JPH0851834A - Lawn mower - Google Patents

Abstract

PURPOSE:To enable a hydraulic fluid to obtain its flow states of lifting, neutral and lowering and further semilifting for applying a smaller lifting driving force than the mower weight and practice of changeover to the semilifting state without any mistake. CONSTITUTION:This lawn mower is obtained by installing a valve mechanism V capable of changing over the flow state of a hydraulic fluid from a lifting state for fully lifting the mower, a free lowering state for freely lowering the mower, a neutral state for stopping the mower in the middle and a semilifting state in which a lifting cylinder for the mower communicates with a hydraulic pump P and further through a throttle 13 to a hydraulic fluid tank T and a smaller lifting driving force than the weight of the mower is applied to the mower, and constituting the valve mechanism V of a main changeover valve 11 capable of changing over the valve mechanism V to three lifted, neutral and lowered positions by operating a lever 10 and an auxiliary changeover valve 12, linked to the main changeover valve 11 and capable of performing the changeover to two states for feeding the hydraulic fluid to the lifting cylinder 7 and for discharging the hydraulic fluid. Furthermore, a linking mechanism 16 between the main changeover valve 11 and the auxiliary changeover valve 12 is provided with flexibility so as to freely lower the mower to a state for once coming into contact with the ground and then afford the semilifting state following the neutral operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lawnmower in which a mower is vertically movable via a hydraulic single-acting lift cylinder.

[0002]

2. Description of the Related Art Conventionally, in the lawnmower as described above, the working oil is circulated to the lift cylinder when the working oil is supplied to the lift cylinder and the mower is fully raised. It was configured to obtain three states: a free descending state in which the mower is freely lowered by discharging it to the tank, and a neutral state in which the supply and discharge of hydraulic oil to the lift cylinder is stopped to stop the mower in the middle. . Then, during the lawn mowing work, the circulation state of the hydraulic oil to the lift cylinder is set to a free descending state in which the mower descends, and the mower state is set so that the gauge wheel of the mower touches the ground and the mower follows the undulation of the ground. By following the floating state, the lawn mowing height can be adjusted to a desired set height.

[0003]

However, as in the prior art described above, the circulation state of the hydraulic oil to the lift cylinder during the lawn mowing operation is set to a free descending state in which the mower constantly descends, and the mower state is set to the mower gauge. When the wheel is in a floating state in which it follows the ground contact with the ground, all of the mower weight is applied to the gauge wheel, which may cause damage to the grass.

Therefore, as a means for solving the above-mentioned drawbacks,
As shown in FIG. 13, the operating state of the working oil flowing to the lift cylinder 7 is set to the rising state in which the working oil is supplied to the lift cylinder 7 to fully lift the mower 4.
Of the hydraulic cylinder T to the hydraulic oil tank T to freely lower the mower 4, a neutral state in which the supply and discharge of hydraulic oil to the lift cylinder 7 is stopped to stop the mower 4 in the middle, and a lift cylinder 7 is connected to the hydraulic pump P1 and is also connected to the hydraulic oil tank T via the throttle 13 so as to be able to switch to a four-position that is switchable to a semi-elevated state in which the mower 4 is provided with an ascending driving force smaller than the mower weight. It is conceivable to provide a possible valve mechanism Va, but in such a case, the lever is switched to four stages of rising, neutral, half rising, and lowering. Inconvenience occurs.

An object of the present invention is to improve the usability by making it possible to surely perform the half ascent switching.

[0006]

In order to achieve the above object, according to the present invention, there is provided a lawn mower in which a mower is movably connected to a traveling machine body through a hydraulic lift cylinder. As for the flow state of the hydraulic oil, a rising state in which the hydraulic oil is supplied to the lift cylinder to fully raise the mower, and a free descending state in which the hydraulic oil in the lift cylinder is discharged to the hydraulic oil tank to freely lower the mower State, a neutral state in which supply and discharge of hydraulic oil to and from the lift cylinder is stopped to stop the mower in the middle, and the lift cylinder communicates with a hydraulic pump and also communicates with the hydraulic oil tank via a throttle. A valve mechanism configured to be switchable to a semi-elevated state in which an ascending driving force smaller than the mower weight is applied to the mower is provided and A main switching valve that can be switched between three positions of higher / neutral / lower, and switching between two positions of a state in which hydraulic oil is supplied to the lift cylinder and a state in which hydraulic oil is discharged from the lift cylinder in cooperation with the main switching valve. A possible sub-switching valve, and the mechanism for linking the main switching valve and the sub-switching valve is allowed to freely lower the mower once to a state where it is grounded, and then the half-elevated state is obtained with a neutral operation. There is flexibility.

