KR102633681B1 - Power transmission mechanism - Google Patents

Abstract

When built into a work machine, a power transmission mechanism is provided that can increase the minimum ground clearance of the aircraft, ensure smoothness when turning, and also ensure straight-line performance.
When the differential mechanism 40 is connected to the first output shaft and the second output shaft and can be driven when there is a difference in rotation speed between the first output shaft and the second output shaft and can absorb the difference in rotation speed, and the steering lever 3a is turned, A switching mechanism 60 that is in an allowable state that allows the driving of the differential mechanism 40 and is switched to a braking state that brakes the driving of the differential mechanism 40 when the operating lever 3a is not pivoted. It is available.

Description

Power transmission mechanism {POWER TRANSMISSION MECHANISM}

The present invention is provided to a work machine that has a power source and a pair of left and right traveling devices, and turns by a speed difference between the left and right traveling devices generated based on a turning operation of a steering operation tool, and the power output from the power source is provided. It relates to a power transmission mechanism that shifts gears and transmits them to the pair of left and right traveling devices.

Patent Document 1 describes a harvesting machine such as a combine, which is an example of a working machine. This combine has a power source such as an engine, a power transmission mechanism consisting of a continuously variable transmission such as HST and a mechanical reducer, and a pair of crawler-type traveling devices provided on the left and right of the harvester body.

In such a combine, the power source or power transmission mechanism is arranged in the center of the body frame, and the power output from the power source is distributed to the left and right by the power transmission mechanism and is configured to be transmitted to each of a pair of left and right traveling devices. .

Japanese Patent Publication No. 2012-211672

In recent years, the size and output of combines have been increasing, and along with the increase in the size and output of combines, the load such as traction and torque on the power transmission mechanism has been increasing. In order to withstand this increased load, structural reinforcement is required in the portion connecting the power transmission mechanism and the traveling device and the bearings of the traveling device. However, structural strengthening leads to larger parts.

In a combine employing a conventional left-right distribution type power transmission mechanism, there was room for improvement in that the minimum ground clearance of the aircraft was lowered because the above-mentioned parts largely protruded from the center of the lower body. In addition, the power transmission mechanism of the left and right distribution type had a large power transmission loss when the combine was turning, and there was room for improvement in terms of smooth turning.

Therefore, in place of the configuration in which the left-right distribution type power transmission mechanism is provided in the center of the fuselage frame, two power transmission mechanisms are provided independently on the left and right sides of the fuselage frame, and a pair of left and right driving mechanisms are provided by the left and right independent power transmission mechanisms. Adoption of a configuration that drives each device is considered.

This left and right independent power transmission mechanism is excellent in terms of eliminating the protrusion in the center of the lower part of the fuselage and ensuring smoothness when turning, but the two continuously variable transmission devices that make up each of the two power transmission mechanisms Due to differences in transmission efficiency and leakage of hydraulic oil (oil leakage) due to the load on the left and right pairs of traveling devices, etc., differences occur in the rotation of the left and right traveling devices, making it difficult to ensure straight driving. There was room.

In particular, in the case of work machines such as self-removable combines, straight movement during row cutting is important, so it was difficult to adopt a left and right independent power transmission mechanism.

The present invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide a power transmission mechanism that can increase the minimum ground clearance of the aircraft when built into a work machine, ensure smoothness when turning, and also ensure straight driving ability. Do it as

In order to achieve the above-described object, a feature of the power transmission mechanism according to the present invention is that it has a power source and a pair of left and right traveling devices, and the speed difference between the left and right traveling devices generated based on a turning operation of the steering operation tool is It is a power transmission mechanism that is provided on a work machine that rotates, and changes the power output from the power source and transmits it to the pair of left and right traveling devices, and is connected to a first hydraulic pump into which the power of the power source is input, and a first hydraulic circuit. a first hydraulic motor connected to the first hydraulic pump, shifting the power input to the first hydraulic pump, and outputting the power from the first output shaft to one of the pair of left and right traveling devices. 1 A continuously variable transmission device, a second hydraulic pump to which power from the power source is input, and a second hydraulic circuit connected to the second hydraulic pump to shift the power input to the second hydraulic pump and a second output shaft. a second continuously variable transmission device having a second hydraulic motor that outputs output from the left and right pair of traveling devices to the other traveling device, and is connected to the first output shaft and the second output shaft, and is connected to the first output shaft and the second output shaft. 2 A differential mechanism that can be driven when there is a difference in rotation speed of the output shaft and absorb the difference in rotation speed, and when the steering operation tool is turned, it is in an allowable state that allows the driving of the differential mechanism, and the steering operation tool is It is provided with a switching mechanism that switches to a braking state that brakes the driving of the differential mechanism when the turning operation is not performed.

In the present invention, since the first continuously variable transmission device and the second continuously variable transmission device are independent, the first continuously variable transmission device and the second continuously variable transmission device can be placed at positions close to each of a pair of left and right traveling devices in the aircraft frame. You can. The differential mechanism and switching mechanism can be laid out with some freedom in the airframe frame. If placed at a higher position than the position where the first continuously variable transmission device and the second continuously variable transmission device are placed, the minimum ground clearance of the aircraft is reduced compared to the conventional configuration in which only the left and right distribution type power transmission mechanism is provided in the center of the aircraft frame. It can be made higher. Additionally, since a continuously variable transmission device is provided for each of the left and right traveling devices, smoothness during turning is ensured.

Additionally, since the differential mechanism and the switching mechanism are provided, even if there is a difference in rotation speed between the first output shaft and the second output shaft, the difference in rotation speed can be eliminated.

