KR101755064B1 - Hydraulic circuit for lifting and lowering reaping part of combine harvester - Google Patents

Abstract

[PROBLEMS] To shorten the time lag occurring when the cutting section is lowered at a high speed.
A first switching valve 7 and a second switching valve 7 which are connected in parallel with the first switching valve 7 and which are supplied from the hydraulic pump 4 to the hydraulic cylinder 2, A first throttle (9) for limiting the flow rate of the hydraulic fluid; a resistance valve (10) connected in series with the first throttle (9) and opening the valve when the primary hydraulic pressure reaches a predetermined pressure; A second throttle 12b for limiting the flow rate of the hydraulic fluid drained by backflowing the check valve 11 and a third throttle valve 12b for limiting the flow rate of the hydraulic fluid having a smaller flow cross-sectional area than the second throttle 12b And a second switching valve (19) capable of selectively switching the flow path of the hydraulic oil to be drained to the flow path of the hydraulic fluid drained through the third throttle (18).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a hydraulically operated hydraulic circuit for an elevator,

The present invention relates to a hydraulic circuit for lifting and lowering a harvesting section of a combine.

Conventionally, the combine is equipped with a cut-off portion that can freely move up and down in front of a machine body. For example, when the cutting height is set, the cutting part has a demand to raise and lower at a low speed and to move up and down at a high speed after completion of work or before starting work. Therefore, a hydraulic circuit for shifting a hydraulic cylinder for lifting and lowering the cut-off portion has been proposed (for example, Japanese Patent Laid-Open Publication No. 06-113603).

In the hydraulic circuit disclosed in JP-A-06-113603, when the cut-off portion is to be lowered, the flow rate of the hydraulic fluid discharged from the hydraulic cylinder is controlled by selectively operating the electronic on-off valves having different flow rates connected in parallel, Off valve for relieving a part of the hydraulic oil from at least one of the electromagnetic opening / closing valves at the time of a low-speed rise, and supplies the hydraulic oil to the hydraulic cylinder The flow rate of the fuel is controlled.

However, in the hydraulic circuit disclosed in JP-A-06-113603, since the hydraulic cylinder is controlled by a so-called bleed-off circuit in order to raise the cut-off portion at a low speed, when the load applied to the preloading portion becomes large, As a result, the amount of relief is increased. As a result, the ascending flow rate is drastically reduced and the ascending speed is greatly lowered.

Further, in the hydraulic circuit, the operating oil drained from the hydraulic cylinder at the time of low-speed rise rises in temperature due to friction when passing through the electromagnetic type opening / closing valve for limiting the flow rate. Since the viscosity of the working oil decreases as the temperature rises, the viscous resistance of the working oil decreases as the temperature rises, so that the working oil easily passes through the electromagnetic opening / closing valve. On the other hand, when a load is applied to the preloading portion, the pressure of the operating oil also rises. Therefore, if a load is applied to the preloading portion in a state in which the temperature rises, the load becomes more likely to pass through the flow path of the electronic opening / closing valve. Since the relief flow rate of the hydraulic fluid increases, the flow rate supplied to the hydraulic cylinder is reduced, so that the rising speed of the preload portion is slowed and the variation in the rising speed is large due to the load applied to the preload portion.

In the bleed-off circuit, the flow rate exceeding the relief flow rate can not be ensured because the discharge flow rate from the hydraulic pump is small even when attempting to raise the cut-off portion at low speed when the engine rotates at low speed during idling, .

In addition, since the throttle for low-speed rise and the throttle for low-speed fall are commonly used in the structure in which two electromagnetic opening / closing valves having different flow rates are selected to change the elevating speed of the preloading portion, matching with the combine main body may be difficult.

Therefore, in order to solve the above problem, the supply flow rate limiting throttle is connected in parallel to the openable switching valve provided in the supply flow passage, and when the low-speed rise is made, the switching valve provided in the supply flow passage is switched to close, To a meter-in-circuit controlled by a supply flow rate throttling valve (Japanese Patent No. 4994296).

