JPH0531706B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention provides that when a shift lever is operated from a neutral range to a forward range, the gear of a gear mechanism is first changed to a gear higher than the lowest speed gear, and then the gear is changed to the lowest speed. The present invention relates to a switching shock prevention device for preventing a shock caused by switching from an upper gear to a lowest gear in a type of automatic transmission for a vehicle. Prior Art A gear mechanism that can switch between multiple gears, and a control device that automatically switches the gears of the gear mechanism according to vehicle conditions such as the operating position of the shift lever, the amount of accelerator operation, and the speed of the vehicle. In order to prevent the vehicle from being shocked by the sudden transmission of torque when the shift lever is operated from the neutral range to the forward range, the gears of the gear mechanism are first set to higher than the lowest gear. 2. Description of the Related Art A type of automatic transmission for a vehicle is known in which the gear is shifted to the lowest gear and then the lowest gear. The automatic transmission is switched from the upper gear to the lowest gear when the vehicle speed or accelerator pedal operation amount exceeds a predetermined value, or when the shift lever is moved to the forward range. This is generally carried out after a certain predetermined period of time has elapsed. However, with such conventional automatic transmissions, the shock of the vehicle due to the rapid change in driving force when switching from the upper gear to the lowest gear is affected by vehicle conditions such as the amount of accelerator pedal operation and vehicle speed. This problem sometimes occurs due to this, and this causes extreme discomfort to the tower occupants. Purpose of the Invention The present invention has been made against the background of the above circumstances, and its purpose is to first shift the gear stage of the gear mechanism to the lowest speed when the shift lever is operated from the neutral range to the forward range. A switching shock prevention device that prevents a shock caused by switching from the upper gear to the lowest gear in a type of automatic vehicle transmission that switches to a gear higher than the gear and then to the lowest gear. The goal is to provide equipment. Composition of the Invention In order to achieve the above object, the switching shock prevention device of the present invention is provided in the automatic transmission for a vehicle, and includes: (1) rotation speed detection means for detecting the engine rotation speed of the vehicle; and (2) the automatic transmission. (3) determining means for determining whether the engine rotational speed or the amount of reduction thereof has reached a predetermined constant value when the gear mechanism of the machine is switched to an upper gear; and switching means for switching the gear stage of the gear mechanism to the lowest speed gear stage based on the transmission speed. Effects of the Invention With this structure, as shown in the claim correspondence diagram of FIG. It is determined that the amount of reduction has reached a predetermined constant value, and the switching means further switches from the upper gear to the lowest gear based on this determination. In other words, the engine speed value or the amount of reduction thereof after the shift lever is operated from the neutral range to the forward range corresponds to the engagement state of the upper gear. Then, a shift to the lowest speed gear is performed. Therefore, regardless of vehicle conditions such as vehicle speed, accelerator operation amount, and time elapsed since the shift lever was operated from the neutral range to the forward range, the gear mechanism changes to the upper gear. Following the change in transmission torque, the change in transmission torque accompanying the change from the upper gear to the lowest gear is performed continuously and smoothly, and the change in transmission torque from the upper gear to the lowest gear is performed continuously and smoothly. Most of the unpleasant shocks caused by this are eliminated. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below based on the drawings. Configuration of the Embodiment FIG. 2 shows the transmission outline of an electronically controlled automatic transmission equipped with a lockup device and an overdrive device.
The driving force input to the torque converter 12 or the lock-up clutch 14 provided in the torque converter 12 and the overdrive mechanism 1
6. The power is transmitted to the output shaft 20 through a planetary gear transmission 18, which is a gear mechanism with three forward speeds and one reverse speed. The torque converter 12 includes a pump 22 that rotates together with the input shaft 10, and a turbine shaft 2 that transmits driving force to the overdrive mechanism 16.
