JP2000158961A - Transmission device for work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and reasonable transmission device requiring no special lubricating-oil feeding mechanism for a wet type CVT provided in a transmission case. SOLUTION: A belt type continuously variable transmission 7 having a wet type structure and a gear transmission mechanism are housed frontward and rearward in a transmission case, while a driving pulley shaft 15j and a driven pulley shaft 18j of the belt type continuously variable transmission 7 are disposed side by side such that both the shafts 18j, 15j have nearly equal levels and the same back-and-forth axial directions as a rotation shaft of the gear transmission mechanism. An input shaft 20 to the belt type continuously variable transmission 7 is disposed left and right between the driving pulley shaft 15j and the driven pulley shaft 18j.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission case in which a gear transmission mechanism and a wet belt continuously variable transmission (hereinafter referred to as "C") are mounted.
VT).
More specifically, the present invention relates to a technique for inexpensively and compactly lubricating a CVT by devising a layout in a migration case.

[0002]

2. Description of the Related Art As a transmission device of this kind, there is Japanese Utility Model 3-.
Japanese Unexamined Patent Publication Nos. 1295 and 7-50727 are known. In the former publication, a CVT is disposed immediately after a main clutch, and a traveling transmission system for transmitting power to a differential mechanism for a rear wheel after gear-shifting the output after the shift is provided in a transmission case. There is an advantage that the CVT can be compactly arranged in the clutch housing which is an oil-free chamber. In the latter publication, a CVT can be retrofitted and removed from below in the front and rear middle part of the transmission case, and the driving steps can be widened.
In addition, there is an advantage that maintenance of the CVT can be easily performed.

[0003]

In a working machine to which a relatively heavy load acts, such as a tractor, a wet type CVT using a belt made of steel or the like is often used in order to enhance the transmission strength and durability. In this wet CVT, it is necessary to supply the lubricating oil to both the drive side and the driven side pulleys. However, when the arrangement structure shown in the former publication is adopted, each lubricating oil must be provided in the transmission case. Since the pulleys are arranged vertically, at least at the normal oil level, at least the upper pulley is not immersed in the lubricating oil. Therefore, a mechanism such as providing an injection nozzle to forcibly supply the upper pulley with the lubricating oil is required.

Therefore, in the arrangement disclosed in the latter publication, both pulleys may be located at relatively low positions in the transmission case, and both pulleys may be partially immersed in lubricating oil. Although it is good in terms of point, many dedicated transmission mechanisms such as bevel gear mechanism and flat gear mechanism are necessary to convert both pulley shafts up and down to convert to the forward and backward transmission direction such as engine power and gear transmission mechanism. However, it is not good in that the structure becomes complicated and the number of parts increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission system that does not require a special lubricating oil supply mechanism when a wet CVT is installed in a transmission case, and that rationally constitutes a simple transmission system.

[0006]

A first aspect of the present invention is a transmission for a working machine, wherein a beltless continuously variable transmission having a wet structure and a gear transmission mechanism are accommodated in a transmission case, and a belt continuously variable transmission is provided. The apparatus is characterized in that the drive shaft and the driven shaft of the apparatus are juxtaposed so as to have substantially the same height level.

According to a second aspect of the present invention, in the first aspect, the input shaft for the CVT is disposed between the rotation axis of the driving pulley and the rotation axis of the driven pulley.

[0008] A third invention is the first or second invention, wherein
The interior of the first case portion accommodating the CVT and the interior of the second case portion accommodating the gear transmission mechanism are communicated so that the lubricating oil can flow freely.

In a fourth aspect based on the third aspect, the first case portion is disposed on the engine side with respect to the second case portion,
A hydraulic cylinder for raising and lowering the working device is disposed above the end of the case portion opposite to the first case portion, and an oil passage is formed so that oil discharged from the hydraulic cylinder returns to the second case portion, and the engine is driven. The lubricating oil suction port of the transmission case for the hydraulic pump is provided in the first case portion.

