JPH09271238A - Lawn mower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute the lawn mower which lowers even a lightweight mower fast and switches the grounded mower into a floating state through easy operation. SOLUTION: This lawn mower has operation positions, i.e., an elevation position U where the mower M is elevated to a control valve V controlling a hydraulic cylinder 17 for elevating and lowering the mower, a neutral position N where the mower M is stopped from moving up, and a floating position F where the mower M is allowed to freely move and down along a ground surface by applying back pressure to the hydraulic cylinder 17 to an extent where grounding pressure is reduced. The neutral position N is formed between the elevation position and floating position F, and a lowering position D where only oil discharging from the hydraulic cylinder 17 is performed is provided at an intermediate position between the neutral position N and floating position F.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a hydraulic cylinder for raising and lowering a mower supported by a traveling machine body so as to be able to move up and down, a raising position for raising the mower by supplying hydraulic oil to the hydraulic cylinder, and the hydraulic cylinder. A neutral position that stops the lifting and lowering of the mower by blocking the supply and drainage of hydraulic oil to the hydraulic cylinder, and a floating pressure that allows the hydraulic cylinder to apply a back pressure that reduces the ground contact pressure to allow the mower to freely move up and down. The present invention relates to an improvement of a lawnmower having a control valve that can be switched between position and position.

[0002]

2. Description of the Related Art Conventionally, there are lawn mowers constructed as described above, which are disclosed in Japanese Patent Application Laid-Open No. 5-328816 or Japanese Patent Application Laid-Open No. 7-274657. When is set to a floating state, hydraulic oil is supplied to the hydraulic cylinder, and at the same time, resistance is applied to the hydraulic oil discharged from the hydraulic cylinder by the orifice to obtain back pressure.

[0003]

In the two conventional examples, when the control valve is set to the floating position, pressure oil is supplied to the hydraulic cylinder for raising the mower and at the same time the orifice is moved from the hydraulic cylinder. Since it is a structure that drains oil through the mower, for example, even if the control valve is set to the floating position when lowering the mower in the raised state, rapid lowering cannot be performed and it takes time for the mower to contact the ground. There is room for improvement in terms of efficiency.
In particular, if the lightweight mower is replaced with a machine with orifice performance set for a relatively heavy mower, the descent speed of the mower will drop significantly. There is room for improvement in terms of.

In the latter of the above-mentioned conventional examples, four operating positions are formed in this order with respect to the control valve: an ascending position, a neutral position, a floating position, and a descending position. Further, since the structure is such that only oil is drained from the hydraulic cylinder in the lowered position, when the mower is lowered, the above-mentioned inconvenience can be solved and the mower can be lowered quickly, but the floating position formed in the control valve is Since it is formed adjacent to the neutral position side, when lowering the mower in the rising state (when the mower is in the rising state, the control valve is held in the neutral position), the control valve is set to the neutral position. There is room for improvement in that it is necessary to return the control valve to the floating position after the moor is lowered to a predetermined height by once operating from the position to the floating position beyond the floating position.

An object of the present invention is to enable a rapid descent even when using a lightweight mower, and to reasonably construct a lawn mower capable of switching a grounded mower to a floating state by a simple operation. .

[0006]

As described in the beginning, the first feature of the present invention (claim 1) is to raise the mower by supplying hydraulic oil to the hydraulic cylinder and hydraulic oil to the hydraulic cylinder. Switch between a neutral position that stops the lifting and lowering of the mower by blocking the supply and drainage of the mower, and a floating position that allows free lifting up and down by following the moor's ground by applying back pressure to the hydraulic cylinder to reduce the ground contact pressure. In a lawnmower equipped with a free control valve, the control valve is configured such that the neutral position is formed between the raised position and the floating position, and the intermediate position between the neutral position and the floating position is controlled by a hydraulic cylinder. This is because it is configured by forming a descending position for only discharging the oil, and its operation is as follows.

A second feature of the present invention (claim 2) is that the control valve is constructed as an artificially operated type, and is not operated at any one of the neutral position and the floating position. The point is that a position holding mechanism for holding the operating position of the control valve is formed, and its operation is as follows.

