to 4 in step 236 and the process proceeds to reset. In this embodiment, as means for increasing the engine torque in steps 210 and 214 described above, the idle speed control valve ISC provided independently of the main throttle valve connected to the accelerator pedal as described above is used. Is controlled. However, instead of this it has been done in recent years,
The engine torque may be increased by means using a linkless throttle valve controlled by a motor having a relatively large capacity which is not directly linked to the accelerator pedal.
Since the linkless throttle valve is controlled by a motor having a relatively large capacity, the opening / closing speed is high, and the opening / closing control can be performed finely. FIG. 6 is a diagram showing a relationship among the output torque of the automatic transmission, the member rotational speed of the automatic transmission, the hydraulic pressure applied to the friction engagement device, and the change of the engine torque with respect to time. In FIG. 6, a manual shift operation from the fifth speed to the third speed is performed at a point a. From point d to point e is the duration of the neutral state to prevent the clutch C ₂ and the brake B ₁ and the tie-up in the shift from the fifth gear to the third speed stage. from point e to point g is a section of the inertia phase state of the brake B _1. As indicated by a chain line in the present embodiment, the torque-up of the engine torque is started at point c is a time-up time of the timer T _1, between the point d to the point f is a time-up time of the timer T ₂ (Almost during neutral state)
The engine torque is increased to almost zero and f
The engine torque is further increased to ΔTe from the point to the point f ′ at which the start time of the inertia phase end processing is detected. Thereafter, during the period from the point f ′ to the point g at the end of the shift, the engine torque is reduced to the first transmission portion 60.
Decrease of the rotational speed of the rotational speed N _C2 of the sun gear 61 of the synchronization is reduced from ΔTe by. C In the control method does not perform the engine torque up (solid line), the clutch C ₂ starts released in neutral state
Point since the neighborhood, that is, in a substantially neutral state, the rotational speed N _C2 of the sun gear 61 of the first transmission part 60 is caused to accelerated e
At the point, the rotation speed is increased to a rotation speed faster by the rotation speed difference ΔN than in the present embodiment indicated by the chain line. It takes time Δt to recover the rotation speed difference ΔN. Since the rotational speed N _C2 of the sun gear 61 becomes zero at the end of the downshift from the fifth speed to the third speed, the speed increase ΔN at the point e and the delay of the return of this speed increase The time Δt extends the shift time accordingly. On the other hand, since the engine torque between the point c in this example (dashed line) to the point f is the torque up to approximately 0 at the, accelerated line speed N _C2 of the sun gear 61 in the neutral sections hardly shifted before Is maintained, and at the point e, the difference between the rotation speeds is Δ Δ as compared with the case where the engine torque is not increased in the neutral state.
N can be kept low. Thus, engagement of the brake B ₁ represents, compared with the case of not increasing the engine torque at the time of neutral towards the case of the present embodiment is rapidly completed (h point → g point). In this embodiment (dashed line), the brake starting from point e
Upon engagement of the B _1, for further engine torque as compared with the duration of the neutral state is increased, the aforementioned inertia torque acting on the brake B ₁ represents is reduced. As a result, the so engagement of the brake B ₁ is carried out immediately, reduces the amount hydraulic pressure according to the brake B _1. By doing so, it is possible to further reduce shift shock during shifting. In this embodiment, at the end of engagement of the brake B _1, an engine torque increases during shifting is reduced according to the deceleration of the line speed N _C2 of the sun gear 61, the final engine torque of the sun gear 61 to the state before the shift Returned in synchronization with rotation. This is because, even if all gear shifts are completed, if the torque of the engine torque decreases faster than the stop of the rotation of the sun gear, the output torque of the automatic transmission changes at the end of the gear shift as shown by the dotted line in FIG. In the case where the decrease in the engine torque is slower than the stop of the rotation of the sun gear 61 at the end of all shifts, the one-dot chain line in FIG. This is because the output shaft torque temporarily increases as shown in FIG.

【The invention's effect】

As described above, according to the present invention, the operation of the friction engagement device can be quickly terminated, and the fluctuation of the output shaft torque of the automatic transmission during the gear shift can be greatly reduced. Thereby, it is possible to obtain an excellent effect that the shift shock is reduced, the shift time is shortened, and the durability of the friction engagement device used in the automatic transmission can be improved. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the gist of the present invention, FIG. 2 is an overall skeleton diagram of a shift control device of an automatic transmission to which an embodiment of the present invention is applied, and FIG. FIG. 4 is a flowchart showing a control flow of the shift control device, FIG. 5 is a flowchart showing an engine torque increase amount in the shift control device, FIG. FIG. 6 is a graph showing the relationship between the output torque of the automatic transmission, the member rotational speed of the automatic transmission, the hydraulic pressure applied to the friction engagement device, and the change of the engine torque with respect to time. 1 ... engine, 40 ... second transmission unit, 60 ... first transmission unit, 61 ... sun gear, 104 ... electronic control type automatic transmission electronic control unit (ECT-EC
U), 105 …… Electronic control fuel injection system Electronic control unit (EFI-EC)
U), 110: Shift position sensor, 120: N _C2 rotation speed sensor, C _2: Clutch, B _1: Brake, SG1: Torque control request, ISC: Idle speed control valve, T _1: Timer (for detecting neutral state start), T ₂ …… Timer (for detecting inertia phase start), ΔTe …… Engine torque increase during inertia phase, N _C2 …… Rotation speed of sun gear 61, N _C2 ′ …… Inertia The rotation speed value of the sun gear 61 for determining the phase end processing start time.

Claims (1)

(57) [Claims] 1. A shift control device for a vehicle automatic transmission configured to increase an engine torque during a clutch-to-clutch shift performed while an engine brake is applied. Means for detecting whether the automatic transmission is in the state, means for detecting whether the automatic transmission is in the inertia phase, means for increasing the engine torque when the automatic transmission is in the neutral state, and automatic transmission. Means for further increasing the engine torque when is in the inertia phase. A shift control device for an automatic transmission for a vehicle, comprising: