JP3445366B2 - Tractor transmission structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a transmission structure for a tractor,
In particular, the present invention relates to a transmission structure in which an additional transmission is provided in a rear half of a front housing which is arranged in front of a transmission case in which a speed change transmission mechanism is installed and constitutes a vehicle body of a tractor together with the transmission case.

[0002]

BACKGROUND OF THE INVENTION As a transmission structure as described above, a device devised so as to easily incorporate both a transmission in a front housing and a transmission mechanism in a transmission case is disclosed in US Pat. No. 5,058,455. In the structure of this U.S. Patent, the front housing is formed with the rear end open and the mission case is formed with the front end open, and the bearing frame is formed on the rear end of the front housing and the inner surface of the front end of the mission case is formed. It is fixedly installed by attaching it to multiple protruding bosses. The transmission provided in the rear half of the front housing comprises a partition wall in the middle of the housing and the bearing frame as a shaft support member, and the bearing frame is simultaneously assembled in the transmission case. Is used as a shaft support member for supporting at the front end. The transmission in the front housing is configured to perform speed change transmission between a driving shaft driven by an engine and an output shaft concentrically arranged with the driving shaft, the output shaft being supported by the bearing frame, and the front end portion thereof being the bearing frame. Is connected in the bearing frame to the drive shaft supported by the. Two embodiments are disclosed in which the transmission provided in the front housing is of a hydraulic clutch type and one embodiment is of a mechanical type. However, in any of the embodiments, the transmission shaft below the drive shaft and the output shaft is disclosed. On the side, an intermediate shaft is provided, and in the hydraulic clutch type, a plurality of hydraulic clutches are arranged on the intermediate shaft.

The structure in which the hydraulic clutch type transmission is provided in the rear half portion in the front housing has the various points to be improved. That is, first of all, since the hydraulic clutch type transmission is provided with a plurality of hydraulic clutches which are relatively large in size and heavy, the transmission is assembled in the rear half of the front housing in a completely assembled state in advance. While it is desirable to assemble the front housing on the front surface of the mission case after that, since the bearing frame is supported on the mission case side, the front part including the bearing frame is not supported. Complete assembly on the housing side cannot be done in advance.

Next, in the structure in which the transmission is provided in the rear half of the front housing of the tractor, lubricating oil is accommodated in the rear half of the housing in order to lubricate the various members of the device. When the hydraulic clutch is installed on the lower level intermediate shaft in the structure of the hydraulic clutch type, the hydraulic clutch or its clutch cylinder is partially immersed in the lubricating oil. Therefore, the clutch / cylinder rotates while discriminating the viscous lubricating oil, and extra energy is consumed. Lubricating oil enters the clutch / cylinder and reaches the clutch friction element, and viscous oil acts as an oil film between the driving-side friction element and the driven-side friction element. Rotation of the driven side friction element occurs due to
Abrasion of the friction element and, in extreme cases, an unexpected start of the vehicle can occur. On the other hand, setting the drive shaft at a low level and the intermediate shaft at a high level is because the drive shaft is driven by the engine and the level cannot be lowered due to the constraints of the engine layout. Since a gear transmission part for lowering the level of the driving shaft is interposed between the shafts, the structure becomes complicated and the cost increases,
Actually it is impossible.

Further, it is not easy to install the hydraulic clutch on the high-level drive shaft instead of on the low-level intermediate shaft. That is, in the hydraulic clutch transmission, a plurality of oil passages for supplying hydraulic oil and lubricating oil to the clutch are provided in the shaft on which the hydraulic clutch is mounted, but the oil passage is rotationally displaced together with the shaft. , Requires a rotary joint portion of an oil passage for connecting to a fixed position hydraulic oil passage and a lubricating oil passage. In the above-mentioned U.S. patent, a plurality of annular oil chambers serving as rotary joints are defined between the bearing frame supporting the rear end of the intermediate shaft and the intermediate shaft, but when the hydraulic clutch is arranged on the driving shaft. No similar structure can be adopted. Because the output shaft supported by the bearing frame is located at the rear of the driving shaft, and it is impossible to form a plurality of annular oil chambers between the driving shaft and the bearing frame at such a position. Because. Then, if the oil passage rotary joint part is moved to the partition wall side in the middle of the front housing, the point that the driving shaft extends back and forth through the partition wall, and the control valve device for shift control Difficulties are expected depending on how to install the connection system while avoiding complication of the connection oil passage structure. That is, in the above-mentioned U.S. patent, the oil passage rotary joint portion is formed using the end portion of the intermediate shaft, and the shaft intermediate portion is not used.
Further, the connecting oil passage structure is simplified by installing valves including a direction switching valve on the upper surface or inside of the above-mentioned bearing frame, but it is similar by utilizing a partition wall which is integrally arranged inside the front housing. It is considered extremely difficult to adopt the structure of.

Next, in the US patent, the control valve device is provided with a pressure reducing valve which is operated by a pedal, and the pressure reducing valve reduces the hydraulic pressure applied to a hydraulic clutch to enable the vehicle to run at a low speed by clutch / slip control. There is. Then, as a structure in which the lubricating oil is supplied to the friction element portion of the hydraulic clutch via the pressure reducing valve, the supply of the lubricating oil is throttled at the pressure reducing action position of the pressure reducing valve, and the clutch / slip control is performed by the rolling phenomenon by the lubricating oil. It avoids the problem that it is not performed accurately, and in the state where the hydraulic pressure acting on the clutch is unloaded by the pressure reducing valve, the supply of lubricating oil is cut off to avoid an unexpected start of the vehicle due to a rolling phenomenon. According to this structure, since the pressure reducing valve is returned to the non-pressure reducing position and the supply of the lubricating oil is restarted, the cooling and removal of the heat generated during the clutch / slip engagement tends to be delayed, and also during the steady state operation of the clutch. Is likely to cause energy loss due to agitation of the lubricating oil by the friction element being engaged due to excessive supply of the lubricating oil.

Therefore, a main object of the present invention is to completely assemble a hydraulic clutch type transmission in advance in the rear half of the front housing while ensuring the ease of incorporation of the transmission in the transmission case. It is to provide a new transmission structure of a tractor which can be incorporated in a state.

An accompanying object of the present invention is to provide a novel transmission structure in which a plurality of hydraulic clutches are arranged on a driving shaft while overcoming the above-mentioned difficulties.

A still further object of the present invention is to provide a transmission structure in which a control valve device including a direction switching valve for controlling the operation of a hydraulic clutch type transmission is provided in a manner that simplifies the oil passage structure. It is in.

Another object of the present invention is to appropriately supply lubricating oil to a hydraulic clutch of a hydraulic clutch type transmission regardless of whether the clutch is inactive, slipping, engaging, or steady. A novel tractor transmission structure provided with a control valve device is provided.

[0011]

SUMMARY OF THE INVENTION The present invention has a partition wall (1a) in the middle, a front housing (1) that the are open rear end, Yes to open the front end, connected to the rear end of the front housing a transmission case (2) which had been, the bearing frame (4) fixedly installed to the front Haujin grayed, through the partition wall
Driving shaft which is supported supported the partition wall condition (7),
An output shaft (10) , which is arranged behind the drive shaft and concentric with the drive shaft and supported by the bearing frame, and the partition wall and the bearing, which are configured to perform speed change transmission between the drive shaft and the output shaft. A first hydraulic clutch type transmission (12) disposed between the frames in the front housing, and having at least one intermediate shaft (11) supported by a partition wall and a bearing frame. The first transmission (12) and the front
A drive shaft (13) and a speed change shaft (14) whose ends are respectively supported by the bearing frame, and the drive shaft (13)
And a transmission shaft (14) in the second transmission (15) and transmission structure of the tractor with <br/> a which are disposed in the transmission case so as to perform the speed change transmission between the first transmission
(12), said drive shaft (7) distributed multiple hydraulic clutch on (54F, 54R) has a front portion housings from the rear of the front housing bearing frame (4) (1)
The output shaft by being fixedly installed on the ring (1).
The rear end of the drive shaft can be supported via
Further, the bearing frame (4) is fixedly installed.
The bearing frame to the front housing (1) of
The mission case can be connected to surround (4).
It is related to the transmission structure of the tractor which is said to be capable.

In this transmission structure, the present invention fixes and supports the bearing frame (4) fixedly installed in the rear end of the front housing (1) on the front housing. This structure for simply performing the fixed support has a plurality of inward bosses (1b) projecting the bearing frame at the rear end of the front housing.
The structure is such that it is formed to have a plurality of outward projections (4a) attached to the.

A plurality of hydraulic clutches (54) of the hydraulic clutch type transmission (12) provided in the rear end of the front housing.
F, 54R) are all arranged on the drive shaft (7). These hydraulic clutches are preferably located above the oil level of the lubricating oil housed in the front housing behind the partition wall (1a). Then, the hollow cylindrical portion (37) supporting the driving shaft (7) is integrally formed with the partition wall (1a), and the clutch operating oil passages (55F, 55R) in the driving shaft are formed.
And the lubricating oil passage (55L) in the partition wall (1a), the clutch operating oil passage (61F, 61R) and the lubricating oil passage (61L).
Oil chamber (60F, 60R, 60L) connected to
Is formed between the hollow cylindrical portion and the driving shaft.

[0014] Oil pressure clutch transmission for controlling the operation of (12), control valve assembly including a directional control valve (78) to (63), be provided by fixedly supported by the front housing (1) I can . This control valve device includes a valve housing (64, 6) so that the oil passage connection structure for the oil passages (61F, 61R, 61L) in the partition wall (1a) of the front housing can be simplified.
6, 67) is brought into close contact with one wall surface (1c) of the front housing, and an oil passage is opened from inside the valve housing toward the wall surface so that an oil passage can be connected within the wall of the front housing. It is desirable to do.

The transmission structure according to the present invention includes the rear ends of the drive shaft (7) and the intermediate shaft (11) of the hydraulic clutch type transmission (12) installed in the rear half of the front housing (1). Since the bearing frame (4) supporting the output shaft (10) is fixedly supported by the front housing, the partition wall (1a) in the middle of the front housing and the bearing frame (4) are used as support members. The transmission (1
2) can be installed in advance in a completely assembled state
It Then, after that, the front housing (1) is brought to the front surface of the mission case (2), and the front end portions of the drive shaft (13) and the speed change shaft (14) of the second transmission (15) in the mission case are bearings. Supported by the frame (4),
The drive shaft (13) can be simultaneously connected to the output shaft (10) to complete the assembly. Furthermore, the hydraulic clutch type transmission (12) includes a plurality of hydraulic clutches (54F, 54F).
R) are all arranged on the drive shaft (7), which is to be arranged at a relatively high level, so that the hydraulic clutch or its clutch cylinder is substantially submerged in the lubricating oil in the lower half in the front housing. Therefore, the energy loss due to the rotation of the clutch / cylinder through the oil and the rotation of the clutch / cylinder due to the oil entering into the friction element of the clutch can be reduced as much as possible.

In order to make the hydraulic clutch type transmission (12) additionally provided by utilizing the extra space in the front housing to have a simple structure with a small number of transmission shafts and a small number of gears, the same transmission is used as the drive shaft. (7) A first gear (49) loosely fitted on the second gear, a second gear (50) fixedly installed on the intermediate shaft (11) and rotationally driven by the first gear, the intermediate shaft (11). A third gear (51) fixedly installed on the output shaft (10) and a fourth gear (52) fixedly installed on the output shaft (10) and rotatably driven by the third gear, the first gear ( 49) is connected to the drive shaft with a first hydraulic clutch (54R) and the fourth gear (52) is connected to the drive shaft with a second hydraulic clutch (54).
F) is preferably provided. With this structure, the first gear (49), the second gear (50), and the third gear (5)
1) and the fourth gear (52) are directly meshed with each other to provide a high and low two-stage transmission, and interposing an idler gear between any of these gear pairs provides a forward-reverse switching transmission. To be done. When the idler gear is provided, it is desirable that the idler gear is supported by the bearing frame (4) so that the idler gear can be easily supported, and the idler gear is interposed between the third gear (51) and the fourth gear (52).

In order to provide a hydraulic pump for supplying oil to the hydraulic clutches (54F, 54R) so as to simplify the oil passage connection between the control valve devices (63), the drive shaft (7) is used. Driven hydraulic pump (7
2) is attached to the front surface of the partition wall (1a) and is connected to the control valve device via an oil passage (75) in the partition wall.

The control valve device (63) is provided in order to reduce the protrusion to the outside of the front housing (1) and to make it easier to connect to the oil passage in the partition wall (1a). Is formed in one side wall of the front housing on the rear side of the partition wall (1a).
2) through which the plate member (64), which is disposed so as to pass through the inside and outside of the front housing and is in close contact with the outer surface (1c) of the front housing on the front end side of the opening, , 66, 67). Such a plate member (64) has a clutch operating oil port (7) that opens toward the outer side surface (1c).
1F, 71R) and a lubricating oil port (71) can be provided, and these ports and the annular oil chamber (60F, 60)
R, 60L) connecting the oil passage (61) in the partition wall.
(F, 61R, 61L) can be formed into a linear shape that can be easily formed and processed. Further, the directional control valve (78) is internally provided outside the front housing in the valve housing which is arranged to extend inside and outside the front housing as described above. Desirable in terms of gaining.

A control valve device (63) fixedly supported by the front housing (1) has a directional control valve (78) and a gradually increasing hydraulic pressure relief valve for gradually increasing the hydraulic pressure applied to the hydraulic clutches (54F, 54R). (86)
And a valve means (90, 91) for lubricating oil supply control for stopping the supply of lubricating oil to the hydraulic clutch in the disengaged state of the hydraulic clutch and starting the supply of the lubricating oil from the state in which the hydraulic clutch is slip-engaged. Can be provided.
The valve means can be configured to control the supply of the lubricating oil in response to the clutch acting hydraulic pressure.

According to this structure, the lubricating oil is not supplied to the hydraulic clutches (54F, 54R) in the neutral state of the transmission (12) with the directional control valve (78) in the neutral position. While the friction element entrainment phenomenon is avoided and unexpected start of the vehicle and wear of the friction element are prevented, the supply of the lubricating oil is started from the state where the hydraulic clutch slips into engagement due to the gradual increase of the working hydraulic pressure, and then gradually. Since the lubricating oil continues to be supplied while the hydraulic pressure of
The heat generated during the clutch-slip engagement will be rapidly cooled and removed, and the friction element wear will be greatly reduced.

The control valve device (63) fixedly supported by the front housing (1) is operated by the pedal (92) in addition to the directional control valve (78), and the hydraulic clutch (5) is operated.
4F, 54R) and a pressure reducing valve means (83) for reducing the hydraulic pressure applied to the hydraulic clutch, and in response to the hydraulic pressure applied to the hydraulic clutch, the supply of the lubricating oil to the hydraulic clutch is stopped and the hydraulic clutch slips in the disengaged state of the hydraulic clutch. A valve means (90, 91) for controlling the lubricating oil supply, which starts supplying the lubricating oil from the engaged state, can be provided.

According to this structure, the clutch friction element is rotated by the lubricating oil under the condition that the pressure reducing valve means (83) is operated to the maximum and the hydraulic clutch is disengaged by the valve means. The situation in which the vehicle unexpectedly starts is prevented. Then, the pressure reducing valve means (83) reduces the clutch working oil pressure to a value at which clutch slip can be obtained, and the lubricating oil is supplied from the state where the vehicle is running at the slow speed, and the friction element is quickly cooled. The influence of the entrainment by the lubricating oil on the vehicle speed control during the vehicle slow speed control by the clutch / slip operation is such that the driver of the vehicle pedals the pedal (92) so that the vehicle speed of the vehicle during the vehicle slow speed travel becomes a desired value. It can be avoided by adjusting the amount of depression.

The above pressure reducing valve means provided in combination with the oil pressure gradually increasing type relief valve (86) or the pressure reducing valve means (83) has a lubricating oil supply passage (88) provided in the control valve device (63) as a clutch. An on-off valve (91) that opens and closes in response to the acting hydraulic pressure, and / or a flow control valve (90) that changes and controls the amount of oil flowing through the passage (88) in response to the acting hydraulic pressure of the clutch can be configured. .

