JPH0627459Y2 - Front wheel drive switching detector for 4-wheel drive tractor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a front wheel drive switching detection device for a four-wheel drive tractor.

(Prior Art) In a four-wheel drive tractor, a detector that moves in a front wheel steering system detects that the front wheel has exceeded a predetermined turning angle, and responds to this detector during turning to determine the drive speed of the front wheel. It is provided with a speedup.

This has the advantage that the front wheels do not resist when turning, there is no earth pushing by the front wheels, and the turning radius can be reduced.

(Problems to be solved by the invention) However, the conventional detector mechanically detects the movement of the drag link in the front wheel steering system and operates the switching valve of the front wheel drive system in an interlocked manner. Therefore, there is a problem that the mechanism is complicated and the durability is deteriorated due to abrasion.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and an object thereof is to make it possible to reliably detect the turning angle of the front wheel by a non-contact method with a simple configuration.

(Means for Solving the Problems) As a means for solving the problem, the present invention detects that the front wheel 5 has become a predetermined turning angle or more by the detector 38, and responds to this detector 38, the front wheel 5 at the time of turning. In a front wheel drive device for a four-wheel drive tractor configured to increase the drive speed of the front wheel, one of the front wheel steering system 8, 9, 13, 15 for operating the front wheels 5 and the fixed side facing the front wheel steering system A member to be detected 36 is provided, and on the other hand, a detector 38 for contactlessly detecting the presence or absence of the member to be detected 36
Is provided.

(Operation) During normal driving, power is transmitted to the front wheels 5 through the low speed gear system 25, and the front wheels 5 are slightly faster than the front and rear wheels.
It is driven by 5/6 four-wheel drive.

When turning, the front wheel case 9 and front wheel 5 are kingpin 12
It turns around. At this time, when the front wheels 5 rotate over a predetermined turning angle, the detected member 36 is disengaged from the detector 38, and it is detected that the turning angle is exceeded, so the solenoid valve 35 operates to the high speed side, and , The power to the front wheels 5 is high speed gear system 26,
This is transmitted through the high speed clutch 32, and the front wheels 5 rotate at a speed twice as high as that of the rear wheels 6.

(Embodiment) The present invention will be described in detail below with reference to the illustrated embodiment.
In FIG. 4 and FIG. 4, reference numeral 1 denotes a tractor vehicle body, which includes an engine 2, a clutch housing 3, a transmission case 4, and the like, and has front wheels 5 and rear wheels 6. 7 is the hood, 8
Is a handle.

The front wheel 5 is supported by the front wheel case 9 via a hub shaft or the like,
The front wheel case 9 is a gear case at both ends of the front axle case 10.
It is rotatably supported around the king pin 12 on 11. The left and right front wheel cases 9 can be steered around the kingpin 12 via a tie rod 14 by a hydraulic cylinder 13 installed in parallel with the front axle case 10. The front wheel case 9 has a kingpin on the gear case 11.
A front wheel case support 15 fitted to a shaft portion 14 formed coaxially with 12 is provided. The front axle case 10 is swingably supported on the Tokurata vehicle body 1 via a center shaft 16 and a bracket 17. Also handle 80, hydraulic cylinder
13, the front wheel case 9, the front wheel case support 15 and the like constitute a front wheel steering system for steering the front wheels 5. 18 is a driver's seat.