4 and a stator 28 fixed via a one-way clutch. The turbine shaft 24 forms the input shaft of the overdrive mechanism 16, and the carrier 30 of the planetary gear system in the overdrive mechanism 16
is connected to. The planetary pinion 32 is rotatably supported by the carrier 30 and is connected to the sun gear 34.
and is meshed with the ring gear 36. There is a clutch C0 between the sun gear 34 and the carrier 30.
and one-way clutch N0 are provided, respectively, and a brake B0 is provided between the sun gear 34 and the housing 38 of the overdrive mechanism 16. The ring gear 36 of the overdrive mechanism 16 is fixed to an input shaft 40 of the planetary gear transmission 18, and a clutch C1 is provided between the input shaft 40 and the intermediate shaft 42. A clutch C2 is provided between the input shaft 40 and the sleeve shaft 44 fitted on the intermediate shaft 42, and the sleeve shaft 4
A brake B1, a brake B2 and a one-way clutch N1 are provided between the transmission housing 45 and the transmission housing 45. Sun gears 46 and 48 fixed to sleeve shaft 44 connect to ring gears 54 and 5 via planetary pinions 50 and 52, respectively.
6, forming two planetary gear sets. One ring gear 56 is connected to the intermediate shaft 4
A carrier 58, which is fixed to the output shaft 20 and rotatably supports the planetary pinion 52, is connected to the output shaft 20 and the other ring gear 54. A brake B3 and a one-way clutch N2 are provided between the transmission housing 45 and the carrier 60, which rotatably supports the other planetary pinion 50. The above clutches C0, C1, C as friction devices
2, and brakes B0, B1, B2, and B3 are hydraulic actuators C0y, C1y, C2y, and B0 respectively operated by hydraulic circuits described below.
y, B1y, B2y, and B3y, and the planetary gear transmission 1
When predetermined elements 8 are braked or engaged with each other, the gear position of the planetary gear transmission 18 is changed as shown in FIG. However, in the table, the circle mark indicates the operating state. Further, C2y' in FIG. 3 is a hydraulic actuator for operating the inner piston of clutch C2, and is operated in the R range.

[Table] Next, the above hydraulic actuators C0y, C1
An example of a hydraulic circuit that supplies hydraulic pressure to Y, C2y, B0y, B1y, B2y, and B3y to operate them will be described. In FIG. 3, the hydraulic circuit includes an oil pump 66 that pumps oil in an oil reservoir 64, a throttle valve 67,
First regulator valve 68, second regulator valve 7
0, control valve 72 operated by a shift lever (not shown), 1-2 shift valve 74, 2-3 shift valve 76, 3-4 shift valve 78, and adjusting the supply of hydraulic pressure to hydraulic actuator B3y. Low coast modulator valve 80, hydraulic actuator B
Intermediate coast modulator valve 82, reverse clutch sequence valve 84, and clutches C1 and C, which adjust the supply of hydraulic pressure to C1y.
Accumulators 86, 8 for smooth engagement between the two
8. Accumulator 90 for smooth engagement of brake B2, lock-up control valve 92 for operating lock-up clutch 14, cut-back valve 94 for reducing line oil pressure in accordance with increase in vehicle speed, shift control circuit to be described later. solenoid valve MV1 that controls the 2-3 shift valve 76, solenoid valve MV2 that controls the 1-2 shift valve 74 and 3-4 shift valve 78, and solenoid valve MV that controls the lock-up control valve 92.
3. Consists of passages connecting each valve and hydraulic actuator. The hydraulic oil pumped from the oil pump 66 is transferred to a predetermined line oil (liquid) by the first regulator valve 68.
The operating valves 72 and 3
-4 shift valve 78, accumulator 86, 88,
90 and to the second regulator valve 70 via passage 104. The second regulator valve 70 regulates predetermined torque converter oil pressure and oil slide oil pressure in accordance with the throttle pressure signal and line oil pressure supplied from the throttle valve 67. The lock-up control valve 92 is biased in one direction by a spring, and includes a spool on one end surface of which is applied hydraulic pressure to the hydraulic actuator B2y and the other end surface of which is applied line hydraulic pressure by a solenoid valve MV3. By moving the spool by solenoid valve MV3, the flow direction of torque converter oil supplied from lockup control valve 92 to torque converter 12 via passages 106 and 108 is changed, and the lockup in torque converter 12 is changed. Clutch 14 is adapted to be actuated. The operation valve 72 is connected to a shift lever (not shown), and depending on the manual operation of the shift lever, the control valve 72 is shifted to each range of P (parking), R (reverse), N (neutral), D (drive), S, and L (low). be moved. The table shows the passage 102 and passages 110, 112, 114, 116 at each range position of the operating valve 72.
