JP2673806B2 - Automatic transmission for wheel loader - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic transmission for a wheel loader. (Prior Art) Generally, a wheel loader excavates the ground with a bucket,
So-called loading work to load it into a dump truck,
It is roughly divided into so-called running such as movement between sites. In order to shorten the loading work time and traveling travel time, the following operation is required. The loading work is typified by a pattern called V shape operation, but based on the second gear, downshifting to the first gear only during excavation,
The maximum speed is 21st shift change up to the 2nd speed. In addition, in order to drive the vehicle, the second speed is used as a base to sequentially shift up according to the vehicle speed, and all speeds are effectively used 1234.
Fast shift change. And this V shape operation (operations I to V indicated by arrows)
In order to minimize the working time, the following operation is required. That is, referring to FIG. 4, the wheel loader a is moved forward at the second forward speed (F2) toward the natural rock b at a high speed (operation I), and when it approaches the natural rock b (0.5 m to 1.0 m). , In order to increase the traction force when performing excavation work, plunge into the natural ground b at the first forward speed (F1) (operation II). When the excavation is completed, the wheel loader a is moved backward from the excavation work position in the second reverse speed (R2) (operation III), and then the traveling direction of the wheel loader a is changed to approach the dump truck c at high speed by F2 (operation I
V). When the loading operation on the dump truck c is completed, the dump truck c leaves at a high speed at R2 (operation V). However, the present applicant has already proposed an automatic transmission that automatically shifts the transmission speed stage during the above-mentioned work. In that case, at the time of starting and running after the F and R switching (driving I, III, It is always in the 2nd speed in IV and V), and is downshifted to the 1st speed only when the vehicle speed falls below the set vehicle speed during excavation (operation II). (Problems to be Solved by the Invention) (1) As described above, the automatic shifting of the wheel loader requires the working and traveling two modes and the switching thereof. On the other hand, in automatic gear shifting of passenger cars and the like, the upper limit of the automatic gear shifting range is restricted by the shift position of the shift lever. For example, when the 2nd speed of the range lever is selected, the shift is 12, and when the 4th speed (D range) is selected, the 1234th speed is set. However, it is good if all selections including R (reverse) can be selected by one lever like a passenger car, but because FR is frequently switched like a wheel loader, the directional lever and range lever are separate, that is, two. Alternatively, even in the case of one, the directional lever needs to be operated in the front-back direction and the range lever must be operated in the rotational direction. In this case, when switching between FR and operating the directional lever, the range lever was accidentally moved and the intention was to set it to 2nd speed, but it was 1st speed, so the vehicle speed did not increase, or it was 4th speed. There is a problem that the rhythm gets out of order because the vehicle speed is too fast and the operator feels and shifts. On the other hand, since it is necessary to select the speed stage in advance according to the work, from the running to the work, 4 → 2 speed,
From work to travel, operations such as 2 → 4 speed work and traveling combined work become complicated, which leads to forgetting to change the shift change. For example, the driving mode (12
When the V shape work is started in 34), it originally plunges into the ground at the 2nd speed and drops at the 1st speed and digs at the 3rd speed while excavating, so the rhythm is broken and the load cannot be loaded smoothly. Also, when loading a dump truck, the vehicle enters the third or higher speed,
Since the vehicle speed is too high and the boom cannot be raised in time, the vehicle may be stopped in front of the dump truck and wait for the boom to rise to the loadable height. As a result, the work is not performed efficiently and the operator is tired. (2) As shown in (1) above, it is necessary to switch between the working mode and the traveling mode, but in the case of work → traveling (2nd speed → 4th speed), at most the 2nd speed Vehicle speed of 4
Even if the range is extended to speed, there is no problem because the vehicle speed will be increased sequentially according to the vehicle speed conditions for automatic shifting, but in the case of running → work (4th speed → 2nd speed), high speed driving of 3rd and 4th speed When the engine is switched, the speed will be reduced to the second speed instantly by switching, the engine will overrun, the engine will be damaged, and the vehicle will be suddenly braked, and the operator will be skipped forward. Receive a sudden shock. An object of the present invention is to solve the above problems. (Means and Actions for Solving Problems) The present invention has been made in view of the above-mentioned points, and based on a signal indicating a speed stage, the speed stage of the transmission is electrically connected to the speed stage indicated by the signal. In an automatic transmission of a wheel loader that employs an electric transmission control that changes gears, for a work mode in which automatic transmission is performed between 1st speed and 2nd speed, and in a traveling mode where automatic transmission is performed between 1st speed, 2nd speed, 3rd speed and 4th speed When a switch for switching between the automatic shift range of the mode and that of the mode is provided at the knob of the working machine lever or at the front end of the wrist rest, and the switch is connected to the position detection circuit of the controller to operate the switch during high speed running. The speed range is selected according to the vehicle speed at that time, and the work mode is entered when the speed falls below the set speed. It is equipped with a notification means to prevent malfunction during switching when moving forward and backward, simplify operation, reduce fatigue, and eliminate shock and engine overrun at high speed switching. . (Example) Next, an example of the present invention will be described with reference to the drawings. FIG. 1 (a) is an outline of a vehicle to which the present invention is applied,
1 shows a wheel loader that employs an electric transmission control that electrically shifts the speed stage of a transmission to the speed stage indicated by the signal based on the signal indicating the speed stage. FIG. 1 (b) shows the arrangement of the driver's seat lever in FIG. 1 (a). In these figures, 1 is a directional lever, 2
Is a range lever (collectively referred to as the T / M shift lever), which detects the position by turning the contacts ON and OFF. 3 is a steering wheel. Reference numeral 5 is a limited auto switch, which is an important point of the present invention, and is attached to the knob of the boom lever 4 or the front end of the wrist rest 6 and detects the ON state by ON / OFF of the contact. Reference numeral 7 denotes an operator seat, and the seats 1 to 7 are arranged in the driver's seat as shown in FIG. 1 (b). FIG. 2 is a block diagram showing the configuration of the controller.