In the mission case 4, as shown in FIG. 5, a main traveling transmission 20, which is interlocked with the engine 2 via a clutch 19,
A traveling auxiliary transmission device 21, a rear wheel diff device 22, etc. are built in, and the rear wheel diff device 22 is interlocked with each rear wheel 6 via a final reduction gear device 23. In addition, below the transmissions 20 and 21, the traveling auxiliary transmission 21
A transmission shaft 24 that is interlocked with the output side of and a transmission shaft 27 that is interlocked with the transmission shaft 24 via a low speed gear system 25 and a high speed gear system 26 are provided in parallel. The transmission shaft 27 projects forward from the power take-out case 28 mounted on the lower abdomen of the mission case 4, interlocks with the front wheel differential device 29 in the front axle case 10, and connects the final reduction device 30 from the front wheel differential device 29. The front wheels 5 are interlocked with each other. Low speed gear system 25 and high speed gear system 26
Can be selectively connected to the transmission shaft 27 by a low speed hydraulic clutch 31 and a high speed hydraulic clutch 32, and each hydraulic clutch 31, 32 is controlled by a solenoid valve 35 having a low speed solenoid 33 and a high speed solenoid 34. In addition, low-speed gear system 25
Indicates that the peripheral speed of the front wheels 5 is slightly higher than that of the rear wheels 6, and the peripheral speed of the front wheels 5 of the high speed gear system 26 is 2 times that of the rear wheels 6.
It is set to double each.

As shown in FIGS. 1 and 2, the front wheel case support 15 is provided with a fan-shaped plate-shaped member 36 to be detected made of a magnetic material.
A detector 38 that is attached by 37 and that detects the presence or absence of the detected member 36 in a contactless manner is fixed to a flange portion 39 at one end of the front axle case 10 via a mounting plate 40 and a bolt 41. The detector 38 has a U-shaped holder 42 and a member to be detected 36
The magnet 43 and the reed switch 44 are incorporated so as to sandwich the magnet from above and below. Since the detected member 36 is also used for detecting the left and right turning angles of the front wheel 5, the angles α and β are different at the front and rear. That is, in the embodiment, since the detected member 36 is present in the front wheel case support 15 on the left side in front view, the angle β on the rear side is
Is set so that the detection of the cutting angle is the same for both the left and right sides.

FIG. 6 shows an electric circuit for controlling the solenoids 33 and 34 of the solenoid valve 35. 45 is a battery, 46 is a main switch, 47 is a fuse, 48 is a three-way selector switch, and two-wheel drive contact 48
It has a, its low speed contact 48b, and high speed contact 48c, and the coil 38 of the detector 38 and the relay 49 is connected to the high speed contact 48c. The relay 49 has a contact 51 connected to the low speed contact 48b, and when the coil 50 is energized, the low speed solenoid 33
To the high speed solenoid 34. 52
・ 53 is a diode for protection.

In the above structure, the changeover switch 48 is set to the two-wheel drive contact
If it is connected to a, the solenoids 33 and 34 are not energized, so the solenoid valve 35 remains neutral and the hydraulic clutches 31 and 32 remain disengaged. Therefore, the power is not transmitted to the front wheel 5 side via the gear system 25 or 26, and only the rear wheel 6 is driven by two wheels.

During normal four-wheel drive, change the switch 48 to the low speed contact 48.
Connect to b. Then, the low speed solenoid 33 of the solenoid valve 35 is excited via the contact 51, and the solenoid valve 35 is switched to the low speed side. Therefore, the low speed hydraulic clutch 31 is connected, and the power is transmitted to the front wheel 5 side via the low speed gear system 25. Transmitted. Therefore, the front wheels 5 rotate at a slightly higher speed than the rear wheels 6, and the front and rear wheels 5 and 6 are driven by four wheels.

When the handle 8 is operated during turning, the hydraulic cylinder 13
The left and right front wheels 5 are steered around the kingpin 12. For example, in the case of a right turn, when the front wheel 5 is cut off as shown by the chain double-dashed line in FIG.
36 rotates in the direction of arrow A in FIG. And angle B
When the member 36 to be detected rotates only and the trailing edge of the member 36 comes off between the magnet 43 of the detector 38 and the reed switch 44, the reed switch 44 is placed in the magnetic field of the magnet 43, and the reed switch 44 is It is turned on to detect that the front wheels 5 have reached a predetermined turning angle. Therefore, a current flows through the coil 50 of the relay 49,
Since the contact 51 is switched to the high speed solenoid 34 side, the solenoid valve 35 operates to the high speed side, the low speed hydraulic clutch 31 is disengaged, and the high speed hydraulic clutch 32 is engaged at the same time. As a result, the front wheels 5 rotate at a peripheral speed almost twice that of the rear wheels 6.