Indicates the communication status with. Note that the circle mark indicates a state of communication.

[Table] When the solenoid valve MV1 is not energized, its valve hole is closed and the hydraulic pressure in the passage 114 is applied to the spool of the 2-3 shift valve 76, and the spool is moved against the biasing force of the spring to shift the 2-3 shift valve 76. 3
Activate shift valve 76. Similarly, when the solenoid valve MV2 is de-energized, its valve hole is closed and the passage 11
4 is applied to the spools of the 1-2 shift valve 74 and 3-4 shift valve 78, and the spools are moved against the spring to shift the 1-2 shift valve 7.
4 and 3-4 shift valves 78 are activated. According to the combination of operations of the solenoid valves MV1, MV2, the aforementioned actuators C0y, C1y, C2
y, B0y, B1y, B2y, and B3y are selectively operated so that the gears of the automatic transmission are switched to first gear (lowest speed) gear, second gear, third gear, and overdrive gear. It's getting old. The throttle valve 67 includes a first spool 118 that is moved according to the amount of operation of the accelerator pedal;
A second spool 120 receives a biasing force corresponding to the movement of the first spool 118 via a spring and is biased toward the first spool 118 by another spring, and the accelerator is approximately proportional to the amount of accelerator operation. A signal oil pressure is supplied to the first regulator valve 68 and the second regulator valve 70 via the passage 122, and the line oil pressure and torque converter oil pressure output from the regulator valves 68, 70 are increased in accordance with the accelerator operation amount. . That is,
The throttle pressure signal output from the throttle valve 67 is increased according to the accelerator operation amount, and the
The line oil pressure output from the regulator valve 68 is increased in accordance with the throttle pressure signal, in other words, the amount of Arcel operation. The cutback valve 94 includes a spool 124 biased in one direction by a spring 123, and the spool 124 is connected to the line when the solenoid valve MV2 is energized and the 1-2 shift valve 74 is deactivated. Hydraulic pressure is applied through the passage 114, the 1-2 shift valve 74, and the passage 126 in a direction that moves the spool 124 against the spring 123, and when the shift lever is operated to the S range. , is applied to the other end surface (spring 123 side) of the spool 124 via a passage 112 to which line hydraulic pressure is supplied. When the spool 124 is placed in the non-acting position according to the biasing force of the spring 123, the throttle pressure signal supplied through the passage 122 is output to the second spool 120 of the throttle valve 67 through the passage 128. However, the spool 124 is
When placed in the active position against the biasing force of 23, a throttle pressure signal is supplied to the second spool 120 via passage 128 as a cutback pressure signal. The second spool 120 of the throttle valve 67 is formed with a pressure receiving surface that applies a force toward the first spool 118 when it receives a cutback pressure signal supplied from the cutback valve 94 through a passage 128. When the spool 124 of the cutback valve 94 is placed in the active position, the throttle pressure signal and line oil pressure are allowed to change. The solenoid valve MV2 that operates the cutback valve 94 is controlled by a shift control circuit (to be described later) to shift to the first gear, which is the lowest speed, according to conditions such as vehicle speed or throttle opening.
Electricity is applied when switching from the first gear to the second gear, and the switching timing is generally delayed as the vehicle speed and throttle operation amount increase, so that line oil pressure that decreases as the vehicle speed increases is obtained. That is, the cutback valve 94 increases the line oil pressure when the vehicle speed is low to maintain the friction capacity of the clutch, brake, etc., and lowers the line oil pressure as the vehicle speed increases, thereby eliminating the need for the oil pump 66. This prevents significant power loss. The speed change control circuit is constructed as shown in FIG. That is, the vehicle speed sensor 130 detects the actual speed of the vehicle and inputs the vehicle speed signal SV to port 1.