[0007]

The operation will be described with reference to FIGS. 2 to 7.
Shows a neutral state in which the lifting and lowering of the mower is stopped, FIG. 4 shows an ascending state, FIG. 5 shows a free descending state, and FIG. 6 shows a half-elevating state. In the embodiment of the present invention, the hydrostatic stepless transmission is shown. (HS
Oil from the charge pump (T) is supplied to the lift cylinder.

Now, when the main switching valve 11 is operated from the neutral state shown in FIG. 3 to the raised state shown in FIG. 4 by operating the lever, the sub switching valve 12 is not operated by the interchange 18 of the linkage mechanism 16, and the present position is reached. Therefore, the hydraulic oil is supplied from the pump P to the lift cylinder 7 via the main switching valve 11, the communication passage a, and the sub switching valve 12.

When the main switching valve is operated from the neutral state shown in FIG. 3 to the free descending state shown in FIG. 5, the sub switching valve 12 is operated.
Is operated via the linkage mechanism 16, and the hydraulic oil from the lift cylinder 7 is discharged to the hydraulic oil tank T via the sub switching valve 12, the communication passage b, and the main switching valve 11.

When the main switching valve is operated from the free descending state shown in FIG. 5 to the semi-elevating state shown in FIG. 6, the sub switching valve 1
2 is not operated by the interchange 18 of the linkage mechanism 16, maintains the current position, and hydraulic oil is supplied from the pump P to the lift cylinder 7 via the main switching valve 11, the communication passage b, and the auxiliary switching valve 12. At the same time, the charge oil is also supplied to the hydrostatic continuously variable transmission (HST) H through the throttle 13, and the throttle 13 causes a back pressure in the lift cylinder 7 to obtain a half-elevated state.

That is, when the mower is once lowered freely and the lever is operated to the neutral position, the hydraulic oil from the hydraulic pump is supplied to the lift cylinder and the hydrostatic continuously variable transmission. A back pressure is generated in the lift cylinder by the hydraulic fluid flowing through the throttle interposed between the mower and the continuously variable transmission, and the internal pressure of the lift cylinder is increased and an ascending driving force smaller than the mower load is applied to the mower. Become so. As a result, the mower weight applied to the gauge wheel can be reduced according to the throttle amount of the throttle. In addition, since the ascending driving force obtained by the back pressure of the throttle is set to be smaller than the mower weight, when the ground is submerged, the mower will resist the ascending driving force due to its own weight and move along the ground. Will follow and descend. That is, by setting the circulation state of the hydraulic oil to the lift cylinder to be a semi-elevated state, it is possible to reduce the mower weight applied to the gauge wheel without causing the gauge wheel to float.

[0012]

According to the present invention, therefore, the half-elevated state cannot be obtained unless the mower is once lowered by a lever operation type in which one side and the other side can be switched in three stages across the neutral position. Therefore, the switching to the half-elevated state is surely performed.

By switching the valve mechanism so that the flow state of the hydraulic oil to the lift cylinder becomes a half-elevated state, the ground load of the gauge wheel of the mower can be reduced and the damage to the lawn can be suppressed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the entire side surface of a front mount type lawnmower. This lawnmower is provided with a front wheel 2 as a pair of left and right drive wheels provided at a front portion of a traveling body 1 and a rear portion of the traveling body 1. The rear wheels 3 are a pair of left and right steered wheels, and the mower 4 is connected to the front portion of the traveling machine body 1 so as to be vertically movable.

The mower 4 includes a housing 4A that covers a plurality of cutting blades (not shown) that are driven in a vertical axis in series, and
It is composed of a pair of left and right gauge wheels 4B provided on the front part of the housing 4A, and is connected to a free end part of a lifting link 5 extending from the front part of the traveling machine body 1. The up-and-down link 5 is pivotally connected to a boss portion 6A connected and fixed to the mission case 6 so as to be vertically swingable around its axis X1, and is expanded and contracted by a hydraulic single-acting lift cylinder 7. A lift arm 8 swingably driven around the core X2 is suspended and connected via a link 9. That is, the mower 4 is driven up and down around the axis X1 by the expansion and contraction operation of the lift cylinder 7. In addition, a long hole 9a is formed in the connecting portion between the lift arm 8 and the link 9 so that the mower 4 can quickly follow the rise of the ground.