Since the switching mechanism is switched to an allowable state that allows the differential mechanism to be driven when the steering operation tool is turned, the differential mechanism is driven by the rotational speed difference. In other words, the rotation speed difference is absorbed by the differential mechanism.

On the other hand, the switching mechanism is switched to a braking state that brakes the driving of the differential mechanism when the steering operation tool is not turning, so the differential mechanism is not driven even if there is a difference in rotation speed. At this time, the rotation speed difference is not absorbed by the differential mechanism, but is absorbed on the first hydraulic motor side and the second hydraulic motor side. That is, the differential mechanism eliminates the rotational difference between the first output shaft and the second output shaft, thereby ensuring straight movement.

By skillfully utilizing the differential mechanism in this way, straight-ahead driving ability is ensured without affecting turning ability when turning.

In the present invention, the switching mechanism is suitable as a hydraulic circuit including a pump mechanism that operates by driving the differential mechanism and a regulation mechanism that regulates the operation of the pump mechanism when the steering operation mechanism is not turning. do.

The pump mechanism operates by driving a differential mechanism that is driven when there is a difference in rotation speed between the first output shaft and the second output shaft. The hydraulic circuit equipped with this pump mechanism regulates the operation of the pump mechanism and brakes the drive of the differential mechanism even when the steering operation tool is not turning and there is a difference in rotation speed between the first output shaft and the second output shaft. You can.

In this way, by regulating or allowing the movement of the pump mechanism due to the difference in rotation speed between the first output shaft and the second output shaft, it is possible to ensure straight movement and rotation properties.

In the present invention, the regulating mechanism is a variable relief valve whose relief pressure varies depending on the turning operation of the steering operating tool, and when the steering operating tool is not turning, the relief pressure is increased to increase the relief pressure in the hydraulic circuit. It is suitable to regulate the flow of hydraulic oil and lower the relief pressure when the steering operation tool is turned to allow the flow of hydraulic oil in the hydraulic circuit.

When the steering mechanism is not being swiveled, by increasing the relief pressure of the variable relief valve, the discharge of hydraulic oil by the pump mechanism can be strongly restricted, and as a result, the driving of the differential mechanism can be braked. When the steering operation tool is turned, by lowering the relief pressure of the variable relief valve, discharge of hydraulic oil by the pump mechanism is permitted, and consequently, driving of the differential mechanism can be permitted. In this way, a regulation mechanism can be constructed without much cost by simply adjusting the relief pressure of the relief valve.

However, the first output shaft and the second output shaft are connected by a mechanical connection mechanism such as a dog clutch or a multi-plate disk, and this mechanical connection mechanism is connected using the elastic force of the spring or the hydraulic force of the hydraulic oil. A configuration of switching between a state that allows and a state that does not allow the difference in rotation speed between the first output shaft and the second output shaft is also considered.

However, the mechanical connection mechanism may cause shock when switching between the connected and not connected states, and also requires a large hydraulic force when switching the connected state, so it is necessary to improve operation feel and fuel efficiency. There is room for doubt.

As described above, by configuring the regulation mechanism with a variable relief valve, the operation of the pump mechanism can be smoothly switched between regulated and non-regulated states depending on the level of the relief pressure, eliminating shock and operational feeling at the time of switching. In terms of things like this, it is superior to mechanical connection mechanisms.

In the present invention, the differential mechanism includes a first side gear driven by the first output shaft, a second side gear driven by the second output shaft, and the first side gear and the second side gear. It has a pinion gear that engages, a gear case accommodating the first side gear, the second side gear, and the pinion gear, and a ring gear installed in the gear case and capable of outputting power to the pump mechanism, A suitable pump mechanism is a rotary pump whose suction side and discharge side can be replaced according to the rotation direction of the ring gear.

The rotation of the first output shaft and the rotation of the second output shaft change depending on the operation situation of the work machine, and a difference in rotation speed may occur in both forward and reverse directions. That is, the ring gear can rotate in either direction.

Therefore, the pump mechanism is configured as a rotary pump whose suction side and discharge side are interchangeable depending on the rotation direction of the ring gear. Thereby, the pump mechanism can be driven no matter which direction the ring gear rotates.

In the present invention, a first transmission shaft through which rotation of the first output shaft is input, a first transmission path for transmitting power from the first output shaft to the first transmission shaft, and the same rotation axis as the first transmission shaft. It is disposed on the second transmission shaft and receives rotation of the second output shaft, and has a second transmission path for transmitting power from the second output shaft to the second transmission shaft, and the first side gear is It is installed on the first transmission shaft, and the second side gear is installed on the second transmission shaft, and the first transmission path and the second transmission path are the rotation direction of the first transmission shaft and the second transmission shaft. Power is transmitted so that the rotation direction of is reverse, and the ring gear does not rotate when the rotation speed of the first transmission shaft and the rotation speed of the second transmission shaft are equal to the rotation speed of the first transmission shaft. When the rotation speed of the second transmission shaft is different, it is suitable if it can rotate and output power to the rotation pump.

With the above-described configuration, when the first output shaft and the second output shaft rotate in the same direction at the same rotation speed, the first transmission shaft and the second transmission shaft rotate in the opposite direction at the same rotation speed.

At this time, the first side gear and the second side gear rotate in the opposite direction at the same rotation speed, and the pinion gear idles with respect to the gear case, so the ring gear does not rotate. Therefore, since the differential mechanism does not output power, the pump mechanism does not drive.

On the other hand, when there is a difference in rotation speed between the first transmission shaft and the second transmission shaft, the ring gear rotates according to the difference in rotation speed. The rotation pump is driven by the rotation of this ring gear.

