JPS629774B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improvement in an electronically controlled automatic transmission in which each gear stage can be obtained by electronically controlling the drive of a shift solenoid. When driving downhill with a hydraulically controlled automatic transmission with its manual valve in the automatic shift (D) range, the highest gear remains selected, and engine braking is hardly expected, especially when driving down a steep hill. In order to avoid using the foot brake frequently when going downhill, the driver should change the manual valve from the D range to the 2nd gear fixed range or 1st gear fixed range, and manually operate the manual valve as described above each time to apply engine braking. It is necessary to do this. This was the same with conventional electronically controlled automatic transmissions, but in order to eliminate this complication, in the past, when the brake pedal was depressed, it automatically shifted from the highest gear even if it remained in D range. An electronically controlled automatic transmission has been developed that is designed to downshift to the immediately preceding low gear. However, with such electronically controlled automatic transmissions, each time the brake pedal is pressed to brake the vehicle, the downshift is performed even when the vehicle is not actually requiring engine braking, causing discomfort to the occupants. The reality was that the driver felt a sense of deceleration every time he braked, which significantly impaired the driving feeling. From this point of view, the present invention is designed to operate only when the acceleration of the vehicle exceeds a set value for each vehicle speed and when the driver takes his foot off the accelerator pedal and depresses the brake pedal, that is, when the engine brake is truly required. This is an improved electronically controlled automatic transmission that automatically downshifts and applies appropriate engine braking only when driving on hills. Hereinafter, the present invention will be explained in detail based on illustrated embodiments. FIG. 1 shows a power transmission system of a typical automatic transmission, in which power is input from an input shaft 1, and this power is transmitted to an intermediate shaft 3 via a torque converter 2. The intermediate shaft 3 can be drivingly engaged with the sun gears 8 and 9 of the front planetary gear set 6 and the rear planetary gear set 7 via the front clutch 4, and is also driveable with the internal gear 10 of the front planetary gear set 6 via the rear clutch 5. Engageable. The sun gears 8 and 9 can be further fixed by a band brake 11, and a carrier 13 supporting the pinion 12 of the front planetary gear set 6 and an internal gear 14 of the rear planetary gear set 7 are respectively coupled to the output shaft 15 to generate the output. Allows power to be output from the shaft. The pinion 16 of the rear planetary gear set 7 is supported by a carrier 17, which can be fixed by a low and reverse brake 18 and can rotate only in one direction via a one-way clutch 19. This transmission system includes a torque converter 2 and a gear train portion including friction elements of a front clutch 4, a rear clutch 5, a band brake 11, and a low and reverse brake 18, which are housed within a converter cover 20 and a transmission case 21, respectively, as shown in FIG. A rear extension 22 is provided at the rear of the transmission case 21. FIG. 2 generally shows the electronic control system of the automatic transmission of the present invention, and this electronic control system includes a cutback solenoid 23 and a
-2 shift solenoid 24, 2-3 shift solenoid 25, vehicle speed sensor 26, throttle opening sensor 27, and idle detection means for detecting when the accelerator pedal is released in conjunction with the accelerator pedal 28;
An idle switch 29 that is turned on when the accelerator pedal 28 is released, and a brake switch 31 that is turned on when the brake pedal 30 is depressed as a brake operation detection means that is linked to the brake pedal 30 and detects when the brake pedal 30 is depressed are shown in the second figure. It is configured in relation to the computer 32 as shown in FIG. Note that a comparator compares the outputs of the idle switch 29, brake switch 31, and slot opening sensor 27 with a predetermined value, and a switch that responds to the output of the comparator and a switch that operates when the depression force on the brake pedal 30 exceeds a predetermined value. They can also be used as needed. The computer 32 processes various information as will be described later, and turns on the 1-2 shift solenoid 24 and the 2-3 shift solenoid 25 as shown in the following table.