The expansion and contraction of the lift cylinder 7 can be obtained by switching the flow state of the hydraulic oil to the lift cylinder 7.
The switching of the flow state of the hydraulic oil with respect to the oil passage connects the lift cylinder 7 and the hydraulic pump P as shown in FIG. 2 by the swinging operation of the lifting operation lever 10 provided in the control section of the traveling machine body 1. This can be done by switching the operating states of the main switching valve 11 and the sub switching valve 12 of the valve unit V as a valve mechanism interposed in the R.

Next, the valve unit V will be described. The valve unit V includes a rotary type main switching valve 11 capable of switching among three positions of rising, neutral and descending, and a rotary type switching valve capable of switching between two positions. The sub switching valve 12 and the adjustable throttle 13 are provided, the main switching valve 11 can be operated by the lever 10, and the sub switching valve 12 is
As shown in FIG. 4, it is operated via a linkage mechanism 16 including a pin 14 provided on the main switching valve 11 and a cam plate 15 provided on the sub switching valve 12, and
A relief valve 17 is installed inside the main switching valve 11. Then, in the casing of the valve unit V,
Pump port Pa, cylinder port Ca communicating with lift cylinder, tank port Ta, hydrostatic stepless device (H
A port Ha communicating with ST) H is provided.

In the linkage mechanism 16 that links the main switching valve 11 and the sub switching valve 12, the engagement recess 15a for the pin 14 of the cam plate 15 is widened so that the mower 4 is once grounded. An interchange 18 is provided which allows the semi-elevated state to be obtained with neutral operation after being freely lowered.

Next, the flow state of the hydraulic oil to the lift cylinder 7 will be described with reference to the hydraulic circuit diagram shown in FIG.

In this riding lawn mower, oil from the charge pump P of the hydrostatic stepless device H is supplied to the lift cylinder 7.

As shown in FIG. 8, the main switching valve 11 is
A supply position A for supplying the hydraulic oil from the hydraulic pump P to the lift cylinder 7, a discharge position B for discharging the hydraulic oil of the lift cylinder 7 to the hydraulic oil tank T, and a stop position for stopping the supply and discharge of the hydraulic oil to the lift cylinder 7. It can be switched to three positions C. The sub switching valve 12 is configured to be switchable between two positions, a supply position D for supplying hydraulic oil to the lift cylinder 7 and a discharge position E for discharging hydraulic oil from the lift cylinder 7.

When the raising / lowering operation lever 10 is at the neutral position, the operating position of the main switching valve 11 is at the stop position C, the auxiliary switching valve 12 is at the supply position D, and the hydraulic oil is supplied to and discharged from the lift cylinder 7. It is in a neutral state where the mower 4 is stopped and the lifting and lowering of the mower 4 is stopped, and the mower 4 can be maintained at a desired height. The hydraulic oil from the hydraulic pump P supplies the charge oil to the hydrostatic stepless device H via the throttle 13.

By switching the operating position of the main switching valve 11 to the supply position A by swinging the raising / lowering operation lever 10, the flow state of the hydraulic oil to the lift cylinder 7 is such that the hydraulic oil from the hydraulic pump P is transferred to the lift cylinder 7. As a result, the mower 4 is supplied, and the mower 4 is lifted, so that the mower 4 can be lifted to a desired height.
In such a case, the supply of hydraulic oil to the hydrostatic stepless device H will be temporarily stopped.

On the other hand, the operating position of the main switching valve 11 is set to the discharge position B by the swinging operation of the elevating operation lever 10, and the auxiliary switching valve 1 is operated.
By switching the operating position of 2 to the discharge position E,
The circulation state of the hydraulic oil to the lift cylinder 7 becomes a free descending state in which the hydraulic oil of the lift cylinder 10 is discharged to the hydraulic oil tank T to lower the mower 4, and the mower 4 can be lowered to a desired height. ing. The hydraulic oil from the hydraulic pump P supplies the charge oil to the hydrostatic stepless device H via the throttle 13. By performing the lawn mowing work in this free descending state, the gauge wheel 4B of the mower 4 comes into contact with the ground due to the self-weight of the mower 4, and the mower 4 follows the undulation of the ground at a desired set height. It becomes a floating state, and the cutting height of the grass can be made uniform at a desired set height.

