JP4449073B2 - Work vehicle having toroidal transmission - Google Patents

Description

  The present invention relates to a work vehicle including a toroidal transmission in a transmission case.

  As shown in Patent Document 1, there is known a work vehicle transmission device that is applied to a work vehicle such as a tractor and that includes a full toroidal type transmission mechanism in a transmission case to control power transmission. In this work vehicle transmission, the transmission power extracted from the output disk of the toroidal transmission mechanism is guided to the planetary gear mechanism on the intermediate transmission shaft side by side to efficiently shift the traveling power in a wide speed range including forward and reverse. Can be output.

However, the above-described transmission for a work vehicle is used for many hydraulically operated devices such as a variator and a HiLo clutch that switches the transmission system of the transmission power by hydraulic control, and a hydraulic clutch type transmission mechanism that controls other transmission systems. Not only does it require hydraulic fluid, but also requires special dedicated hydraulic fluid to ensure the transmission efficiency of the power roller that is in rolling contact between the input and output disks of the toroidal transmission mechanism. In exchange, it has a problem of being forced to bear a large cost for hydraulic oil.
JP 2003-74659 A

  The problem to be solved is to provide a work vehicle transmission that can reduce the cost burden of necessary hydraulic oil while ensuring high efficiency transmission characteristics by the toroidal transmission mechanism.

  The invention according to claim 1 is provided with a hydraulic cylinder for raising and lowering the work implement at the rear part of the transmission case, and a variator mechanism for continuously changing the input power transmitted from the engine by driving a power roller in the case and the speed change thereof The power transmission torque is transmitted to the drive wheels via a toroidal transmission mechanism having a hydraulic clutch type HiLo clutch that switches between high and low two stages, and the input power transmitted from the engine is transmitted as work machine system power via a hydraulic clutch mechanism. In the work vehicle for transmitting to the PTO shaft, the inside of the transmission case is divided into two sections by dividing the front and rear by a partition wall, and the variator of the toroidal transmission mechanism is installed in the front section, and the power roller While the first hydraulic fluid that drives the tank is filled, the rear compartment of the case While interior at least the HiLo clutch and a hydraulic clutch mechanism, characterized in that the HiLo internal piston of the clutch and the hydraulic clutch mechanism, and filled with a second hydraulic fluid for driving the working machine lifting hydraulic cylinder. The variator of the toroidal transmission mechanism is partitioned from other compartments by a partition wall in the transmission case, and hydraulic oil is individually supplied to each compartment by a separate hydraulic system.

  According to a second aspect of the present invention, in the configuration of the first aspect, the hydraulic system of the work vehicle is provided on a support shaft of a power roller provided in the variator and an input / output disk of the variator, and both disks are moved in an approach direction. A first system for supplying the first hydraulic oil to the cylinder chamber that presses the cylinder chamber and a second system for supplying the second hydraulic oil to the hydraulic clutch mechanism. It is characterized by supplying pressure oil. The first hydraulic oil is supplied only to the power roller and the end load of the variator by the first system, and the second hydraulic oil is supplied to the hydraulic clutch mechanism by the second system.

  According to a third aspect of the present invention, in the configuration of the first aspect, the hydraulic system of the work vehicle includes a control valve that adjusts the hydraulic pressure in the end load chamber of the variator to a predetermined pressure. The hydraulic pressure acting on the end load is adjusted to a predetermined hydraulic pressure with high responsiveness by the control valve.

The work vehicle transmission of the present invention has the following effects.
The effect of the invention according to claim 1 is that the hydraulic oil is supplied separately in different sections of the transmission case by different hydraulic systems separately for the variator and other devices, so that the transmission efficiency of the toroidal transmission mechanism is improved. In addition, the dedicated hydraulic oil required for the variator can be minimized and the required cost can be reduced.

  The effect of the invention according to claim 2 is that, in addition to the effect of claim 1, the hydraulic oil is supplied to the power roller and the end load by the first hydraulic system for the variator. By concentrating in a limited manner, transmission by the power roller can be secured.