OFF control is performed, whereby each of the friction elements described above can be selectively operated by a well-known desired hydraulic circuit according to the manual valve selection position of the automatic transmission. (The circles in the table below indicate which friction elements are selectively activated.)

【table】

[Table] In order to perform such ON/OFF control of the 1-2 shift solenoid 24 and the 2-3 shift solenoid 25, the computer 32 in the present invention is configured as shown in FIG. This computer 32
comprises a throttle opening detection circuit 33 that receives a signal from the throttle opening sensor 27, and a vehicle speed detection circuit 34 that receives a signal from the vehicle speed sensor 26, and these circuits each process the input signal to detect the throttle. A signal TH corresponding to the opening degree and a signal V corresponding to the vehicle speed are output. Throttle opening signal TH is D
The vehicle speed signal V
1-2 shift determination circuit 35 for D range, 2-3 shift determination circuit 36 for D range, 1 for 1st speed fixed range
It is input to the -2 speed change determining circuit 37 and the 2-3 speed change determining circuit 38 for fixing the second speed. The shift determination circuits 35 and 36 are further connected to a power supply +V via a D range switch 39, which is closed when the manual valve of the automatic transmission is in the D range.
is connected, and when the D range switch 39 is closed and the power supply voltage is input, the speed change determining circuits 35 and 36 are activated. It is assumed that a high (H) level signal is output to the AND gates 42 and 43. Further, the shift determining circuits 35 and 36 store the required 1-2 shift pattern and 2-3 shift pattern, respectively, and during operation when the switch 39 is closed, these shift patterns and
It compares the input throttle opening signal TH and vehicle speed signal V to determine the operating state, and outputs an H level or low (L) level signal to circuits 40 and 41 as described later. . The shift determination circuits 37 and 38 are supplied with power +V via a 1st speed range switch 44 and a 2nd speed range switch 45, which are closed when the manual valve of the automatic transmission selects the 1st speed fixed range and the 2nd speed fixed range, respectively. The speed change determining circuits 37 and 38 are activated when the 1st speed range switch 44 and the 2nd speed range switch 45 are closed and the power supply voltage is input, but are otherwise inactive and the circuits 46,
It is assumed that an H level signal is outputted to the NAND gates 42 and 43 via the gate 47. Also, the speed change determination circuit 3
7 and 38 store the vehicle speeds when the engine reaches the upper limit of the allowable rotation speed in the first and second gears, respectively, and when the switches 44 and 45 are closed, these vehicle speeds and the input values are stored. The vehicle speed signal V is compared to determine whether the vehicle speed is such that the engine overruns, and the circuits 46 and 4
It is assumed that an H level or L level signal is output to the terminal 7. Note that the 1-2 shift solenoids 24 and 2-3 described above are connected to the output terminals of the NAND gates 42 and 43.
It is assumed that the shift solenoids 25 are connected to each other, and these solenoids are turned ON when an H level signal is output to the corresponding NAND gate, and turned OFF when an L level signal is outputted to the corresponding NAND gate. In the present invention, an engine brake control circuit described below is added to the above-mentioned speed change control circuit. This engine brake control circuit includes, in addition to the idle switch 29 and brake switch 31, an acceleration detection circuit 48, two acceleration setting circuits 49a and 49b, comparators 50 and 51, and vehicle speed range discrimination circuits 57 and 58. Provide a means of discrimination. The acceleration detection circuit 48 inputs the signal from the vehicle speed sensor 26, continuously detects the increase or decrease in this signal at fixed time intervals, calculates the acceleration of the vehicle by calculating the increase or decrease in the vehicle speed within a unit time, and calculates the calculated value. (Acceleration signal) G is supplied to one input terminal of comparators 50 and 51. Further, the acceleration setting circuits 49a and 49b are selectively activated for each vehicle speed range determined by the circuits 57 and 58.
Comparators 50 and 5b respectively compare signals G _L ′ and G _{L ″ related to low set accelerations for each corresponding vehicle speed range and signals G H ′} and G _H ″ related to high set accelerations for each corresponding vehicle speed range.
