JPH0512577B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a starting gear switching device for an electronically controlled automatic transmission, and particularly to one that improves gear selection during starting. [Prior Art] Conventionally, in an electronically controlled automatic transmission mounted on a vehicle such as a truck, it is disclosed, for example, in Japanese Patent Application No. 60-241866, that the starting gear can be selected by changing the driving range. ing. The driving range switching disclosed herein is, for example, as shown in the table below. <Table> Selected by switching the driving range

[Table] By the way, when starting on a flat road, starting in 2nd gear is 1 →
There is no shift time lag when switching to 2nd gear, so it is very smooth and effective, but when overloaded or starting on a steep slope, this can cause clutch slippage and wear, so it is necessary to start in 1st gear instead of 2nd gear. It is necessary to switch to . However, with the above-mentioned conventional systems, the switching is left to the driver's selection of the driving range, so if the driver is overloaded or starts or stops on a long steep slope, it is difficult to select range 2 or D5. If the clutch was left in place repeatedly, the temperature of the clutch would rise and there was a risk of problems such as slippage and wear. [Problems to be Solved by the Invention] As mentioned above, in the conventional system in which the starting gear can be selected by switching the driving range,
Since the switching is left to the selection of the driving range by the driver, there is a risk that the appropriate starting gear may not be selected depending on the driving condition, and the clutch may slip or wear due to repeated starting in second gear. There is. Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to effectively protect the clutch even when the clutch is overloaded or when an inappropriate driving range is selected for steeply climbing roads. An object of the present invention is to provide a starting gear switching device for an electronically controlled automatic transmission. [Means for Solving the Problems] The starting gear switching device for an electronically controlled automatic transmission of the present invention includes a control means that selects a starting gear to 1st speed or 2nd speed by switching the driving range of the driving range selection means; A device comprising a temperature sensor that detects the temperature of the clutch housing, and a switching means that switches the starting gear selected from the second gear to the first gear by the control means when the temperature detected by the temperature sensor exceeds a set value. It is. [Function] By switching the driving range of the driving range selection means, if the control means selects the starting gear to 2nd speed and the vehicle remains overloaded or repeatedly starts and stops on a long steep slope, the clutch housing temperature will decrease. begins to rise rapidly. This clutch housing temperature is detected by a temperature sensor, and when the clutch housing temperature exceeds a set value, the switching means is activated and the starting gear, which has been selected as 2nd gear by the control means, is switched to 1st gear. It turns out. Therefore, starting and stopping will not be repeated with the starting gear remaining in the second gear. [Example] An example of the present invention will be described below based on FIGS. 1 to 6. FIG. 1 shows an example of a starting gear switching device for an electronically controlled automatic transmission according to the present invention. Reference numeral 10 denotes a driving range selection means, which selects a neutral position N, a reverse position R, and each range position 1, 2, D3, D4, D5 of a plurality of driving ranges by operating the chain lever 5. D3,
When either of the range positions D4 and D5 is selected, the selection information guided to the control circuit 20 is transferred to the selected gear range preset by the range position (e.g. In the above-mentioned table), the optimum gear to be selected according to the operating condition is determined by calculation. The gear selection command, which is the calculation result, is sent to the control circuit 20.
In addition to a transmission (for T/M) actuator 40, the actuator 40 operates a clutch 50 and operates a T/M 60 to automatically change gears. Note that for the range positions 1 and 2, the neutral position N, and the reverse position R, gears are switched based on gear selection commands that correspond one to one. As described above, the control circuit 20, the T/M actuator 40, etc. described above constitute the control means of the present invention. Further, a display command is applied to the display device 70 from the control circuit 20, so that the range selected by the driving range selection means 10 and the gear position actually switched are displayed on the display device 70. . In an automatic transmission system with such a configuration,
A temperature sensor 80 is attached to the clutch housing 51 to detect the temperature thereof. As the temperature sensor, a temperature switch 81 as shown in the illustrated example that turns on when the temperature exceeds a set value _T2 , or a thermistor that continuously detects a temperature rise is suitable. Furthermore, when the temperature detected by the temperature sensor 80 exceeds a set value, a switching means is provided for switching the starting gear selected by the control means from the second gear to the first gear. Although this switching means 21 can be provided outside the control circuit 20, it is appropriate to use the arithmetic unit 22 within the control circuit 20 as shown in the illustrated example. In addition, 23 is an A/D converter, 24 is an I/O
25 is a drive circuit, and 90 is an engine. In this way, the present starting gear switching device is constructed by adding the temperature switch 81 and the switching means 21 to the existing automatic transmission system. The control circuit 20 has various functions shown in the flowchart of FIG. In other words, it is determined whether the vehicle speed is greater than a predetermined value _S1 , and if it is, it is assumed that there is no need to perform this control and the vehicle immediately exits the flow, but if it is not, it is time to start, where this control is required. enters this flow, and the driving range is D5,
