JP4741342B2 - Hydraulic circuit structure of work vehicle - Google Patents

Description

  The present invention relates to a hydraulic circuit structure of a work vehicle including a traveling mission case and a traveling hydraulic continuously variable transmission.

In an agricultural combine that is an example of a work vehicle, as disclosed in Patent Document 1, a mission case (8 in FIGS. 2 and 3 of Patent Document 1), a hydraulic continuously variable transmission (a diagram in Patent Document 1). 2 and 9) of FIG. 3, and configured to supply lubricating oil of an oil-bathed transmission case as hydraulic oil to a hydraulic continuously variable transmission through a filter (Patent Document 1). (See oil passages 53 and 43 and charge pump 44 in FIG. 3).
The combine disclosed in Patent Document 1 includes a work device and a work pump (52 in FIG. 3 of Patent Document 1) that supplies the working oil to the work device. It is configured to supply to.

JP-A-2004-132466 (FIGS. 1, 2, and 3)

In Patent Document 1, since a filter for hydraulic oil supplied from the mission case to the hydraulic continuously variable transmission and a filter for hydraulic oil supplied from the mission case to the work pump are required, the hydraulic circuit can be simplified. There is room for improvement.
An object of the present invention is to simplify a hydraulic circuit in a hydraulic circuit structure of a work vehicle when a transmission case, a hydraulic continuously variable transmission, and a work pump are provided.

[I]
(Constitution)
The first feature of the present invention resides in the following configuration in the hydraulic circuit structure of a work vehicle.
A traveling transmission case and a traveling hydraulic continuously variable transmission are provided, and the hydraulic oil in the transmission case is configured to be supplied to the hydraulic continuously variable transmission through a filter. comprises a working pump for supplying, Ri Oh comprises a supply oil passage for supplying the surplus hydraulic oil of the hydraulic stepless transmission in the working pump, and the lower the working pump case covering the hydraulic stepless transmission Connecting the supply oil passage to the work pump to supply the excess hydraulic oil in the case covering the hydraulic continuously variable transmission to the work pump, and the upper part of the case covering the hydraulic continuously variable transmission and the transmission over a case, Ru tare connect the oil return passage.

(Function)
According to the first feature of the present invention, the hydraulic oil of the transmission case is supplied to the hydraulic continuously variable transmission through the filter, and the excess hydraulic oil of the hydraulic continuously variable transmission is supplied to the work pump via the supply oil passage. Supplied. As a result, the hydraulic oil in the transmission case that has passed through the filter is supplied to both the hydraulic continuously variable transmission and the work pump, and the filter is supplied to the hydraulic continuously variable transmission. It is shared by the filter for the working oil and the filter for the working oil supplied to the work pump.

Since the hydraulic continuously variable transmission is a precision hydraulic device, the filter for the hydraulic fluid supplied to the hydraulic continuously variable transmission is generally composed of a fine mesh paper filter, etc. Is sufficiently cleaned and supplied to the hydraulic continuously variable transmission.
Thus, according to the first feature of the present invention, the hydraulic oil in the transmission case is sufficiently cleaned by the filter and supplied to the hydraulic continuously variable transmission, and the excess hydraulic oil from the hydraulic continuously variable transmission is supplied to the work pump. Since the oil is supplied, the working pump is supplied with the hydraulic oil sufficiently cleaned by the filter.
Further, according to the first feature of the present invention, the excess hydraulic oil in the case covering the hydraulic continuously variable transmission (the excess hydraulic oil of the hydraulic continuously variable transmission) is supplied to the work pump. Excess hydraulic oil in a state where hydraulic oil is sufficiently supplied to the inside and outside of the step transmission will be supplied to the work pump, and if there is insufficient hydraulic oil inside and outside the hydraulic continuously variable transmission. Such a situation does not occur.
Further, according to the first feature of the present invention, surplus hydraulic oil in the case covering the hydraulic continuously variable transmission (excess hydraulic oil in the hydraulic continuously variable transmission) is supplied to the work pump via the supply oil passage. In this case, the remaining hydraulic oil supplied to the work pump is returned to the transmission case via the return oil passage. By connecting the return oil path across the upper part of the case covering the hydraulic continuously variable transmission and the transmission case, the air in the case covering the hydraulic continuously variable transmission is transferred to the mission case via the return oil path. Since the supply oil path is connected to the lower part of the case covering the hydraulic continuously variable transmission, the air in the case covering the hydraulic continuously variable transmission is less likely to enter the supply oil path. Become.