The low set acceleration signals G _L ′ and G _{L ″ correspond to the upper limit acceleration for each vehicle speed range in which the vehicle does not require engine braking, and the high set acceleration signals G L ′ and G L} ″ are supplied to the other input terminal of G _H ′ and G _H ″ correspond to the lower limit acceleration for each vehicle speed range in which the vehicle requires engine braking. The vehicle speed range determination circuits 57 and 58 include comparators 59, 60, and 6 to which signals from the vehicle speed sensor 26 are input.
1, 62 and AND gates 63, 64.
In the low vehicle speed range, the comparator 59 outputs an H level signal when the lower limit value is exceeded, and the comparator 60 outputs an H level signal when the upper limit value is exceeded, and the H level signal is sent to the AND gate 63.
By outputting a level signal, the vehicle speed determination circuit 57 determines the low vehicle speed range and accelerates the acceleration setting circuit 4.
Activate 9a. On the other hand, in a high vehicle speed range, the vehicle speed discrimination circuit 58 discriminates the high vehicle speed range by the same action of the comparators 61, 62 and the AND gate 64, and operates the acceleration setting circuit 49b. Therefore, the acceleration setting circuits 49a and 49b are used separately in the low vehicle speed range and the high vehicle speed range, and these acceleration setting circuits 49
The low set acceleration signals GL _' , GL _' ' and the high set acceleration signals GH', _{GH '} ' of a and 49b are set to match the corresponding vehicle speed range. When the acceleration setting circuit 49a is operated in a low vehicle speed range, these set acceleration signals _GL ' and _GH ' are sent to the comparators 50 and 51, respectively, and when the acceleration setting circuit 49b is operated in a high vehicle speed range, The set acceleration signals G _L ′ and G _H ″ from now on are input to comparators 50 and 51, respectively. The comparator 50 outputs an H signal when the acceleration signal G is smaller than the set acceleration signal G _L ′ or G _L ″. When the acceleration signal G is larger than the set acceleration signal G _L ′ or G _L ″, the L level signal is input to the OR gate 52, and the comparator 51 determines that the acceleration signal G is the set acceleration signal G _H ' or G _H '', the H level signal is set, and the acceleration signal G is the set acceleration signal G _H ' or G
When it is larger than _H '', an L level signal is input to each NOR gate 53.The other input terminal of the OR gate 52 is connected to the power supply +V, and is supplied with the voltage of the power supply +V (H level signal). However, when it is turned on, it can be grounded via the idle switch 29, and at this time, the resistor 5
4, an L level signal can be supplied to the other input terminal of the OR gate 52.
One of the other two input terminals of the NOR gate 53 is connected to the power supply +V like the other input terminals of the OR gate 52, and the other is connected to the power supply +V through the resistor 55.
In addition to connecting it to V, it can also be grounded appropriately through the brake switch 31, so that when the brake switch 31 is OFF, an H level signal is sent from the power supply +V to the input terminal, and a high level signal from the power supply +V is sent to the input terminal when the brake switch 31 is OFF.
When ON, L level signals are input in the presence of the resistor 55, respectively. The output terminal of the OR gate 52 is connected to the set input terminal S of the flip-flop circuit 56, the output terminal of the NOR gate 53 is connected to the reset input terminal R of the flip-flop circuit 56, and the output terminal Q of the flip-flop circuit 56 is connected to the set input terminal S of the flip-flop circuit 56. Connect to input terminal. Flip-flop circuit 56
When an H level signal is input to the set input terminal S, an H level signal is output from the terminal Q, and when an H level signal is input to the reset input terminal R, an L level signal is output from the terminal Q. At the same time, this L level signal is held until an H level signal is input to the set input terminal S. The electronic control circuit of the automatic transmission of the present invention configured as described above operates as described below. The driver wishes to start and presses the manual valve D.