  The effect of the invention according to claim 3 is that the end load is adjusted to the predetermined hydraulic pressure with high responsiveness in addition to the effect of claim 1, so that the speed change characteristics of the variator can be ensured with high accuracy. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a side view of an agricultural tractor showing an example of a work vehicle according to the present invention. The agricultural tractor has an engine c mounted on the front part of the machine body including a front wheel a and a rear wheel b, transmits the rotational power of the engine c to the transmission 1, and the power appropriately decelerated by the transmission 1 is transmitted to the front wheel. It transmits to a and the rear wheel b, and it is comprised so that it may output to the working machine K1 via the PTO shaft k of the rear part. For operation by the operator, a monitor m for displaying the driving state on the front side of the steering wheel h, a forward / reverse switching lever n and an accelerator lever L for switching forward and backward, a brake pedal t1 and an accelerator pedal p at the base, A shift lever 7 and the like are arranged on the side of the cockpit q provided in the upper part of the mission case 2, and are configured to be automatically shiftable by a control unit (not shown).

  FIG. 2 and FIG. 3 show a sectional view of a principal part of the transmission and a perspective front view thereof, respectively. The transmission 1 supports a case input shaft 3, a work transmission shaft 4, a travel transmission shaft 5, a middle work intermediate shaft 6, a front wheel output shaft 7, and the like in the transmission case 2 in parallel in the front-rear direction. By constructing a transmission mechanism necessary for each, the received engine power is shifted and output to the traveling system and the working system. The transmission case 2 is made of a casting, and includes a front case 2a, a mid case 2b, and a rear case 2c. The front case 2a is divided into front and rear compartments A and B so as to cross the inside of the front case 2a. A metal partition wall 9 is formed.

  The case input shaft 3 is supported by the front end portion of the transmission case 2 and receives engine power. The work transmission shaft 4 is provided with a gear 4a receiving power from the case input shaft 3 at the front end, extends rearward so as to pass through the partition wall 9 and run through the transmission case 2, and has a work transmission control at the rear end. As a part, a PTO forward / reverse switching clutch 12 and the like are provided.

  The traveling transmission shaft 5 includes a gear 5a that receives rotational power in the same direction from the case input shaft 3 on the front side, and includes a variator 21 of the toroidal transmission mechanism, a differential portion 22 that follows the rear side of the partition wall 9, and two HiLo clutches. The height switching unit 23, the drive pinion 24, and the like are provided on the same axis.

  The work intermediate shaft 6 includes a switching unit 31 that switches from the middle position of the transmission case 2 to the rear end and switches the rotation direction of the work intermediate shaft 6 in the forward and reverse directions. The switching unit 31 switches the rotational direction of the power transmitted to the front portion of the work intermediate shaft 6 via the PTO forward / reverse switching clutch 12 and transmits the normal rotation power or the reverse rotation power.

  The front wheel output shaft 7 is provided with a gear 7a for receiving branching power from the rear stage portion of the traveling transmission shaft 5 at the rear end portion, and at the front portion is provided with a front wheel speed increasing clutch 32 for switching speed increase by hydraulic control. Front wheel power is output to the front part of 2.

  The variator 21 of the full toroidal transmission mechanism provided in the traveling transmission shaft 5 is disposed in the front section A of the mission case 2 together with a pump 21a that supplies the dedicated hydraulic fluid. This speed change mechanism has two input disks 41 and 42 arranged in the front-rear direction, an output disk 43 arranged between them, and an opposing surface formed in an annular concave shape so that the opposing surfaces are equally divided by 120 °. It is comprised by the power roller 44 ... interposed by the circumferential space | interval. The front input disk 41 is integrally supported by the traveling transmission shaft 5 while receiving the end load hydraulic pressure in the axial direction, and the output disk 43 is attached with a sleeve-shaped transmission member 45 extending rearward. The output disk 43 outputs continuously variable transmission power according to the inclination of the power rollers 44 by pivotally supporting the upper input disk 42 and supporting the rear input disk 42 on the transmission member 45. Each power roller 44 is provided with a hydraulic cylinder 44a, and the inclination angle is controlled by its forward / backward position, and transmission is ensured by receiving dedicated hydraulic oil through an oil passage formed in each cylinder rod 44b.