(The invention's effect)
According to a first aspect of the present invention, in a hydraulic circuit structure of a work vehicle, when a transmission case, a hydraulic continuously variable transmission, and a work pump are provided, a filter for hydraulic oil supplied to the hydraulic continuously variable transmission, Filters for hydraulic oil supplied to the work pump can be shared, the number of filters can be reduced, and the hydraulic circuit can be simplified. According to the first feature of the present invention, the working oil sufficiently cleaned by the filter is supplied to the work pump, and the performance deterioration of the work pump can be prevented.
Further, according to the first feature of the present invention, when surplus hydraulic oil of the hydraulic continuously variable transmission is supplied to the work pump, a state where the hydraulic oil is insufficient inside and outside the hydraulic continuously variable transmission. Therefore, the state that the hydraulic continuously variable transmission is defective due to lack of hydraulic oil does not occur.
Further, according to the first feature of the present invention, the remaining hydraulic fluid supplied to the work pump is returned to the transmission case via the return oil passage, so that the case covering the transmission case and the hydraulic continuously variable transmission is provided. And the working oil will circulate without difficulty in the work pump, the load on the hydraulic circuit system will be reduced, and the air in the case covering the hydraulic continuously variable transmission will be less likely to enter the supply oil path, The work pump performance can be prevented from deteriorating.

[II]
(Constitution)
The second feature of the present invention resides in the following configuration in the hydraulic circuit structure of the work vehicle of the first feature of the present invention.
An oil cooler is provided in the supply oil passage.

(Function)
According to the second feature of the present invention, the “action” described in the preceding item [I] is provided in the same manner as the first feature of the present invention, and in addition to this, the following “action” is provided.
As described in [I] above, the hydraulic oil in the transmission case is supplied to the hydraulic continuously variable transmission through the filter, and the excess hydraulic oil in the hydraulic continuously variable transmission is supplied to the work pump via the supply oil passage. According to the second feature of the present invention, excess hydraulic oil of the hydraulic continuously variable transmission whose temperature has increased in the hydraulic continuously variable transmission is cooled by an oil cooler and supplied to the work pump. Become so.

(The invention's effect)
According to the second feature of the present invention, the “effect of the invention” described in the preceding item [I] is provided in the same manner as the first feature of the present invention. In addition, the following “effect of the invention” is provided. ing.
According to the second feature of the present invention, excess hydraulic oil of the hydraulic continuously variable transmission whose temperature has increased in the hydraulic continuously variable transmission is cooled by an oil cooler and supplied to the work pump. The work pump performance can be prevented from deteriorating.

[1]
As shown in FIG. 1, a cutting part 2 is provided on the left side of the front part of the aircraft supported by the right and left crawler travel devices 1, a driving unit 3 is provided on the right side of the front part of the aircraft, and a rear left side of the aircraft. The threshing device 4 is provided with a glen tank 5 on the right side of the rear part of the machine body to constitute a two-stripe combine that is an example of a work vehicle. A main frame 6 is supported so as to be swingable up and down around a horizontal axis (not shown) of the machine body, and a cutting portion 2 is supported by the main frame 6. A single-acting hydraulic cylinder 7 (corresponding to a working device) (see FIG. 5) is connected between the airframe and the main frame 6, and when the hydraulic cylinder 7 is extended, the reaping part 2 is driven upward, and the hydraulic pressure is increased. When the cylinder 7 is contracted, the cutting unit 2 is driven downward.

A mission case 8 is disposed between the front portions of the right and left crawler traveling devices 1, and the structure of the mission case 8 will be described.
As shown in FIGS. 2 and 3, the transmission case 8 has a two-part structure of a right case portion 9 and a left case portion 10, and a case portion 10 a (a hydrostatic continuously variable transmission 11) is formed on the left case portion 10. The hydrostatic continuously variable transmission 11 is housed in the case portion 10a of the left case portion 10. The case portion 10a of the left case portion 10 of the mission case 8 is closed by the valve plate 12 in a state where the hydrostatic continuously variable transmission 11 is housed in the case portion 10a of the left case portion 10 of the mission case 8. A pump plate 13 is connected to the valve plate 12.