In this way, by adjusting the direction of rotation transmitted to the first side gear and the second side gear, the differential mechanism can be configured to be driven only when there is a rotation difference between the left and right output shafts.

In the present invention, the hydraulic circuit includes a suction part that sucks hydraulic oil from a hydraulic oil reservoir that stores hydraulic oil, a discharge part that discharges hydraulic oil to the hydraulic oil reservoir, and a connection passage connecting the suction part and the discharge part. wherein the connection flow path branches off into a first flow path and a second flow path on the suction part side, and merges into one flow path on the discharge part side, and the regulating mechanism is provided in the connection flow path. A third flow path is provided at the part after joining, and connects a midway part of the first flow path and a midway part of the second flow path, and the rotary pump is provided in the third flow path, and is provided in the first flow path. Hydraulic oil from the hydraulic oil reservoir to the rotary pump in the side portion between the connection portion of the third flow path and the suction portion and the portion between the connection portion of the third flow path and the suction portion in the second flow path. Provided with a check valve that allows the flow but regulates the flow of hydraulic oil from the rotary pump to the hydraulic oil reservoir, a portion between the connection portion of the third passage and the confluence of the second passage in the first passage, and In the portion between the connection part of the third flow path and the confluence part of the first flow path in the second flow path, flow of hydraulic oil from the rotary pump to the regulating mechanism is permitted, but the flow of hydraulic fluid from the regulating mechanism to the rotary pump is permitted. It is suitable if it is equipped with a discharge selection shuttle valve that regulates the flow of hydraulic oil.

The rotary pump is driven according to the rotation of the ring gear, sucks hydraulic oil from the hydraulic oil reservoir through the first flow path or the second flow path, and discharges the hydraulic oil into the hydraulic oil reservoir through the second flow path or the first flow path.

At that time, the hydraulic oil is transferred from the hydraulic oil reservoir to the rotary pump in the side portion between the connection portion of the third passage and the suction section in the first passage and in the portion between the connection portion of the third passage and the suction section in the second passage. It is provided with a check valve that allows the flow of hydraulic oil but regulates the flow of hydraulic oil from the rotary pump to the hydraulic oil reservoir, and in the portion between the connection portion of the third passage and the confluence of the second passage in the first passage and in the second passage. A discharge selection shuttle valve that allows the flow of hydraulic oil from the rotary pump to the regulating mechanism but regulates the flow of hydraulic oil from the regulating mechanism to the rotary pump at a portion between the connection portion of the third flow path and the confluence portion of the first flow path. Since it is provided, the flow path used is appropriately switched depending on the suction and discharge direction of the rotary pump.

Since the regulating mechanism is provided in the portion after the first flow path and the second flow path join, the flow of the hydraulic oil can be regulated or permitted even if the rotary pump discharges the hydraulic oil through either the first flow path or the second flow path.

1 is an overall view of the work machine.
Fig. 2 is a schematic explanatory view of the power transmission mechanism according to the present invention as seen from the front side.
3 is an explanatory diagram of a hydraulic circuit.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the power transmission mechanism concerning this invention will be described based on the drawings.

Figure 1 shows the front part of a self-contained combine 1 (hereinafter referred to as combine 1) as a harvester, which is an example of a work machine. In the following description, phrases accompanying relative directions such as “front”, “back”, “left”, “right”, “up”, “down” are basically based on the forward direction of the combine (1). do. In addition, regardless of the front-back direction or the left-right direction, “inside” and “outside” refer to the center side of the fuselage as “inside” and the outside of the fuselage as “outside.”

The combine (1) is a harvester that harvests and threshes rice and barley while independently packaging, and is equipped with an operating unit (3) in the front right area of the fuselage frame (9) and a harvesting unit in the front left area. It is provided with (4), a threshing device 5 is provided in the rear left area, a grain tank 6 is provided in the rear right area, and a crawler type travel is an example of a pair of left and right traveling devices in the lower part. It is equipped with devices 2 and 2 (see FIGS. 1 and 2).

The operating unit 3 includes a steering lever 3a as a steering control tool for manipulating the traveling direction of the combine 1, and a shift control tool (shift lever) for steplessly manipulating the driving direction and speed of the combine 1. It is equipped with seats for me and the pilot. When the operator riding in the driver's seat operates the steering lever 3a or the shift operation tool, the combine 1 can perform various operations such as forward and backward, straight forward, and turning left and right.

The harvesting unit 4 is configured to harvest multiple tanks at once. Therefore, the combine 1 can harvest multiple tanks of rice or barley at a time while moving straight through the field. When performing round-trip cutting, the field is turned around at the end of the field, moved to the opposite side of the uncut land, and the next multiple rows of rice or barley are repeatedly harvested.

The engine 7, which is the power source of the combine 1, is below the support frame of the control part of the driving part 3 of the fuselage frame 9, and is located on the axles 2b and 2b of the pair of left and right traveling devices 2 and 2. It is supported on an engine support frame 9a (see FIG. 2) located at a higher position.

The power of the output shaft 7a of the engine 7 is transmitted to the reaping unit 4, the threshing device 5, etc. through a transmission mechanism such as a transmission belt provided by the work transmission device (not shown).

Likewise, the power of the output shaft 7a of the engine 7 is transmitted to the power transmission mechanism 10 directly connected to the output shaft 7a.

As shown in FIG. 2, the power transmission mechanism 10 is a mechanism for transmitting the power of the engine 7 to the left and right pair of traveling devices 2, 2, and the left and right pair of hydrostatic first stepless It is equipped with a transmission device 20 and a second continuously variable transmission device 30.