  The differential portion 22 is configured around a shaft end member 51 that is integrally attached to the rear end portion of the traveling transmission shaft 5. The shaft end member 51 is connected to the rear input disk 42 and rotates integrally therewith, and the differential gear body 53 is pivotally supported. The rotational force of the output disk 43 is transmitted to the differential gear body 53 via the transmission member 45. Receive. In the subsequent stage of the differential gear body 53, the inner and outer transmission members 54, 55 that output the second speed differential power including the reverse rotation stop region are meshed and transmitted, and one of them is connected to the high / low switching unit 23 by hydraulic operation. By performing reverse rotation input, a continuous shift output is transmitted to the drive pinion 24 with the same rotational direction when switching the second-speed differential power. A travel output shaft 56 is arranged on the same axis line behind the inner transmission member 54 at the rear stage of the height switching unit 23.

  The PTO forward / reverse switching clutch 12 at the rear end portion of the work transmission shaft 4 is a transmission control unit for connecting / disconnecting the work system power by hydraulic control, and is switched to transmit to the work intermediate shaft 6 so that a forward / reverse output can be selected from the subsequent stage. Part 31 is configured. Further, intermediate gears 8a and 8b receiving branching power from an extension shaft 56e connected to the rear stage of the travel output shaft 56 are supported on the work intermediate shaft 6, and a gear 7a receiving rotational force of the intermediate gears 8a and 8b is output to the front wheels. By providing the shaft 7, the traveling power is branched from the traveling output shaft 56 and transmitted to the front wheel output shaft 7.

Next, the configuration of the hydraulic system of the work vehicle transmission 1 will be described.
The hydraulic system of the work vehicle transmission 1 supplies hydraulic oil individually by configuring the hydraulic system individually for each of the sections A and B partitioned forward and backward by a partition wall 9 traversing the transmission case 2. To do. The hydraulic system in the front section A has jurisdiction over the variator 21 at the front stage of the traveling transmission shaft 5 that requires a dedicated hydraulic oil (first hydraulic oil), and the hydraulic system in the other section B has a common hydraulic oil (first hydraulic oil). The second stage oil) is responsible for the rear stage of the traveling transmission shaft 5 and other transmission devices of the work machine system.

  The hydraulic system of the variator 21 will be described in detail. As shown in the hydraulic system diagram of FIG. 4, a pump 21a is disposed on the inner bottom of the section A of the mission case 2, and the pump 21a causes each power roller 44 to Exclusive hydraulic fluid is supplied from the shaft end of the cylinder rod 44b of the hydraulic cylinder 44a. With this hydraulic oil, lubrication and cooling are performed in order to ensure transmission between the input disks 41 and 42 and the output disk 43.

  The hydraulic cylinder 44a for operating all the power rollers 44 is provided with a set pressure variable reduce valve 62, 62 that receives hydraulic pressure from the electromagnetic proportional pressure reducing valves 61, 61 to the pilot piston, symmetrically with respect to both expansion and contraction directions. The power transmission tilt angle is controlled by advancing and retracting each power roller 44 based on the portions 44c and 44c.

  In addition, a pressure control valve 63 is provided on the end load of the variator 21, and by receiving the hydraulic pressure on the power roller hydraulic cylinder 44a side, the hydraulic pressure is linked to the operating pressure of the hydraulic cylinder 44a to the internal piston R1 for end load. Supply. The pressure control valve 63 ensures the responsiveness by pilot control by the end load pressure, and is provided with a reduce position 63a as necessary to control the maximum pressure so that it is substantially the same as the higher pressure of the cylinder pressure. As the pressure, the rolling contact pressure of each power roller 44 is adjusted while preventing overload pressure. These dedicated hydraulic fluids are circulated only in the front compartment A.