  As shown in FIGS. 2 and 5, the hydrostatic continuously variable transmission 11 is configured by connecting a variable displacement hydraulic pump 14 and a hydraulic motor 15 by a pair of oil passages 16 and has a neutral stop position. It is configured to be steplessly variable to the forward high speed side and the reverse high speed side. The input shaft 17 of the hydrostatic continuously variable transmission 11 (hydraulic pump 14) protrudes rightward from the mission case 8 (right case portion 9), enters the valve plate 12 and the pump plate 13, and the input shaft 17 The input pulley 17a is fixed to. A transmission belt (not shown) is wound around the output pulley (not shown) of the engine (not shown) and the input pulley 17a of the input shaft 17, and the engine power is transmitted to the input shaft 17. Has been.

  As shown in FIG. 2, a shift gear 19 is externally fitted to the output shaft 18 of the hydrostatic continuously variable transmission 11 (hydraulic motor 15) so as to be integrally rotatable and slidable by a spline structure and supported by the transmission case 8. A low speed gear 21 and a high speed gear 22 are fixed to the transmission shaft 20. As a result, the shift gear 19 is slid and engaged with the low speed gear 21 and the high speed gear 22, whereby the power of the output shaft 18 is shifted in two steps, and transmitted to the transmission shaft 20.

  As shown in FIG. 2, the transmission shaft 23 is supported by the transmission case 8, and the transmission gear 24 fixed to the transmission shaft 20 and the transmission gear 25 fixed to the transmission shaft 23 are engaged with each other. Right and left side gears 26 are externally fitted to the transmission shaft 23 so as to be rotatable and slidable relative to each other, and transmission gears 27a fixed to the right and left axles 27 are engaged with the right and left side gears 26. The drive sprocket 1a (see FIG. 1) of the crawler traveling device 1 is fixed to the ends of the right and left axles 27. The right and left occlusal portions 23a are fixed to the right and left ends of the transmission shaft 23, and springs 28 for urging the right and left side gears 26 to the right and left occlusal portions 23a of the transmission shaft 23 are provided. The right and left side brakes 29 are configured between the right and left side gears 26 and the transmission case 8 by friction plates.

  The state shown in FIG. 2 is a state in which the right and left side gears 26 are engaged with the right and left occlusal portions 23a of the transmission shaft 23 by the urging force of the spring 28, and the power of the transmission shaft 20 is transmitted to the transmission gear 24, 25, transmitted to the right and left axles 27 through the transmission shaft 23, the right and left occlusal portions 23a of the transmission shaft 23, and the right and left side gears 26, the aircraft is moving straight.

As shown in FIG. 2, the transmission shaft 30 is supported by the transmission case 8, the transmission gear 31 is fixed to the transmission shaft 30, and the low-speed gear 30 a and the high-speed gear 30 b are integrally formed on the transmission shaft 30. The transmission gear 32 fixed to the input shaft 17 and the transmission gear 31 are engaged with each other. The transmission shaft 33 is supported by the transmission case 8, the transmission gears 34 and 35 externally fitted to the output shaft 33 are engaged with the low-speed gear 30a and the high-speed gear 30b of the transmission shaft 30, and the shift gear 36 is splined. It is fitted on the output shaft 33 to be rotatable therewith and slidable within the structure. As a result, the shift gear 36 is slid and engaged with the transmission gears 34, 35, whereby the power of the input shaft 17 is shifted in two steps, high and low, via the transmission shaft 30 and transmitted to the output shaft 33. The power of the output shaft 33 is transmitted to the cutting unit 2 via an output pulley 33a fixed to the output shaft 33 and a transmission belt (not shown).

[2]
Next, the hydraulic circuit structure of the steering operation system will be described.
As shown in FIGS. 2 and 5, a trochoid charge pump 37 and a hydraulic pump 38 are attached to the input shaft 17 in the pump plate 13, and the charge pump 37 and the hydraulic pump 38 are driven by the input shaft 17. Yes. As shown in FIGS. 3 and 4, a filter 39 (a fine paper filter) is attached to the upper portion of the left case portion 10 of the mission case 8, and as shown in FIGS. Lubricating oil is supplied as hydraulic oil to the charge pump 37 and the hydraulic pump 38 via the internal oil passage 40, the filter 39 and the internal oil passage 41.