Japanese Laid-Open Patent Publication No. 06-113603 Japanese Patent Publication No. 4994296

According to the hydraulic circuit disclosed in Japanese Patent No. 4,994,296, it is possible to exhibit an excellent effect of suppressing fluctuation of the rising speed of the preloading portion in accordance with the relief flow rate of the operating oil, and at the same time, There has been a slight time lag between the start of the rapid descent operation and the start of the actual descent of the preload portion when descending the cutoff portion at a high speed, particularly in a case where the hydraulic oil flow rate is low and the oil temperature is high during idling.

Therefore, the main object of the present invention is to provide a hydraulic circuit for an example of a combine capable of shortening the time lag occurring when the hydraulic circuit disclosed in Japanese Patent No. 4994296 is further improved to lower the cut portion at a high speed do.

As a result of diligent research conducted by the present inventors, it has been found that the time lag that occurs when the cutting section is lowered at a high speed is a phenomenon in which, when the cutting section is lowered at high speed, the hydraulic oil from the hydraulic pump is supplied to the feed flow rate limiting throttle The first throttle) and the second throttle (the first throttle).

In order to achieve the above object, an example of a combine relating to the present invention is a hydraulic circuit for driving a hydraulic cylinder for lifting and lowering a cut portion of a combine by operating oil sent from an oil tank through a hydraulic pump A pilot operated check valve for allowing a reverse flow of the hydraulic fluid from the hydraulic cylinder using a pilot pressure, a first position for opening a secondary side port for the hydraulic primary side port and the hydraulic cylinder operating fluid, A second position for opening the secondary side port for the pressure operating path and for opening the secondary port and the tank port for the hydraulic cylinder operating flow path and a second position for opening the secondary side port for the hydraulic pressure primary working fluid, A first switching valve connected in parallel to the first switching valve, A first throttle for limiting the flow rate of the operating fluid supplied from the first throttle valve to the hydraulic cylinder, and a second throttle valve connected in series with the first throttle, and passing through the first throttle when the first switch valve is in the second position A second throttle for limiting the flow rate of the operating fluid drained by flowing backward through the pilot operated check valve; and a second throttle valve A third throttle having a flow path cross-sectional area for limiting the flow rate of the hydraulic fluid to be drained and a second switching valve capable of selectively switching the flow path of the hydraulic fluid to be drained through the flow path of the hydraulic fluid drained through the third throttle .

The pilot operated check valve includes a check valve body, a seat on which the check valve body can be separated, a spring for urging and urging the check valve body to the seat, It is preferable that the pilot piston be disposed so as to be freely slidable with respect to the center axis.

According to the present invention, by connecting the resistance valve in series with the first throttle that raises the cut-off portion by restricting the hydraulic oil flow rate, the pilot operation type check valve can be operated by pilot operation before the hydraulic oil from the hydraulic pump is drained through the first throttle The pilot pressure is quickly supplied to the pilot operation type check valve to open the valve of the pilot operation type check valve even when the flow rate of the operating oil is small during idling or the like. The time lag can be reduced.

1 is a side view showing a main part of a general combine.
Fig. 2 is a hydraulic circuit diagram showing an embodiment of an oil pressure circuit for an example of a combine relating to the present invention. Fig.
3 is a cross-sectional view of a main portion showing a hydraulic circuit block unit to which the hydraulic circuit of Fig. 2 is mounted.
Fig. 4 is a hydraulic circuit diagram showing a modification of a hydraulic circuit for an example of a combine relating to the present invention. Fig.
Fig. 5 is a hydraulic circuit diagram showing another modification of the hydraulic circuit for an elevator for an elevator according to the present invention. Fig.

Examples of combine related to the present invention Embodiments of the hydraulic circuit for lifting and lowering the attaching portion will be described below with reference to Figs. 1 to 5. Fig. Throughout the drawings and the entire embodiments, the same components are denoted by the same reference numerals.