  As shown in the hydraulic system diagram of FIG. 5, the other hydraulic system using the general hydraulic oil is the range of the rear section B of the transmission case 2, that is, the front wheel drive shift clutch 32 at the rear stage of the traveling transmission shaft 5, and the like. , Lubrication and hydraulic control of equipment such as the PTO forward / reverse switching clutch 12 for controlling the work system of the work transmission shaft 4, and a brake control cylinder 71 for turning, a hydraulic cylinder 72 for lifting and lowering the work machine, a working machine rolling hydraulic cylinder 73, Supply oil of the power steering cylinder 74, the working cylinder 75, and other working actuators is controlled by the dual pump 70.

  In particular, the high / low switching portion 23 by the HiLo clutch at the rear stage portion of the travel transmission shaft 5 supplies the hydraulic pressure from the hydraulic control valve 76 to the travel output shaft 56 at the subsequent stage, and performs PAB open control at the neutral position. By supplying hydraulic pressure to both, responsiveness at the time of Hi-Lo switching and smooth shifting can be achieved.

  If necessary, the hydraulic control valve 76 is provided with a relief valve 78 whose pressure can be changed by an electromagnetic proportional pressure reducing valve 77 to control the clutch pressure, thereby further improving the response at the time of clutch switching and further smooth shifting. It becomes possible. Further, when the airframe is suddenly braked (brake operating switch or output shaft rotation is suddenly reduced, etc.), the engine brake operation can be performed by hydraulically controlling the pressure so that the clutch slips moderately. In this brake response control, by controlling the power rollers 44 of the variator 21 so as to return to the vicinity of the geared neutral before the airframe stops, a smooth speed change at the time of re-start is possible.

  As shown in the input / output signal system diagram of FIG. 6, these hydraulic system control units 81 can change the set pressure by the electromagnetic proportional pressure reducing valves 61 and 61 based on the pressure of the power roller 44 by the detection units 44 c and 44 c. In addition to controlling the reduction valves 62, 62 to control the expansion and contraction of all the hydraulic cylinders 44a, the pressure control valve 63 for adjusting the end load pressure, the pressure control valve 76 for switching the HiLo clutch 23 to the high and low, and the clutch pressure of the HiLo clutch 23 The control pressure control valves 77 and 78 are controlled. By controlling the drive of the hydraulic equipment in this way, the above-described shift control can be performed.

  Next, a second hydraulic system configuration example of the variator 21 will be described. In the following description, the same members as those described above are denoted by the same reference numerals, and description thereof is omitted. As shown in the hydraulic system diagram of FIG. 7, a normal open type electromagnetic proportional pressure reducing valve 92 is provided at the end load, and relief valves 93, 93 are provided for expansion / contraction control of the hydraulic cylinder 44a. When the end load pressure is too high as the pilot pressure by the electromagnetic proportional pressure reducing valve 92, the reaction pressure on the end load side is quickly controlled to be substantially the same as the higher one of the expansion and contraction operating pressure of the hydraulic cylinder 44a. be able to.

  FIG. 8 is a hydraulic system diagram of a third hydraulic system configuration example of the variator 21. By configuring the pressure control unit of the hydraulic cylinder 44a with an electromagnetic proportional pressure reducing valve, the reaction pressure on the end load side can be quickly controlled as described above, and is approximately the same as the higher operating pressure of the hydraulic cylinder 44a. Overload pressure can be prevented. In addition, since the electromagnetic proportional pressure reducing valve has a pressure control of 21 kgf / cm 2 (up to a maximum of 50 kgf / cm 2), a wide range of current-pressure characteristics can be obtained, so that a fine pressure can be obtained in terms of control.

