JP3017638B2 - Work vehicle speed detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the speed of a working vehicle provided with a hydrostatic continuously variable transmission.

[0002]

2. Description of the Related Art A vehicle speed detecting device for a working vehicle as described above detects an operating angle of a trunnion shaft of a hydraulic pump amplified by a sector gear by a vehicle speed sensor comprising a rotary potentiometer via a pickup gear. Structured ones are commonly used. However,
In the hydrostatic continuously variable transmission, the hydraulic oil becomes pulsating due to its configuration and the trunnion shaft vibrates with the pulsation. If the vehicle speed detecting device is configured as described above, the trunnion shaft The vibration of the vehicle speed is transmitted to the vehicle speed sensor as it is, causing problems such as abnormal wear inside the vehicle speed sensor and detection of an abnormal value by the vehicle speed sensor. Therefore, conventionally, for example, as shown in FIG. 6, the above-described disadvantage is solved by interposing a coupling 40 configured to be able to absorb vibration between the pickup gear 38 and the vehicle speed sensor 39. Things have been suggested. [See Japanese Patent Application No. 6-60539]

[0003]

However, if the vehicle speed detecting device is configured to be able to absorb vibrations as in the above-mentioned prior art, the structure of the vehicle speed detecting device becomes complicated and the manufacturing cost increases. There is room for improvement in simplifying the structure and reducing manufacturing costs. Further, when the vehicle speed is controlled by detecting the operation angle of the trunnion shaft of the hydraulic pump, the operation of the trunnion shaft is affected by the operating efficiency of the hydraulic pump and the hydraulic motor constituting the hydrostatic continuously variable transmission. Since the vehicle speed based on the detection value from the vehicle speed sensor for detecting the angle is different from the actually obtained vehicle speed, there has been a problem that accurate vehicle speed control cannot be performed. For example, in a working vehicle equipped with a hydrostatic continuously variable transmission that is independent of the left and right traveling devices, even if the operation angles of both trunnion shafts detected by the vehicle speed sensor are the same, Due to the effect of the operating efficiency of the hydraulic pump and the hydraulic motor that constitute the hydrostatic continuously variable transmission, a difference occurs between the actually obtained vehicle speeds of the left and right traveling devices, resulting in inconvenience such as poor straight-line performance. I was

[0004] It is an object of the present invention to avoid inconveniences such as abnormal wear inside the sensor and detection of abnormal values of the sensor due to vibration of the trunnion shaft, and to be affected by the operating efficiency of the hydraulic pump and the hydraulic motor. It is an object of the present invention to provide a vehicle speed detecting device of a working vehicle including a hydrostatic continuously variable transmission that can perform vehicle speed control with high accuracy.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, a brake disk is shiftably fitted via a spline to a rotor incorporated in a hydraulic motor of a hydrostatic continuously variable transmission, and a spline is provided. A rotation detection sensor that detects the spline as a gear for detecting the number of rotations,
It was provided facing the spline.

[0006]

According to the present invention, the spline formed in the rotor of the hydraulic motor is used as a gear for detecting the number of revolutions, and the actual number of revolutions of the hydraulic motor is directly detected by a rotation detection sensor opposed to the spline. Therefore, it is possible to avoid inconveniences such as abnormal wear inside the sensor due to vibration of the trunnion shaft and detection of an abnormal value of the sensor as in the case of detecting the operation angle of the trunnion shaft of the hydraulic pump. There is no difference between the vehicle speed based on the detection value from the rotation detection sensor and the actually obtained vehicle speed due to the influence of the operating efficiency of the pump and the hydraulic motor. Further, thereby, in the working vehicle having the hydrostatic continuously variable transmission independent of the left and right traveling devices, the hydraulic motors provided in the respective hydrostatic continuously variable transmissions are completely synchronized. Therefore, the straight running performance of the working vehicle can be improved. Furthermore, there is no need to provide a member for absorbing vibration as in the case of detecting the operation angle of the trunnion shaft of the hydraulic pump, and the spline for fitting the brake disc is also used as a gear for detecting the number of revolutions. Since it is not necessary to newly provide a gear for detecting the number of revolutions, the configuration can be simplified and the manufacturing cost can be reduced. In addition, since the rotation detection sensor is of a non-contact type facing the spline of the rotor and is built in the hydraulic motor, the durability can be improved. .

[0007]

Thus, according to the present invention, it is possible to avoid inconveniences such as abnormal wear inside the sensor and abnormal value detection of the sensor due to vibration of the trunnion shaft, and to improve the operating efficiency of the hydraulic pump and the hydraulic motor. It has become possible to provide a vehicle speed detection device for a working vehicle including a hydrostatic continuously variable transmission that can perform accurate vehicle speed control without being affected by the influence.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a wireless remote-controlled mower as an example of a working vehicle will be described below with reference to the drawings.