The first continuously variable transmission device 20 includes a first hydraulic pump 21, a first hydraulic motor 22, and a first hydraulic circuit connecting the first hydraulic pump 21 and the first hydraulic motor 22. It is available.

The first hydraulic circuit is comprised of flexible hydraulic hoses 23 and 24. Hydraulic oil passes between the first hydraulic pump 21 and the first hydraulic motor 22 through hydraulic hoses 23 and 24.

The second continuously variable transmission device 30 includes a second hydraulic pump 31, a second hydraulic motor 32, and a second hydraulic circuit connecting the second hydraulic pump 31 and the second hydraulic motor 32. It is available.

The second hydraulic circuit is comprised of flexible hydraulic hoses 33 and 34. Hydraulic oil passes between the second hydraulic pump 31 and the second hydraulic motor 32 through hydraulic hoses 33 and 34.

By configuring the first hydraulic circuit and the second hydraulic circuit with flexible hydraulic hoses 23, 24, 33, 34, the first hydraulic pump 21 and the second hydraulic pump 31 are positioned close to the engine 7. Each can be independently supported, and the first hydraulic motor 22 and the second hydraulic motor 32 can be independently supported at positions close to the traveling device 2.

That is, the first hydraulic pump 21, the second hydraulic pump 31, the first hydraulic motor 22, and the second hydraulic motor 32 are distributed and arranged in a plurality of frames constituting the fuselage frame 9. Therefore, each frame only needs to have independent strength, and it can be constructed inexpensively compared to a configuration in which all pumps and motors are supported using a single strong frame.

The first hydraulic pump 21 and the second hydraulic pump 31 are variable displacement pumps driven by power input from the output shaft 7a of the engine 7, respectively.

The angle of the swash plate provided in the first hydraulic pump 21 and the angle of the swash plate provided in the second hydraulic pump 31 are determined by the steering device and hydraulic pressure connected to the steering lever 3a or the shift operation device of the driving unit 3. By means of a mechanism (not shown), the angle of the swash plate is independently changed steplessly to the neutral position, forward side, or backward side. The more the angle of the swash plate is inclined with respect to the surface perpendicular to the pump axis on which the swash plate is provided, the greater the discharge amount of hydraulic oil. The smaller the angle of the swash plate is with respect to the surface perpendicular to the pump axis, the smaller the discharge amount of hydraulic oil is.

The first hydraulic motor 22 and the second hydraulic motor 32 are constant capacity motors driven by hydraulic oil supplied from the first hydraulic pump 21 and the second hydraulic pump 31, respectively. The motor is equipped with a swash plate at a fixed angle on the first output shaft 25 and the second output shaft 35. The first output shaft 25 rotates at a rotation speed according to the discharge amount of hydraulic oil supplied from the first hydraulic pump 21, and the second output shaft 35 rotates at a rotation speed according to the discharge amount of hydraulic oil supplied from the second hydraulic pump 31. It rotates at the number of revolutions.

With the above-described configuration, the first continuously variable transmission device 20 stepslessly changes the power input from the output shaft 7a of the engine 7 according to the angle of the swash plate of the first hydraulic pump 21, It is output from the first output shaft 25 of the motor 22.

Likewise, the second continuously variable transmission device 30 stepslessly changes the power input from the output shaft 7a of the engine 7 according to the angle of the swash plate of the second hydraulic pump 31, thereby driving the second hydraulic motor 32 It is output from the second output shaft 35.

The first output shaft 25 penetrates the motor case of the first hydraulic motor 22 and protrudes toward the right side (outside) and left side (inside) of the combine 1.

The driving wheel 2a of the traveling device 2 is connected to the portion 25a of the first output shaft 25 that protrudes toward the outside of the combine 1 via the deceleration transmission mechanism 8a.

The reduction transmission mechanism 8a is composed of, for example, a planetary gear mechanism in which a plurality of gears having a predetermined transmission ratio are combined, and the rotation of the first output shaft 25 is reduced at a predetermined transmission ratio to reduce the rotation of the first output shaft 25 to the traveling device 2. It is transmitted to the driving wheel (2a) of.

Similarly, the second output shaft 35 penetrates the motor case of the second hydraulic motor 32 and protrudes toward the left (outside) and right (inside) sides of the combine 1.

The driving wheel 2a of the traveling device 2 is connected to the portion 35a of the second output shaft 35 that protrudes toward the outside of the combine 1 via the deceleration transmission mechanism 8b.

The reduction transmission mechanism 8b is composed of, for example, a planetary gear mechanism in which a plurality of gears having a predetermined transmission ratio are combined, and the rotation of the second output shaft 35 is reduced at a predetermined transmission ratio to reduce the rotation of the second output shaft 35 to the traveling device 2. It is transmitted to the driving wheel (2a) of.

By having the first continuously variable transmission device 20 and the second continuously variable transmission device 30 and the left and right pair of traveling devices 2, 2 of the same configuration, when the work machine moves straight, the first output shaft 25 and the second output shaft 25 The risk of a difference in rotation speed occurring on the output shaft 35 is reduced. However, due to individual differences in the transmission efficiency of the first continuously variable transmission device 20 and the second continuously variable transmission device 30, oil leakage due to the load applied to the pair of left and right traveling devices 2, 2, etc. A difference in rotation speed may occur between the first output shaft 25 and the second output shaft 35.

Therefore, the power transmission mechanism 10 is provided with a differential mechanism 40 and a switching mechanism 60 to eliminate the difference in rotation speed between the first output shaft 25 and the second output shaft 35 that occurs when the work machine moves straight. there is.

The differential mechanism 40 is connected to the first output shaft 25 and the second output shaft 35, and can be driven when there is a difference in rotation speed between the first output shaft 25 and the second output shaft 35 to absorb the difference in rotation speed. It is an instrument.