First, as shown in Fig. 1, a general combine is provided with a preload portion 1 at the front portion thereof. The preload portion 1 is vertically movable by driving the hydraulic cylinder 2, Ascend and descend. The hydraulic cylinder 2 may be a single-acting hydraulic cylinder.

2 is a hydraulic circuit diagram showing an embodiment of a hydraulic circuit for an example of a combine relating to the present invention.

The hydraulic circuit basically supplies hydraulic oil from the oil tank 3 to the piston chamber 2a of the hydraulic cylinder 2 by the hydraulic pump 4 to move the piston 2b to be connected to the piston rod 2c The piston 2b is returned to its original position by draining the working oil of the piston chamber 2a to the oil tank 3 while raising the preload portion 1 1).

The electromagnetic switching valve 6, the oil passage 5b, the first switching valve 7 and the oil passage 5b are provided in order from the hydraulic pump 4 between the hydraulic pump 4 and the hydraulic cylinder 2. [ The check valve 11, the flow path 5d, the slow return valve 12 and the flow path 5e are connected and the bypass flow path 8 is connected to the flow path 5b and the flow path 5c A first throttle 9 connected to the bypass passage 8 in parallel with the first switching valve 7 and connected to the bypass passage 8 in series with the first throttle 9 A resistance valve 10 is connected.

The resistance valve 10 is a kind of sequence valve. When the bypass flow path 8 on the primary side exceeds the set pressure, the bypass flow path 8 is opened. The pilot operated check valve 11 is provided with an external pilot port. When hydraulic oil of a predetermined pilot pressure is supplied to the pilot pressure operating passage 11a communicating with the external pilot port, the pilot operated check valve 11 of the pilot operated type check valve 11, (See Fig. 3) to allow reverse flow of the operating oil. The set pressure of the resistance valve 10 is set to be larger than the pilot pressure of the pilot operation type check valve 11. [ The slow return valve 12 has a check valve 12a and a second throttle 12b connected in parallel to the check valve 12a.

The term " throttle " refers to a mechanism for reducing the cross-sectional area of the flow to provide resistance in the passage or fluid passage, and includes fixed throttle, variable throttle, throttle valve, throttle switching valve and the like.

The electronic switching valve 6 is an open center four-port three-position switching valve having a pair of solenoids 6a and 6b and springs 6c and 6d in the illustrated example. The electromagnetic switching valve 6 is in the neutral position shown in Fig. 2 due to the balance of the springs 6c and 6d in the non-excited state. In the neutral position, the hydraulic fluid fed from the hydraulic pump 4 to the oil passage 5a is drained to the oil tank 3 through the oil passages 13a, 13b, and 14. When the one solenoid 6a is energized, the flow paths 5a and 5b are opened. When the solenoid 6b of the other solenoid 6b is energized, the oil passage 5a and the oil passage 15 are opened, and hydraulic oil, which is pumped from the hydraulic pump 4 to the oil passage 5a, flows through the oil passage 15, (Not shown) for driving other working equipment such as a tank elevator and an auger elevator.

The first switching valve 7 is a solenoid valve including a pair of solenoids 7a and 7b and a pair of springs 7c and 7d in the illustrated example. The first switching valve 7 is a solenoid valve including a pressure-feed primary port P, a tank port T Port, three-position three-position switching valve of the pump-closed center, which has a secondary port A for the pilot pressure operating fluid and a secondary port B for the hydraulic cylinder operating fluid. When the solenoids 7a and 7b are not energized, the first switching valve 7 is switched to the neutral position (Fig. 2) in which the ports PB between the flow paths 5b and 5c are closed by the springs 7c and 7d Shown in Fig. The first switching valve 7 is switched from the neutral position to a position for opening the flow path from the port P to the port B between the flow paths 5b and 5c by energizing one of the solenoids 7a . When the solenoid 7b of the other solenoid is energized, the flow from the port P to the port A is switched to the position where the flow from the port B to the port T is opened.