The flow rate control valve (90) is provided with the lubricating oil supply passage (8) when the hydraulic pressure applied to the hydraulic clutches (54F, 54R) is increased to almost normal hydraulic pressure.
It is particularly preferable that the oil is drained from 8) to a part of the oil. That is, according to this, when the clutch enters the steady operation state, the amount of lubricating oil supplied is reduced to the extent that residual heat at the time of clutch / slip engagement is cooled and removed, and excess lubricating oil is supplied to the friction element during engagement. It is possible to reduce the energy loss due to the agitation of the lubricating oil of the same element. By providing both the on-off valve (91) and the flow rate control valve (90) described above, the lubricating oil supply start time at the time of starting the clutch engagement and the lubricating oil supply amount at the time of the steady clutch operation are independent of each other. Can be adjusted.

Other features and advantages of the present invention can be clearly understood from the following description with reference to the accompanying drawings.

[0026]

FIG. 1 schematically shows the entire transmission system of a tractor equipped with a preferred embodiment of the present invention. The body of the illustrated tractor is composed of a front housing 1, a transmission case 2 and a rear housing 3, which are arranged in series in the front and rear and connected. The front housing 1 is formed to have a partition wall 1a opened at the front and back, and a bearing frame 4 fixed to the rear end of the housing 1 is arranged in the rear end of the housing 1. The mission case 2 is formed such that the front and rear are open and the partition wall 2a is provided in the middle. The rear housing 3 has a front wall 3a and a support wall 3b that is erected on the inner bottom surface in the rear end portion, and is formed so that the opening at the rear end is closed by a rear lid 3c.

Similarly, as shown in FIG. 1, the engine 5 is arranged at the forefront of the machine body, and the hollow traveling system drive shaft 7 and the PTO driven by the engine 5 via the buffer spring mechanism 6 are used.
A PTO system drive shaft 9 driven via a clutch 8 is arranged in the front housing 1. The traveling system drive shaft 7 extends through the partition wall 1a, and the PTO drive shaft 9 extends through the hollow drive shaft 7 in the front-rear direction. A hollow output shaft 10 supported by the bearing frame 4 on an extension line of the driving shaft 7, and a partition wall 1a below the shafts 7, 10 and an intermediate shaft 11 supported by the bearing frame 4 are connected to the front housing 1 An auxiliary transmission device 12 for transmitting a speed change between the driving shaft 7 and the output shaft 10 is arranged behind the partition wall 1a in the front housing 1.

A bearing frame 4 is provided in the mission case 2.
And hollow drive shaft 13 supported by the partition wall 2a, respectively
The transmission shaft 14 is arranged vertically, and the drive shaft 13 is arranged concentrically with the output shaft 10 and is connected to the output shaft 10 in the bearing frame 4. In the front half of the mission case 2, a main transmission device 15 that transmits a speed change between a drive shaft 13 and a speed change shaft 14 is arranged.

In the latter half of the mission case 2, a hollow intermediate shaft 16 and a transmission shaft 14 arranged on an extension of the drive shaft 13 are provided.
And a propeller shaft 17 arranged on an extension line of the auxiliary transmission device 1 for performing speed change transmission between the speed change shaft 14 and the propeller shaft 17.
8 are arranged. Propeller shaft 17 is rear housing 3
A small bevel gear 19 is provided at the rear end projecting inward, and this bevel gear 19 is meshed with a large input bevel gear 20 of a differential device for left and right rear wheels (above, not shown), It is said that the vehicle is driven by driving the wheels.

The PTO system drive shaft 7 is connected to a transmission shaft 21 penetrating the hollow drive shaft 13 and the intermediate shaft 16, and further connected to two transmission shafts 22 and 23 arranged in the rear housing 3. There is. A PTO shaft 24 that is supported by the support wall 3b and the rear lid 3c and extends rearward of the machine body is provided, and the transmission shaft 23 is connected to the PTO shaft 24 by gears 25 and 26 reduction mechanisms.

FIGS. 2 and 3 show the vertical side surface of the front housing 1. As shown in FIG. 2, the PTO clutch 8
Is a diaphragm spring 8c mounted on the PTO system drive shaft 9 between the thrust ring 8a mounted on the engine flywheel 5a and the pressure plate 8b.
By retracting the pressure plate 8b, the diaphragm spring 8c is frictionally engaged with the thrust ring 8a to obtain a clutch engagement. The traveling system drive shaft 7 is connected to the flywheel 5a between the cover member 6a attached to the thrust ring 8a and the drive shaft 7 via the buffer spring mechanism 6 including a diaphragm spring 6b and a torsion spring 6c. . In order to operate the PTO clutch 8, a bearing mechanism 29 which is attached to the partition wall 1a and is slidable on a support cylinder 28 fitted on the driving shaft 7, a lever 30 which is swung by the bearing mechanism 29, and a lever 30 A pin 31 is provided for moving the pressure plate 8b forward and backward by moving the pressure plate 8b forward and backward. Bearing mechanism 29
Is a yoke 3 attached to a sideways clutch operating shaft 32.
The clutch operating shaft 32 is connected to a PTO clutch lever (not shown) outside the front housing 1 by being slid by the swing of 3.

The structure of the auxiliary transmission 12 will be described with reference to FIG. 3 and FIG. 4 showing the cross section of the rear half of the front housing 1. First, the bearing frame 4 has a plurality of projections 4a on its outer edge at the rear end. The projection 4a is abutted against the plurality of bosses 1b projecting on the inner surface of the rear end of the front housing 1 from the mission case 2 side, and is attached to the boss 1b by the bolts 35. There is. The front housing 1 and the transmission case 2 are flange-matched and fastened by bolts 36 screwed from the front housing 1 side.

Similarly, as shown in FIGS. 3 and 4, the driving shaft 7 is formed such that the outer diameter of the partition wall 1a is enlarged from the substantially front end face position to the rear end. The thick hollow cylindrical portion 3 that supports the driving shaft 7 at the starting end of the outer diameter enlarged portion
7 is formed on the partition wall 1a, and the other hollow cylindrical portion 38 is integrally connected to the hollow cylindrical portion 37 so as to face the front of the intermediate shaft 11 and is formed on the partition wall 1a. There is. Further, the bearing frame 4 has hollow support cylinders 4b, 4c arranged vertically.
And an intermediate level hollow support cylinder portion 4d is formed. The middle part of the driving shaft 7 and the front end of the intermediate shaft 11 are hollow cylindrical parts 3 respectively.
At the rear end positions of 7, 38, they are supported by the partition wall 1a via ball bearings 39, 40. Also, the output shaft 1
0 is supported by the upper support cylinder portion 4b of the bearing frame 4 via a pair of ball bearings 41 and 42, and the front end portion of the drive shaft 13 spline-connected to the output shaft 10 is the support cylinder portion 4b. Is supported by a ball bearing 44. The rear end of the intermediate shaft 11 and the front end of the speed change shaft 14 are supported by the lower support cylinder portion 4c of the bearing frame 4 via ball bearings 45 and 46, respectively. The rear end of the driving shaft 7 is supported by the output shaft 10 via a ball bearing 47, and is supported by the bearing frame 4 via the output shaft 10.

The auxiliary transmission 12 is fixedly installed on the first gear 49, which is loosely fitted on the drive shaft 7, and on the intermediate shaft 11.
The second gear 50 meshed with the gear 49, the third gear 51 fixedly installed on the intermediate shaft 11, the fourth gear 52 integrally formed at the front end of the output shaft 10, and the support cylinder portion 4d of the bearing frame 4. And an idler gear 53 supported by a shaft 53a via a ball bearing and meshed with both the third and fourth gears 51 and 52.