A third aspect of the present invention (claim 3) is that the hydraulic pump applies hydraulic fluid to the hydraulic cylinder so that back pressure acts on the hydraulic cylinder when the control valve is set to the floating position. Charging oil for a hydrostatic stepless transmission that forms an orifice in a branch oil passage branched from an oil passage that supplies the oil, and adjusts the exhaust oil from the branch oil passage infinitely the traveling speed of the traveling machine body. It is in communication with the road and its action is as follows.

[Operation] According to the first feature, when the mower in the raised state is lowered to start the work, the control valve is switched from the neutral position to the lowered position so that only the oil is drained from the hydraulic cylinder. To lower the mower, and when the mower descends to an appropriate height, switch it to the floating position to apply back pressure to the hydraulic cylinder and set the mower in the floating state to perform work. Since the neutral position, the lowered position, and the floating position are sometimes formed in this order, when lowering the mower, it is only necessary to operate the control valve in the order of the neutral position, the lowered position, and the floating position. As in the latter case of the conventional example, a complicated operation is performed such that the floating position is exceeded and the lower position is operated, and then the floating position is returned. Becomes the trouble of performing the work is eliminated.

According to the second feature, the position holding mechanism does not hold the state where the control valve is operated to the lowered position. Therefore, when the mower is lowered during work, the control valve is It is necessary to operate the control valve in the lowered position and to artificially hold the operating position, and avoid the erroneous operation of leaving the control valve in the lowered position after the mower is lowered to prevent the operator from operating the control valve. Can be operated to a floating position.

According to the third feature described above, when the control valve is set to the floating position, the hydraulic oil from the branch oil passage flows to the charge oil passage side. By providing a relief valve or forming an orifice, the pressure required for charging can be easily obtained, and the oil passage of the continuously variable transmission can be charged without using a charge pump.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, an engine 3 is arranged at the front of a traveling body including a front wheel 1 that can be steered and a rear wheel 2 that is driven, and a steering handle is provided at the center of the body. 4 with the driver's seat 5 at the rear
Each of which is provided with a hydrostatic type continuously variable transmission 7 and a transmission case 8 which are connected to a lower portion of a rear portion of the machine body through which a power from the engine 3 is transmitted via a transmission shaft 6.
Further, a mower M is provided at an intermediate position between the front wheels 1 and the rear wheels 2 to form a riding type lawnmower.

In the mower M, three blades 11 rotating about the longitudinal axis are installed in the cutting blade housing 12, and the drive shaft of the blade 11 at the central position is interlocked with a gear interlocking mechanism (not shown). By providing an input shaft 13 on the upper surface of the cutting blade housing 12 and providing a belt transmission system (not shown) for transmitting the power from the input shaft 13 to the two blades 11 on the left and right, the power transmitted to the input shaft 13 The configuration is such that the three blades 11 can be driven simultaneously.
The cutting blade housing 12 has a roller 14 at the front,
A gauge wheel 15 is provided at the rear part. Further, the mower M is supported in a suspended state with respect to the machine body frame 16 via a link mechanism L, and is configured to be movable up and down with respect to the machine body by a driving force of a hydraulic cylinder 17 linked with the link mechanism L. There is.

The link mechanism L has a pair of left and right main links 18 whose front end is supported at an intermediate position of the machine frame 16 and whose rear end is supported by the rear end of the mower M, and the front end of which is the front end position of the machine frame 16. A pair of left and right front links 19 supported at the front end of the mower M.
By associating the intermediate portion of the main link 18 with the hydraulic cylinder 17 via the lift link 20 and the crank 21, the hydraulic cylinder 17 is driven to move up and down. or,
A power transmission system for transmitting the power from the mission case 9 to the input shaft 13 of the mower M through the drive shaft 24 is formed.
Is configured to be freely driven.

Further, step 27 at the front position of the driver's seat 5
A shift pedal 28 is arranged on the right side of the vehicle, and a rocking operation type operation lever 29 for controlling the up and down movement of the mower M is provided on the side of the driver's seat 5.
The lifting lever 29 and the control valve V for the hydraulic cylinder 17 are mechanically linked to each other.