32. The accelerator operation amount sensor 134 detects the operation amount of the accelerator (not shown) or the opening degree of the throttle, and supplies an accelerator operation amount signal SA to the input port 132. Range operation position sensor 1
36 detects the operating position of a shift lever (not shown) and supplies an operating position signal SP representing the operating position to the input port 132. A pattern select switch 138 supplies a driving pattern signal SR representing a driving pattern selected from among economy driving, normal driving, power driving, etc. to the input port 132. and,
Engine rotation sensor 140 detects the rotation of an engine (not shown) and supplies an engine rotation signal SE to input port 132. The input port 132 connects the CPU 142, ROM 144,
It is connected to RAM 146 and output port 148. The CPU 142 utilizes the temporary storage function of the RAM 146 according to the program stored in advance in the ROM 144, and sends signals SV, SA, SP, SR,
Arithmetic processing is performed based on the SE, and drive signals SD1, SD2, and SD3 are supplied to the solenoid valves MV1, MV2, and MV3 through the output port 148, respectively,
The solenoid valves MV1, MV2, and MV3 are driven and controlled. Operation of the Embodiment Hereinafter, the operation of the embodiment will be explained according to the flowchart shown in FIG. First, the I/O processing in step S1 is executed, and the states of the input and output signals at the input port 132 and output port 148 are stored. Next, step S2
In step S3, it is determined whether the shift lever is operated to the neutral range based on the operation position signal SP.
is executed and the contents of register S are set to 0. This register S indicates whether or not the operation of the shift lever from the neutral range to the forward range, for example, the drive range, has been completed, and when the contents of register S are set to 1, the operation is completed. is displayed. Then, step S4 is executed, and the timer T that measures time after the shift from the neutral range to the drive range is executed.
1, and a timer T2, which is counted after the switching operation from the neutral range to the drive range is performed and the conditions of step S18, which will be described later, are satisfied, are reset, and their contents are set to 0. After that, the well-known shift calculation of step S5, step S
6, the lock-up determination in step S7, etc. are executed, and steps S1 and subsequent steps are executed again. Steps S5 and S6 include the vehicle speed signal SV supplied from the vehicle speed sensor 130, the accelerator operation amount signal SA supplied from the accelerator operation amount sensor 134, and the pattern select switch 138.
Based on the driving pattern signal SR supplied from
A solenoid valve MV1 is used to select a predetermined gear from a shift diagram stored in advance in the ROM 144
The one to be driven is selected from among MV2 and MV3, and drive signals SD1, SD2, and SD3 are selectively output at predetermined timings in order to reduce the shock of the transmission due to gear change during running. In step S7, in advance
In the shift diagram stored in the ROM 144, it is determined whether the vehicle condition consisting of the vehicle speed and the amount of accelerator operation is within a preset lock-up activation range, and if so, the lock-up clutch 14 is activated. Solenoid valve MV3 is driven. Here, the shift diagram is stored for each driving pattern, and one of them is selected according to the driving pattern signal SR. However, when the shift lever is in the neutral range, the passage 102 for supplying line hydraulic pressure in the operation valve 72 is replaced by the passages 110, 112, 114, 11.
Since the solenoid valves MV1 and MV2 are not connected to any of the solenoid valves MV1 and MV2, neither the solenoid valves MV1 nor MV2 are operated because the accelerator operation amount and the vehicle speed are both normally zero. Therefore, the spool of the 3-4 shift valve 78 is placed in a non-active position according to the biasing force of the spring, and line hydraulic pressure is supplied to the hydraulic actuator C0y. As a result, the clutch C0 is actuated to fix the turbine shaft 24 and the input shaft 40, the overdrive mechanism 16 is deactivated, and the gear position of the automatic transmission is placed in a neutral condition. If it is determined in step S2 that the shift lever is not in the neutral range, step S8 is executed to determine whether the contents of register S are 1 or not, in other words, from the neutral range of the shift lever to the drive range. It is determined whether or not the switching has been completed. If the process has been completed, steps 85 to S7 are executed, and the gear stage of the automatic transmission is changed according to the vehicle speed, throttle opening, and driving pattern. That is, when the operation valve 72 is located in the drive range, the passages 102 and 114 are communicated, and the line oil pressure is changed to the 2-3 shift valves 76, 3-4.
