JP4194101B2 - Hydraulic operation structure of agricultural machine - Google Patents

Description

  The present invention relates to a hydraulic operation structure used in farm work machines such as rice transplanters and tractors.

As a hydraulic operation structure of a rice transplanter which is an example of a farm work machine, for example, as shown in Patent Document 1, a hydraulic cylinder that drives pressure oil from a hydraulic pump up and down a power steering device and a seedling planting device , Etc., are configured to be supplied in series to a plurality of hydraulic actuators.
JP-A-6-209617

  The multiple hydraulic actuators do not necessarily have the same maximum required flow rate. In this case, the discharge amount of the hydraulic pump is matched to the maximum required flow rate of the hydraulic actuator that requires the most flow rate. An excessively high flow rate of pressure oil is supplied to the hydraulic actuator having a small maximum required flow rate, resulting in an excessively high operating speed. Therefore, the displacement of the control valve of the hydraulic actuator with a small maximum required flow rate in the valve opening direction is mechanically limited with a stopper bolt to prevent the maximum opening, so that It is also practiced to prevent excessive pressure oil from being supplied.

  However, in the means for restricting and adjusting the opening degree of the control valve, there is a risk that if the adjustment is wrong, the pressure oil at a flow rate higher than necessary may be supplied. In addition, even after adjustment, the stopper bolt may be inadvertently operated and pressure oil may not be supplied at a predetermined flow rate.

  The present invention has been made paying attention to such points, and when pressure oil from a hydraulic pump is supplied in series to a plurality of hydraulic actuators having different maximum required flow rates, hydraulic operation with a small maximum required flow rate is performed. The main purpose is to supply the apparatus with pressure oil at an appropriate flow rate so that the apparatus can be suitably operated.

The hydraulic operation structure of the agricultural machine according to the first invention is configured to supply pressure oil from a hydraulic pump in series to a plurality of hydraulic actuators having different maximum required flow rates, and control of a hydraulic actuator having a low maximum required flow rate the upstream side oil passage of the valve, to form a branch passage interposed a pressure compensating valve for a constant differential pressure across the control valve, in a fully opened state of the control valve, the hydraulic actuating device less the maximum required flow rate The maximum opening of the spool of the control valve when the control valve is fully open is set so that the maximum amount of oil supplied is limited to a predetermined flow rate smaller than the pump discharge flow rate.

  According to the above configuration, even if the control valve of the hydraulic actuator having a small maximum required flow rate is fully opened, the pressure oil supplied from the control valve to the hydraulic actuator is limited to a predetermined flow rate that is smaller than the pump discharge flow rate. .

Therefore, according to the first invention, the supply flow rate may change due to an adjustment error, such as a means for mechanically limiting the opening degree of the control valve to control the flow rate of the pressure oil supplied to the hydraulic actuator. When supplying pressure oil from a hydraulic pump in series to a plurality of hydraulic actuators having different maximum required flow rates, supply the hydraulic oil with an appropriate flow rate to a hydraulic actuator having a lower maximum required flow rate and operate it appropriately. be able to.
And the means to restrict | limit the maximum oil amount supplied to a hydraulic actuator to the predetermined flow volume smaller than a pump discharge flow rate can be comprised easily.

The hydraulic operation structure of the agricultural machine according to the second invention is the above first invention,
A hydraulic power steering device is a hydraulic actuator having a large maximum required flow rate.

  According to the above configuration, the hydraulic power steering device can be operated strongly by supplying the required amount of pressure oil and light steering can be performed, and an appropriate amount of pressure oil can be supplied to the hydraulic operation device having the minimum required flow rate. It can be suitably operated without causing excessively fast operation.

The hydraulic operation structure of the agricultural machine according to the third invention is the first invention,
The hydraulic actuator with the largest required flow rate is a hydrostatic continuously variable transmission.

  According to the above configuration, a sufficient amount of pressure oil for charging is supplied to the hydrostatic continuously variable transmission, and an appropriate amount of pressure oil is supplied to a hydraulic actuator having a small maximum required flow rate so that it can be suitably operated. Can do.

The hydraulic operation structure of the agricultural machine according to the fourth invention is the invention according to any one of the first to third inventions,
A hydraulic actuator having a small maximum required flow rate is a hydraulic cylinder for raising and lowering the working device.

  According to the above configuration, the hydraulic cylinder is operated at a desired low speed to smoothly move the working device up and down smoothly while supplying a sufficient amount of pressure oil to a hydraulic operating device having a maximum required flow rate and operating properly. It becomes easy to maintain the height stably.

The hydraulic operation structure of the agricultural machine according to the fifth invention is the invention according to any one of the first to fourth inventions,
The pump discharge flow rate when the engine driving the hydraulic pump is in an idling state is set to be substantially the same as the limited predetermined flow rate.

  According to the above configuration, even in a non-working state in which the engine rotation is reduced to the idling state, the hydraulic actuator having a small maximum required flow rate can be operated at a predetermined speed.