  As shown in FIG. 6, wall portions 9 b and 10 b are integrally formed along the vertical direction inside the front portions of the right and left case portions 9 and 10 of the mission case 8, so that the right and left sides of the mission case 8 are formed. Wall portions 9c, 10c are integrally formed in the middle portion of the case portions 9, 10 along the front-rear direction, and the wall portions 9b, 10b, 9c, 10c of the right and left case portions 9, 10 of the mission case 8 are formed. Are matched.

  Thereby, as shown in FIG. 6, the internal oil passage 40 is formed by the wall portions 9 b and 10 b of the right and left case portions 9 and 10 of the mission case 8. The mission case 8 is divided into an upper part and a lower part by the wall parts 9c, 10c of the right and left case parts 9, 10 of the mission case 8, and the wall parts 9b of the right and left case parts 9, 10 of the mission case 8, Through the communication part 57 between 10b, 9c, 10c, the transmission case 8 communicates with the upper part and the lower part. The input shaft 17, the transmission shaft 30 and the output shaft 33 are arranged at the upper part of the mission case 8, and the output shaft 18, the transmission shafts 20 and 23, and the right and left axles 27 are arranged at the lower part of the mission case 8. An oil supply port 10 d is formed in the upper part of the left case portion 10 of the transmission case 8, and the oil level L1 of the lubricating oil (hydraulic oil) stored in the transmission case 8 is the input shaft 17, the transmission shaft 30, and the output shaft 33. The position is set.

  As shown in FIG. 5, a sequence valve 43 and a power steering switching valve 44 are connected to an internal oil passage 42 from the hydraulic pump 38, and an oil chamber between the transmission shaft 23 and the right and left side gears 26 is connected. The hydraulic oil for the switching valve 44 is supplied, and a variable relief valve 45 is connected to the oil chamber between the transmission shaft 23 and the right and left side gears 26. A friction plate type turning assist clutch 46 (see FIG. 2) is formed between the right axle 27 and the transmission gear 27 a of the left axle 27, and a pressure reducing valve is connected to the internal oil passage 47 branched from the internal oil passage 42. 48, a relief valve 49 and a turning assist clutch 46 are connected.

  As shown in FIGS. 1 and 5, a control tower 50 is provided at the front of the operation unit 3, and an operation lever 51 is provided on the control tower 50, so that the operation lever 51 can be operated in the front-rear direction and the left-right direction. It is configured. The operation lever 51 and the switching valve 44 are mechanically linked so that the switching valve 44 is operated by operating the operation lever 51 in the left-right direction. The switching valve 44 and the variable relief valve 45 are mechanically connected. Are linked together.

  The state shown in FIGS. 2 and 5 is a state in which the operation lever 51 is operated to the neutral position, and the right and left side gears 26 are applied to the right and left occlusal portions 23 a of the transmission shaft 23 by the biasing force of the spring 28. The rotation assist clutch 46 is in a transmission state, and the power of the transmission shaft 20 is transmitted through the transmission gears 24 and 25, the transmission shaft 23, the right and left occlusion portions 23 a of the transmission shaft 23, and the right and left side gears 26. As a result, the airframe is traveling straight, being transmitted to the right and left axles 27.

  As shown in FIGS. 2 and 5, for example, when the operation lever 51 is operated to the right from the neutral position, the right side gear 26 is moved to the right side of the transmission shaft 23 by the action of the switching valve 44 and the variable relief valve 45. The turning assisting clutch 46 is moved to the half transmission state away from the occlusion portion 23a, and the power of the left axle 27 is decelerated and transmitted to the right axle 27 via the turning assisting clutch 46 in the half transmission state. As a result, the right axle 27 is driven to decelerate with respect to the left axle 27, and the airframe gently turns to the right due to the drive speed difference between the right and left crawler travel devices 1. As the operation is performed in the right direction, the operating pressure of the turning assist clutch 46 decreases, the right axle 27 is decelerated, and the right turning radius becomes smaller.