According to the first aspect of the present invention, the CVT
Since the drive shaft and the driven shaft are arranged side by side, a mechanism for changing the rotational direction of a bevel gear or the like as in the latter publication can be dispensed with. Since the drive shaft and the driven shaft are arranged at substantially the same height level, both the contact portion between the drive pulley and the belt and the contact portion between the driven pulley and the belt are immersed in the oil sump in the transmission case. The lubrication can be performed, and sufficient lubrication can be performed without using a lubricating oil supply mechanism such as an injection nozzle.

According to the second aspect of the present invention, since the input shaft for the CVT such as the engine output shaft is disposed between the drive shaft and the driven shaft of the CVT, for example, the drive pulley shaft and the input shaft are coaxial. As compared with the case where the CVT portion is extended in the lateral direction of the transmission case in the lateral direction without bias, the gear transmission mechanism can be set in the left and right center part of the vehicle body easily, and the weight balance in the horizontal direction In addition, the transmission case can be made straight and the strength balance can be made favorable.

According to the third aspect of the present invention, the gear transmission mechanism accommodating portion and the CVT accommodating portion of the transmission case communicate with each other so that the lubricating oil can flow freely. Compared to the case where the lubricating oil deteriorates differently, the management of the oil replacement time is not troublesome, and the lubricating oil circulates evenly and circulates in each case housing part. There is no need to provide a mechanism for causing this, and a simple circulation structure is required.

According to the fourth aspect of the present invention, in the tractor or the like, the hydraulic cylinder to which the pressure oil is supplied is disposed at the rear end of the transmission case. Returning to the housing case and providing a suction port for the engine-driven pump from the CVT housing case located at the front end of the transmission case, supply of hydraulic oil to the hydraulic cylinder by the pump, Both the circulation of the lubricating oil and the lubricating oil can be realized in a state of functioning smoothly. In addition, the suction port and the pump are close to each other, so that the required pipe length can be minimized.

[Effect] In the working machine according to any one of claims 1 to 4, the driving and driven pulley and the belt can be driven without a special lubricating oil supply mechanism while having a simple structure with no extra power transmission mechanism or parts. The contact portion with the CVT can be lubricated as necessary, and a transmission device with a wet CVT can be provided in a reasonable condition.

In the transmission according to the second aspect, the arrangement of the input shaft on the CVT can be easily arranged with the gear transmission mechanism, the transmission can be formed in a simple transmission case shape, and the weight balance between the left and right is advantageous. It has many advantages.

According to the third aspect of the present invention, the lubricating oil can be circulated throughout the entire transmission, and the CVT
And contribute to improving the durability of the gear transmission mechanism,
There is an advantage that lubricating oil can be easily managed.

In the transmission according to the fourth aspect of the present invention, it is preferable that lubrication and supply of pressure oil to the hydraulic device and circulation of the transmission lubricating oil function well while keeping the required piping length short and highly efficient. A hydraulic structure was obtained.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a transmission device of a tractor, which is an example of a working machine. Reference numeral 1 denotes an engine mounted on the front of the body, 2 denotes a monobody structure that is connected to a rear surface of the engine 1 and supports a rear axle 3. Mission case, 4
Is a hydraulic cylinder for lifting and lowering the working device, and 5 is a floor step of the operating unit.

As shown in FIGS. 2 and 3, the transmission case 2 has various gear shifts such as a clutch housing portion 2A having a main clutch 6, a first case portion 2B having a CVT 7, and a sub-transmission mechanism 13. 2nd case part 2 provided with mechanism
C. The second case portion 2C includes a front case portion 2a including a hydraulic clutch 8 for traveling speed change and a forward / reverse switching mechanism 9, and an intermediate portion including a super speed reduction mechanism 10 and a front wheel transmission mechanism 11 for traveling. It comprises a case part 2b and a differential case part 2c provided with a differential mechanism 12.
Note that cy1 is a speed change cylinder that drives the forward / reverse switching mechanism 9.