  FIG. 1 shows a riding rice transplanter that is an example of an agricultural machine according to the present invention. This rice transplanter is a parallel four driven by a hydraulic cylinder 4 which is shortened by pressure oil supply at the rear of a four-wheel drive type traveling machine body 3 having a steerable front wheel 1 and a non-steerable rear wheel 2. A seedling planting device 6 as a working device is connected via an elevating link mechanism 5 having a continuous link structure, and a fertilizer application device 8 is provided at a rear portion of a driver seat 7 provided at a rear portion of the traveling machine body 3. An engine 10 is mounted and accommodated in the front bonnet 9, and a reserve seedling stand 11 is provided upright on both the left and right sides of the bonnet 9.

  The seedling planting device 6 has a four-row planting specification and is connected and supported in a freely rolling manner at the lower end of the lifting link mechanism 5 so as to place a mat-like seedling and reciprocate horizontally by a fixed stroke. A set stand 15, four sets of rotary planting mechanisms 16 that cut out seedlings one by one from the lower end of the seed set stand 15 and plant them on the rice field, and three leveling floats 17 for leveling the planting location on the rice field A pair of left and right drawing markers 18 for scratching and forming a running reference line for the next stroke on the rice field during the reciprocating planting operation are provided.

  The drawing marker 18 is supported so as to be able to undulate and swing in a drawing action posture (see FIG. 1) that has fallen laterally outward of the aircraft and a stowed storage posture, and is oscillated and biased toward the drawing action posture. In response to the raising operation of the seedling planting device 6, the left and right drawing markers 18 selected by the driver are mechanically erected and swung in the retracted posture. It is configured to oscillate and swing to the acting posture.

  This rice transplanter is provided with a hydraulic operation structure that operates a plurality of hydraulic actuators with pressure oil from a hydraulic pump 26, and FIG. 2 shows a hydraulic circuit diagram thereof.

  In FIG. 2, reference numeral 20 denotes a hydraulic power steering device which is one of the hydraulic actuators, and includes a control valve 21 linked to the steering handle 12 and a torque motor linked to a steering link mechanism for steering the front wheels. 22, a relief valve 23 for limiting the operating pressure, and the like.

Reference numeral 25 denotes a lift control unit that controls the operation of the hydraulic cylinder 4, which is one of the hydraulic actuators. The hydraulic pump 26 is driven by the engine 10, the lift control valve 27, the lowering lock on-off valve 28, The slow return valve 29, the pressure compensation valve 30 that makes the differential pressure across the control valve 27 constant, the relief valve 31 for limiting the operating pressure, and the like are incorporated in a common casing.
A branch path 33 with a pressure compensation valve 30 interposed is formed in the upper oil path 32 of the control valve 27.

  Reference numeral 35 denotes a hydrostatic continuously variable transmission 35 which is one of hydraulic actuators, and is mounted on the traveling machine body 3 as a traveling main transmission. The hydrostatic continuously variable transmission 35 includes an axial plunger type variable displacement pump 36 driven by the engine 10 and an axial plunger type constant displacement motor 37 that transmits a shift output to a travel transmission system. The hydraulic circuit is provided with a charge oil passage c and a relief valve 38 for limiting the charge pressure.

  The oil discharged from the hydraulic pump 26 is supplied in series in the order of the power steering device 20, the lift control unit 25, and the charge oil passage c of the hydrostatic continuously variable transmission 35.

  The control valve 27 of the raising / lowering control unit 25 is one in which the spool 27 s is displaced based on the height detection of the seedling planting device 6 with respect to the field surface, and among the three leveling floats 17 provided in the seedling planting device 6 The central one is used as a sensor float SF for height detection and linked to the control valve 27 as follows.

  That is, the sensor float SF is supported so as to be able to swing up and down around the rear fulcrum p, and the front portion of the sensor float SF and the spool 27 s of the control valve 27 are interlocked and connected via the sensor wire 41. When the seedling planting device 6 is in a predetermined height range with respect to the field surface T and the contact pressure acting on the sensor float SF is within the predetermined range, the vertical posture of the sensor float SF with respect to the seedling planting device 6 is The spool 27s of the control valve 27 is neutral and the hydraulic cylinder 4 is in a stopped state.

  When the seedling planting device 6 sinks with respect to the surface T, the sensor float SF is oscillated and displaced upward due to an increase in ground pressure, and this displacement is transmitted to the control valve 27 via the sensor wire 41, and the spool 27s is spring 42. The hydraulic cylinder 4 is shortened by receiving the supply of pressure oil, the seedling planting device 6 is raised, and the vertical position of the sensor float SF is returned to a predetermined range. The spool 27s returns to neutral, and the raising operation of the seedling planting device 6 is stopped.