If you make a sharp turn with a work machine with a large amount of overhang attached to the tractor, there is a risk of falling or the like, which is dangerous. Therefore, as shown in FIG. 8, the rotation speed of the high-speed gear system 26 is detected by the pulse detector 54, and when the rotation speed is equal to or higher than a certain vehicle speed via the switch circuit 55, the detector 38 and the relay 49.
If the circuit is turned off, a sudden turn at high speed can be prevented even if an erroneous operation is performed. In particular, this has the advantage that the actual vehicle speed can be controlled.

The detector 38 may be a combination of a magnet 43 and a pickup coil, or the like. The reed switch 44 is a contact type, but if a pickup coil is used, it can be a non-contact type and the durability is further improved. Further, the member to be detected 36 and the detector 38 may be mounted opposite to each other, and as long as they are a portion which rotates by steering and a fixed side, these may be attached to anything, and are not limited to the embodiment. is not.

(Comparative Example) FIG. 9 shows a comparative example. When the steering system is an all-hydraulic system consisting of the controller 56 and the hydraulic cylinder 13 which are interlocked with the steering wheel 8, the pressure switches 59 and 60 are installed in the conduits 57 and 58 connecting the controller 56 and the hydraulic cylinder 13, respectively, and the front wheels The pressure increase in pipe 57 when 5 is cut to the limit is detected by pressure switch 59 or 60.
It is possible to energize the coil 50 of the relay 49 when the switch 60 is turned on. In addition, 61 is an oil tank and 62 is a pump.

However, since this requires expensive pressure switches 59 and 60, there is a problem in manufacturing cost.

According to the present invention, the detected member 36 is provided on one side of the front wheel case 9 above the kingpin 12 and on the front axle case 10 side, and the presence or absence of the detected member 36 on the other side. Since the detector 38 is provided so as to detect contactlessly, one of the detected member 36 and the detector 38 rotates around the kingpin 12 in correspondence with the cutting angle of the front wheel 5, and the other is concerned with the cutting angle. In order to maintain the fixed state without detecting the relative movement position of the detected member 36 by the detector 38, the turning angle of the front wheel 5 can be easily and surely detected. It is structurally very simple to construct, has excellent durability, and can be implemented at extremely low cost.

[Brief description of drawings]

1 to 7 exemplify one embodiment of the present invention, in which FIG. 1 is an enlarged front view of a main part, FIG. 2 is a plan view of the same, and FIG. 3 is a side view of a tractor. FIG. 4 is a sectional front view of the front wheel support portion, FIG. 5 is a configuration diagram of a power transmission system, FIG. 6 is an electric circuit diagram, FIG. 7 is an operation explanatory diagram, and FIG. 8 is another embodiment. The electric circuit diagram shown in FIG. 9 is a configuration diagram showing a comparative example. DESCRIPTION OF SYMBOLS 1 ... Tractor body, 5 ... Front wheel, 6 ... Rear wheel, 8 ... Steering wheel, 9 ... Front wheel case, 10 ... Front axle case, 36 ... Detected member, 38 ... Detector.

Claims (1)

[Scope of utility model registration request] 1. A front wheel case 9 is rotatably supported by a front axle case 10 around a kingpin 12, and the front wheel 5 is steered around the kingpin 12 through the front wheel case 9 so that the front wheel 5 has a predetermined turning angle or more. It is detected by the detector 38 that this
In a front wheel drive device of a four-wheel drive tractor adapted to increase the drive speed of the front wheels 5 in response to 38 when turning, a front wheel case 9 above the kingpin 12 and a front axle case 10 are used.
A front wheel drive of a four-wheel drive tractor characterized in that a member to be detected 36 is provided on one of the sides and a detector 38 is provided on the other side so as to detect the presence or absence of the member to be detected 36 without contact. Switching detection device.