It is supplied to the shift valve 78, the 1-2 shift valve 74, the accumulator 86, and the hydraulic actuator C1y. At the same time, the solenoid valve MV1 is actuated to place the spool of the 2-3 shift valve 76 in the non-operating position, and the 1-2 shift valve 76 is placed in the non-operating position.
The spool 4 is placed in the active position against the spring. At this time, line oil pressure is applied to the spool of the 3-4 shift valve 78 via the passage 114 due to the non-operation of the solenoid valve MV2.
Since the line oil pressure is also applied to the other end of the spool, the spool of the 3-4 shift valve 78 is placed in the non-operating position according to the biasing force of the spring.
As a result, when the vehicle speed is low, clutch C1 is operated in addition to clutch C0, and the planetary gear transmission 18 is switched to the first gear according to the shift diagram. Next, when the vehicle speed reaches a predetermined constant level, when the solenoid valve MV2 is operated according to the shift diagram, 1-2
Since the spool of the shift valve 74 is placed in the non-operating position according to the biasing force of the spring, the passage 1
4. Line hydraulic pressure is supplied to the accumulator 90 and hydraulic actuator B2y via the 1-2 shift valve 74.
is supplied to As a result, the brake B2 is further actuated and the planetary gear transmission 18 is switched to the second gear. At this time, line hydraulic pressure is also supplied from the 1-2 shift valve 74 to the cutback valve 94, and the spool 1 of the cutback valve 94 is
24 is placed in the active position against the biasing force of the spring 123. Therefore, a cutback pressure signal is supplied from cutback valve 94 to throttle valve 67 via passage 128, and the throttle pressure signal and line oil pressure are corrected. When the vehicle speed and accelerator operation amount reach another predetermined value, the solenoid valve MV1 is de-energized according to the shift diagram, and the spool of the 2-3 shift valve 76 resists the biasing force of the spring. and placed in the working position. Therefore, the line oil pressure that was being supplied to the 2-3 shift valve 76 via the passage 114 is reduced to 2-3.
3 through the shift valve 76 to the accumulator 88 and the hydraulic actuator C2y, further actuating the clutch C2. As a result, the planetary gear transmission 18 is switched to the third gear. Further, when the vehicle speed and the accelerator operation amount reach other predetermined values, the solenoid valve MV2 is deactivated and the spools of the 1-2 shift valve 74 and the 3-4 shift valve 78 resist the spring. Therefore, the supply of line hydraulic pressure to the hydraulic actuator C0y is blocked, while the line hydraulic pressure is supplied from the 3-4 shift valve 78 to the hydraulic actuator B0y. Therefore, the operation of clutch C0 is stopped and at the same time brake B
0 is activated, the overdrive mechanism 16 is activated, and the speed of the input shaft 40 with respect to the turbine shaft 24 is doubled. As a result, the entire automatic transmission is switched to the fourth gear (overdrive). If the contents of the register S are not 1 in step S8, step S9 is executed, and the contents of timer T1 are predetermined, in other words, the elapsed time after the shift lever was switched from the neutral range to the drive range. It is determined whether the time is longer than a certain time T10. If not, steps S10 and S11 are executed, and the register NEMAX is reset to 0.
(0) and a signal for switching the planetary gear transmission 18 to the third gear is output. That is, a drive signal SD2 for energizing the solenoid valve MV2 is output from the output port 148, and a drive signal SD1 for de-energizing the solenoid valve MV1 is output, and the clutches C1,
Line hydraulic pressure is supplied to hydraulic actuators C1y, C2y, and B2y that drive brake C2 and brake B2, and engagement of the third gear is started. The above steps are repeated until the content of timer T1 reaches time T10, but as soon as it reaches time T10, steps S12 and subsequent steps are executed via step S9'. Step S9' constitutes engine rotational speed detection means, in which the actual engine rotational speed NE at that point in time is calculated and stored based on the engine rotational speed signal SE from the engine rotational sensor 140. In this case, if the engine rotation signal SE is a pulse signal synchronized with the engine rotation, the rotation speed NE is calculated by counting the pulse signals within a unit time, and the engine rotation signal SE is the engine rotation speed. If the code signal represents a magnitude corresponding to , then the rotational speed NE is calculated by converting the code signal. Then, in step S12, it is determined whether the contents of the register NEMAX are 0 or not. If it is 0, register NEMAX is set in step S13.
