JPH0321790B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a control device for an automatic transmission, and more particularly to a neutral control device for an automatic transmission that automatically puts the automatic transmission into a neutral state under certain conditions. Automatic transmissions configured by combining a torque converter and a gear transmission mechanism such as a planetary gear mechanism are widely used, and the torque converter used therein includes a pump impeller, a turbine runner, and a stator disposed between them. , circulates fluid, or hydraulic oil, from an engine-driven pump impeller to transmit power to the turbine. In such an automatic transmission, when the vehicle is stopped, power transmission between the torque converter and the gear transmission mechanism is manually cut off, or the gear transmission mechanism itself is put into a idling state to stop the automatic transmission. It is possible to set the transmission to neutral, but in driving conditions where the vehicle starts and stops frequently, it is cumbersome to manually set the transmission to neutral each time the vehicle stops, and it is necessary to use the brake to stop the transmission output shaft and reduce torque. It is common to maintain a stopped state of the vehicle by placing the converter in a stalled state. However, under such a torque converter stall condition, there are problems such as vibrations occurring in the converter and vehicle creep, and the load on the engine to drive the torque converter inevitably increases. This results in increased fuel consumption. An automatic transmission intended to solve such problems is described in Japanese Patent Publication No. 19962/1983. This automatic transmission automatically shifts to neutral under the conditions that the accelerator pedal is released, that is, the accelerator is fully closed, the brake pedal is depressed, and the vehicle speed is low. It's summery. Therefore, in this device, when the vehicle is stopped or at an extremely low speed, when the brake pedal is depressed, the vehicle enters a neutral state, and when the foot is released from the pedal, the neutral state is released. However, during warm-up operation immediately after starting the engine, the temperature of the hydraulic oil in the automatic transmission is low, and the viscosity of the hydraulic oil is high. This causes problems such as worsening of the feeling when starting the vehicle, and also has unfavorable results in terms of safety. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an automatic transmission system that prevents phenomena such as vibration of the transmission or creep of the vehicle by placing the transmission in a neutral state when the accelerator pedal is released or the brake is applied. In a neutral control device for a transmission, an automatic transmission system that improves the responsiveness of an automatic transmission, especially the ability to start, by setting the automatic transmission to a neutral state as necessary after the hydraulic oil temperature has sufficiently increased. The purpose of the present invention is to provide a neutral control device for a machine. Such an object of the present invention is to provide a torque converter;
In an automatic transmission comprising a planetary gear mechanism, a plurality of frictional engagement members that switch a power transmission path of the planetary gear mechanism, and a fluid actuator that operates on and off of the frictional engagement members, an electromagnetic means for controlling the supply and discharge of fluid; a vehicle speed sensor for detecting that the vehicle speed is below a set vehicle speed; a stop operation detection sensor for detecting the operation of equipment to stop the vehicle; Alternatively, when determining a condition in which all outputs from the two sensors are generated after the oil temperature of the automatic transmission reaches a predetermined value or more, a signal is issued to the electromagnetic means to bring the automatic transmission into a neutral state. This is achieved by providing a controller. According to the present invention, the vehicle speed becomes equal to or lower than the set vehicle speed,
Even if the accelerator pedal is released or the brake pedal is depressed and the vehicle is stopped,
If the oil temperature of the automatic transmission is not sufficiently high, the automatic transmission will not be in a neutral state. Engine temperature, engine cooling water temperature, etc. can be used to detect whether the oil temperature of the automatic transmission has risen sufficiently, and the neutral state is reached after these temperatures exceed a predetermined temperature. Just try to get it. Alternatively, the wall temperature of the automatic transmission may be detected by a temperature sensor. Furthermore, in addition to the configuration of the present invention, a configuration may be adopted in which it is detected whether or not the cheese yoke is in operation so that the neutral state does not occur when the teak yoke is in operation. Furthermore, a timer can be used instead of temperature detection so that the engine can be brought to a neutral state after a predetermined period of time after starting. As described above, when the neutral state is created according to the present invention, the oil temperature of the automatic transmission is sufficiently high, and according to the present invention, the responsiveness when returning from the neutral state to the drive state, that is, the good starting feeling. Neutral control can be performed. Embodiments of the present invention will be described below with reference to the drawings. Referring to FIG. 1, there is shown a schematic diagram of an automatic transmission according to an embodiment of the present invention, which includes a torque converter 10, a first planetary gear mechanism 12, a second planetary gear mechanism 14, The rotational force of the crankshaft 16 is transferred to the torque converter 1.