A first gear 49 is mounted on the drive shaft 7 to drive the drive shaft 7.
A hydraulic clutch 54R for selectively engaging with
A hydraulic clutch 54F for selectively connecting the fourth gear 52 to the drive shaft 7 is provided. The clutch cylinders of these hydraulic clutches 54F and 54R are integrally formed with each other and fixed to the drive shaft 7. The lower half of the front housing 1 and the lower part of the transmission case 2 are oil reservoirs in which lubricating oil is stored. As shown in FIG. 3, the oil level OL of the oil reservoir is the intermediate shaft 11 The clutch cylinders of the hydraulic clutches 54F and 54R, which are set at substantially the center line positions of the above, are designed to rotate without being immersed in oil. As clearly shown in FIG. 5, which is an enlarged view of a part of FIG. 3, the boss portions of the gears 49 and 52 have extending portions 49a and 52a extending into the clutch cylinder, and the hydraulic clutches 54 and 52, respectively.
R and 54F are friction multi-plate type in which the extending portions 49a and 52a have friction discs 54a that are non-rotatably supported and steel discs 54b that are non-rotatably supported by the clutch cylinder are alternately arranged. ,It is configured.
The steel disk 54b is formed into a cone shape in the clutch non-engaged state as shown in the hydraulic clutch 54R, and is flattened into a flat plate in the clutch engaged state as shown in the hydraulic clutch 54F. Each hydraulic clutch 54R, 54F has a piston 5 urged to move in the clutch disengaging direction by a return spring 54c as usual.
4d is provided, and as shown in the hydraulic clutch 54F, hydraulic pressure is applied to the piston 54d to obtain frictional engagement between the disks 54a and 54b to achieve clutch engagement. The auxiliary transmission 12 connects the fourth gear 52 to the driving shaft 7 by the hydraulic clutch 54F to directly connect the driving shaft 7 and the output shaft 10 to the output shaft 10 in the vehicle forward direction, and the hydraulic clutch 54R to the first. The gear 49 is connected to the drive shaft 7 to connect the gears 49, 5
By connecting the drive shaft 7 and the output shaft 10 via 0, 51, 53 and 52, the output shaft 10 is rotationally driven in the backward direction of the vehicle, and is configured as a forward / reverse switching type. It is also possible to easily form a high-low two-stage switching type transmission that corresponds to a structure in which the idler gear 53 is eliminated and the third and fourth gears 51 and 52 are directly meshed.

In order to supply hydraulic oil to the hydraulic clutches 54F and 54R, hydraulic oil passages 55F and 55R are bored in the driving shaft 7 as shown in FIGS.
It is led into the F and 54R. As shown in FIGS. 3 and 6, the drive shaft 7 is also provided with two lubricating oil passages 55L for supplying lubricating oil to the disks 54a and 54b of the hydraulic clutches 54F and 54R. Each lubricating oil passage 5
On the hydraulic clutches 54F and 54R side, 5L is communicated with an annular groove 56 formed on the outer peripheral surface of the boss portion of the clutch cylinder as shown in FIG. 5, and lubricating oil is supplied from the annular groove 56 toward the disks 54a and 54b. A throttle oil hole 57 and an oil hole 58 for guiding are formed in the inner cylindrical portion of each piston 54d. The arrangement of the throttle oil holes 57 and the oil holes 58 is such that the annular groove 56 communicates only with the throttle oil holes 57 in the clutch non-engaged state as shown in the hydraulic clutch 54R.
As shown in 4F, in the clutch engaged state, the annular groove 56 is set to communicate with the oil hole 58 by the movement of the piston 54d. The hydraulic oil passage 55 of the drive shaft 7
The F and 55R and the lubricating oil passage 55L are perforated from the rear end face side of the driving shaft, and are sealed with a ball seal 59 as shown in the oil passages 55F and 55R in FIG.

As shown in FIGS. 3, 4 and 6, between the driving shaft 7 and the hollow cylindrical portion 37 of the partition wall 1a supporting the driving shaft 7,
By sealing the three annular grooves formed on the outer peripheral surface of the driving shaft 7 with the inner peripheral surface of the hollow cylindrical portion 37, the three annular oil chambers 6 are formed.
0F, 60R, and 60L are sectioned. The hydraulic oil passages 55F and 55R in the drive shaft 7 are respectively provided in the annular oil chamber 6
0F and 60R, and the two lubricating oil passages 55L communicate with the common annular oil chamber 60L. The partition wall 1a is formed with laterally-operated hydraulic oil passages 61F and 61R and a lubricating oil passage 61L in a thick portion connected to the hollow cylindrical portion 37, and communicated with the annular oil chambers 60F, 60R and 60L, respectively. is there.

As shown in FIG. 4 and FIGS. 6 and 7, an opening 62 is provided on one side wall of the front housing 1 at the rear side of the partition wall 1a, and a control valve for controlling the operation of the auxiliary transmission 12. The device 63 is fixedly supported on the front housing 1 by passing through the opening 62 and straddling the inside and outside of the front housing 1. The valve housing of the control valve device 63 includes a plate member 64 along the outer surface of the side wall, an outer housing member 66 along the outer surface of the plate member 64 with a seal sheet 65 interposed therebetween,
And the front housing 1 along the inner surface of the plate member 64
An inner housing member 67 positioned inside is fastened. A bolt 68 is used to attach the valve housing to the front housing 1, and a bolt 69 for fastening between the plate member 64 and the outer housing member 66 and a bolt 70 for fastening between these members 64, 66 and the inner housing member 67. Is also provided.

As shown in FIGS. 4 and 6, at the front end portion of the plate member 64, hydraulic oil ports 71F and 71R are formed, which are open toward the outer surface 1c of the front housing 1 at the position of the partition wall 1a.
A lubricating oil port 71L and a pump port 71P are formed. Of these, the operating oil ports 71F, 71R and the lubricating oil port 71L are located on the extension lines thereof, and are the linear operating oil passages 61F in the partition wall 1a. 61R and the lubricating oil passage 61L communicate with each other as they are, the annular oil chambers 60F, 6
It is linearly connected to 0R and 60L. A hydraulic pump 72 for supplying hydraulic oil to the hydraulic clutches 54F, 54R is configured as an internal gear type having a driving shaft 7 as a pump shaft, and is mounted on the front surface of the partition wall 1a. The suction port of the hydraulic pump 72 communicates with the inside of the partition wall 1a to a suction passage 73 that opens to the other side surface of the front housing 1. As shown schematically in FIG.
The suction pipe 74 connected to the No. 3 is introduced into the oil sump in the mission case 2. The discharge port of the hydraulic pump 72 is connected to the plate member 6 by the discharge passage 75 in the partition wall 1a.
4 to the pump port 71P.

The outline of the control valve device 63 will be described with reference to the circuit diagram of FIG. In the drawing, the oil sump in the rear half of the front housing 1 and in the transmission case 2 is indicated by reference numeral 77. First, the control valve device first operates the hydraulic oil passages 61F, 55F and 61R, 55.
The hydraulic clutch 54 is provided by the oil passages 79F and 79R corresponding to R.
It has a directional control valve 78 connected to F and 54R. The direction switching valve 78 has a neutral position N that disconnects both hydraulic clutches 54F and 54R, a forward action position F and a reverse action position R that selectively actuate the hydraulic clutches 54F and 54R. The oil passage shutoff valve 8 is provided in the discharge oil passage 80 of the hydraulic pump 72.
1, the oil passage cutoff valve 81 is connected to the pressure reducing valve 83 by the oil passage 82, and the pressure reducing valve 83 is connected to the direction switching valve 78 by the oil passage 84. In the oil passage 85 branched from the oil passage 82, a gradually increasing hydraulic pressure relief valve 86 for setting the hydraulic pressure applied to the hydraulic clutches 54F and 54R is inserted. The relief oil passage 88 of the main relief valve 87 that sets the oil pressure of the oil passage 80 is guided in the direction of the hydraulic clutches 54F, 54R, and the lubricating oil passage 61L,
It is used to supply lubricating oil to the disks 54a, 54b of the hydraulic clutches 54F, 54R by means of an oil passage corresponding to 55L. The relief oil passage 85a of the gradually increasing hydraulic pressure relief valve 86 is connected to the oil passage 88.
A secondary relief valve 89 for setting a lubricating oil pressure is connected to the oil passage 88, a flow rate control valve 90 is connected, and an opening / closing valve 91 is inserted.