And a relief valve 16 as a pressure control valve is connected to the flow path 5a between the hydraulic pump 4 and the electronic switching valve 6. [ The relief valve 16 drains part of the operating oil to the oil tank 3 through the oil passages 17 and 14 when the operating oil fed from the hydraulic pump 4 to the oil passage 5a exceeds the set pressure, The pressure of the operating oil to be supplied to the cylinder 2 is kept constant.

The oil passage 14 connected to the oil tank 3 is connected to the oil passage 5d connected to the secondary port (the hydraulic cylinder 2 side) of the pilot operation type check valve 11. [ The oil passage 14 is provided with a third throttle valve 18 and a second switching valve 19 for opening and closing the flow of hydraulic oil drained from the third throttle valve 18 to the oil tank 3. The third throttle (18) has a flow passage cross sectional area smaller than that of the second throttle (12b) built in the slow return valve (12). The second switching valve 19 is an electromagnetic two-position switching valve which is elastically supported by a spring 19a at the position of a check valve that closes the flow path 14 when not energized. By energizing the solenoid 19b And is switched to a position for opening the flow path 14.

The solenoid 6a of the electromagnetic switching valve 6 and the solenoid 7b of the first switching valve 7 are energized so that the operating oil from the oil passage 5b is discharged through the pilot pressure operating passage 11a as a pilot pressure, the built-in check valve is pushed open to allow backflow of operating fluid. The working oil backwashing the pilot operated check valve 11 is supplied to the oil tank 3 through the oil passage 5c, the first switching valve 7 (ports B and T), the oil passage 20 and the oil passage 14, .

The hydraulic circuit is built in the hydraulic circuit block unit 21. 3 is a cross-sectional view showing a main portion of the hydraulic circuit block unit 21 in which the hydraulic circuit is incorporated.

3, in the resistance valve 10, the valve body 10a on the rod is pressed and held by the spring 10b on the seat 8a formed at the end (step portion) of the bypass passage 8 . The operating fluid is supplied to the primary side of the bypass flow path 8. When the primary side pressure exceeds the set pressure, the valve element 10a is separated from the seat 8a and the working fluid flows through the bypass flow path 8, ). When the valve body 10a is separated from the seat 8a, the distance between the seat body 8a and the seat 8a is restricted by the spring force of the spring 10b.

3, the pilot operated check valve 11 includes a check valve body 11b, a seat 11c, a spring 11d for pressing the check valve body 11b to the seat 11c, And a pilot piston 11e. The pilot piston 11e is disposed opposite to the check valve body 11b with the seat 11c interposed therebetween, and is provided so as to be freely slidable in left and right in Fig. 3, the pilot piston 11e is pushed to the right in Fig. 3, and the rod portion 11g passes through the passage hole of the seat 11c, and the pressing force of the spring 11d is applied to the pilot pressure actuation passage 11a, The check valve body 11b is pressed against the right side of Fig. 3 to open the valve.

When working fluid is supplied from the hydraulic pump outside the drawing to the oil passage 5b, it is supplied to the bypass oil passage 8 and the pilot pressure operation oil passage 11a. The resistance valve 10 provides resistance to the hydraulic oil flowing through the bypass passage 8 to secure the pilot pressure required for valve opening of the pilot operation type check valve 11 even when the supply flow rate of the operating oil is small, The valve body 10a of the resistance valve 10 is designed to be separated from the seat 8a after the pilot piston 11e separates the check valve body 11b from the seat 11c.