The driving power is the main clutch 6, the CVT
7, forward / reverse switching mechanism 9, auxiliary transmission mechanism 13, super reduction mechanism 1
0, and can be transmitted to the left and right rear axles 3 and 3 via the differential mechanism 12 and can be transmitted to the front wheel drive shaft 14 via the front wheel transmission mechanism 11 from the auxiliary transmission mechanism 13 having the front-rear rotating shaft 13a. It is also configured. The power for the PTO is generated by the PTO projecting rearward from the differential case portion 2c via the drive pulley shaft 15j of the CVT 7 and the PTO transmission mechanism 16.
It is transmitted to the shaft 17. Note that cy2 is a transmission cylinder that drives and drives the sub transmission mechanism 13.

As shown in FIGS. 3 to 5, the CVT 7 includes a driving pulley 15 having a split pulley structure having a fixed pulley piece 15a and a movable pulley piece 15b, and a fixed pulley piece 1 similarly.
A wet belt is formed by winding a steel belt 19 over a driven pulley 18 having a split pulley structure including a movable pulley 8a and a movable pulley piece 18b. The drive shaft of the drive pulley 15 (same as the rotation shaft of the drive pulley of claim 2) 15j
And the driven shaft 18j of the driven pulley (same as the rotating shaft of the driven pulley of claim 2) are both in the front-rear direction and at substantially the same height level (the driving shaft 15j is slightly higher), and are located on the left and right of the first case portion 2B. The input shaft 20 via the main clutch 6 is disposed at a position slightly above the left and right sides of both pulley shafts 15j and 18j.

An inner cylinder 26 made of sheet metal is integrally connected to the movable pulley piece 15b on the driving side which is spline-fitted to the driving shaft 15j, and an outer cylinder 27 mounted on the driving shaft 15j so as to be axially immovable. A drive-side hydraulic cylinder 28 that can be forcibly moved in a direction in which the movable pulley piece 15b approaches the fixed pulley piece 15a by slidably fitting the inner cylinder 26 is formed. The supply and discharge of the pressure oil to and from the drive side hydraulic cylinder 28 is performed via a movable pulley piece 15b and a supply and discharge oil passage 33 formed inside the drive shaft 15j.

Similarly, an outer cylinder 30 integrally connected to a movable pulley piece 18b splined to the driven shaft 18j,
The movable pulley piece 18b is fixed to the fixed pulley piece 18 by fitting the driven shaft 18j with an inner cylinder 31 that is not axially movable.
The driven hydraulic cylinder 29 is configured to be forcibly movable in a direction approaching a. The supply and discharge of pressure oil to and from the driven hydraulic cylinder 29 is performed via a movable pulley piece 18b and a supply / discharge oil passage 34 formed inside the driven shaft 18j. Do it. The driven hydraulic cylinder 29 is provided with a winding spring 32 for urging the movable pulley piece 18b in a direction approaching the fixed pulley piece 18a.

The hydraulic cylinder 4 integrally formed on the upper part of the differential case portion 2c is of a single-acting type in which the lift arm 4a is operated upward by supply of pressurized oil and the lift arm 4a is operated downward by discharge of oil. Drain the oil in the differential case 2c
Alternatively, the oil passage is formed so as to return to the intermediate case portion 2b, that is, the second case portion 2C, and the lubricating oil suction port 22 of the transmission case 2 for the hydraulic pump 21 which is arranged beside the engine 1 and driven by the engine is It is provided below the first case part 2B.