The differential mechanism 40 will be described. The differential mechanism 40 includes a portion 25b of the first output shaft 25 that protrudes toward the inside of the combine 1, and a portion 35b of the second output shaft 35 that protrudes toward the inside of the combine 1. It is placed in between.

The differential mechanism 40 includes a first side gear 41 driven by the first output shaft 25, a second side gear 42 driven by the second output shaft 35, and a first side gear 41. ) and a pinion gear 43 engaging with the second side gear 42, and a gear case 44 accommodating the first side gear 41, the second side gear 42, and the pinion gear 43, It is provided with a ring gear 45 installed in the gear case 44.

The first side gear 41 is connected to the first output shaft 25 through the first transmission path 50.

The first transmission path 50 includes a first connection portion 53a connecting the first output shaft 25 and the first transmission shaft 52a, and a first bevel gear 54a provided on the first transmission shaft 52a. and a second bevel gear (54b) that engages with the first bevel gear (54a) and transmits power to the second transmission shaft (52b), and connects the second transmission shaft (52b) and the third transmission shaft (52c). The second connection portion 53b, the third bevel gear 54c provided on the third transmission shaft 52c, and the third bevel gear 54c engage to transmit power to the fourth transmission shaft 52d. It is provided with a 4th bevel gear 54d, a 3rd connection part 53c which connects the 4th transmission shaft 52d, and the 1st transmission shaft 51. And, a first side gear 41 is provided on the first transmission shaft 51.

The first connection portion 53a connects the first output shaft 25 and the first transmission shaft 52a, for example, by spline coupling, so that relative movement in the axial direction is possible and relative rotation is not possible in the circumferential direction.

The second connection portion 53b connects the second transmission shaft 52b and the third transmission shaft 52c, for example, by spline coupling, so that relative movement in the axial direction is possible and relative rotation is not possible in the circumferential direction.

The third connection portion 53c connects the fourth transmission shaft 52d and the first transmission shaft 51, for example, by spline coupling, so that relative movement in the axis direction is possible and relative rotation is not possible in the circumferential direction.

That is, the first connecting portion 53a, the second connecting portion 53b, and the third connecting portion 53c allow relative movement of the first hydraulic motor 22 and the differential mechanism 40.

The first bevel gear (54a), the second bevel gear (54b), the third bevel gear (54c), and the fourth bevel gear (54d) each have a number of teeth that increases the rotation of the first output shaft (25) to move the first gear (54b). It is set to be able to be transmitted on the coax (51). The rotation speed of the first output shaft 25 is increased by the first transmission path 50, that is, the torque is reduced and transmitted to the first transmission shaft 51.

For example, when the differential mechanism 40 is directly connected to the first output shaft 25, each gear provided in the differential mechanism 40 needs to be made of expensive materials that can withstand high torque. Since the rotation of the first output shaft 25 can be accelerated by the first transmission path 50, that is, transmitted to the first transmission shaft 51 in a low torque state, each gear provided in the differential mechanism 40 is It can be constructed from inexpensive materials.

The second transmission path 55 is also basically configured in the same manner as the first transmission path 50.

That is, the second transmission path 55 includes a first connection portion 58a connecting the second output shaft 35 and the first transmission shaft 57a, and a first bevel gear provided on the first transmission shaft 57a ( 59a), a second bevel gear (59b) that engages with the first bevel gear (59a) and transmits power to the second transmission shaft (57b), the second transmission shaft (57b), and the third transmission shaft (57c) The second connection portion 58b connecting the third bevel gear 59c provided on the third transmission shaft 57c engages with the third bevel gear 59c to provide power to the fourth transmission shaft 57d. It is provided with a fourth bevel gear 59d for transmission, and a third connection portion 58c for connecting the fourth transmission shaft 57d and the second transmission shaft 56. And, a second side gear 42 is provided on the second transmission shaft 56.

However, the arrangement of the 4th bevel gear 59d that meshes with the 3rd bevel gear 59c is different from the arrangement of the 4th bevel gear 54d in the 1st transmission path 50. While the fourth bevel gear 54d is provided on the first transmission shaft 51 with its teeth facing inward, the fourth bevel gear 59d is provided on the second transmission shaft 56 with its teeth facing outward.

Accordingly, when the first output shaft 25 and the second output shaft 35 are rotating in the same direction at the same rotation speed, the first transmission shaft 51 and the second transmission shaft 56 are rotating in the opposite direction at the same rotation speed. rotates to

At this time, the first side gear 41 and the second side gear 42 of the differential mechanism 40 rotate in the reverse direction at the same rotation speed, and the pinion gear 43 idles with respect to the gear case 44, so the ring Gear 45 does not rotate. Therefore, since the differential mechanism 40 does not output power, the pump mechanism 61 is not driven.

On the other hand, when there is a difference in rotation speed between the first transmission shaft 51 and the second transmission shaft 56, the ring gear 45 rotates according to the difference in rotation speed. The pump mechanism 61 is driven by rotation of the ring gear 45.

In addition, the differential mechanism 40 is at a higher position than the position where the first hydraulic motor 22 and the second hydraulic motor 32 are supported, and the position where the differential mechanism 40 is supported in the body frame 9 , the portions of the body frame 9 where the first hydraulic motor 22 and the second hydraulic motor 32 are supported are supported at portions where they are not rigidly connected.

In a combine employing a conventional left-right distribution type power transmission mechanism, the power transmission mechanism protrudes from the center of the lower part of the body, making it difficult to increase the minimum ground clearance of the body, whereas the combine 1 has a power transmission mechanism 10 ), the first hydraulic pump 21, the second hydraulic pump 31, and the differential mechanism 40 can be placed at a relatively high position in the fuselage frame 9, thereby reducing the minimum ground clearance at the center of the lower part of the fuselage. It can be made higher.