As shown in FIG. 1, this mowing machine is a Frehler mower type as an example of a working device which is suspended and supported at the front of a traveling machine body 1 via a link mechanism 2 and a lift arm 3 so as to be able to move up and down. , A pair of left and right crawler-type traveling devices 5 provided on the traveling body 1, an engine 6 mounted on a rear portion of the traveling body 1, a control device 7 disposed on the right front of the engine 6, and the like. ing.

Each of the right and left crawler type traveling devices 5 includes a track frame 5A, a drive sprocket 5B provided at the rear end of the track frame 5A, a tension wheel 5C provided at a front end of the track frame 5A, a drive sprocket 5B and a tension wheel. 5C, a plurality of idler wheels 5D, and a driving sprocket 5B and a tension wheel 5B.
And a crawler belt 5E wound around C and the like, and are hydraulically driven by a hydrostatic continuously variable transmission 8 provided for each of them.
As shown in FIG. 2, the left and right hydrostatic continuously variable transmissions 8
Are configured to drive respective fixed displacement hydraulic motors M for driving the left and right crawler traveling devices 5 by hydraulic oil from a variable displacement hydraulic pump P driven by an output shaft 6a of the engine 6. As shown in FIG. 1, the trunnion shafts 9 and 10 of the respective variable displacement hydraulic pumps P are rotated to change the swash plate angle (not shown) so that the forward / reverse movement is steplessly changed. I can do it.

As shown in FIG. 3, the fixed displacement hydraulic motor M is provided with the track frame 5 with the horizontal axis X.
A, a substantially cylindrical main body case 11 connected and fixed to the outer surface of A
, A valve block 12 incorporating a relief valve and the like
Are connected and fixed to each other to form a driving chamber 13, and a rotating shaft 14 having a horizontal axis X as an axis is suspended in the driving chamber 13. A rotor 16 having a plurality of axial plungers 15 arranged along the circumferential direction is spline-fitted to the rotating shaft 14. A swash plate 17 for receiving a shoe 15 a pivotally supported on the tip of the plunger 15 is fixed to the inner side surface of the main body case 11. On the outer side of the main body case 11, a rotatable case 19 is fitted via a bearing 18 so as to be rotatable around a horizontal axis X. The driving sprocket 5B of the crawler type traveling device 5 is mounted on the rotatable case 19. They are connected so as to be able to rotate together. An output shaft 20 having a horizontal axis X as an axis is rotatable integrally with the rotating shaft 14, and the main body case 11
The output shaft 20 and the rotary case 19 are interlocked via a planetary gear type reduction mechanism 21 housed in the rotary case 19.

A brake disk 22 is fitted to the rotor 16 via a spline 16a formed on the outer peripheral surface thereof so as to be shiftable.
Is held between the body case 11 and the piston 23 by the biasing force of a coil spring 24 interposed between the ring-shaped piston 23 which is shiftably fitted in the body case 11 and the valve block 12. Has become. or,
An oil chamber 25 is formed between the main body case 11 and the piston 23, and the electromagnetic switching valve 26 shown in FIG. The holding of the brake disc 22 by the piston 23 is released.
The electromagnetic switching valve 26 is urged to return to the hydraulic oil discharge state by a coil spring 26a. That is, spline 16
a, the brake disk 22, the piston 23, and the electromagnetic switching valve 26 constitute a negative brake B that performs a braking operation on the crawler traveling device 5.

The rotor 1 on the inner peripheral surface of the main body case 11
6 is provided with a pickup coil type rotation detecting sensor S for detecting the spline 16a as a gear for detecting the number of rotations at a portion opposed to the spline 16a, and is detected by the rotation detecting sensor S per unit time. The control device 7 controls the operation of the first electric motor m1 and the second electric motor m2 based on the number of teeth (pulse signal) of the spline 16a, and rotates the trunnion shafts 9 and 10 of the respective variable displacement hydraulic pumps P. By changing the swash plate angle (not shown) by moving the vehicle, the vehicle speed can be controlled according to an operation command from the remote control device R shown in FIG. That is, the rotation detection sensor S functions as a vehicle speed detection sensor. A vehicle speed detection device Z for controlling the vehicle speed by the control device 7, the spline 16a, and the rotation detection sensor S is configured, and the turning operation lever 27 provided in the remote control device R is positioned at the neutral position. When the shift operation lever 28 is operated to the front or rear in a state where the shift operation lever 28 is operated, the control device 7 according to the operation command causes the traveling body 1 to move forward or backward at a desired speed corresponding to the operation amount of the shift operation lever 28. When the turning operation lever 27 is operated left or right while operating the transmission operation lever 28, the control operation of the control device 7 in accordance with the operation command causes the transmission operation lever 28 and The traveling body 1 can be turned left or right at a desired speed and turning radius according to the operation amount of the turning operation lever 27. Incidentally, in a state where the turning operation lever 27 and the speed change operation lever 28 are respectively located at the neutral positions, the electromagnetic switching valve 26 is switched to the hydraulic oil discharge state, and the negative brake B is operated. The braking of the traveling body 1 is stopped.