The content of is replaced with the actual engine rotational speed NE based on the engine rotational signal SE, and step S14 is executed, the timer T2 is reset and its content is set to 0, and then the steps from step S11 described above are executed. In the above steps, the contents of the register NEMAX are replaced with the actual engine speed NE, so step S
In step S12, it is determined that the contents of the register NEMAX are not 0, and step S15 is executed. In step S15, it is determined whether the contents of the register NEMAX are greater than the new actual engine rotational speed NE. That is, as the shift lever is operated to the forward range, the engine rotational speed is slightly increased in order to maintain good idle rotation, and the peak value of the engine rotational speed NE is set at step S13.
To store in register NEMAX in
It is determined whether the engine rotational speed NE is trending upward or downward. register
If the contents of NEMAX are not larger than the actual engine speed NE, that is, if the engine speed is increasing, the steps after step S13 are repeatedly executed and the contents of register NEMAX are sequentially rewritten. When the engine rotation speed NE reaches a peak value as shown at time C in FIG. 6, steps S16 and subsequent steps are executed. In step S16, it is determined whether the content of timer T2 is greater than time T20. The time T20 is
This is the time it takes for the rotational speed reduction amount △NE to reach a certain amount of reduction, for example 50 rpm, after the engine rotational speed NE reaches its peak value, and is determined in step S19, which will be described later. Since the contents of the register representing time T20 are set to a value relatively larger than the normal size of T20, the contents of timer T2 are smaller than time T20, and the next step S17 is executed.
In step S17, the register NEMAX
The actual engine speed NE is subtracted from the peak value stored in , and the amount of decrease ΔNE is calculated.
In step S18, it is determined whether the amount of decrease ΔNE is larger than a predetermined constant amount of decrease of 50 rpm. If the amount of decrease ΔNE has not yet reached 50 rpm, steps S11 and subsequent steps described above are executed, but when the amount of decrease ΔNE reaches the value 50 rpm as shown at time A in FIG. 6, step S19 is executed. , register T representing time T20
The contents of T20 are replaced by the actual contents of timer T2. Here, in steps S17 and S18, from the neutral state to the third gear, which is the upper gear stage.
When the gear is switched to the higher gear, the engine rotation speed NE changes to the 6th gear in response to the engagement state of the 3rd gear.
As shown in the figure, it is determined that the rotation speed has changed to a value corresponding to a certain engagement state, for example, 50 rpm, and therefore steps S17 and S18 form a determining means. Furthermore, in step S9, the execution of steps S12 and subsequent steps are masked for a certain period of time T10 immediately after the shift lever is operated, so that changes in the engine speed NE that are likely to occur immediately after switching to the third gear are avoided. The accompanying malfunctions are prevented, and T10 is preset to such a value. In step S20, it is determined whether the content of timer T2 is greater than the sum of times T20 and T30. In a state where step S20 can be executed first, the contents of timer T2 are smaller than the sum of the times T20 and T30, so steps S11 and subsequent steps are repeatedly executed. At this time, the content of timer T2 is
Since it is larger than 0, step S1
7, S18, S19 are bypassed, and step S
After step S16, step S20 is executed. If further time elapses and the content of timer T2 becomes greater than the sum of times T20 and T30, step S21 is executed and a drive signal for exciting solenoid valve MV1 is generated.
A drive signal SD2 for de-energizing SD1 and solenoid valve MV2 is output from output port 148, and the supply of line hydraulic pressure to hydraulic actuators C2y and B2y that were driving clutch C2 and brake B2 is released. The third gear is quickly switched to the first gear. Here, in step S20, the engine speed reduction amount ΔNE is a constant value in step S18,
For example, this is a delay means for executing step S21 after a time T30 has elapsed since the speed reaches 50 rpm, and the time T30 is the delay time. Further, the delay time T30 is a delay time T30 when the shift lever is switched from the neutral range to the drive range, following the change in transmission torque caused by switching from the neutral state to the third gear. The change in transmitted torque that occurs when changing to the first gear continues continuously and smoothly, thereby minimizing the shock that occurs when changing from the third gear to the first gear. The solenoid valves MV1 and MV2 and the clutch C are appropriately set to values such that the time when the engagement of the first speed gear starts and the time when the engagement of the third gear is completed are approximately the same.