That is, as shown in FIGS. 3 to 8, the control valve V associated with the operating lever 29 has a raised position U for raising the mower M and a neutral position N for stopping the raising and lowering of the mower M.
The lower position D for lowering the mower M and the floating position F for grounding the mower M in a floating state are operable in this order. The floating state means that the ground load of the gauge wheel 15 of the mower M is reduced by applying a pressure to the hydraulic cylinder 17 to such an extent that the mower M is not raised, and corresponds to the fluctuation of the ground level during the work. This is a state in which the mower M can be smoothly moved up and down.

The control valve V is constructed by incorporating a spool 35 slidably operated with respect to the valve casing 34, a relief valve 36 and a variable orifice 37, and the valve casing 34 is provided with the engine 3 described above. Pump port P to which hydraulic oil from the driven hydraulic pump 38 is supplied
And hydraulic oil controlled by the spool 35 to the hydraulic cylinder 1
7, a cylinder port C for supplying / discharging the working oil, a tank port T for discharging the working oil, a charge port CH for sending the working oil to a charge oil passage of the continuously variable transmission 7, and a steering operation of the steering handle 4. A steering port PS for sending to a power steering unit 39 (the linkage with the steering handle 4 is not described in detail) that drives and operates the front wheels 1 is formed.

Further, the continuously variable transmission 7 is an oil passage system for supplying hydraulic oil from a variable displacement type axial plunger type hydraulic pump 39 operated by the speed change pedal 28 to an axial plunger type hydraulic motor 40. Is equipped with
An oil passage system for supplying pressure oil from the charge port CH is formed to the charge oil passage 41 of the continuously variable transmission 17, and the charge oil passage 41 is set by the relief valve 42 provided in the charge system. The charge pressure is determined by the pressure applied.

A relief oil passage 44 having a relief valve 36 and an orifice oil passage 45 (an example of a branch oil passage) having a variable orifice 37 are formed in a state of branching from the main oil passage 43 from the pump port P. An oil passage system is formed so that the relief oil passage 44 communicates with the charge port CH and the steering port PS, and the orifice oil passage 45 communicates with the charge port CH and the steering port PS via the spool 35. Further, the spool 35 has a plurality of lands and is configured to control the flow of hydraulic oil by a sliding operation in the axial direction, and when the spool 35 is operated to the neutral position N, the spool N is operated. Is configured to be held in a neutral position by a mechanism having a ball 47 that is engaged with the small diameter portion of the spool 46 by the urging force of the spring 46.
Is operated to return to the neutral position side by the urging force of the operation spring 48 acting on the spool end when the operating force is released after operating
When the spool 35 is operated in the direction from the neutral position N to the lowered position D, the urging force of the operation spring 48 causes the spool 35 to move.
Is operated to the floating position F, and the stopper ring 31 formed on the outer surface of the spool 35 contacts the valve casing 34 so that the spool 35 is held at the floating position F by the urging force of the operation spring 48. It is configured.

Incidentally, the position holding mechanism of claim 2 is constituted by the system for holding the spool 35 only at the two positions of the neutral position N and the floating position F, and the position holding mechanism is constituted in this way. Therefore, when the mower M in the raised position is quickly lowered, the spool 35 is operated from the neutral position N to the lowered position D, and the operated position is artificially held. Furthermore, the variable orifice 3
7 is equipped with a rotary operation type adjustment knob (not shown),
The opening of the orifice can be adjusted by rotating the adjustment knob.

When the spool 35 is operated to the raised position U, hydraulic oil from the hydraulic pump 38 is supplied to the hydraulic cylinder 17 to raise the mower M, and when the spool 35 is operated to the neutral position N. At the same time that the supply and discharge of hydraulic oil to the hydraulic cylinder 17 is blocked to prevent the mower M from moving up and down, the hydraulic oil from the hydraulic pump 38 is sent to the charge port CH and the steering port PS via the variable orifice 37, and the spool 35 is moved. When operated to the lowered position D, the working oil from the hydraulic cylinder 17 is transferred to the tank port T.
At the same time, the hydraulic oil from the hydraulic pump 38 is sent to the charge port CH and the steering port PS via the variable orifice 37, and when the spool 35 is operated to the floating position F, the hydraulic oil from the hydraulic pump 38 is discharged. At the same time as supplying the hydraulic oil to the hydraulic cylinder 17, the hydraulic oil from the oil passage communicating with the hydraulic cylinder 17 is sent to the charge port CH and the steering port PS via the variable orifice 37, so that the hydraulic cylinder 17 is not moved. It acts as pressure.