The assembling structure of the rotation detection sensor S will be described in detail. The rotation detection sensor S is screwed to the main body case 11 and is fixed by a nut 29 to prevent rotation. The connection terminal 30 of the rotation detection sensor S is buried in the valve block 12 with a connection portion protruding between the track frame 5A and the motor cover 31, and is formed in each of the main body case 11 and the valve block 12. The rotation detection sensor S is connected to the rotation detection sensor S via a lead wire 32 inserted through the lead wire insertion hole. The rotation detection sensor S and the control device 7 are connected to the track frame 5A and the motor cover 3
1 and a wire harness 33 and a connector 34 passing therethrough.
And are connected through. With the above configuration, oil leakage from the fixed displacement hydraulic motor M and the lead wire 3
2 and the wire harness 33 are prevented from being disconnected,
The attachment of the rotation detection sensor S to the fixed displacement hydraulic motor M is facilitated. In addition, by providing the rotation detection sensor S in the fixed displacement hydraulic motor M which is the output side of the hydrostatic stepless transmission 8, the influence on the operating efficiency of the variable displacement hydraulic pump P and the fixed displacement hydraulic motor M is obtained. The vehicle speed can be controlled with high accuracy without receiving the vehicle speed.

[0015] As shown in FIG.
The crawler belt 5E is formed by connecting a plurality of metal shoe plates 5a integrally formed with link plates a in an endless state. A resin grounding body 5b having a grounding pattern formed thereon is baked or screwed and fixed to the shoe plate 5a. When the grounding body 5b is fixed with screws, there is an advantage that the grounding body 5b can be replaced. A pair of front and rear brackets b are erected on each of the left and right ends of the shoe plate 5a, and the front ends of the brackets b
The spike pin 35 is pivotally connected to the pivot shaft 36 so that the posture swing can be switched between a working posture protruding from the ground contact surface and sticking to the ground and a non-working posture in which the distal end is separated from the grounding body 5b and directed outward. Is to be pivoted through. This spike pin 35 is attached to each shoe plate 5
a or a predetermined shoe plate 5a, or may be provided at each of the left and right ends or at both the left and right ends of the shoe plate 5a. The symbol 37 shown in FIG.
By the swinging operation to the side, the spike pin 35 and the pivot 36
Are wedge-shaped fittings which hold the spike pin 35 in the working posture or the non-working posture by engaging the spike pin 35 in a state in which the spike pin 35 is prevented from swinging. In other words, when traveling on a paved road surface, the spike pins 35 can be switched to the non-acting position to travel without damaging the paved road surface, etc. In addition, a highly uneven work area or humus is deposited. When the vehicle travels on a work site with a low gripping force, the slip of the traveling machine body 1 can be suppressed by switching the spike pins 35 to the working posture.

[Other Embodiments] The working vehicle to which the present invention is applied is not limited to the lawn mower illustrated in the above embodiment, but may be a hydrostatic type such as a backhoe or a lawnmower. Any type of work vehicle may be used as long as it is a work vehicle provided with the step transmission 8.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is an overall side view of a wireless remote control mower.

FIG. 2 is a hydraulic circuit diagram of a mower.

FIG. 3 is a vertical sectional front view of a fixed displacement hydraulic motor showing an assembly structure of a rotation detection sensor.

FIG. 4 is a block diagram showing a control configuration.

FIG. 5 is a vertical sectional front view of a crawler traveling device showing a configuration of a shoe plate.

FIG. 6 is a diagram showing an assembling structure of a vehicle speed detection sensor according to the related art.

[Explanation of symbols]

 Reference Signs List 8 hydrostatic continuously variable transmission 16 rotor 16a spline 22 brake disk M hydraulic motor S rotation detection sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-87340 (JP, A) JP-A-60-74057 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01P 3/488 B60K 17/10

Claims (1)

(57) [Claims] 1. A spline (1) is attached to a rotor (16) built in a hydraulic motor (M) of a hydrostatic continuously variable transmission (8).
A rotation detection sensor (S) that fits the brake disk (22) so as to be shiftable via 6a) and detects the spline (16a) as a gear for detecting the rotation speed.
Is a vehicle speed detecting device for a working vehicle, which is provided so as to face the spline (16a).