2. T30 depending on the response characteristics of brake B2 etc.
There is no problem even if it is 0. Furthermore, the predetermined constant reduction amount (50 rpm) used in step S18 is a value that allows the engagement state of the third gear to be reliably detected, and is also set to an appropriate value in relation to the above T30. It will be done. Then, step S22 is executed, and the contents of the register S are set to the number 1 indicating the end of the operation from the neutral range to the drive range.
The above steps are executed repeatedly. As described above, according to this embodiment, the amount of decrease ΔNE in the engine rotational speed corresponding to the actual engagement state of the third gear of the planetary gear transmission 18 is a predetermined value representing a constant engagement state. For example, based on reaching 50 rpm, the third gear is switched to the first gear, so the vehicle speed, accelerator operation amount, and shift lever are changed from the neutral range to the forward range. Regardless of the vehicle state such as the elapsed time, following a change (increase) in the transmitted torque due to the change from the neutral state to the 3rd gear, the change from the 3rd gear to the 1st gear The accompanying change (increase) in the transmitted torque occurs smoothly and continuously, and the unpleasant shock caused by the changeover is almost eliminated. Although the embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other aspects. For example, in the embodiments described above, the third gear is used as the upper gear, but the second gear or the fourth gear may also be used. In short, any type of automatic transmission that uses a gear higher than the first gear can be used. Further, the control circuit including the above-mentioned means for switching from the third gear to the first gear, which is included in the shift control circuit shown in FIG. A calculator that calculates the amount of decrease from the value, a setting device that outputs a preset value such as 50 rpm, and the signals output from the calculator and the setting device are compared, and the actual engine rotation speed NE is determined in advance. It goes without saying that it can also be constructed with a hard logic circuit including a comparator that outputs a determination signal when the value is greater than a predetermined value. Further, in the above-described embodiment, the engagement state of the third gear is determined based on the fact that the engine rotational speed reduction amount ΔNE reaches a predetermined constant reduction amount, but the engine rotational speed NE The determination may be made based on whether or not the value has reached a constant value NE0, which is set lower than the peak value in advance. That is,
In the flowchart of FIG. 5 described above, steps S10, S13, S15, S16, S17,
S19 is removed and NENE0 and T2T3 are removed in steps S18 and S20.
All you have to do is judge 0. The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to claims of the present invention. Second
The figure is a schematic diagram of an electronically controlled automatic transmission to which an example of the present invention is applied. FIG. 3 is a hydraulic circuit of the electronically controlled automatic transmission shown in FIG. FIG. 4 is a block diagram showing a shift control circuit of the electronically controlled automatic transmission of FIG. 2. 5 and 6 are a flow chart and a time chart explaining the operation of the circuit of FIG. 4. 18: Planetary gear transmission (gear mechanism), Step S9': Engine rotation speed detection means, Steps S17, S18: Determination means, Steps S20, S
21: Switching means, ΔNE: Engine speed reduction amount.

Claims (1)

[Claims] 1. A gear mechanism capable of switching to multiple gear stages;
and a control device that automatically switches the gear stage of the gear mechanism according to vehicle conditions such as the operation position of the shift lever, the amount of accelerator operation, and the speed of the vehicle, and when the shift lever is operated from a neutral range to a forward range. In an automatic transmission for a vehicle of the type in which the gear of the gear mechanism is first changed to a gear higher than the lowest gear, and then switched to the lowest gear, the gear is changed from the upper gear to the lowest gear. A switching shock prevention device that prevents a shock caused by switching to a gear, the device comprising: rotational speed detection means for detecting the engine rotational speed of the vehicle; determining means for determining whether the engine rotational speed or the amount of reduction thereof has reached a predetermined constant value; and switching for switching the gear of the gear mechanism to the lowest speed gear based on the determination by the determining means. 1. A switching shock prevention device for an automatic transmission for a vehicle, comprising means.