As shown in FIG. 8, the pressure reducing valve 83 is a pedal 92.
Is configured to be displaced through the rotating arm 93, and the flow path between the oil passages 82 and 84 and the non-depressurized position A where the oil passage 82 is connected to the oil passage 84 almost as it is is narrowed. A hydraulic clutch is formed by connecting the oil passage 84 to the oil sump 77 while shutting off the pressure reduction position B where the oil is drained to the oil sump 77 by throttling to reduce the set hydraulic pressure by the relief valve 86 and the end of the oil passage 82. It has a hydraulic unload position C that cuts off 54F and 54R. The oil passage shutoff valve 81 has an oil passage shutoff position I that shuts off the end of the oil passage 80 and connects the oil passage 82 to the oil sump 77, and an oil passage open position II that connects the oil passages 80 and 82. Is configured to be urged by the valve spring 81a toward the oil passage shutoff position I, and the oil pressure of the oil passage 82 is guided to the opposite side of the valve spring 81 by the oil passage 94. The oil passage shutoff valve 81 is connected to the rotating arm 93 and is connected to the rod member 9
5, when the pressure reducing valve 83 is moved to the hydraulic pressure unloading position C, it is moved from the oil passage cut-off position I to the oil passage opening position II, and thereafter to the same position II by the oil pressure of the oil passage 82 acting via the oil passage 94. It is supposed to be stopped. These valves 8
More specific functions of 1, 83 will be described later.

As is well known, the gradual increase hydraulic pressure relief valve 86 is provided with a control piston 97 for receiving the base end of the hydraulic pressure setting spring 96, so that the hydraulic pressure of the oil passage 82 is supplied to the oil chamber 98 behind the control piston 97. The control piston 97 is gradually advanced and the spring force of the spring 96 is gradually increased to gradually increase the spring force of the oil passage 8.
It is configured to gradually increase the hydraulic pressure to be set to 2.
When the direction switching valve 78 is returned to the neutral position N, the oil chamber 9
In order to quickly drain the oil from 8, the oil chamber 98 is also connected to the directional switching valve 78 by the oil passage 100.
The oil passage 100 is connected to the oil sump 77 at the neutral position N of 8.

Similarly, as shown in FIG. 8, the flow control valve 90 has a first position where oil does not drain from the oil passage 88 as shown in the drawing, and a portion of the oil passage 88 from the oil passage 88 via an internal throttle 90a. A second position for draining oil to the oil sump 77, and is urged to move in the first position direction by the valve spring 90b, and from the opposite side of the valve spring 90b, the pressure reducing valve 83 and the direction switching valve. The oil pressure of the oil passage 84 between 78 is made to act by the pilot oil passage 101. The on-off valve 91 has a closed position for shutting off the oil passage 88 and an open position for opening the oil passage 88 as shown in the drawing, and the valve spring 91a.
Is urged to move toward the closed position by the pilot oil passage 10 as well as the flow control valve 90.
2, the valve spring 91a is operated from the opposite side. Therefore, these valves 90, 91 respond to the hydraulic pressure of the oil passage 84 which is made to act on the hydraulic clutch 54F or 54R, and the hydraulic clutch 5
The supply of the lubricating oil to the 4F and 54R will be controlled, the details of which will be described later.

In FIG. 8, the lubricating oil control mechanism attached to each of the hydraulic clutches 54F and 54R described above with reference to FIG. 5 is also shown as two valves 103, and each of these valves 103 is the throttle oil. It has a hole 57 inside and is urged to move to the position for supplying the lubricating oil only through the throttle oil hole 57 by the return spring 54c.

A specific structure of the control valve device 63 will be described. As shown in FIGS. 6 and 7, a housing portion 66a is integrally formed on the outer surface of the outer housing member 66, and FIG. The gradually increasing hydraulic pressure relief valve 86 and the direction switching valve 78 described above are arranged vertically and are installed along the front-rear direction. Further, the oil passage cutoff valve 81, the pressure reducing valve 83, the main relief valve 87, the secondary relief valve 89, the flow control valve 90 and the opening / closing valve 91 described with reference to FIG. 8 are arranged in the inner housing member 67 in the front-rear direction,
The interior is arranged as shown in FIGS. The rotating arm 93 described with reference to FIG. 8 is supported by the outer housing member 66 and the plate member 64 and the partition wall 1a so as to be rotatably displaceable, and is attached to the lateral operation shaft 105 arranged at the front position of the inner housing member 67. , This operation axis 10
An arm 106 for operation is attached to the outer end of 5. The plate member 64 is generally used for forming an oil passage, and the plate member 64 and the outer housing member 6 are used.
The connecting oil passage between the six is formed in the seal sheet 65, and the oil passage in the plate member 64 and the oil passage in the inner housing member 67 are connected by arranging the corresponding oil passages face to face.

The valve structure within the outer housing member 66 is shown in FIGS. 9 and 11, and the valve structure within the inner housing member 67 is shown in FIGS.

As shown in FIGS. 9 and 11, the directional control valve 78
Is provided by a spool fitted in a valve hole formed in the housing portion 66a along the front-rear direction. The oil passage 84 led from the pressure reducing valve 83 is provided in the valve hole.
Pump port 78P, hydraulic clutch 54F,
Clutch port 78 connected to 54R
F, 78R, two oil drain ports 78T1, 78T2 connected to the oil sump 77, and an oil return port 78D for connecting the oil passage 100 led from the oil chamber 98 of the relief valve 86 are opened respectively. is there. Direction switching valve 78
Has a land for connecting and disconnecting the ports appropriately and an oil passage inside, and at the neutral position N shown in FIG.
P, clutch ports 78F, 78R and oil return port 7
All 8D are supposed to communicate with the oil drain port 78T1 or 78T2. Further, at the forward action position F shown in FIG. 11, the pump port 78P and the clutch port 78F communicate with each other, the clutch port 78R and the oil drain port 78T1 communicate with each other, and the oil return port 78D is blocked. Conversely, at the reverse action position R obtained by retracting the switching valve 78 from the neutral position in FIG. 9, the pump port 78P and the clutch port 78R are in communication, the clutch port 78F and the oil drain port 78T1 are in communication, and the oil return port 78D. Is meant to be blocked.

In order to perform displacement operation of the direction switching valve 78, a laterally operating shaft 108 rotatably supported by the housing portion 66a is provided, and a shifter 109 attached to this operating shaft 108 is provided at the rear end of the switching valve 78. Is engaged with. In order to releasably restrain the switching valve 78 at the respective positions N, F, R, three annular detent grooves 110N, 110F, 110R are formed on the outer peripheral surface of the switching valve spool, and inside the respective detent grooves. The ball 112 facing the spring 111
Is provided in the housing portion 66a. Note that the detent grooves 110N, 110 adjacent to each other are formed on the outer peripheral surface of the switching valve spool.
A circular surface portion is not formed between F and 110N and 110R, and in a state where the ball 112 is in contact with such a circular surface portion, the spool is positionally constrained and a desired switching valve position may not be obtained. Avoided. As shown in FIGS. 6 and 7, the operating shaft 108 projects outside the housing member 66, and an operating arm 113 is attached to the outer end thereof.

As shown in FIGS. 9 and 11, the valve body 86A of the gradually increasing hydraulic pressure relief valve 86 and the control piston 97 are fitted in a hole formed in the housing portion 66a along the front-rear direction. It is arranged in 114. A pump port 8 to which the oil passage 85 is connected to the valve case 114.
6P, a hydraulic action port 86S connected to the oil passage 85 via the throttle 99 in the housing portion 66a and opened in the oil chamber 98, an oil relief port 86T1 connected to the oil passage 85a, an oil An oil drain port 86T2 leading to the sump 77 and an oil return port 86D connected to the oil passage 100 are formed. A throttle oil passage 86a for guiding the oil pressure of the pump port 86P to the oil chamber 115 formed on the opposite side of the control piston 97 is formed in the valve body 86A. Further, a pin portion 86b protruding toward the control piston 97 is integrally formed on the valve body 86A, and a tubular portion 97a into which the pin portion 86b can be inserted is integrally provided so as to project from the front surface of the control piston 97. . The hydraulic pressure setting spring 96 (FIG. 8) is composed of three coil springs 96a, 96b, 96c in the illustrated example. Of these, the spring 96a arranged at the outermost periphery is arranged so as to contact the valve body 86A and the control piston 97 at both ends in a state where the valve body 86A and the control piston 97 are maximally separated from each other as shown in FIG. Has been done. In addition, the spring 96b at the center in the radial direction is in contact with the valve body 86A at one end in the state of FIG. 9, and is separated from the control piston 97 by a certain distance while being guided by the tubular portion 97a at the other end. Has been placed. The innermost spring 96c is disposed in the tubular portion 97a, and
As shown in FIG. 1, when the valve body pin portion 86b rushes into the tubular portion 97a due to the forward movement of the control piston 97, the pin portion 86b
It is designed so as to abut on b. The end of the spring 96c is to be received by a screw plug 97b screwed to the control piston 97, and a shim 97c for adjusting the spring force of the spring 96c can be interposed between the screw plug 97b and the spring 96c as necessary. ing. In FIGS. 9 and 11, 114a is an annular step formed on the inner peripheral surface of the valve case 114 to regulate the most advanced position of the control piston 97. Further, 86c is a stopper pin fixed to the valve body 86A, and when the valve body 86A performs a relief operation in a state where the oil temperature is low, the valve body 86c is based on the high viscosity of the oil.
This is to prevent an overlift phenomenon in which A excessively moves.