When the range is set, the switch 39 is closed and the shift determining circuits 35 and 36 start operating. At this time, the throttle opening signal TH and the vehicle speed signal V are low, and the shift determining circuits 35 and 36 compare the stored shift patterns with the above signals TH and V, and determine that these signals are in the 1st speed range. determine the
An L level signal is supplied to NAND gates 42 and 43 via circuits 40 and 41. As a result, the NAND gates 42 and 43 output H level signals to the 1-2 shift solenoid 24 and the 2-3 shift solenoid 25, respectively, and turn on these solenoids, regardless of other input signals. As is clear from Table 1, the automatic transmission is brought into a state where the first gear is selected. Thus, the driver can start the vehicle in the first gear by depressing the accelerator pedal. After that, when the vehicle is sufficiently accelerated, the shift determining circuit 35 determines whether the throttle opening signal TH, the vehicle speed signal V, or both of these signals are in the 2nd speed range by comparison with the 1-2 shift pattern stored therein. circuit 4 to the NAND gate 42.
0 and then switches to output an H level signal. On the other hand, while driving in this D range, switch 4
4 is open, the speed change determination circuit 37 is connected to circuit 4.
An H level signal is supplied to the NAND gate 42 via the gate 6. Therefore, the NAND gate 42 is switched to output an L level signal to the 1-2 shift solenoid 24, turning this solenoid OFF.
By the way, the NAND gate 43 is connected to the speed change determining circuit 36.
Since the signal from the 2-3 shift solenoid 25 remains at the L level, the signal at the H level continues to be output to the 2-3 shift solenoid 25, and this solenoid remains ON. Therefore, the automatic transmission uses both solenoids 24 and 25.
As is clear from Table 1, the OFF and ON select the second gear, and shift up from the first gear to the second gear. As the vehicle accelerates further, the shift determining circuit 36 also determines the throttle opening signal by comparing it with the 2-3 shift pattern stored therein.
A circuit 41 is connected to the NAND gate 43 that determines that TH and vehicle speed signal V, or both, have entered the 3-speed gearbox.
After that, the signal is switched to output an H level signal. On the other hand, while driving in this D range, switch 4
5 is open, the speed change determination circuit 38 is connected to circuit 4.
An H level signal is supplied to the NAND gate 43 via the gate 7. Further, during acceleration, the driving vehicle continues to depress the accelerator pedal 28 (see FIG. 2), the idle switch 29 is opened, and an H level signal is input to the OR gate 52. Therefore, regardless of other input signals, the OR gate 52
A high level signal is supplied to the set input terminal S of the flip-flop circuit 56, and the flip-flop circuit 56 outputs a high level signal from the output terminal Q to the NAND gate 43.
A level signal is being input. Therefore, since H level signals are input to all input terminals of the NAND gate 43, the 2-3 shift solenoid 25
The solenoid is switched to supply an L level signal to the solenoid, and this solenoid is turned off. Incidentally, the input signal to the NAND gate 42 remains unchanged even after the shift up to the second speed, and the input signal to the 1-2 shift solenoid 24 remains unchanged.
remains OFF even after this shift-up. Therefore, the automatic transmission has both solenoids 24 and 2.
5 is turned off, the third gear is selected as is clear from Table 1 above, and a shift-up from the second gear to the third gear is performed. When the manual valve of the automatic transmission is set to the 2nd speed fixed range, the switch 45 is closed and the shift determining circuit 38 is activated, and the switches 39 and 44 are opened and the shifting determining circuits 35 to 37 are inactivated.
At this time, since the speed change determining circuits 35 to 37 are inactive, they are handled via circuits 40, 41, and 46, respectively.
An H level signal is supplied to NAND gates 42 and 43. Furthermore, when this second-speed fixed range is selected, the driver intentionally uses engine braking, the vehicle is rarely accelerated, and the comparators 50 and 51 respectively indicate G<G _L ' or G<G _L ″ and G
<G _H ′ or G<G _H ″ and supplies an H level signal to the OR gate 52 and the NOR gate 53;
These gates 52 and 53 input H level and L level signals to the set input terminal S and reset input terminal R of the flip-flop circuit 56, respectively.