Next, the switching mechanism 60 will be described. The switching mechanism 60 is in an allowable state that allows the differential mechanism 40 to be driven when the steering lever 3a is swiveled, and when the steering lever 3a is not swiveled, the differential mechanism 40 ) is a mechanism that switches to a braking state that brakes the drive.

As shown in FIG. 3, the switching mechanism 60 is a hydraulic circuit 63, and the hydraulic circuit 63 is provided with a pump mechanism 61 and a regulating mechanism 62.

The pump mechanism 61 is a mechanism that operates by driving the differential mechanism 40.

The ring gear 45 of the differential mechanism 40 does not rotate when the first transmission shaft 51 and the second transmission shaft 56 rotate in reverse at the same rotation speed, and the first transmission shaft 51 and the second transmission shaft 56 do not rotate. When the rotation speed of the transmission shaft 56 is different, it rotates to output power to the pump mechanism 61.

The ring gear 45 may deviate from the rotation side of the first transmission shaft 51 toward the acceleration side or toward the deceleration side of the rotation of the first transmission shaft 51 and toward the acceleration side or toward the deceleration side from the rotation of the second transmission shaft 52, depending on the operation status of the work machine. It can rotate in any direction by combining the deviations of . That is, rotation in both forward and reverse directions can be input from the ring gear 45 to the pump mechanism 61.

Accordingly, the pump mechanism 61 employs a gear pump as a rotary pump whose suction side and discharge side can be replaced according to the rotation direction of the ring gear 45. As a result, it is possible to respond to any direction in which the ring gear 45 rotates.

The hydraulic circuit 63 includes a suction part 65 that suctions hydraulic oil from the hydraulic oil reservoir 64, a discharge part 67 that discharges hydraulic oil to the hydraulic oil reservoir 64, and a suction part 65. ) and a connection passage 68 connecting the discharge portion 67. The hydraulic oil reservoir 64 is disposed near the hydraulic circuit 63.

The connection flow path 68 branches into a first flow path 70 and a second flow path 71 on the suction part 65 side, and is divided into a second flow path 71 at the confluence part 69 on the discharge part 67 side. Joining the Euro.

The regulating mechanism 62 is provided downstream of the confluence portion 69 of the first flow path 70 and the second flow path 71 in the connection flow path 68.

The connection flow path 68 has a third flow path 72 connecting the middle part of the first flow path 70 and the middle part of the second flow path 71. The pump mechanism 61 is provided in the third flow path 72.

The side portion between the connection portion 73 and the suction portion 65 of the third passage 72 in the first passage 70 and the connection portion 74 of the third passage 72 in the second passage 71. ) and the suction part 65 are provided with check valves 75 and 76.

The check valves 75 and 76 are configured to allow the flow of hydraulic oil from the hydraulic oil reservoir 64 to the pump mechanism 61, but to regulate the flow of hydraulic oil from the pump mechanism 61 to the hydraulic oil reservoir 64.

The portion between the connecting portion 73 of the third flow path 72 in the first flow path 70 and the confluence portion 69 of the second flow path 71 and the third flow path in the second flow path 71 ( A discharge selection shuttle valve 77 is provided in a portion between the connection portion 74 of the 72) and the confluence portion 69 of the first flow path 70.

The discharge selection shuttle valve 77 is configured to allow the flow of hydraulic oil from the pump mechanism 61 to the regulating mechanism 62 but to regulate the flow of hydraulic oil from the regulating mechanism 62 to the pump mechanism 61.

The regulating mechanism 62 is a mechanism that regulates the operation of the pump mechanism 61 when the steering lever 3a is not turned, and is a variable relief valve whose relief pressure varies depending on the turning operation of the steering lever 3a. It is composed by In addition, the variable relief valve may be configured to interlock mechanically with the steering lever 3a, or may be configured to interlock electrically.

The variable relief valve is a mechanism that regulates the flow of hydraulic oil in the hydraulic circuit 63 by increasing the relief pressure when the steering lever 3a is not being turned.

The pump capacity of the pump mechanism 61 is preferably larger than the motor capacity of the first hydraulic motor 22 and the second hydraulic motor 32, and the relief pressure is at least the first continuously variable transmission device 20 or the second hydraulic motor 32. It is preferable that it is set higher than the relief pressure of the relief valve provided in the continuously variable transmission device 30 for the purpose of protecting the hydraulic circuit.

With these configurations, the braking torque capable of braking by the pump mechanism 61 can be made larger than the driving torque that can output the first hydraulic motor 22 and the second hydraulic motor 32, which are hydraulic motors for traveling. This makes reliable braking possible.

When the flow of hydraulic oil in the hydraulic circuit 63 is regulated, the pump mechanism 61 and the ring gear 45 cannot rotate. For example, even if there is a difference in rotation speed between the first output shaft 25 and the second output shaft 35, the rotations of the first transmission shaft 51 and the second transmission shaft 56 are forced to coincide, that is, The rotation speeds of the first output shaft 25 and the second output shaft 35 are identical.

Additionally, the variable relief valve is configured to lower the relief pressure when the steering lever 3a is turned and allow the hydraulic oil to flow in the hydraulic circuit 63. Ring gear 45 and pump mechanism 61 according to the difference in rotation speed of the first output shaft 25 and the second output shaft 35, that is, the difference in rotation speed between the first transmission shaft 51 and the second transmission shaft 56. ) rotates.