Add judgment of 2 or D4, D3, 1. D4,
When D3,1, a gear selection command to shift the starting gear to 1st speed is output, and a display command to set the gear position display to "1" is output. When D5, 2, it is further determined whether the clutch housing temperature switch 81 is ON or OFF, and if it is ON, the starting gear should be shifted from 2nd gear to 1st gear, and the driving range is D4, D3, 1. Proceed to the first gear shift, which is the same step taken at the time.
On the other hand, when it is OFF, a 2nd gear selection command is output without changing the starting gear, which is currently 2nd gear, and a display command to set the gear position display to "2" is output. Here, when determining the clutch housing temperature, when using a thermistor instead of a temperature switch, it is necessary to determine the temperature T ₀ before exceeding the set value T ₂ .
When the temperature from T ₀ to _{T 2} is detected from T 0 to just before the set value, D4, D3, D3,
Outputs a blinking command to blink 1. By the way, in the case of vehicles, especially trucks, if the vehicle is started repeatedly on a hill in second gear for a long period of time in a constant load state, the clutch facing temperature will rise rapidly.
It is known that the temperature of the clutch housing 51 increases accordingly. Figure 3 shows the temperature rise of the clutch facing and clutch housing when the start-stop cycle shown in Figure 4 is repeated for a long period of time, and it can be seen that there is a large difference compared to that on a flat road. . Therefore, a temperature switch having switching characteristics as shown in FIG. 5 is attached to the clutch housing 51, and the clutch housing temperature is set to a set value _T2 such that the clutch facing temperature increases, causing slippage and wear. If you set it as , when the temperature switch is turned on,
This means that a limit can be detected where repeated rapid starts can cause damage to the clutch. Now, switching of the starting gear in the above-mentioned configuration will be explained below with reference to the case shown in FIG. Initially, when the vehicle speed decreases and reaches S ₂ while driving in 3rd gear or higher, the control circuit 20 switches the T/M
control the actuator 40 for T/M60.
Shift down quickly. When the vehicle speed further drops to S ₁ , the clutch housing temperature switch 8
If 1 is ON (temperature is _T2 or higher), it will shift down to 1st gear instead of holding it in 2nd gear, so
This prevents the clutch temperature from rising when starting. When temperature switch 81 is OFF, D4, D3,
The normal starting gear is selected not only in the 1st range, but also in the D5 and 2nd ranges. As mentioned above, in this example, the set value is T ₂
A temperature switch 81 set at
When the temperature switch 81 is ON, that is, when the clutch housing temperature exceeds the set value, the starting gear is changed from 2nd gear only in the 2 or D5 range. Since the system switches to 1st gear, it is possible for the driver to select the wrong range when overloaded or starting on a steep slope.
Even if you repeat the cycle in the D5 range, there is no risk of fatal problems with the clutch such as slipping or wear due to increased clutch temperature. Therefore, slippage and wear of the clutch can be effectively prevented even when driving in traffic jams on long steep uphill roads such as the Hakone Turnpike or Irohazaka. In addition, if a thermistor is used instead of a temperature switch so that D4, D3, and 1 on the range display on the display device flash when the temperature rise approaches the set value, the driver may experience problems. Since it is possible to detect this in advance and prompt the driver to select the first gear start, it is possible to more effectively prevent clutch slippage and wear. [Effects of the Invention] In summary, according to the present invention, the starting gear selected as 2nd gear is switched to 1st gear when the clutch housing temperature exceeds a set value. Even if the vehicle starts and stops repeatedly on a steeply ascending slope, it is no longer necessary to drive with the starting gear set to 2nd speed, and slippage and wear of the clutch can therefore be effectively prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a starting gear switching device for an electronically controlled automatic transmission according to an embodiment of the present invention, FIG. 2 is a flowchart explaining various functions of the control circuit shown in FIG. 1, and FIG. A temperature characteristic diagram of the clutch casing and clutch housing that appears when starting and stopping are repeated, using uphill roads and flat roads as parameters. Figure 4 is an explanatory diagram of the starting and stopping cycle that is the condition for the characteristics shown in Figure 3. , FIG. 5 is a switching characteristic diagram of the temperature switch shown in FIG. 1, and FIG. 6 is an explanatory diagram showing the process in which gears are changed according to the flowchart shown in FIG. 2. In the figure, 10 is a driving range selection means, 20 is a control circuit, 21 is a switching means, 51 is a clutch housing, 60 is a transmission, 70 is a display device, and 80 is a temperature sensor.

Claims (1)

[Scope of Claims] 1. A control means for selecting the starting gear to 1st or 2nd speed by switching the driving range, a temperature sensor for detecting the temperature of the clutch housing, and a control means for controlling the starting gear when the detected temperature exceeds a set value. A starting gear switching device for an electronically controlled automatic transmission, comprising a switching means for switching a starting gear selected as second speed to first speed. 2. Claim 1, wherein the control means has a display means for displaying the switched driving range, and is configured to blink the display on the display means before the detected temperature exceeds a set value. The starting gear switching device described.