Since the preferred hydraulic pressure increasing type relief valve 86 shown above is designed to set the hydraulic pressure by the three springs 96a, 96b, 96c arranged as described above, the directional control valve 78 is in the neutral position. The rising mode of the hydraulic pressure from the time of shifting from N to the operating position F or R is changed in three stages. In FIG. 12, the same mode is shown as a relationship between time t and hydraulic pressure P. That is, at the time of displacement of the direction switching valve 78 (t = 0), the spring 96a
A low initial hydraulic pressure P0 corresponding to the initial spring force is set, and this initial hydraulic pressure P0 is gradually advanced by the oil that the control piston 97 gradually flows into the oil chamber 98, and the spring 96a
By gradually increasing the spring force of, the hydraulic pressure P1 at time t1 is gradually increased. Control piston 9 at time t1
7, the next spring 96b moves the piston 97
It is the time to touch the
Both a and 96b are involved in setting the hydraulic pressure, and the next time t2
By the time, the hydraulic pressure P is increased to the hydraulic pressure P2 more rapidly than before. The time t2 is the pin 86b of the valve body 86A.
Is the time when the control piston 97 is inserted into the tubular portion 97a of the control piston 97 and abuts on the spring 96c so that the spring 96c also starts to participate in setting the hydraulic pressure. As shown in FIG. 11, the control piston 97 abuts on the stepped portion 114a. The hydraulic pressure P is relatively rapidly increased to the regular hydraulic pressure Pa set in the state of FIG. The start of the vehicle is obtained at a point S midway until time t1, for example, and the vehicle gradually enters a normal operating state as a buffer due to the subsequent gradual increase in hydraulic pressure. Spring 96 involved in setting the normal hydraulic pressure Pa
Since c is provided inside the control piston 97, the normal hydraulic pressure can be easily adjusted by the shim 97c or the like, and even if the same adjustment is performed, the initial pressure P0 and the hydraulic pressure rising characteristics up to time t2 are changed. Never be done. Three springs 96a, 96b, 96c arranged as described above
As a result, the delay time of the hydraulic pressure rise is lengthened, and even when the main transmission device 15 and the auxiliary transmission device 18 in the mission case 2 shown in FIG. .

Next, the specific structure of the pressure reducing valve 83 is shown in FIGS.
1 and FIGS. 13-16 will be described. 10 and 11
As shown in FIG.
Has a valve body 83A fitted in a valve hole in the front-rear direction formed in the lower part of the. A pump port 83P connected to the oil passage 82 guided from the oil passage cutoff valve 81, a clutch port 83C connected to the oil passage 84 guided to the direction switching valve 78, and an oil sump in the valve hole. Two oil drain ports 83T1 and 83T2 connected to 77 are opened respectively. The valve body 83A is formed in a hollow shape having a partition wall 83a in the middle, a spring 118 and a load piston 119 are fitted to the rear side of the partition wall 83a, and a poppet 120 is fitted to the front side of the partition wall 83a. is there.
The rod 120a of the poppet 120 is attached to the operation bar 121 fitted to the front end of the valve hole by a pin 122. The rotation arm 93 is engaged with the operation bar 121 on the front side of the housing member 67. There is. Operation bar 1
The second half of 21 has a hollow shape, inside and outside of which coil springs 123 and 124 are arranged, and a ring 125 is formed.
Is acted on the valve element 83A via the. In the valve body 83A, a pair of radial throttle oil holes 83b before and after the partition wall 83a,
83c, and a radial oil hole 83d for communicating the hollow portion of the valve element 83 with the oil drain port 83T1 on the front side thereof, and a radial oil hole 83d on the front end face in contact with the ring 125 toward the oil drain port 83T2. Oil holes 83e are formed respectively.

The pressure reducing valve 83 is supposed to change the position by sliding the operation bar 121 by the rotating arm 93. First, in order to obtain the non-pressure reducing position A and the hydraulic pressure unloading position C described above with reference to FIG. In the following, That is, the pressure reducing valve 83 is shown in FIGS.
13 shows the non-depressurized position A, and at the same position A, the valve body 83A largely communicates between the pump port 83P and the clutch port 83C via the outer periphery of the small diameter portion 83f at the center as clearly shown in FIG. Is output to the clutch port 83C without reducing the hydraulic pressure. The hydraulic unloading position C, which is moved by fully depressing the pedal 92 (FIG. 8), is shown in FIG. 14. At this time, the operation bar 121 is largely pulled out, and the urging force of the springs 123 and 124 is reduced. Valve body 83A
Is displaced to the illustrated position by the urging force of the spring 118, and the pump port 8 is moved by the land on the rear side of the small diameter portion 83f.
3P is blocked, and the clutch port 83C is communicated with the oil drain port 83T1 on the outer circumference of the small diameter portion 83f to unload the oil pressure of the clutch port 83C.

Next, as shown in FIG. 14, the outer peripheral spring 124 of the inner and outer springs 123, 124 for urging the valve body 83A via the ring 125 is, as shown in FIG. Although separated from each other, the spring 124 is further configured as follows. That is, as shown in FIG. 15, the spring 124 has an open winding portion 124a having high rigidity and a close winding portion 124b having low rigidity, and is pushed by the operation bar 121 and the bar 121 and the ring 125. When compressed between the coils, first, the coils of the densely wound portion 124b are first compressed until they come into close contact with each other, and then the sparsely wound portion 124a is compressed. 16 (a),
8B and 8C show three pressure reducing modes of the pressure reducing valve 83 within the range of the pressure reducing position B described above with reference to FIG. 8. In any of these modes, the valve body 83A is provided with a throttle oil hole 83c. Actuating oil pressure of clutch port 83C and spring 1
18 is urged to move forward by the urging force of 18 and is urged rearward by the urging force of the spring 123 or the springs 123 and 124, and the clutch port 8
Oil drain port 83T1 from 3C through throttle oil hole 83b
The oil is drained in a small proportion to the small diameter part 8
It oscillates back and forth so as to open and close the pump port 83P at the land end on the rear side of 3f, reduces the hydraulic pressure of the pump port 83P and outputs it to the clutch port 83C. 16A shows a state in which the operation bar 121 is pulled out considerably large and the spring 124 is separated from the ring 125. In this state, the degree of pressure reduction by the pressure reducing valve 83 is determined corresponding to the urging force of the spring 123. A large pressure reduction is obtained. 16B shows the inner and outer springs 123, 1
Although 24 also contacts the ring 125, the outer peripheral side spring 124 shows a state in which the operation bar 121 is pulled out to such an extent that only the close-wound portion 124b (FIG. 15) thereof is compressed. The degree of pressure reduction is determined corresponding to the biasing force of the spring 123 and the biasing force of the close-wound portion 124b of the spring 124, and a moderate pressure reduction is obtained. 16C shows the tightly wound portion 124 of the outer peripheral spring 124.
The state in which the operation bar 121 is pulled out to such an extent that the coil b is closely contacted and the sparsely coiled portion 124a is compressed is shown. It is determined corresponding to the urging force applied to the power, and the degree of pressure reduction becomes relatively small. A more detailed decompression action will be described later.

