JPS633527Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a work vehicle such as a tractor, and more specifically, the present invention includes an operating tool that can shift a hydraulic continuously variable transmission between a forward range and a reverse range; A contact-type sensor that detects the position of the engine, and a check mechanism that allows the engine to start only when the operating tool is in a neutral gear shift position based on the detection result of the sensor. Regarding work vehicles with safety devices.

In this type of work vehicle, when starting the engine, if the operator forgets to move the gear shift control tool to the neutral gear position, or if the operator makes a mistake, the gear shift device may be operated in the forward or reverse gear state. In order to prevent the aircraft from moving forward or backward unexpectedly if the engine is started while the gear is still in the position, the engine can only be started when the gear shift control tool is in the neutral gear position. Conventionally, for example, as described in Japanese Utility Model Publication No. 47-21029, a sensing part of a contact type sensor is located at the shift neutral position of the operating path of the speed change operating tool, and this sensing part and the speed change operating tool are connected to each other. Since the shift operating tool was configured to detect that it was in the neutral shift position by direct contact with the gear shift tool, there was a problem that the detection accuracy was poor.

That is, the gear shift operating tool is configured so that it can be operated continuously across the forward range and the reverse range with the gear shifting neutral position in between, and when the operating tool is operated to the gear shifting neutral position located halfway along this operating path. For example, as shown in FIG. 6, when the shift operating tool 13 comes into contact with the shift operating tool 13 that has been operated from the forward operating region F to the shift neutral position N, the shift operating tool 13 moves to the shift neutral position. When the sensor 25' is provided to detect that the gear shift operation tool 13 is operated
When the shift operation tool 13 is operated and moved from the reverse operation area R to the shift neutral position N, as shown by the imaginary line, the shift operation tool 13
sensor 2 before reaching the shift neutral position N.
5' comes into contact with the gear shift operation tool 13 and the detection is activated, not only the gear shift neutral position but also a certain range before and after the gear shift neutral position, that is, a certain range including the forward and backward gear shifting range. Even when the operating tool is operated at the same time, it is likely to be determined that the operating tool is at the neutral shift position, resulting in a problem of poor detection accuracy.

Therefore, a method of forming a groove in the guide groove of the operating tool that can be inserted only when the operating tool is accurately operated to the neutral shift position, and biasing the operating tool to engage this groove has been considered. However, the assembly of the entire device requires precision, and a biasing mechanism must be separately provided to the operating tool, resulting in an increase in manufacturing costs.

Furthermore, since the position of the operating tool is detected by direct contact with the operating tool, the mounting position of the sensor is limited, and there is a problem that there is little freedom in design.

The present invention was developed in view of the above-mentioned circumstances, and by effectively utilizing the structure that urges the operating tool to return to the neutral position, the operating position of the gear shift operating tool can be detected with high precision with a simple structure. At the same time, the purpose is to allow the mounting position of the sensor to be set relatively freely.

The characteristic structure of this invention to achieve the above purpose is as follows:
In the above-mentioned work vehicle with an engine start safety device, a swinging member that swings in opposite directions between a forward range and a reverse range between the neutral position in conjunction with the operation of the operating tool from the neutral position of gear change; a contact member that can come into contact with the swinging member via a roller; and a pressing force that urges the contact member to pass through the pivot shaft of the swinging member via the roller. the roller is pivotally supported on one of the swinging member and the abutment member, and the other is provided with a spring that imparts a
As the swinging member swings from the neutral position, the roller is rolled to move the abutment member against the biasing force of the spring, and the biasing force of the spring causes the roller to roll. forms a cam surface that causes the swinging member to return to the neutral position by rolling, thereby forming a biasing mechanism that urges the operating tool to return to the neutral shift position, and the operating tool returns to the neutral shift position. The present invention is configured to bring the sensing portion of the sensor into contact with the abutting member to detect that the operating tool is in the gear shift neutral position when the operating tool returns, and the following effects can be obtained from this configuration. play.

That is, a sensor is provided in contact with the interlocking member of the biasing mechanism that biases the operating tool to return to the neutral position, which can be easily installed at any location in the linking mechanism between the operating tool and the continuously variable transmission. Therefore, since it is configured to detect that the operating tool is in the gear shift neutral position,
Although a sensor is attached to the biasing mechanism, the sensor can be provided at a relatively arbitrary location by selecting the mounting position of the biasing mechanism.

Among the interlocking members provided in the biasing mechanism, the interlocking member is located at one end of its movement range at the neutral speed change position, and even when the speed is changed from the neutral speed position in either the forward or backward direction, one end of this movement range Since the sensor is brought into contact with the contact member that is moved from the side in the same direction to detect that the gear is in the neutral position, it has become possible to detect that the operating tool is in the neutral gear position with a simple structure and with high accuracy. .

Hereinafter, embodiments of the configuration of the present invention will be described based on the drawings.

An engine 2 is supported in a vibration-proof manner at the front of the vehicle body frame 1, and a hydraulic continuously variable transmission 5 with a cooling fan connected to the engine 2 via a shaft 3 and capable of switching forward and backward is provided at the rear of the vehicle body frame 1. A transmission unit 8 formed by connecting a reduction gear 6 and a differential gear 7 is fixedly supported, and the front and rear wheels 9, 1 are fixedly supported.
A tractor (an example of a working vehicle) is equipped with a power take-off shaft 12 for driving a working device 11 such as a mower installed between the transmission gear 5 and the
The operating system and engine start safety device are configured as follows.