  As shown in FIGS. 2 and 5, when the operation lever 51 is further operated to the right, the turning assist clutch 46 is operated in a disconnected state, power is not transmitted to the right axle 27, and the right axle 27 is free. Rotating state. When the operation lever 51 is further operated in the right direction, the right side gear 26 presses the right side brake 29 by the action of the variable relief valve 45 to perform the braking operation, the right axle 27 is braked, and the airframe is transmitted to the right. Turn around. When the operation lever 51 is operated to the left from the neutral position, the left side gear 26 and the turning assisting clutch 46 are operated in the same manner as described above, and the aircraft slowly turns to the left and turns to the left.

[3]
Next, the hydraulic circuit structure for the hydrostatic continuously variable transmission 11 will be described.
As shown in FIGS. 2 and 5, the internal oil passage 52 of the valve plate 12 from the charge pump 37 is connected to the oil passage 16 via a pair of check valves 53 and a throttle 54, and the internal oil passage 52 A relief valve 56 is provided in the internal oil passage 55 of the valve plate 12 branched from the inner end of the case portion 10a of the left case portion 10 of the transmission case 8 (hydrostatic continuously variable transmission 11). It is connected.

  As shown in FIGS. 2 and 5, an internal oil passage 58 (corresponding to a supply oil passage) is located at the bottom of the case portion 10a (hydrostatic continuously variable transmission 11) of the left case portion 10 of the mission case 8. A return oil passage 59 is formed at the top of the case portion 10a (hydrostatic continuously variable transmission 11) of the left case portion 10 of the mission case 8 as shown in FIG. The return oil passage 59 communicates with the upper part of the mission case 8 (a position higher than the oil level L1 of the lubricating oil (operating oil) stored in the mission case 8).

  As a result, as shown in FIGS. 2, 5, and 6, the lubricating oil in the mission case 8 is supplied as hydraulic oil to the charge pump 37 via the internal oil passage 40, the filter 39 and the internal oil passage 41. Is supplied to the oil passage 16 through the internal oil passage 52, and excess hydraulic oil in the oil passage 16 passes through the internal oil passage 55 and the relief valve 56 and the case portion 10 a of the left case portion 10 of the transmission case 8. Is supplied to the (hydrostatic continuously variable transmission 11), and the case portion 10a (hydrostatic continuously variable transmission 11) of the left case portion 10 of the transmission case 8 is substantially filled with hydraulic oil (mission case 8). The oil level of the case portion 10a (hydrostatic continuously variable transmission 11) of the left case portion 10 is higher than the oil level L1 of the lubricating oil (hydraulic oil) stored in the transmission case 8. The position).

  As shown in FIG. 5, surplus hydraulic fluid in the case portion 10a (hydrostatic continuously variable transmission 11) of the left case portion 10 of the mission case 8 causes the internal oil passage 58 as described in [4] described later. Thus, the remaining hydraulic oil supplied to the work pump 60 is returned to the upper portion of the transmission case 8 via the return oil passage 59.

[4]
Next, a hydraulic circuit structure for the work pump 60 will be described.
As shown in FIG. 5, a gear pump type work pump 60 is provided in the vicinity of the engine, and the work pump 60 is driven by the power of the engine. As shown in FIGS. 2, 3, 4, and 5, an internal oil passage 58 is directed to the front outside at the lowermost portion of the case portion 10 a (hydrostatic continuously variable transmission 11) of the left case portion 10 of the mission case 8. An external pipe 61 (corresponding to a supply oil path) is connected to the internal oil passage 58, and the external pipe 61 is connected to the work pump 60.

  As shown in FIGS. 2, 3, and 4, a fan 62 is fixed to the input shaft 17, and an L-shaped guide plate 63 that covers the front side and the lower side of the fan 62 is fixed to the mission case 8 as a mudguard. The wind generated by the rotation of the fan 62 is configured to flow from the left side to the right side in FIG. 3 so as to cool the upper portion of the transmission case 8 and the hydrostatic continuously variable transmission 11. The external piping 61 is disposed along the front and upper portions of the transmission case 8 so that the external piping 61 is located in the wind passage by the rotation of the fan 62, and the hydraulic oil supplied to the work pump 60. Is cooled in the external pipe 61.