As described above, the switching mechanism 60 is in an allowable state that allows the differential mechanism 40 to be driven when the steering lever 3a is turned, and also when the steering lever 3a is not turned. , the operation of the differential mechanism 40 is smoothly switched to a braking state.

The relationship between the turning amount (lever angle) of the steering lever 3a and the relief pressure of the variable relief valve is not limited to being a linear relationship.

Even if an actuator is provided that operates based on the turning operation of the steering lever 3a and operates the spool of the variable relief valve, the relationship between the turning operation amount of the steering lever 3a and the variable relief pressure is set to a quadratic curve relationship, etc. do.

For example, it is also possible to set the reduction rate of the relief pressure of the variable relief valve to increase as the turning amount of the steering lever 3a increases.

Additionally, the relationship between the turning amount (lever angle) of the steering lever 3a and the relief pressure of the variable relief valve may be freely selected according to the driver's preference.

As described above, the power transmission mechanism 10, which can increase the minimum ground clearance of the aircraft when built into the combine 1, ensures smoothness during turning, and also ensures straight-line driving ability, is realized.

[Other Embodiments]

(1) In the above-described embodiment, the fourth bevel gear 54d is provided on the first transmission shaft 51 with its teeth facing inward, while the fourth bevel gear 59d is provided with its teeth facing outward. Although the case where it is provided on the transmission shaft 56 has been described, the reverse may also be possible. That is, while the fourth bevel gear 54d is provided on the first transmission shaft 51 with its teeth facing outward, the fourth bevel gear 59d is provided on the second transmission shaft 56 with its teeth facing inward. It's okay.

(2) In the above-described embodiment, the case where the switching mechanism 60 is comprised of the hydraulic circuit 63 provided with the pump mechanism 61 and the regulating mechanism 62 has been explained. However, the switching mechanism 60 is not limited to this configuration.

For example, the switching mechanism 60 may be configured as a rack gear-shaped member whose posture can be switched between a position that engages with the ring gear 45 and a position that does not engage.

To explain in detail, the rack gear-shaped member is configured to change its posture according to the turning operation of the steering lever 3a, and is positioned in engagement with the ring gear 45 when the steering lever 3a is not turning. When the posture is changed, the rotation of the ring gear 45 is braked, and the steering lever 3a is turned, the posture is changed to a position that does not engage with the ring gear 45, and the ring gear 45 Allow rotation.

In addition, the gear case 44 is provided with a disk-shaped member instead of the ring gear 45, and the switching mechanism 60 is capable of switching the posture between a position that engages the disk-shaped member and a position that does not engage the disk-shaped member. It may be configured with a disc brake mechanism.

To explain in detail, the disc brake mechanism is configured to change its attitude according to the turning operation of the steering lever 3a, and when the steering lever 3a is not turning, the attitude is changed to the position where the disk-shaped member is held. This switches, the rotation of the disk-shaped member is braked, and when the steering lever 3a is being swiveled, the posture is switched to a position where the disk-shaped member is not clamped, allowing rotation of the disk-shaped member.

In addition, the gear case 44 is provided with a drum-shaped member in place of the ring gear 45, and the switching mechanism 60 is a drum whose posture can be switched to a position that is in contact with the drum-shaped member or a position that is not in contact with the drum-shaped member. It may be composed of a brake mechanism.

To explain in detail, the drum brake mechanism is configured to change its attitude according to the turning operation of the steering lever 3a, and when the steering lever 3a is not turning, the attitude is switched to a position in contact with the drum-shaped member. , the rotation of the drum-shaped member is braked, and when the steering lever 3a is turning, the attitude is changed to a position that does not contact the drum-shaped member, and rotation of the drum-shaped member is allowed.

(3) In the above-described embodiment, the case where the pump mechanism 61 is a gear pump as a rotary pump has been described as an example. However, the pump mechanism 61 is not limited to a gear pump. For example, a rotary pump such as a trochoid pump may be used, or a positive displacement pump such as an axial pump may be used. A pump is employed that rotates in both forward and reverse directions in accordance with the rotation of the ring gear 45 of the gear case 44 and is capable of suction and discharge.

(4) Transmission of power from the first output shaft 25 to the first transmission shaft 51 by the first transmission path 50 is not limited to the configuration by engaging gears. For example, from the first output shaft 25 to the first transmission shaft 51 by a power transmission belt disposed on a pulley installed on the first transmission shaft 52a and a pulley installed on the fourth transmission shaft 52d. It may be configured to transmit power.

Likewise, the transmission of power from the second output shaft 35 to the second transmission shaft 56 by the second transmission path 55 is not limited to the configuration by engaging gears. For example, from the second output shaft 35 to the second transmission shaft 56 by a power transmission belt disposed on a pulley installed on the first transmission shaft 57a and a pulley installed on the fourth transmission shaft 57d. It may be configured to transmit power.

However, a method of draping a power transmission belt wound between the first transmission shaft 52a and the fourth transmission shaft 52d, and a power transmission belt wound between the first transmission shaft 57a and the fourth transmission shaft 57d. The way the belt is worn is different. The power transmission belt on either side needs to be crossed.

Accordingly, when the first output shaft 25 and the second output shaft 35 are rotating in the same direction at the same rotation speed, the first transmission shaft 51 and the second transmission shaft 56 are rotating in the opposite direction at the same rotation speed. rotates to

The above-described embodiments are all examples of the present invention, and the present invention is not limited by the above description, and the specific configuration of each part can be appropriately changed and designed within the range where the effect of the present invention is exhibited.

The agricultural machine according to the present invention is not limited to a self-removing type combine and may be a normal type combine. In addition, it is not limited to combines and can be used for other harvesting purposes. In addition, it is not limited to a harvester, but can also be used for other work such as a harvester or tractor.