From the output terminal Q to the flip-flop circuit 56
The NAND gate 43 is caused to perform an operation such as outputting an H level signal. Even if the vehicle were to accelerate, this state would only occur when the driver depresses the accelerator pedal significantly, and in this case, the OR gate 5 is turned off by turning off the idle switch 29.
2 and the NOR gate 53, and in any case, the flip-flop circuit 56
supplies an H level signal to the NAND gate 43 from the output terminal Q. Then, when the manual valve is set to the 2nd speed fixed range as described above, if the vehicle speed signal V is greater than the set vehicle speed stored in this circuit, the shift determination circuit 38 sends a NAND signal via the circuit 47 to the NAND
An H level signal is supplied to the gate 43. Therefore, in this case, the NAND gates 42 and 43 are all input with H level signals, and each outputs an L level signal, and the 1-2 shift solenoid 24
And turn off the 2-3 shift solenoid 25. Therefore, the automatic transmission selects the third gear as shown in Table 1, even though the automatic transmission is in the two-speed fixed range, and can prevent engine overrun when switching to the second-speed fixed range at high vehicle speeds. However, in the same state, if the vehicle speed is lower than the set vehicle speed stored in the shift determination circuit 38, the shift determination circuit 38 compares the set vehicle speed with the vehicle speed signal V and sends an L level signal to the NAND gate 43 via the circuit 47. 2-3 shift solenoid 25 is turned ON.
As a result, the automatic transmission can be fixed at the second speed, as is clear from Table 1 above, together with the 1-2 shift solenoid 24 being turned off as described above. When the manual valve of the automatic transmission is set to the 1st speed fixed range, the switch 44 closes to put the shift determining circuit 37 into an operating state, and the switches 39 and 45 open to put the shift determining paths 35, 36, and 38 into an inactive state. At this time, since the speed change determining circuits 35, 36, and 38 are inactive, H level signals are supplied to the corresponding NAND gates 42, 43 via circuits 40, 41, and 47, respectively. Also, at this time, for the same reason as explained when setting the 2nd speed fixed range, the flip-flop circuit 56 outputs an H signal from the output terminal Q to the NAND gate 43.
Supply a level signal. At this time, if the speed change determination circuit 37 determines that the vehicle speed signal V is larger than the set vehicle speed stored therein, the speed change determination circuit 37 transmits the signal via the circuit 46.
An H level signal is input to the NAND gate 42.
Therefore, in this case, the NAND gates 42 and 43 will all be input with H level signals, and each will receive an L level signal.
A level signal is output to turn off the 1-2 shift solenoid 24 and the 2-3 shift solenoid 25. Therefore, although the automatic transmission has a fixed range of 1st gear, it is possible to select the 2nd gear as shown in Table 1 above and prevent engine overrun when switching to the fixed range of 1st gear at high vehicle speeds. . However, in the same state, the vehicle speed is
If the vehicle speed is lower than the set vehicle speed stored in the vehicle, the shift determination circuit 37 compares the set vehicle speed with the vehicle speed signal V and supplies an L level signal to the NAND gate 42 via the circuit 46, and supplies an H level signal to the NAND gate. output, and the 1-2 shift solenoid 24
By turning ON, the automatic transmission can be fixed at the first speed as is clear from Table 1 above, in conjunction with the 2-3 shift solenoid 25 being turned OFF as described above. Next, the control mode of the engine brake will be explained. While the vehicle is running in third gear with the manual valve of the automatic transmission in the D range, the vehicle shifts to downhill running, and the driver takes his foot off the accelerator pedal 28 (see FIG. 2) and presses the brake pedal 30. (see Figure 2), if the vehicle receives acceleration due to a slope that requires engine braking, the acceleration signal G changes from the set acceleration signal G _L ' or G
_L '' is naturally larger than the set acceleration signal G _H ' or G _H ''. Therefore, comparators 50 and 51 input L level signals to OR gate 52 and NOR gate 53, respectively. In this driving state, the accelerator pedal is released and the brake pedal is depressed as described above, so both the idle switch 29 and the brake switch 31 are turned on. Therefore, the remaining input terminals of the OR gate 52 and the NOR gate 33 also receive L level signals. Therefore, the OR gate 52 sends an L level signal to the set input terminal S of the flip-flop circuit 56, and the NOR gate 52 also sends an L level signal to the set input terminal S of the flip-flop circuit 56.