In the figure, the directional position detection sensor 1 ', the accelerator pedal position detection sensor 3', which is the input side, the auto,
The manual changeover switch 4 and the limited auto switch 5 are connected to the ON-OFF detection circuit 11 of the controller 9, and the position or ON state is detected by ON-OFF of the contacts. Similarly, the vehicle speed detection sensor 6'and the engine rotation sensor 7'on the input side are connected to the rotation detection circuit 12 of the controller 9. The controller 9 is provided between the detecting means and switches on the input side and the T / M shift solenoid valve 8 and the buzzer or lamp 10 on the output side. In addition to having circuits 11 and 12, a CPU 14, a program memory 15, a T / M shift solenoid valve drive circuit 16 and a buzzer or lamp drive circuit 17
In addition, an appropriate setting signal calculated by the CPU 14 based on each input signal is provided as an output to the T / M shift solenoid valve 8 and the buzzer or lamp 10. In the present invention, as described above, the left hand has the steering handle and the right hand has the work implement lever, so that the changeover switch between the working mode (12th speed) and the traveling mode (1234th speed) is used. By attaching the to the knob of the boom lever or the front end of the wrist rest, the operation is simplified and operator's fatigue is reduced. FIG. 3 shows the operation in a flowchart.
A so-called manual shift is performed in which the speed is selected by the position of the range lever 2 in the automatic mode or the manual mode by the automatic manual changeover switch 4 '. (Refer to A) In the case of auto, automatic shift is performed as in B, and upshift or downshift is performed depending on the vehicle speed. As for A and B, there is no difference from the conventional one. The present invention is characterized in that a portion (function) indicated by X is added. The first mode (working mode) for automatically shifting between first and second forward speeds and forward and reverse speeds and forward and reverse speeds The second mode (running mode) for automatically shifting between the first and fourth speeds can be switched by the limit switch. High-speed running in the second mode (3rd and 4th gear)
When the changeover switch 5 is operated to the first mode, the speed stage is selected according to the vehicle speed at that time, and the first mode is set when the vehicle speed becomes equal to or lower than the set vehicle speed. Further, after the changeover switch 5 is operated, the warning buzzer or the warning lamp 10 is operated until the first mode is set, that is, until the gear is automatically downshifted to the second speed. Therefore, according to this embodiment, when working, the left hand has the steering handle 3 and the right hand has the work implement lever 4 (boom lever or bucket lever) (or is on the wrist rest 6), Working mode (1
2nd speed (limited auto) and running mode (12
By attaching the changeover switch 5 for the 34th speed (full automatic) to the nose of the boom lever 4 or the front end portion of the wrist rest 6 as described above, it is possible to prevent malfunction of the directional lever 1 at the time of FR switching. By eliminating the mode switching by the range lever 2 and simplifying the operation, the operator's fatigue can be reduced. When the speed stage is other than the 1st and 2nd speeds, and the 3rd and 4th speeds, the work mode is set only when the vehicle speed at the time of switching is equal to or lower than the settable vehicle speed. When the vehicle speed is lowered by braking or the like to reach the set vehicle speed, the work mode is switched to. In addition, during this time, "Because the vehicle speed is high, I can not enter the work mode,
To warn you that you need to slow down the vehicle,
The buzzer or the lamp 10 is turned on (blinking) to notify the operator to that effect. When the work mode is once entered, the run mode is not returned unless the changeover switch 5 is pressed again. In this way, even if the switches are switched during high-speed running, the instantaneous engine will not be overrun and damaged, or the vehicle will not be suddenly braked and shocked. No discomfort. The invention can be applied not only to an automatic transmission but also to an automatic transmission and a manual combined vehicle. (Effects of the Invention) The present invention is configured as described above in detail. When working, the left hand has the steering handle and the right hand has the work implement lever, and the work mode and traveling mode changeover switch is operated. By attaching the knob of the machine lever or the front end of the wrist rest, the operation is facilitated and simplified, so that it is possible to prevent operator's malfunction and reduce fatigue. In addition, the present invention completely eliminates the problem of causing a discomfort to the operator by causing a downshift at the time of a dumping approach, causing a sudden braking due to the downshift, and spilling the load. Therefore, smooth work can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a schematic view of a vehicle to which the present invention is applied, FIG. 1 (b) is a layout view of a driver's seat lever of FIG. 1 (a), and FIG. FIG. 3 is a block diagram of the configuration of the controller of the present invention, FIG. 3 is an operation flowchart of the present invention, and FIG. 4 is an explanatory diagram showing an operation pattern of a work for excavating a wheel loader to a dump truck. 5 …… Limited auto switch 8 …… T / M shift solenoid valve 9 …… Controller 10 …… Buzzer or lamp 11 …… ON / OFF detection circuit 12 …… Rotation detection circuit, 14 …… CPU 16 …… T / Solenoid valve drive circuit for M shift 17 ... Buzzer or lamp drive circuit

Claims (1)

(57) [Claims] In a wheel loader automatic transmission that employs an electric transmission control that electrically shifts the speed stage of a transmission to the speed stage indicated by the signal based on the signal indicating the speed stage, A switch for switching between the two automatic shift ranges is provided on the knob of the working machine lever or the front end of the wrist rest, and the switch is connected to the position detection circuit of the controller. The automatic transmission for a wheel loader is characterized in that it is equipped with an alarm means for selecting a speed stage according to the vehicle speed of the vehicle, shifting to a working mode when the speed becomes lower than a set speed, and warning the operator during this period. .