2: Travel device
3a: Control lever (steering control tool)
7a: output shaft
10: Power transmission mechanism
20: first continuously variable transmission device
21: first hydraulic pump
22: first hydraulic motor
25: first output shaft
30: second continuously variable transmission device
31: second hydraulic pump
32: second hydraulic motor
35: second output shaft
40: Differential mechanism
41: first side gear
42: second side gear
43: pinion gear
44: gear case
45: ring gear
50: first electric path
51: 1st transmission shaft
55: second electric path
56: 2nd transmission shaft
60: conversion mechanism
61: pump mechanism
62: Regulatory body
63: hydraulic circuit
64: Hydraulic oil reservoir
65: suction part
67: Discharge part
68: Connection flow path
69: confluence
70: 1st Euro
71: 2nd euro
72: 3rd euro
73: connection part
74: connection part
75: check valve
76: check valve
77: Discharge selection shuttle valve

Claims (7)

A work machine is provided with a power source and a pair of left and right traveling devices, and turns by a speed difference between the left and right traveling devices generated based on a turning operation of a steering operation tool, and shifts the power output from the power source to the It is a power transmission mechanism that transmits power to a pair of left and right traveling devices,
A first hydraulic pump into which the power of the power source is input, connected to the first hydraulic pump by a first hydraulic circuit, shifts the power input to the first hydraulic pump, and the pair of left and right are transmitted from the first output shaft. A first continuously variable transmission device having a first hydraulic motor that outputs output to one of the traveling devices;
A second hydraulic pump to which the power of the power source is input, is connected to the second hydraulic pump by a second hydraulic circuit, and changes the power input to the second hydraulic pump to shift the left and right pairs from the second output shaft. a second continuously variable transmission device having a second hydraulic motor that outputs output to another of the traveling devices;
A differential mechanism connected to the first output shaft and the second output shaft and capable of absorbing the difference in rotation speed when there is a difference in rotation speed between the first output shaft and the second output shaft;
When the steering operation tool is swiveled, a transition is made to an allowable state that allows driving of the differential mechanism, and when the steering operation tool is not swiveled, it is switched to a braking state that brakes the driving of the differential mechanism. Equipped with equipment,
The switching mechanism is a hydraulic circuit provided with a pump mechanism that operates by driving the differential mechanism and a regulation mechanism that regulates operation of the pump mechanism when the steering operation mechanism is not turning,
The differential mechanism includes a first side gear driven by the first output shaft, a second side gear driven by the second output shaft, and a pinion gear engaging the first side gear and the second side gear. , a gear case accommodating the first side gear, the second side gear, and the pinion gear, and a ring gear installed in the gear case capable of outputting power to the pump mechanism,
The pump mechanism is a rotary pump whose suction side and discharge side can be replaced according to the rotation direction of the ring gear,
A first transmission shaft to which rotation of the first output shaft is input,
a first transmission path that transmits power from the first output shaft to the first transmission shaft;
a second transmission shaft disposed on the same rotation axis as the first transmission shaft and to which rotation of the second output shaft is input;
Provided with a second transmission path for transmitting power from the second output shaft to the second transmission shaft,
The first side gear is installed on the first transmission shaft,
The second side gear is installed on the second transmission shaft,
The first transmission path and the second transmission path transmit power so that the rotation direction of the first transmission shaft and the rotation direction of the second transmission shaft are opposite to each other,
The ring gear does not rotate when the rotation speed of the first transmission shaft and the rotation speed of the second transmission shaft are the same, and rotates when the rotation speed of the first transmission shaft and the rotation speed of the second transmission shaft are different. It is possible to output power to the rotary pump,
A power transmission mechanism wherein rotation of the ring gear drives the differential mechanism. The method according to claim 1, wherein the regulating mechanism is a variable relief valve whose relief pressure varies depending on the turning operation of the steering operating tool, and when the steering operating tool is not turning, the relief pressure is increased to increase the relief pressure in the hydraulic circuit. A power transmission mechanism that regulates the flow of hydraulic oil in the hydraulic circuit and lowers the relief pressure when the steering operation tool is turned, thereby allowing the flow of hydraulic oil in the hydraulic circuit. The hydraulic circuit according to claim 1 or 2, wherein the hydraulic circuit includes a suction part that sucks hydraulic oil from a hydraulic oil reservoir that stores hydraulic oil, a discharge part that discharges hydraulic oil to the hydraulic oil reservoir, and the suction part and the discharge part. Provided with a connection flow path for connection,
The connection flow path branches into a first flow path and a second flow path on the suction part side, and merges into one flow path on the discharge part side,
The regulating mechanism is provided at a portion of the connection flow path after confluence,
A third flow path connecting the middle part of the first flow path and the middle part of the second flow path is provided, and the rotary pump is provided in the third flow path,
From the hydraulic oil storage portion to the side portion between the connection portion of the third flow path and the suction portion in the first flow path and the portion between the connection portion of the third flow path and the suction portion in the second flow path. Provided with a check valve that allows the flow of hydraulic oil to the rotary pump but regulates the flow of hydraulic oil from the rotary pump to the hydraulic oil reservoir,
In the portion between the connection portion of the third flow path and the confluence portion of the second flow passage in the first flow passage and in the portion between the connection portion of the third flow passage and the confluence portion of the first flow passage in the second flow passage. and a discharge selection shuttle valve that allows flow of hydraulic oil from the rotary pump to the regulating mechanism but regulates the flow of hydraulic oil from the regulating mechanism to the rotary pump. delete delete delete delete

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