By configuring the hydraulic system for raising and lowering the lawn mower in this manner, the mower M can be moved up and down by operating the operating lever 29, and the operating lever 29 is moved from the neutral position to the front floating position F. When the operation lever 29 is operated, it always passes through the lowered position D. Therefore, for example, when the operation lever 29 is operated from the neutral position N toward the floating position F, the mower M is operated at the operation position where the descent is started. The mower M can be quickly lowered by an operation of consciously holding the lever 29. When the mower M reaches the grounded state by this operation, the operation lever 29 is further moved forward to move to the floating position. Just operate F
The operating lever 29 is held at the floating position F, and the mower M is hung on the traveling machine body while a suitable pressure is applied to the hydraulic cylinder 17 to lightly move up and down following the field scene. Can be done.
Further, in this lawnmower, the hydraulic cylinder 17 is operated in a floating state by operating the adjusting knob of the variable orifice 37.
It is possible to adjust the back pressure to be applied to, and to arbitrarily adjust the back and forth of the ground or the weight of the mower M when the mower M is replaced.

[Other Embodiments] In addition to the above embodiment, the present invention engages with a position control ball 47 when a spool of a control valve is operated to a floating position F, for example. It is possible to form the position holding mechanism in a detent type by forming the small diameter portion that forms the position holding mechanism, and it is also possible to form the position holding mechanism by a member that is connected to the spool of the control valve and outside the valve casing.

[0024]

Therefore, a lawn mower which enables a high speed descent even when a lightweight mower is used and which can switch a grounded mower to a floating state by a simple operation has been rationally constructed. ). Further, at the time of work, the mower is always supported in a floating state so that it can be properly moved up and down following the ground (Claim 2), and the hydraulic oil for the continuously variable transmission also serves as a hydraulic system for obtaining the floating state. Can be charged (Claim 3).

[0025]

[Brief description of drawings]

FIG. 1 is an overall side view of a lawn mower.

[Figure 2] Overall plan view of the lawn mower

FIG. 3 is a hydraulic circuit diagram

FIG. 4 is a longitudinal sectional view of the control valve showing the position of the spool.

FIG. 5 is a cross-sectional view of a control valve showing a relief valve and a variable orifice.

FIG. 6 is a longitudinal sectional view of a control valve showing a relief valve and a variable orifice.

FIG. 7 is a side view of the control valve.

FIG. 8 is a plan view of the control valve.

[Explanation of symbols]

 7 Continuously Variable Transmission 17 Hydraulic Cylinder 37 Orifice 38 Hydraulic Pump 41 Charge Oil Path 43 Oil Path 45 Branch Oil Path M Mower U Up Position N Neutral Position D Down Position F Floating Position V Control Valve

Claims (3)

[Claims] 1. A hydraulic cylinder for raising and lowering a mower supported movably up and down on a traveling machine body, and a raising position for raising the mower by supplying hydraulic oil to the hydraulic cylinder, and supply and discharge of hydraulic oil to and from the hydraulic cylinder. It is possible to switch between a neutral position that stops the lifting and lowering of the mower due to the blockage of the mower and a floating position that allows free lifting and lowering that follows the ground of the mower by applying a back pressure to this hydraulic cylinder to reduce the ground pressure. A lawnmower equipped with a control valve, wherein the control valve forms the neutral position between the rising position and the floating position, and further, from a hydraulic cylinder to an intermediate position between the neutral position and the floating position. A lawn mower configured with a descending position that only discharges the oil. 2. The position holding device for controlling the control valve, wherein the control valve is artificially operated, and can hold the operating position of the control valve only at any one of the neutral position and the floating position when not operated. The lawn mower according to claim 1, wherein a mechanism is formed. 3. A branch oil passage branched from an oil passage for supplying hydraulic oil from the hydraulic pump to apply a back pressure to the hydraulic cylinder when the control valve is set to the floating position. 3. An orifice is formed and oil discharged from this branch oil passage is communicated with a charge oil passage of a hydrostatic continuously variable transmission that continuously adjusts the traveling speed of the traveling machine body. Lawn mower.