Next, the specific structure of the oil passage shutoff valve 81 is shown in FIG.
This will be described with reference to 0 and 11. The oil passage cutoff valve 81 is provided by fitting into a valve hole in the front-rear direction formed in the upper portion of the inner housing member 67, and the oil passage 80 guided from the hydraulic pump 72 is connected to the valve hole. Pump port 81
P and the clutch port 81C connected to the oil passage 82 guided to the pressure reducing valve 83 are opened.
The shut-off valve 81 uses the valve spring 81a to connect the ports 8
It is urged to move between 1P and 81C in a blocking direction. The oil hole 81b for draining oil from the clutch port 81C into the oil sump 71 at the oil passage cut-off position I described above with reference to FIG. 8 and the port 8 from the opposite side of the valve spring 81a.
The throttle oil hole 81c that applies the hydraulic pressure of 1C is
Is formed in. The oil passage 94 described above with reference to FIG. 8 is shared with the main passage in the shutoff valve 81, and is provided by a hollow portion 81d in the shutoff valve 81 and a radial oil hole 81e continuous with the hollow portion 81d. The rod member 95 described above with reference to FIG. 8 is fitted into the small diameter portion on the front end side of the valve hole, and the rear end surface 95a pushes the annular stepped portion 81f in the hollow portion 81 of the valve 81 to open the shutoff valve 81. Spring 81
It is designed to be pushed and displaced against the force a.

The oil passage shutoff valve 81 is the pressure reducing valve 8 as described above.
3 is moved to the hydraulic unload position C, the rod member 95
11 is moved to the oil passage opening position II, and the ports 81P, 8 are moved by the hollow portion 81d and the oil hole 81e as shown in FIG.
Connect between 1C. FIG. 11 shows a state in which the pressure reducing valve 83 is then returned to the non-pressure reducing position A, whereby the rod member 95 is also pushed out by the hydraulic pressure in the hollow portion 81d so as to contact the rotating arm 93. In this state, the shutoff valve 81 is held at the position shown in FIG. 11 by the oil pressure of the oil passage 82 acting through the oil hole 81e. As described above with reference to FIGS. 1 and 2, the driving system drive shaft 7 is driven by the engine without passing through the clutch because the oil passage cutoff valve 81 is provided. That is, the valve 81
10 when the direction switching valve 78 is moved to the operating position F or R.
8 remains in the oil passage cut-off position, and the oil passage is opened only after the pedal 92 of FIG. 8 is fully depressed to move the pressure reducing valve 83 to the hydraulic pressure unload position C. And pressure reducing valve 83
In the above position C, the hydraulic clutch 54F or 54R is not engaged due to the hydraulic pressure unloading, and the transmission of power is cut off, so that the auxiliary transmission 12 (FIGS. 1 and 3) performs the clutch function. After that, the transmission 12 is connected to the pedal 9
Transmission is gradually started by releasing the depression of 2.

Another valve arranged in the inner housing member 67 will be described with reference to FIGS. 10 and 11. The main relief valve 87 faces the oil passage 80 and has a valve spring 87a.
Is urged in the non-relief direction so as to be arranged along the front-rear direction, and the relief oil flows out to the oil passage 88. The secondary relief valve 89 faces the oil passage 88 and is urged in a non-relief direction by a valve spring 88a so as to be arranged along the front-rear direction, and the relief oil is made to flow into the oil sump 77. The flow rate control valve 90 is arranged along the front-rear direction in a valve hole that opens an annular groove 88a formed in the middle of the oil passage 88, and the throttle 90a is provided by a radial throttle oil hole. When the oil pressure of the pilot oil passage 101 guided to the front side is retracted to the position shown in FIG. 11 against the force of the valve spring 90b, a part of the oil from the oil passage 88 is passed through the throttle 90a and the valve hole. Is drained into the oil sump 77. Further, the on-off valve 91 is arranged in the valve hole which opens the annular grooves 88b, 88c in the middle of the oil passage 88, and the pilot oil passage 1
When hydraulic pressure is applied via 02, the valve spring 91a
It is supposed that it is displaced to the position shown in FIG. 11 against the force, and the annular grooves 88b and 88c are made to communicate with each other on the outer circumference of the intermediate small diameter portion to release the cutoff of the oil passage 88.

FIG. 11 described above illustrates a state in which the vehicle is traveling in a steady state with the direction switching valve 78 set to the forward action position F, and the pressure reducing valve 83 is not pressure-reduced. The gradually increasing hydraulic pressure relief valve 86 establishes a normal clutch working hydraulic pressure in the oil passages 82 and 84 in the illustrated state,
The hydraulic pressure causes the flow control valve 90 to drain a part of the oil from the oil passage 88, and the open / close valve 91 is in a position to open the oil passage 88. The secondary relief valve 89 takes the relief operation position as shown in the figure to set the hydraulic pressure of the oil passage 88, that is, the lubricating hydraulic pressure. The main relief valve 87 does not perform a relief operation because the oil pressure of the clutch oil supply circuit is determined by the gradually increasing relief valve 86. Instead, the relief operation of the latter relief valve 86 causes an oil relief port from the pump port 86P of the same relief valve 86. Oil that is relieved to 86T1 is supplied to the oil passage 88 as lubricating oil via the oil passage 85a. The lubricating oil control mechanism attached to the hydraulic clutches 54F and 54R, which is illustrated as the valve 103 in the same manner as shown in FIG. 8, is the valve 1 on the hydraulic clutch 54F side.
Only 03 is moved to a position where the lubricating oil is supplied without being throttled.

FIG. 17 shows the external appearance of the main part of the front housing 1. As shown in the figure, a step 121 is provided at a position outwardly of the outer housing member 66 of the valve housing at a position outside thereof, a mounting boss 122 on the outer surface of the front housing 1 and a mounting boss on the outer surface of the mission case 2 ( (Not shown), the housing portion 66 is installed.
a is located below the step 121, and the arm 10
6, 113 are also located below the step 121. The operating shaft 3 for operating the PTO clutch 8 described with reference to FIG.
2 also has an arm 122 attached below step 121, and this arm 122 is connected by a rod 123 to a PTO clutch lever (not shown). A support 125 is erected inside the engine hood 124 on the upper surface of the front housing 1, and the pedal 92 for operating the pressure reducing valve is provided.
Are rotatably supported by a column 125 around a support shaft 126. A pedal return spring 127 is stretched between the pedal 92 and the bonnet 124, and a pair of stoppers 128, 129 for restricting the rotation range of the pedal 92 are fixedly provided on the column 125 and on the outer surface of the front housing 1. Has been done. The arm 106 is an arm 92 that rotates together with the pedal 92.
The rod 130 is connected to a. Further, the arm 103 for displacing the direction switching valve is provided with an operation cord 131.
Is connected to a shift lever 78a schematically shown in FIG.

Here, the schematic structure of the main transmission 15 and the auxiliary transmission 18 shown in FIG. 1 will be described. First, the main transmission 15 has four gears 131, 13 on the drive shaft 13.
2, 133, and 134 are loosely fitted and installed, and four gears 135, 136, and 13 meshed with these gears, respectively.
7, 138 are fixedly installed on the speed change shaft 14, and four speed change gear trains are provided. The drive shaft 13 is provided with two compound synchronous clutches 139 and 140 for selectively connecting the gears on the drive shaft 13 to the drive shaft 13 so as to obtain four speeds.

The speed change shaft 14 is connected to the intermediate shaft 16 by reduction gears 142 and 143 rows. Intermediate shaft 1
Two transmission gears 144, 145 are fixedly installed on the gear 6, and two shift gears 146, 147 engageable with the gears 144, 145 are slidably mounted on the propeller shaft 17. Has been. A clutch 148 that can be engaged by the displacement of the shift gear 147 is disposed between the transmission shaft 14 and the propeller shaft 17. As described above, the sub-transmission device 18 is configured to be able to obtain a three-speed shift by shifting the shift gears 146 and 147.

FIG. 18 is a schematic graph showing the pressure reducing action of the pressure reducing valve 78 and the action of the lubricating oil supply control valve mechanism including the flow rate control valve 90 and the opening / closing valve 91. In FIG. 18, the horizontal axis represents the stroke of the pressure reducing valve operating pedal 92, S0 represents the non-depressed position, and S5 represents the maximum depressed position. P shown on the vertical axis represents the clutch hydraulic pressure,
Q indicates the amount of lubricating oil supplied to the engaged hydraulic clutch 54F or 54R, respectively. The fluctuation of the oil pressure P is shown by a solid curve C1, and the fluctuation of the lubricating oil amount is shown by a broken curve C2.