3 inputs an H level signal to the reset input terminal R of the flip-flop circuit 56, and the flip-flop circuit 56 inputs the NAND gate 4 from the output terminal Q.
An L level signal is supplied to 3. As a result, D
In order to switch the 2-3 shift solenoid 25, which had been in the OFF state while driving in the third gear range, to the ON state, the NAND gate 43 now supplies an H level signal to the shift solenoid 25, and the automatic The transmission is automatically downshifted from 3rd gear to 2nd gear, and engine braking can be applied appropriately while in D range. Even if the driver takes his or her foot off the brake pedal, the engine brake is applied only when the idle switch 29 is turned OFF by pressing the accelerator pedal, or when the slope of the Furisaka road becomes gentler and the acceleration received by the vehicle is reduced to G. <G _L ′ or G _L ″.In other words, in the former condition, the OR gate 5 is turned off by turning off the idle switch 29.
2, and under the latter condition, the comparator 50 outputs an H-level signal, so that the H-level signal is input to the OR gate 52, and the OR gate 52 operates under either of the above conditions. When one condition is satisfied, an H level signal is input to the set input terminal S of the flip-flop circuit 56. At this time, the flip-flop circuit 56 switches to output an H level signal from the output terminal Q to the NAND gate 43, and this NAND gate
As is clear from the above, the speed change determining circuit 3
Coupled with the fact that H level signals are being continuously input from 6 and 38, the 2-3 shift solenoid 2
Input an L level signal to 5 and turn this solenoid on.
Now turn it off. Therefore, in the automatic transmission, the 1-2 shift solenoid 24 continues to operate during this period.
Since it remains OFF, it is possible to select third gear and automatically release engine braking. Thus, since the automatic transmission of the present invention has its electronic control section configured as described above, it automatically shifts from the third gear to the second gear even when driving in the third gear with the D range set as described above. engine braking can be applied by downshifting, and this engine braking is applied only when really necessary, i.e. when the driver takes his foot off the accelerator pedal and depresses the brake pedal, and when the vehicle is driving downhill. Since it is applied only when the acceleration exceeds the set value for each vehicle speed G _H ′ (low vehicle speed range) or G _H ″ (high vehicle speed range), the above-mentioned downshift is performed unnecessarily every time the brake is applied, unlike conventional brakes. As a result, the driving feeling can be improved without causing the occupants to often feel an unpleasant sense of deceleration.Furthermore, when the above three conditions are met and engine braking is required, downshifting is performed immediately and reliably, so there is no delay in the occurrence of engine braking. There is no problem such as engine braking occurring when it is unnecessary.Moreover, once the above-mentioned downshift is performed, the acceleration that the vehicle receives due to downhill driving has reached a value G that does not require engine braking. 2nd gear is maintained and engine braking is required until the speed drops to _L ' (low vehicle speed range) or G _L '' (high vehicle speed range), or the driver depresses the accelerator pedal to accelerate the vehicle. you can get as much as you want,
Further, as soon as this engine braking becomes unnecessary, the holding of the second speed is released, and the speed change determining circuits 35 and 36 automatically shift up to, for example, the third speed, thereby allowing a transition to normal driving. Furthermore, in order to vary the acceleration setting values G _H ′ and G _H ″ for determining whether or not engine braking is necessary, depending on the vehicle speed,
Engine braking can be applied as desired in any vehicle speed range, and even in conditions that require engine braking, such as when driving downhill on a highway, the system detects slight acceleration and downshifts appropriately. It is possible to apply engine braking by doing this. In this case, the set acceleration G _H '' in the high vehicle speed range is the set acceleration G in the low vehicle speed range.