In the hydraulic circuit according to the first embodiment having the above configuration, when the preload portion 1 is raised at a high speed, the solenoid 6a of the electromagnetic switching valve 6 is energized to open the flow paths 5a and 5b The solenoid 7a of the first switching valve 7 is energized to open the ports PB between the flow paths 5b and 5c. As a result, from the hydraulic pump 4, the flow path 5a, the electronic switching valve 6, the flow path 5b, the first switching valve 7 (ports P and B), the flow path 5c, The hydraulic oil is supplied to the hydraulic cylinder 2 through the check valve 11, the oil passage 5d, the slow return valve 12, and the oil passage 5e. At this time, the operating oil reaches the predetermined pressure to open the resistance valve 10 and pass the bypass flow path 8. However, since the flow rate is limited by the first throttle 9, The flow rate of the hydraulic oil passing through is smaller than the flow rate of the hydraulic oil passing through the first switching valve 7. 3, the pilot piston 11e is in fluid communication with the oil passage 5c through the oil passage 5c, The operating fluid of the pilot pressure operating oil chamber 11f of the pilot piston 11e is drained through the pilot pressure operating passage 11a and the oil passage 20. [

The solenoid 6a of the electromagnetic switching valve 6 is energized to open the port between the flow paths 5a and 5b and the first switching valve 7 is opened, As a non-energized state, and closes the ports PB between the flow paths 5b and 5c. As a result, from the hydraulic pump 4, the flow path 5a, the electronic switching valve 6, the flow path 5b, the first throttle 9 of the bypass path 8, the resistance valve 10, The operating oil is supplied to the hydraulic cylinder 2 through the pilot operated check valve 11, the oil passage 5d, the slow return valve 12 and the oil passage 5e. In this case, since the entire flow rate of the hydraulic fluid from the hydraulic pump 4 passes through the first throttle 9 through the bypass flow path 8, except for the amount that is drained from the relief valve 16, 2 is limited by the first throttle 9 and the rising speed of the preload portion 1 is lower than that in the case of the high speed rise.

The solenoid 6a of the electromagnetic switching valve 6 is energized to switch the position between the flow paths 5a and 5b to be opened so that the first switching valve 7 The solenoid 7b is energized to open the port PA so that the flow path 5b and the pilot pressure operating path 11a communicate with each other and the port BT is opened to connect the flow path 5c and the flow path 20, To the position where it is drained to the oil tank (3). As a result, the operating oil supplied to the pilot pressure operating passage 11a functions as pilot pressure, allowing the check valve body 11b in the pilot operation type check valve 11 to open the valve to allow backflow of the operating oil. The hydraulic fluid in the piston chamber 2a of the hydraulic cylinder 2 flows through the oil passage 5e, the second throttle 12b of the slow return valve 12, the oil passage 5d, the pilot operated check valve 11, And the oil passage 5c to be drained from the first switch valve 7 (ports B and T) to the oil tank 3 through the oil passages 20 and 14. [ The hydraulic oil drained to the oil tank 3 is limited in the drain flow rate by the second throttle 12b.

When the preload part 1 is lowered at a low speed, the solenoid 19b of the second switching valve 19 is energized to open the flow path 14. As a result, the operating fluid accumulated in the piston chamber 2a of the hydraulic cylinder 2 flows through the oil passage 5e, the second throttle 12b of the slow return valve 12, and the third throttle 18, and is drained to the oil tank 3. Since the third throttle 18 has a smaller flow cross-sectional area than the second throttle 12b, the flow rate through the flow path 14 is determined by the third throttle 18. At this time, the hydraulic oil from the hydraulic pump 4 is drained to the oil tank 3 through the oil passages 13a, 13b, and 14 at this time.

As described above, when the preload portion 1 is raised at a low speed, the flow rate of the hydraulic oil is restricted by the first throttle 9, thereby lowering the piston moving speed of the hydraulic cylinder 2. [ Therefore, unlike the conventional bleed-off circuit, the hydraulic cylinder 2 can be driven by switching to the meter circuit at the time of the low-speed rise of the preload portion 1, so that the fluctuation due to the relief flow rate can be suppressed. Since the primary pressure of the first throttle 9 is regulated by the relief valve 16 even if the flow rate of the operating oil is limited by the first throttle 9, The fluctuation of the flow rate of the operating oil is prevented.