  Further, when the seedling planting device 6 floats with respect to the surface T, the ground pressure acting on the sensor float SF decreases, and the sensor float SF swings and displaces downward, and this displacement is transmitted to the control valve 27 via the sensor wire 41. Then, the spool 27 s of the control valve 27 is displaced from the neutral to the lowering operation side by the spring 42, and the pressure oil supplied through the power steering device 20 flows in a short circuit, and the hydraulic cylinder 4 is exhausted and extended. When the seedling planting device 6 is actuated to lower its own weight and the vertical swing posture of the sensor float SF is returned to a predetermined range, the spool 27s returns to the neutral position and the descending operation of the seedling planting device 6 stops. Thus, by controlling the hydraulic cylinder 4 so that the contact pressure acting on the sensor float SF is maintained within the set range, the seedling planting device 6 is maintained in a predetermined height range with respect to the field surface T, Therefore, planting at a stable depth is carried out regardless of the aircraft's ups and downs or tilting back and forth.

  Here, the discharge amount of the hydraulic pump 26 when the engine 10 is accelerated to the maximum working rotational speed (for example, 3000 rpm) is 7.5 [l / min], but can be supplied to the hydraulic cylinder 4. The opening degree of the control valve 27 is set as follows so that the maximum flow rate is limited to about 3.5 [l / min]. The discharge amount of the hydraulic pump 26 when the engine 10 is reduced to the idling speed (for example, 1400 rpm) is about 3.5 [l / min], which is equivalent to the maximum flow rate that can be supplied to the hydraulic cylinder 4.

  FIG. 3 is a characteristic diagram showing the flow rate of the pressure oil with respect to the spool displacement of the control valve 27. When the spool 27s is operated to the maximum opening degree in the descending operation direction, the amount of oil flowing out from the hydraulic cylinder 4 is 5.3 [l. In contrast, the maximum amount of oil that can be supplied to the hydraulic cylinder 4 is about 3.5 [l / min] when the spool 27s is operated to the maximum opening degree in the upward operation direction. Different opening settings are made for the operating direction and the upward operating direction.

  As described above, at the time of the ascending operation, the maximum opening amount of the control valve 27 is narrowed to reduce the maximum flow rate to the hydraulic cylinder 4 that is a hydraulic operation device having a small maximum required flow rate to a predetermined flow rate smaller than the maximum pump discharge flow rate. By limiting the flow rate in the ascending operation direction, it is possible to prevent the seedling planting device 6 at the time of planting operation from being raised too quickly and becoming a shallow planting state, When raising the seedling planting device 6 to change the aircraft direction in the headland after completing the planting run of one stroke, the seedling planting device 6 will rise rapidly even if the control valve 27 is operated to the maximum opening. In other words, the drawing marker 18 that is erected and swung to the retracted position in conjunction with the raising operation of the seedling planting device 6 is also slowly raised, and the marker that has entered the surface T Phenomenon as tip is rapidly pulled splashing mud until the operating portion is avoided.

  [Other Examples]

  In a manual steering type model that does not include the hydraulic power steering device 20, as shown in FIG. 4, the pressure oil from the hydraulic pump 26 is directly supplied to the elevation control unit 25.

Side view of riding rice transplanter Hydraulic circuit diagram Characteristic line of control valve for lifting Hydraulic circuit diagram of another embodiment

Explanation of symbols

4 Hydraulic actuator (hydraulic cylinder)
10 Engine 20 Hydraulic actuator (Power steering device)
26 Hydraulic pump 27 Control valve
27s spool
30 Pressure compensation valve
32 Upper oil passage
33 branch path 35 hydraulic actuator (hydrostatic continuously variable transmission)

Claims (5)

The pressure oil from the hydraulic pump (26) is supplied in series to a plurality of hydraulic actuators (4, 20, 35) having different maximum required flow rates,
A pressure compensation valve (30) for making the differential pressure across the control valve (27) constant is interposed in the upper oil passage (32) of the control valve (27) of the hydraulic actuator (4) having a small maximum required flow rate . Forming a branch (33),
In the fully opened state of the control valve (27), the control valve (27) is controlled so that the maximum amount of oil supplied to the hydraulic actuator (4) having a small maximum required flow rate is limited to a predetermined flow rate smaller than the pump discharge flow rate. 27) A hydraulic operation structure of a farm machine characterized in that the maximum opening degree of the spool (27s) of the control valve (27) is set in a fully opened state .   The hydraulic operation structure for agricultural machines according to claim 1, wherein the hydraulic actuator having a maximum required flow rate is a hydraulic power steering device (20).   The hydraulic operation structure for agricultural machines according to claim 1, wherein the hydraulic actuator having a maximum required flow rate is a hydrostatic continuously variable transmission (35).   The hydraulic operation structure for an agricultural machine according to any one of claims 1 to 3, wherein the hydraulic actuator having a small maximum required flow rate is a hydraulic cylinder (4) for raising and lowering the working device.   The pump discharge flow rate when the engine (10) for driving the hydraulic pump (26) is in an idling state is set to be substantially the same as the limited predetermined flow rate. The hydraulic operation structure of the agricultural machine according to claim 1.

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