0 to the output shaft 18 of the torque converter 10. The output shaft 18 is connected to a connecting shell 22 via a front clutch 20 and to an internal gear 26 of the first planetary gear mechanism 12 via a rear clutch 24. The connecting shell 22 is connected to sun gears 21 and 23 of the first and second planetary gear mechanisms. Furthermore, the connecting shell 22 is adapted to engage with the brake band 25, and when engaged, its movement is restricted. First planetary gear mechanism 1
The second planetary carrier 28 is connected to an internal gear 30 and an output gear 32 of the second planetary gear mechanism. The planetary carrier 34 of the second planetary gear set 14 is adapted to be restrained by a low and reverse brake 36 and a one-way clutch 38. Further, the internal gear 30 of the second planetary gear mechanism is adapted to engage with the parking gear 40, and when the two engage, the movement of the output gear 32 is restricted. Note that hydraulic oil is supplied to the torque converter 10 by an oil pump 42. FIG. 2 shows a hydraulic control circuit for operating each clutch and brake to obtain a required gear. In this control circuit, a pressure line 1 is connected to an oil pump 42 driven by an engine output shaft.
The pressure of the hydraulic oil discharged at 01 is adjusted by the pressure regulating valve 102 and guided to the select valve 103.
The select valve 103 has positions 1, 2, D, N, R, and P, and when the select valve 103 is in the 1, 2, and D positions, the pressure line 101 is connected to the valve 103.
It communicates with ports a, b, and c of. The port A-line 126 is connected to the actuator 104 for actuating the rear clutch 24, so that the rear clutch 24 is held engaged when the valve 103 is in the above-mentioned position. Further, port a is connected to the first governor valve 106 via the second governor valve 105, and when the vehicle speed exceeds a set value, the line 10
7, a vehicle speed signal pressure is generated. The vehicle speed signal pressure on line 107 is applied to 1-2 shift valve 108, 2-3 shift valve 109, and pressure modifier valve 122 to operate these valves according to the vehicle speed. Port c is connected to a second lock valve 111, and the pressure in line 101 is applied to the valve 111 to maintain its spool in the upper position in the figure. The pressure at port b is controlled by the second lock valve 111.
is applied to the valve 111 so that pressure from port c is applied to the valve 111.
When the valve 111 is not acting, it acts to push the spool of the valve 111 downward. Port a is further connected to the 1-2 shift valve 108 via a line 112, and a line 113 from the shift valve 108.
When the spool of the second lock valve 111 is in the upper position, the line 115 leading to the engagement side pressure chamber of the actuator 114 of the brake band 25 is
connected to. Additionally, port c is line 116
It is connected to the 2-3 shift valve 109 through
This line 116 indicates that the vehicle speed exceeds the set value by 2-3
It is connected to line 117 when shift valve 109 is actuated. The line 117 is connected to the release side pressure chamber of the actuator 114 of the brake band 25, and when hydraulic pressure is introduced into the pressure chamber, the actuator 114 moves the brake band 25 in the release direction against the pressure of the engagement side pressure chamber. Activate. Also,
Pressure in line 117 is also directed to actuator 118 of front clutch 20, causing it to engage. The select valve 103 has a port d leading to the pressure line 101 in one position, and this port d
reaches the 1-2 shift valve 108 via line 119, and further via line 120 to the low and
It is connected to the actuator 121 of the reverse brake 36. Further, the hydraulic control circuit is provided with a pressure modifier valve 122, a downshift valve 123, a throttle backup valve 124, and a vacuum throttle valve 125, but the configuration and operation of the control circuit described above are conventional. Since it is the same as a known one, detailed explanation will be omitted. In this example, a neutral valve 130 is further provided in the pressure line 126. This neutral valve 130 is a solenoid valve, and is normally in an open state.