Then, in the free descending state of the mower,
By switching the operating position of the main switching valve 11 from the discharge position B to the stop position C by swinging the raising / lowering operation lever 10, the flow state of the hydraulic oil to the lift cylinder 7 communicates with the hydraulic pump P and through the throttle 13. By communicating with the hydrostatic continuously variable transmission H and causing the working oil to flow to the throttle 13 to generate back pressure,
The distribution state of the hydraulic oil to the lift cylinder 7 becomes a semi-elevated state in which the ascending driving force smaller than the mower weight is applied to the mower 4, and the mower weight applied to the gauge wheel 4B can be reduced to the extent that the gauge wheel 4B is not levitated. Has become.

[Other Embodiments] In this another embodiment, when the riding lawn mower is of the power steering type, the charge pump P of the hydrostatic stepless device H is replaced by replacing the valve unit V1 shown in FIG. Oil from can be supplied to the lift cylinder 7 and the power steering device PS.

The difference from the above embodiment is that the relief valve 17 of the valve unit V1 is changed from a ball type to a poppet type, and the relief valve 17 is used as a relief valve for the power steering device PS and the lift cylinder 7. From the pump P, the relief valve 17
The difference is that a connection port Ra leading to
The other points are exactly the same.

When the power steering device is used, the holder 17a of the relief valve 17 is screwed in to close the passage at the tip, and the operating pressure of the power steering device acts on the relief valve 17 via the connection port Ra. ing.

In this alternative embodiment, the steering device can be applied to the manual type.

When the steering device is of the manual type, a blind plug is screwed into the connection port Ra to close the oil passage to the relief valve 17, and between the main switching valve 11 and the holder 17a of the relief valve 17. The relief pressure is changed to be low by interposing a collar 19 on the.

Further, the mower 4 can be changed to various types, and for example, the flare type may be adopted.

It should be noted that although reference numerals are given in the claims for convenience of comparison with the drawings, the present invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

[Figure 1] Overall side view of a front-mounted lawn mower

FIG. 2 is a sectional view of a valve unit.

FIG. 3 is an operation diagram showing a neutral state of the valve.

FIG. 4 is a function diagram showing a lifted state of a valve.

FIG. 5 is an operation diagram showing a lowered state of the valve.

FIG. 6 is an explanatory diagram showing an operating state of the linkage mechanism.

FIG. 7 is an explanatory diagram showing a switching state between power steering and manual steering.

[Fig. 8] Hydraulic circuit diagram

FIG. 9 is a sectional view showing a part of a valve unit of another embodiment.

FIG. 10 is a sectional view showing the relief valve switching state of the same.

FIG. 11 is a circuit diagram when the valve unit is used in a power steering device.

FIG. 12 is a circuit diagram when the power steering device is not used.

FIG. 13 is a schematic diagram of a comparative example.

[Explanation of symbols]

 1 traveling machine body 2 front wheel 3 rear wheel 4 mower 10 lift cylinder 14 hydraulic pump 15a throttle portion 16 hydraulic oil tank 23a throttle portion V valve mechanism

Claims (1)

[Claims] 1. A lawn mower in which a mower (4) is movably connected to a traveling machine body (1) through a hydraulic lift cylinder (7), the hydraulic oil being supplied to the lift cylinder (7). In the flow state, the hydraulic oil is supplied to the lift cylinder (7) to raise the mower (4) to the full state, and the hydraulic oil of the lift cylinder (7) is discharged to the hydraulic oil tank (T). A free lowering state in which the mower (4) is freely lowered, a neutral state in which the supply and discharge of hydraulic oil to the lift cylinder (7) is stopped to stop the mower (4) in the middle, and the lift cylinder (7) ) To the hydraulic pump (P) and also to the hydraulic oil tank (T) through the throttle (13) to give the mower (4) a driving force lower than the mower weight. Switchable to The valve mechanism (V) is provided, and the valve mechanism (V) can be switched to three positions of rising, neutral, and descending by operating the lever (10), and the main switching valve (11). ), The auxiliary switching valve (12) capable of switching between two positions, a state in which hydraulic oil is supplied to the lift cylinder (7) and a state in which hydraulic oil is discharged from the lift cylinder (7).
And the main switching valve (11) and the auxiliary switching valve (1
A lawn mower provided with a mechanism (16) for linking with (2) that allows the mower (4) to freely descend once to a grounded state and then obtain the half-elevated state with neutral operation. .