The first case portion 2B and the second case portion 2C are separated from each other, and a large number of holes 23a are formed in a partition wall 23 for supporting a bearing for shaft support. The interior of the transmission case 2 is configured such that the lubricating oil can flow freely, and the interior of the differential case portion 2c and the later-described suction port 22 are in oil passage communication within the transmission case 2. Accordingly, the pressure oil discharged from the hydraulic pump 21 is supplied from the control valve V to the hydraulic cylinder 4 through a supply oil passage 24 such as an external pipe, and the drain oil is discharged to the transmission case 2.
After flowing in the interior from the rear to the front, a circulation path is formed in which the oil returns to the hydraulic pump 21 through a return oil passage 25 such as an external pipe connected to the suction port 22.

Since the driven pulley shaft 18j on which the hydraulic clutch 8 is arranged coaxially is located slightly below the driving pulley shaft 15j, the hydraulic clutch 8 is sufficiently immersed in the oil level L in the transmission case 2. At the same time, each of the pulleys 15 and 18 is also constantly immersed in lubricating oil, so that a good lubrication and cooling function with the belt 19 can be exhibited.

Next, the speed change operation structure of the CVT 7 will be described in detail. As shown in FIGS. 9 to 11, a control valve 35 for controlling the supply and discharge of hydraulic oil to and from the drive-side hydraulic cylinder 28, and a hydraulic pump 3
6 and a variable pressure relief valve 37 for setting the line pressure, etc., constitute a speed-change hydraulic circuit, and a speed-change lever 38 interlocked with the spool 35s of the control valve 35 is provided.
In the control valve 35, a pump port 35a, a cylinder port 35b communicating with the oil supply / discharge passage 33 on the driving side, and a drain port 35c discharging oil toward a shift hold valve (not shown) are formed in this order. Have been.

The control valve 35 is provided with a supply position p for supplying pressure oil to the drive side hydraulic cylinder 28 by a spool operation,
A discharge position d for discharging oil from the drive side hydraulic cylinder 28,
There are three positions, a neutral position n between these two positions. A shift lever 38 is interlockedly connected to one end of the spool 35s via a first spring 39, and a movable pulley piece 15b on the driving side is connected to the other end via a second spring 40, which is the same component as the first spring 39. This slide movement direction and spool 35s
Are linked to each other in the same direction as the moving direction.

The first spring 39 associated with the operation of the shift lever 38
The elastic force generated by the expansion and contraction of the spring and the elastic force generated by the expansion and contraction of the second spring 40 due to the distance movement of the movable pulley piece 15b associated with the lever operation cancels out the feedback that the switched control valve 35 automatically returns to neutral. The control means A is constituted. That is, the spool 35s is provided with both springs 39 and 40.
The biasing force is canceled at the equilibrium position.

The operation of the feedback control means A will be described. First, when the shift lever 38 is operated to the high speed side Hi, the first spring 39 is extended and the spool 35s is moved to the second spring 40 side as shown in FIG. The pushing force is weakened, and the force by which the second spring 40 pushes the spool 35s toward the first spring 39 is relatively increased, so that the spool 35s moves toward the first spring 39. Then, the control valve 35 is switched to the supply position p, and the pump port 35a and the cylinder port 35b communicate with each other, supply pressure oil to the drive side hydraulic cylinder 28 to move the movable pulley piece 15b closer to the fixed pulley piece 15a. Then, the winding ratio of the belt 19 is forcibly increased to change the speed ratio to the speed increasing side.

The approach movement of the movable pulley piece 15b causes the second spring 40 connected to the rod to be stretched and the force for pushing the spool 35s toward the first spring 39 to be weakened. After the movable pulley piece 15b moves until the pressing urging force with the first spring 39 extended by the operation is balanced, that is, the control valve 35 returns to the neutral position n, the operation is automatically stopped. That is, the speed ratio is changed to the high-speed side by the amount by which the shift lever 38 is moved to the high-speed side, and the speed is increased.