  FIG. 9 is a hydraulic system diagram of a fourth hydraulic system configuration example of the variator 21. Hydraulic fluid is supplied from the shaft end of the cylinder rod 44b through relief valves 94, 94 for expansion / contraction control of the hydraulic cylinder 44a. In the case of forward / reverse control (less than 10 km / h), the power roller 44 is quickly moved to the opposite side (reverse side) by controlling the piston pressure on the end load side so as to slightly lower the load of the power roller 44. Operate and respond quickly to back and forth operations.

It is a side view of the work vehicle of this invention. FIG. 2 is a cross-sectional view of a main part of an axis development of the work vehicle transmission of FIG. 1. It is a see-through | perspective front view of the transmission for work vehicles of FIG. It is a hydraulic system diagram of the hydraulic system of a variator. It is a hydraulic system diagram of a hydraulic system using general hydraulic oil. It is an input-output signal system diagram of the control part of a hydraulic system. It is a hydraulic system figure which shows the 2nd hydraulic system structural example of a variator. It is a hydraulic system figure which shows the 3rd hydraulic system structural example of a variator. It is a hydraulic system figure which shows the 4th hydraulic system structural example of a variator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission device 2 Transmission case 3 Case input shaft 4 Work transmission shaft 5 Traveling transmission shaft 6 Work intermediate shaft 7 Front wheel output shaft 9 Partition wall 12 Transmission switching clutch (hydraulic clutch type transmission mechanism)
12a Pressure control valve 21 Variator 21a Pump 22 Differential part 23 HiLo clutch (high / low switching part)
32 Front wheel speed increasing clutch (hydraulic clutch type speed change mechanism)
41, 42 Input disk 43 Output disk 44 Power roller 44a Hydraulic cylinder 44b Cylinder rod 56 Traveling output shaft 63 Pressure control valve 70 Double pump 72 Working machine lifting hydraulic cylinder 75 Working cylinder (working actuator)
81 Control unit A Front compartment B Rear compartment c Engine R1 Internal piston

Claims (3)

The work case elevating hydraulic cylinder (72) is provided at the rear of the transmission case (2), and the input power transmitted from the engine (c) is driven into the power roller (44, 44...) In the case (2). Is transmitted to the drive wheels (a, b) via a toroidal transmission mechanism having a variator mechanism (21) for continuously variable transmission and a hydraulic clutch type HiLo clutch (23) for switching transmission torque of the transmission power between high and low. In the work vehicle for transmitting the input power transmitted from the engine (c) to the PTO shaft (K) through the hydraulic clutch mechanism (12) as work machine system power,
The inside of the transmission case (2) is divided into two compartments (A, B) by dividing it forward and backward by a partition wall (9), and the variator (21) of the toroidal transmission mechanism is placed in the front compartment (A). While being filled with the first hydraulic oil that drives the power roller (44, 44 ...),
The rear section (B) of the case (2) includes at least the HiLo clutch (23) and the hydraulic clutch mechanism (12), and the internal pistons of the HiLo clutch (23) and the hydraulic clutch mechanism (12), And a working vehicle having a toroidal type transmission, which is filled with a second hydraulic fluid for driving the working machine lifting / lowering hydraulic cylinder (72).   The hydraulic system of the work vehicle is provided on a support shaft of a power roller (44) provided in the variator (21) and an input / output disk (41, 42, 43) of the variator (21). , 42, 43), a first system for supplying the first hydraulic oil to the cylinder chamber (R1) for pressing in the approach direction, and a second system for supplying the second hydraulic oil to the hydraulic clutch mechanism (12). A work vehicle having a toroidal transmission according to claim 1, wherein the working oil is supplied with pressure oil from each of the pumps (70, 21a). The toroidal transmission according to claim 1, wherein the hydraulic system of the work vehicle is provided with a control valve (63) for adjusting the hydraulic pressure in the end load chamber (R1) of the variator (21) to a predetermined pressure. Work vehicle with a machine.

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