  As shown in FIG. 5, a switching valve 65 is connected to an external pipe 64 from the work pump 60, the switching valve 65 is connected to the hydraulic cylinder 7, and an external pipe 67 as a return oil path from the switching valve 65 is provided. As shown in FIGS. 3 and 6, the external piping 67 is connected to the lower portion of the left case portion 10 of the mission case 8. A pilot check valve 66 positioned between the switching valve 65 and the hydraulic cylinder 7 is provided in the switching valve 65, and a relief valve 68 extending over the external pipes 64 and 67 is provided in the switching valve 65.

  As shown in FIG. 1, the switching valve 65 is disposed below the floor 69 of the operation unit 3, and the operation lever 51 and the switching valve 65 are mechanically linked by a wire (not shown). The switching valve 65 is configured to be operated by operating the operation lever 51 in the front-rear direction. As shown in FIG. 5, the switching valve 65 has a neutral position, a lowered position, a low-speed raised position, and a high-speed raised position. The state shown in FIG. 5 is a state where the operation lever 51 is operated to the neutral position and is closed. The hydraulic cylinder 7 is stopped by the pilot check valve 66.

  As shown in FIG. 5, when the operation lever 51 is operated in the forward direction and the switching valve 65 is operated to the lowered position, the pilot check valve 66 is opened by the pilot pressure, and the hydraulic oil in the hydraulic cylinder 7 is supplied to the pilot check valve. 66, the lowering position of the switching valve 65 and the external pipe 67 are returned to the lower part of the transmission case 8, and the hydraulic cylinder 7 is contracted to drive the cutting unit 2 downward. As shown in FIGS. 3 and 6, when the hydraulic oil in the hydraulic cylinder 7 is returned from the external pipe 67 to the lower portion of the transmission case 8, the wall portions 9 c and 10 c of the right and left case portions 9 and 10 of the transmission case 8 are used. The temporary increase in the oil level L1 of the lubricating oil (hydraulic oil) stored in the mission case 8 is suppressed, and the oil level L1 of the lubricating oil (hydraulic oil) stored in the mission case 8 is 8 so as not to reach the fuel filler opening 10d of the left case 10.

[First Alternative Embodiment of the Invention]
In the hydraulic circuit structure shown in FIG. 5 of the best mode for carrying out the invention] before described, it may also comprise an oil cooler 72 to the external pipe 61.

[Second Embodiment of the Invention]
Oite the aforementioned [best shape condition for carrying out the invention, as shown in FIG. 1, the unloader 74 for discharging the grain that is stored in the grain tank 5, the hydraulic cylinder 75 for vertically driving the unloader 74 You may comprise so that the working oil of the working pump 60 may be supplied to (equivalent to a working device). When equipped with a hydraulically driven posture control mechanism (corresponding to a working device) (not shown) that drives the right and left crawler travel devices 1 up and down independently to maintain the posture of the airframe horizontally, the work pump 60 The hydraulic oil may be supplied to the attitude control mechanism. Instead of the hydrostatic continuously variable transmission 11, a hydraulic-mechanical continuously variable transmission (hydro-mechanical transmission) (HMT) may be used as the hydraulic continuously variable transmission.
The present invention can be applied not only to a combine but also to a construction vehicle such as an agricultural tractor, a riding rice transplanter, or a hall loader.

Combine right side view Longitudinal front view of the mission case Front view of mission case Right side view of the mission case Diagram showing hydraulic circuit structure Side view of the interior of the right and left case section of the transmission case

7, 75 Working device 8 Mission case 10a, 70a Case 11 Hydraulic continuously variable transmission 39 Filter 58, 61, 71 Supply oil passage 59 Return oil passage 60 Work pump 72 Oil cooler

Claims (2)

A traveling mission case and a traveling hydraulic continuously variable transmission are provided.
The hydraulic oil of the transmission case is configured to be supplied to the hydraulic continuously variable transmission through a filter,
Comprises a working pump for supplying hydraulic oil to the work device, Oh Ri comprises a supply oil passage for supplying the surplus hydraulic oil of the HST to the working pump,
A supply oil path is connected across the lower part of the case covering the hydraulic continuously variable transmission and the work pump, and the excess hydraulic oil in the case covering the hydraulic continuously variable transmission is supplied to the work pump. and Yes in the HST device over the case of the upper and the transmission case cover, back hydraulic circuit structure of connecting the oil passage tare Ru work vehicle.   The hydraulic circuit structure of the work vehicle according to claim 1, wherein an oil cooler is provided in the supply oil passage.

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