The speed change operation system includes an operation pedal 13, which is an example of an operation tool, and is located at the foot of the movement section and is swingable around a horizontal axis a.
and a pivot shaft 14 of this pedal 13.
An arm 15 fixed to the transmission unit 5 and an operating arm 16 fixed to the trunnion shaft 5a in the vertical position of the transmission 5 are interlocked and connected by a rod 17, and a stay 22 connected to the transmission unit 8 has a A pair of stopper bolts 22 and 23 are provided to limit the swing range of the operating arm 16, that is, the maximum forward position and the maximum reverse position. A swinging member 18 is fixed to the pedal pivot shaft 14, and the swinging member 18
A roller 20 pivotally supported by a swinging arm type abutment member 21 that is swing-biased by a spring S is brought into contact with the V-shaped cam surface 19 formed in the cam surface 19 to elastically press it. , constitutes a biasing mechanism A that biases the pedal 13 to return to the gear shift neutral position.

The transmission device 5 increases the forward speed as the pedal 13 swings from the neutral position in a direction that displaces its front end downward, and the pedal 13 swings in a direction that displaces its backward end downward from the neutral position. As the speed increases, the reverse speed increases.

The engine starting safety device includes the pedal 13
a sensor 25 for detecting whether or not the transmission gear has been moved to a neutral position through the contact member 21; and a control lever for a belt tension type clutch 26 interposed in the transmission mechanism to the power take-off shaft 12. 27
Sensor 2 that detects whether it is in the cut operation position
8, and both of these sensors 25,
A check mechanism 29 is provided that allows the engine 2 to start only when both 28 are in the presence detection state,
It is configured.

The former sensor 25 is the contact member 21
When is in the neutral shift position, it comes into contact with this contact member 21 and is turned ON, and when the contact member 21 is in the shift position, the contact with the contact member 21 is released.
This is a switch that turns it off.

The latter sensor 28 contacts the clutch operating lever 27 and turns ON when the clutch operating lever 27 is in the disengaged operating position, and releases the contact when the clutch operating lever 27 is in the engaged operating position. This is a switch that turns OFF.

The check mechanism 29 includes an engine starting circuit 34 that includes a battery 30, a starter motor 31, a main switch 32, and a starter switch 33.
Both the sensors 25 and 28 are interposed in series connection with the starter switch 33,
It is configured.

Note that although reference numerals are written in the claims section of the utility model registration for convenience of comparison with the drawings, the present invention is not limited to the structure of the attached drawings by such entry.

[Brief explanation of the drawing]

Figures 1 to 5 show an embodiment, where Figure 1 is a partially cutaway side view, Figure 2 is an enlarged longitudinal sectional side view of the main part, Figure 3 is an enlarged cross-sectional plan view of the main part, and Figure 4 is an enlarged cross-sectional side view of the main part. The figure is an enlarged plan view of the main part, and FIG. 5 is a circuit diagram. FIG. 6 is a schematic diagram used to explain the conventional example. 5... Hydraulic continuously variable transmission device, 13... Speed change operating tool, 19... Cam surface, 14... Pivot shaft, 18...
Swing member, 20... roller, 21... contact member,
A...Biasing mechanism, S...Spring, 25...Sensor, 29...Checking mechanism, 12...Power take-off shaft, 28...Sensor, 2...Engine.

Claims (1)

[Claims for Utility Model Registration] 1. An operating tool 13 capable of shifting the hydraulic continuously variable transmission 5 between a forward range and a reverse range, and a contact for detecting that the operating tool 13 is in a neutral shift position. The sensor 25 is provided with a sensor 25 of the formula
Based on the detection result by 5, the operating tool 13
In a work vehicle equipped with an engine start safety device that is provided with a check mechanism 29 that allows the engine 2 to start only when the control tool 13 is in the neutral gear position, the neutral position is set in conjunction with the operation of the operating tool 13 from the neutral gear position. a swinging member 18 that swings in opposite directions between the forward movement region and the reverse movement region while sandwiching the swinging member 18; A spring S is provided which biases and applies a pressing force to the swinging member 18 in the direction of passing through the pivot shaft 14 via the roller 20, and the swinging member 18 and the abutting member 21 are connected to each other. the roller 20 on one of the
and on the other hand, as the swinging member 18 swings from the neutral position, the roller 20 is rolled to move the contact member 21 against the biasing force of the spring S. , and a cam surface 19 is formed that causes the roller 20 to roll by the urging force of the spring S to return the swinging member 18 to the neutral position, thereby returning the operating tool 13 to the neutral position for shifting. A biasing mechanism A is configured to force the operating tool 13 to return to the neutral shift position by bringing the sensing portion of the sensor 25 into contact with the contact member 21 when the operating tool 13 returns to the neutral shift position. A work vehicle equipped with an engine start safety device, characterized in that it is configured to detect a certain occurrence. 2. A working vehicle with an engine start safety device according to claim 1, wherein the target working vehicle is a tractor equipped with a power take-off shaft 12 for driving a working device. 3. The check mechanism 29 includes a sensor 28 that detects whether or not the operating tool 27 of the clutch 26, which is interposed in the transmission mechanism to the power take-off shaft 12, is in the cut operation position, and the sensor 25. A work vehicle equipped with an engine start safety device according to claim 2, which allows the engine 2 to start only when the detection state is detected.