Since the hydraulic pump 4 is driven by an engine (not shown), the discharge flow rate of the hydraulic pump is lowered when the engine rotates at a low speed, for example, when the vehicle is idling or running in a humid environment. The bleed-off circuit can not ensure a flow rate exceeding the relief flow rate because the discharge flow rate from the hydraulic pump is low in the bleed-off circuit, so that the engine can not be raised at low speed. The relief pressure of the operating oil is ensured even if a part of the operating oil is drained from the relief valve 16, so that the speed can be raised at a low speed.

Further, since the first throttle 9 for limiting the supply flow rate is provided separately from the second and third throttle valves 12b and 18 for limiting the drain flow rate, matching with the combine main body is facilitated.

Further, in the conventional hydraulic circuit configuration without the resistance valve 10, which is a characteristic part of the present invention, when the preload part 1 is lowered as described above, the hydraulic pressure is supplied from the hydraulic pump 4 to the oil passage 5b The working oil flows through the bypass passage 8 and the first throttle 9, the oil passage 5c, the port BT of the first switching valve 7, the oil passage 20 and the oil passage 14, 3, the time lag is generated in opening the pilot operated check valve 11, particularly when the flow rate of the hydraulic fluid to be injected is small. However, in the present invention, the resistance valve 10, it is possible to immediately generate the pilot pressure necessary for opening the pilot operated check valve 11, so that the time lag can be reduced.

The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the technical idea of the present invention.

For example, as shown in Fig. 4, the second throttle 12b may be formed in the flow path 20 instead of the slow return valve 12 of the first embodiment, and as shown in Fig. 5 The second switching valve 19A is formed on the oil tank 3 side of the second throttle 12b of the oil passage 20 and the third throttle 18 is connected in parallel with the second switching valve 19A Circuit configuration.

1 Example Mounting
2 Hydraulic cylinders
3 Oil tanks
4 Hydraulic Pump
7 First switching valve
9 First throttle
10 resistance valve
11 Pilot operated check valve
12b second throttle
18 Third throttle
19, 19A Second switching valve

Claims (2)

A hydraulic circuit for driving a hydraulic cylinder for lifting and lowering a cut portion of a combine by hydraulic oil sent from an oil tank through a hydraulic pump,
A pilot operated check valve for allowing a reverse flow of hydraulic oil from the hydraulic cylinder using a pilot pressure,
A first position for opening the secondary side port for the hydraulic pressure primary side port and the secondary side port for the hydraulic cylinder operating fluid, and a second position for opening the secondary side port for the hydraulic pressure primary operating port and the pilot pressure operating path, A first switching valve capable of switching between a second position for opening the tank port and a third position for closing the secondary pressure side port for the hydraulic pressure cylinder and the secondary side port for the hydraulic cylinder operating flow path,
A first throttle connected in parallel with the first switching valve for limiting a flow rate of hydraulic oil supplied from the hydraulic pump to the hydraulic cylinder,
A check valve that is connected in series with the first throttle and that secures the pilot pressure of the pilot operated check valve by regulating the hydraulic fluid passing through the first throttle when the first switch valve is in the second position, Wow,
A second throttle for limiting the flow rate of hydraulic fluid drained by flowing backward through the pilot operated check valve,
A third throttle having a flow path cross-sectional area smaller than that of the second throttle, for limiting the flow rate of the hydraulic fluid to be drained,
And a second switching valve capable of selectively switching the flow path of the hydraulic oil to be drained to the flow path of the hydraulic fluid drained through the third throttle,
Wherein the set pressure of the resistance valve is larger than the pilot pressure of the pilot operated check valve. The method according to claim 1,
Wherein the pilot operation type check valve includes a check valve body, a seat on which the check valve body is movable, a spring for pressingly supporting the check valve body by the seat, The pilot piston being arranged to be freely slidable relative to the pilot piston.

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