Next, when the speed change lever 38 is operated to the low speed Lo side, as shown in FIG. 11, the first spring 39 is compressed to move the spool 35s to the second spring 40 side, and the control valve 35 is moved to the discharge position. d to the drive side hydraulic cylinder 2
Oil is drained from 8. Then, the line pressure and the spring 3 described later
2, the movable pulley piece 18b moves closer to the fixed pulley piece 18a and is operated in a direction in which the winding radius of the belt 19 of the driven pulley 18 becomes larger. The piece 15b moves in a direction away from the fixed pulley piece 15a, and is decelerated.

As the movable pulley piece 15b moves away from the drive side by the deceleration operation, the second spring 40 is compressed and the force pressing the spool 35s against the first spring 39 is increased. The point where the urging force with the first spring 39 is balanced, that is, the control valve 3
After the movable pulley piece 15b moves until the position 5 returns to the neutral position n, it automatically stops. That is, the shift lever 3
The gear ratio is also changed to the low speed side by the amount that the 8 is moved to the low speed side, and the speed is reduced.

The variable relief valve 37 includes a valve element 42, a spool 43 slidable inside the valve element 42, a spring receiving member 44 slidably fitted in the valve element 42, a spool 43 and a spring receiving member. 44 is a compression-type wound spring interposed between
5 and the pump port 35a
A first port 37a communicating with a pump oil passage 41 that communicates with the oil supply / discharge passage 34 on the driven side and a drain port 37b are formed.

The spring receiving member 44 is connected via a connecting member 46 so as to move integrally with the driving side movable pulley piece 15b, and is positioned by the driving side movable pulley piece 15b. In FIG. 9, when the spring receiving member 44 is moved to the left (opposite the spool 43 side) by a high-speed operation, as shown in FIG. As a result, the relief pressure, that is, the line pressure is reduced by the throttle action with the drain port 37b slightly opened so that the weakened spring force and the line pressure are balanced.

When the spring receiving member 44 is moved to the right (toward the spool 43) by the low-speed operation of the shift lever 38, the force of pressing the spool 43 of the winding spring 45 is increased by the compressed amount, and as a result, the relief pressure is increased. That is, the line pressure increases. However, it goes without saying that deceleration from the lowest speed state where the reduction ratio is the maximum is impossible.

The line pressure is such that the movable pulley piece 18b on the driven side is always pressed and urged toward the fixed pulley piece 18a in cooperation with the spring 32, whereby the tension function of the belt 19 and the pressure are released. If the control becomes impossible, a fail-safe function in which the gear ratio is automatically operated to the deceleration side is exhibited.

That is, due to the connection between the driving side movable pulley piece 15b and the spring receiving member 44, the line pressure decreases when the speed ratio is changed to the speed increasing side, and the line pressure decreases when the speed ratio is changed to the speed reducing side. It is controlled to rise. Specifically, as shown in the graph of FIG.
When the speed is 5 (double speed), the line pressure is 16 kgf / cm ² , when the reduction ratio is the maximum of 2.5, the line pressure is 28 kgf / cm ² , and the line pressure changes linearly at the reduction ratio between them. .

When the running load increases and the belt tension exceeds a certain value by the automatic change control of the line pressure, the movable pulley piece 1
The force that spreads 5b exceeds the pressing force of the drive side hydraulic cylinder 28 due to the line pressure, and the movable pulley piece 15b moves in a direction away from the fixed pulley piece 15a, and functions to automatically reduce the speed and increase the torque. . That is, when the traveling load such as turning in a wet field is significantly increased, the CVT 7 is automatically decelerated, and problems such as insufficient driving force and engine stall are avoided.

FIG. 6 shows the PTO in the front case 2a.
A portion of a first support wall 59 (a portion indicated by arrows BB) disposed between the speed change mechanism 16 and the forward / reverse switching mechanism 9 is shown. The first support wall 59 forms the forward / reverse switching mechanism 9. The pair of transmission shafts 9a, 9b and the front-rear transmission shaft 13a of the auxiliary transmission mechanism 13 are supported by bearings, and are attached to the inward rib portions of the front case portion 2a with bolts.