When the solenoid 130a is energized by the signal, it cuts off the line 126 and connects the rear clutch 24 side to the drain. In the above control circuit, the relationship between the gear position and the operation of the clutch and brake is shown in the table below.

【table】

[Table] The ○× marks in the table indicate that it does not contribute to operating power transmission. Note that when pressure is introduced to both the engagement side and the release side of the brake band 25, the brake operates on the release side due to the difference in area of the actuator.
Furthermore, the 1-2 shift valve 108 and the 2-3 shift valve 109 can be configured to be electromagnetic valves, and can be operated using an appropriate electronic circuit to obtain the required gear. In this case, the governor valve 105,1
06 becomes unnecessary. Referring to FIG. 3, a control circuit for the neutral valve 130 is shown.
The solenoid 130a is connected to a power source 201 via an ignition switch 200. Further, the solenoid 130a is connected to an NPN type transistor 202, and this transistor 2
02 controls its excitation and demagnetization. The base of this transistor 202 is connected to an AND circuit 203, one terminal 203a of this AND circuit 203 is grounded via a vehicle speed switch 204 on the one hand, and a power source is connected via a resistor 205 and an ignition switch 200 on the other hand. 201. This vehicle speed switch 204 sets the vehicle speed according to a signal from the vehicle speed sensor, for example, 8 to 15 km/hr.
Closes when: 1 of AND circuit 203
One terminal 203b is connected to the accelerator switch 20 on the other hand.
6, and is connected to a power source 201 via a resistor 207 and an ignition switch 200. The accelerator switch 206, which is one of the stop operation detection sensors, is activated by the accelerator pedal and closes when the amount of depression of the accelerator pedal is zero. Terminal 203 of AND circuit 203
c is connected to the output terminal of the NOR circuit 208. One input terminal 208a of the NOR circuit 208
is grounded via a brake oil pressure switch 209, which is one of the stop operation detection sensors, and further connected to a power source 201 via a resistor 210 and an ignition switch 200. The brake oil pressure switch is, for example, a pressure switch installed in the brake oil pressure passage, and is connected when the brake oil pressure exceeds a set value.
Another terminal 208b of the NOR circuit 208 is grounded via a handbrake switch 211, which is one of the stop operation detection sensors, and is further connected to a resistor 2.
12, connected to a power source 201 via an ignition switch 200. Handbrake switch 211 is in a closed state when the handbrake is activated. Furthermore, one input terminal 20 of the AND circuit 203
3d is connected to the warm air detection circuit 213. The warm-up detection circuit 213 detects, for example, the engine temperature, and outputs a high-level signal when the engine temperature reaches a predetermined temperature or higher. Engine coolant temperature may be used instead of engine temperature. Alternatively, the wall temperature of the automatic transmission may be detected by a temperature sensor and a high level signal may be output when the wall temperature exceeds a predetermined temperature. Additionally, the check switch can be interlocked so that a low level signal is output when the check switch is in operation. Furthermore, a timer may be incorporated in the detection circuit so that the timer is activated in response to engine start-up, and a high-level signal is output from the detection circuit after the set time of the timer has elapsed. When the engine is started and under normal running conditions, the ignition switch 200 is closed and the AND circuit 2
The voltage of the power supply 201 is applied to the terminals 203a and 203b of the AND circuit 203, but since the input is inverted and inputted at a low level, the inputs of the AND circuit 203 do not match and its output is at a low level. Therefore, transistor 202 is not conductive and solenoid 130a is not energized and is not in a neutral state. Now, if the vehicle speed is below the set vehicle speed, the amount of accelerator depression is zero, and the brake oil pressure exceeds the set pressure,
Speed switch 204, accelerator switch 20
6. The brake oil pressure switches 209 are closed. As a result, the terminal 20 of the AND circuit 203