It is desirable to set it to a value smaller than _H ′. This is because if the set acceleration is the same regardless of vehicle speed,
At high vehicle speeds, running resistance increases, and when coasting by releasing the accelerator pedal, it is almost impossible for the vehicle to exceed the set acceleration, and engine braking is very necessary when coasting at high vehicle speeds. Nevertheless, this is because there is a risk that it may become virtually impossible to ensure engine braking at all. Furthermore, by changing the number and characteristics of vehicle speed determination circuits 57, 58 and acceleration setting circuits 49a, 49b, it is possible to freely change downshift timing and obtain engine braking characteristics most suitable for the vehicle. Furthermore, according to the present invention, the third
Configuring the embodiment illustrated in the figure into a digital circuit,
ROM instead of acceleration setting circuits 49a and 49b
It is clear from the above-mentioned gist of the present invention that it is possible to store set values in a (Read Only Memory) and retrieve and compare the set values corresponding to each vehicle speed range.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a general gear train of an automatic transmission, Fig. 2 is a diagram of an electronic control system of the automatic transmission of the present invention, and Fig. 3 is a block diagram showing the electronic control section of the automatic transmission of the present invention. . 1...Input shaft, 2...Torque converter, 3...
...Intermediate shaft, 4...Front clutch, 5...Rear clutch, 6...Front planetary gear set, 7
...Rear planetary gear set, 8,9...Sun gear, 10,14...Internal gear, 11...
Band brake, 12, 16...Pinion, 1
3, 17...Carrier, 15...Output shaft, 18...
...Low and reverse brake, 19...One-way clutch, 20...Converter cover, 21...
Transmission case, 22...Rear extension,
23...Katsutobutsu solenoid, 24...1-
2 shift solenoid, 25...2-3 shift solenoid, 26...vehicle speed sensor, 27...throttle opening sensor, 28...accelerator pedal, 29...
...Idle switch, 30...Brake pedal,
31... Brake switch, 32... Computer, 33... Throttle opening detection circuit, 34...
Vehicle speed detection circuit, 35...1-2 shift determination circuit for D range, 36...2-3 shift decision circuit for D range, 37...1-2 shift decision circuit for 1st speed fixed range, 38...2nd speed 2-3 speed determination circuit for fixed range, 39...D range switch, 42, 43...
NAND gate, 44...1 speed range switch, 4
5... Two-speed range switch, 48... Acceleration detection circuit, 49a, 49b... Acceleration setting circuit, 5
0, 51, 59-62...Comparator, 52...OR
Gate, 53...NOR gate, 54, 55...
Resistor, 56...Flip-flop circuit, 57,5
8...Vehicle speed range discrimination circuit, 63, 64...AND gate.

Claims (1)

[Scope of Claims] 1. An electronically controlled automatic transmission in which each gear stage is obtained by electronically controlling the drive of a shift solenoid, comprising an idle detection means for detecting release of an accelerator pedal and an idle detection means for detecting release of an accelerator pedal, and an idle detection means for detecting release of an accelerator pedal; A brake operation detection means for detecting a brake operation, and an acceleration determination means for detecting that the acceleration of the vehicle has exceeded a set value, and the acceleration determination means is configured such that the set value differs depending on the vehicle speed, and the idle detection means When the detection signals from the means, the brake operation detecting means, and the acceleration determining means are all gathered, the shift solenoid is driven and controlled to automatically downshift from the high speed gear to the low speed gear so that engine braking can be applied. An electronically controlled automatic transmission characterized by: 2. The electronically controlled automatic transmission according to claim 1, wherein the acceleration determining means decreases the set value as the vehicle speed increases.