FIG. 7 shows a shaft arrangement structure at a portion (a portion taken along the line CC) of the intermediate case portion 2b viewed from the front end portion of the differential case portion 2c. Reference numeral 16j denotes a PTO input shaft directly connected to the drive pulley shaft 15j. Yes, 16a is a PTO transmission shaft, 16a
b is a PTO reverse rotation axis. FIG. 8 shows the front case part 2.
(a) shows the portion (the arrow DD portion) of the second support wall 60 portion bolted to the rear end portion as viewed from the intermediate case portion 2b;
A pair of transmission shafts 10a, 10 constituting the super reduction mechanism 10
b, the drive shaft 11a of the front wheel transmission mechanism 11, the driven shaft 11b directly connected to the front wheel drive shaft 14, and the like are supported by bearings.

[Brief description of the drawings]

FIG. 1 is a side view of a tractor.

FIG. 2 is a partially cutaway side view of a transmission case.

FIG. 3 is a diagram showing a transmission structure in a transmission case.

FIG. 4 is a cross-sectional plan view of a transmission case in a CVT portion.

FIG. 5 is a sectional view taken along line AA in FIG. 2;

FIG. 6 is a sectional view taken along line BB in FIG. 2;

FIG. 7 is a sectional view taken along line CC in FIG. 2;

FIG. 8 is a sectional view taken along line DD in FIG. 2;

FIG. 9 is a system diagram showing a shift operation structure of a CVT.

FIG. 10 is a system diagram showing a shift operation structure of the CVT when operated at high speed.

FIG. 11 is a system diagram showing a shift operation structure of a CVT when a low-speed operation is performed.

FIG. 12 is a diagram showing a relationship graph between a gear ratio of a CVT and a line pressure.

[Explanation of symbols]

 Reference Signs List 2 Transmission case 2B First case portion 2C Second case portion 4 Hydraulic cylinder 7 Belt continuously variable transmission 13 Gear transmission mechanism 15 Drive pulley 15j Drive shaft, rotation shaft 18 Follower pulley 18j Drive shaft, rotation shaft 20 Input shaft 21 Hydraulic pump 22 Suction port

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16H 57/02 541 F16H 57/02 541A 57/04 57/04 H F-term (Reference) 3D039 AA04 AA13 AB12 AC34 AC37 AC64 AC77 AD11 3J050 AA02 AB03 AB07 BA03 BB13 CE03 CE05 DA06 3J063 AA14 AB02 AB23 AC07 BA03 BA11 BB50 CA01 CA04 CB22 CB25 CB41 CB47 CD42 CD46 XD03 XD23 XD47 XD62 XD64 XD72 XE15 XE22

Claims (4)

[Claims] 1. A continuously variable transmission having a wet structure and a gear transmission mechanism are accommodated in a transmission case, and a drive shaft and a driven shaft of the continuously variable belt have substantially the same height. Gearbox of the working machine juxtaposed with 2. The transmission of a working machine according to claim 1, wherein an input shaft for the belt continuously variable transmission is disposed between left and right of a rotation shaft of the driving pulley and a rotation shaft of the driven pulley. 3. A first housing for accommodating the belt continuously variable transmission.
3. The transmission of a working machine according to claim 1, wherein the inside of the case portion and the inside of the second case portion that accommodates the gear transmission mechanism are communicated so that the lubricating oil can flow freely. 4. 4. A hydraulic device for ascending and descending a working device, wherein the first case portion is disposed on an engine side with respect to the second case portion, and an upper portion of the second case portion opposite to the first case portion has an upper end. A cylinder is arranged, and an oil passage is configured so that oil discharged from the hydraulic cylinder returns to the second case portion.
The transmission of a working machine according to claim 3, wherein a lubricating oil suction port of the transmission case for a hydraulic pump driven by an engine is provided in the first case portion.