3a, 203b and the input terminal 208a of the NOR circuit 208 are lowered by voltage drops across the resistors 205, 207, 210, and are inverted and input to the AND circuit 203 and the NOR circuit 208 at a high level. Therefore, the output of the NOR circuit 208 becomes a high level, and if the signal from the warm-up detection circuit 213 is at a high level, the inputs of the AND circuit 203 match, and its output changes to a high level. As a result, the transistor 202 becomes conductive and the solenoid 1
A current flows through 30a, and solenoid 130a is energized. Therefore, the neutral valve 130 operates to cut off the line 126 and connect the rear clutch 24 side to the drain. As a result, the supply of hydraulic pressure to the rear clutch 24 of the automatic transmission is cut off, and the automatic transmission is placed in a neutral state. Note that after the engine is started, in a stopped state before starting, the handbrake switch 211 is closed, so a neutral state is similarly created. As mentioned above, in this example, the warm air detection circuit 213
Unless that signal is at a high level, the inputs of the AND circuit 203 will not match and a neutral state will not be created. In other words, the automatic transmission cannot enter the neutral state until the oil temperature in the automatic transmission has risen sufficiently to enable the automatic transmission to return from the neutral state to the drive state with good responsiveness. It is possible to maintain a good feeling when starting, and it is also favorable in terms of safety. Note that the neutral control valve 130 is connected to the pressure line 1.
01, in which case hydraulic pressure supply to all friction elements of the gear transmission mechanism is cut off. 4 to 6 show examples of program flowcharts when the present invention is implemented using a microcomputer. In FIG. 4, T _A represents the oil temperature of the automatic transmission, and T _AO represents the reference oil temperature of the automatic transmission, which is preferably about 60°C. 5 and 6 are flowcharts for carrying out the present invention using a microcomputer by other means according to the present invention. In this example, a timer is used to measure the time after the engine has started. , a neutral state can only be achieved after a predetermined period of time has elapsed. FIG. 6 shows the contents of the idle cut subflow shown in FIG. In this embodiment, a neutral state is obtained after a predetermined period of time only when the engine is started with the engine in operation.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an automatic transmission according to an embodiment of the present invention, FIG. 2 is a hydraulic control circuit diagram of the automatic transmission of FIG. 1, and FIG. 3 is a control of a neutral control valve according to the present invention. 4 is a flowchart of an embodiment of the present invention using a microcomputer, and FIGS. 5 and 6 are flowcharts of other embodiments of the invention using a microcomputer. Explanation of symbols, 10...Torque converter, 12
...First planetary gear mechanism, 20...Front clutch, 24...Rear clutch, 25...Brake band, 36...Low and reverse brake, 1
30... Neutral control valve, 200... Ignition switch, 201... Battery, 204
... Vehicle speed sensor, 206 ... Accelerator switch,
209...Brake oil pressure switch, 211...Hand brake switch, 213...Warm-up detection circuit.

Claims (1)

[Claims] 1. An automatic transmission comprising a torque converter, a planetary gear mechanism, a plurality of frictional engagement members that switch the power transmission path of the planetary gear mechanism, and a fluid actuator that operates on and off the frictional engagement members, An electromagnetic means for controlling supply and discharge of fluid to the fluid actuator, a vehicle speed sensor for detecting that the vehicle speed is lower than a set vehicle speed, and a stop operation detection sensor for detecting the operation of a device to be stopped.
After a predetermined time has elapsed since the engine was started or the oil temperature of the automatic transmission exceeds a predetermined value,
A neutral control device for an automatic transmission, comprising: a controller that issues a signal to the electromagnetic means to put the automatic transmission into a neutral state when a condition is determined under which all outputs from the two sensors are generated. .