As described above with reference to FIGS. 16A, 16B, and 16C, the pressure reducing valve 83 has three pressure reducing modes. When the pedal 92 is depressed from the position S0 to the position S1, the mode shown in (c) of FIG. 16 appears. Decompression in the same mode is obtained up to S2, and the compression degree of the spring 123 and the spring 124 are loose. The clutch acting hydraulic pressure P can be reduced to between the hydraulic pressures P1 and P2 lower than the normal hydraulic pressure P0 set by the relief valve 86 according to the degree of compression of the winding portion 124a. When the pedal 92 is further depressed, the mode shown in FIG. 16B appears, and the spring 123 is moved between the pedal positions S2 and S3.
And the compression degree of the tightly wound portion 124b of the spring 124 are adjusted to reduce the clutch operating oil pressure P to lower oil pressures P2 and P2.
Decompression control can be performed for 3 hours. When the pedal 92 is further depressed, the mode shown in FIG. 16A appears, and the compression degree of the spring 123 is adjusted between the pedal positions S3 and S4 to reduce the clutch operating oil pressure P between the lower oil pressures P3 and P4. You can control. A point Ca shown on the curve C1 shows a point where the piston 54d of the hydraulic clutch 54F or 54R has moved to the maximum so that the disks 54a and 54b are brought into close contact with each other, and a point Cb shows the main transmission 15 and the auxiliary transmission shown in FIG. The complete engagement position of the hydraulic clutch 54F or 54R in the case of setting the lowest speed among the 12 speeds in combination with the device 18 is illustrated. The point Cb is the transmission 15,18.
Shifts to the higher speed side, and as the axle load of the vehicle increases, shifts to the right on the curve C1 as seen in FIG. The travel control for slipping the hydraulic clutch 54F or 54R at the above-described lowest speed to drive the vehicle at a very low speed is performed at a point C.
By controlling the amount of depression of the pedal 92 between a and Cb, it is possible to freely change and control the very slow running speed of the vehicle.

The load of the valve spring 91a of the opening / closing valve 91 is Cb.
It is set so that the opening / closing valve 91 is moved to the open position of the oil passage 88 by the hydraulic pressure of the oil passage 84 corresponding to the pedal position Sa at which the pedal depression amount is slightly larger. On the other hand, the load of the valve spring 90b of the flow control valve 90 causes the flow control valve 90 to move to the position shown in FIG. 11 when the oil pressure in the oil passage 84 is increased to almost the normal oil pressure Pa, and a part of the oil is removed from the oil passage 88. It is set so that the amount of lubricating oil Q is drained and reduced from Q1 to Q2. Therefore, the pedal 92 is moved to the position Sa
With a large depression from the hydraulic clutch 54F or 5
Since the lubricating oil is not supplied to the 4R, the friction elements 54a and 54b of the clutch do not rotate together due to the drag due to the viscosity of the lubricating oil, and the unexpected start of the vehicle due to the phenomenon is prevented. Further, when the clutch is engaged by making the pedaling amount shallow through the position Sa from the state where the pedal 92 is largely depressed, a high flow rate Q1 of lubricating oil is supplied from the pedal position Sa to the hydraulic clutch. The heat generated during the clutch slip engagement from the point Ca to the point Cb is rapidly cooled and removed. After the pressure is increased to the normal hydraulic pressure Pa, the lubricating oil is not continuously supplied with the high flow rate Q1 or stopped with the flow rate Q set to zero, but the lubricating oil is reduced to the low flow rate Q2 and continuously supplied. By cooling and removing the residual heat at the time of clutch / slip engagement, the friction elements 54a and 54b are prevented from being worn, and energy loss and oil temperature rise due to the lubricating oil agitation of the friction elements 54a and 54b can be suppressed. Since the flow control valve 90 and the on-off valve 91 are separately provided as described above, the lubricating oil supply start point Sa and the lubricating oil low flow rate Q2 shown in FIG. 18 can be set independently of each other. By providing the lubricating oil control mechanism illustrated as the valve 103 in FIGS. 8 and 11 on the hydraulic clutches 54F and 54R side, the lubricating oil supply system common to both hydraulic clutches 54F and 54R is adopted, and It is possible to keep the amount of lubricating oil supplied to the hydraulic clutch in the operating state to a small value to prevent the occurrence of the entrainment phenomenon due to the lubricating oil in the clutch, and to secure a sufficient amount of lubricating oil for the hydraulic clutch in the operating state.

FIG. 19 shows a modified example of the support structure of the bearing frame 4. In this modified example, the flange 4e is integrally formed on the outer periphery of the rear end of the bearing frame 4 to form the front housing 1.
The bearing frame 4 is fastened and fixed together at the flange 4e by bolts 36 that fasten between the transmission case 2 and the transmission case 2. Between the rear end surface of the front housing 1 and the flange 4e, a temporary fixing pin 150 also serving as a positioning pin is arranged. Only the rear end portion of the auxiliary transmission 12 is illustrated. It can be installed in the latter half of the housing 1 in a completely assembled state while being temporarily fixed to the housing 1. The structure of the other part of the modification of FIG. 19 is made substantially the same as the corresponding part of the above-mentioned embodiment.

FIG. 20 shows a modification of the pressure reducing valve 83 in the hydraulic pressure unload position corresponding to FIG. In this modification, the head 1 is used instead of the poppet 120 of the above-described embodiment.
The pin 160 with 60a is attached to the operation bar 121, and the pin head 160a serves as a spring receiving member in place of the ring 125 in the state shown in the drawing.
A sleeve 161 that engages from the opposite side is used. The squeezing oil hole 161a corresponding to the squeezing oil hole 83e is the sleeve 1
It is provided in 61. When the operation bar 121 is pushed further from the state shown in the drawing, the pin head 160a moves the sleeve 1
When separated from 61, the springs 123 and 124 move and urge the valve body 83A through the sleeve 161.
Other structures are substantially the same as those of the pressure reducing valve described above.

[Brief description of drawings]

FIG. 1 is a schematic partially developed vertical sectional side view showing an entire transmission mechanism of a tractor equipped with a preferred embodiment of the present invention.

FIG. 2 is a vertical side view showing a front half of a front housing of the tractor.

FIG. 3 is a vertical cross-sectional side view showing a rear half of the front housing.

FIG. 4 is a cross-sectional plan view of the rear half of the front housing.

FIG. 5 is an enlarged view of a part of FIG.

6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is an exploded perspective view of a valve housing for the control valve device shown in FIGS.

FIG. 8 is a circuit diagram showing a hydraulic circuit provided in the illustrated tractor.

9 is a cross-sectional view taken substantially along the line IX-IX in FIG.

10 is a cross-sectional view taken substantially along the line XX of FIG.

FIG. 11 is a schematic cross-sectional view showing the connection mode and operation of the valves of the control valve device shown in FIGS.

FIG. 12 is a schematic graph showing the operation of the gradually increasing hydraulic pressure relief valve shown in FIGS.

13 is an enlarged sectional view showing the pressure reducing valve shown in FIGS.

14 is a cross-sectional view showing the pressure reducing valve of FIG. 12 in a hydraulic unload position.

FIG. 15 is a side view showing a one-coil spring provided in the pressure reducing valve.

FIG. 16 is a cross-sectional view showing the pressure reducing action of the pressure reducing valve of FIGS.

FIG. 17 is a side view showing the main part of the front housing of the illustrated tractor.

FIG. 18 is a schematic graph showing the operation of the pressure reducing valve and the lubricating oil control valve mechanism shown in FIGS.

FIG. 19 is a vertical cross-sectional side view similar to a portion of FIG. 3, showing a modification of the bearing frame support structure provided in accordance with the present invention.

FIG. 20 is a sectional view similar to FIG. 14, showing a modified example of the pressure reducing valve.

[Explanation of symbols]

1 front housing 1a partition wall 1b Boss 1c Side wall outer surface 2 mission case 4 bearing frame 4a protrusion 5 engine 5a flywheel 7 Driving shaft 10 Output shaft 11 Intermediate axis 12 Auxiliary transmission 13 Drive axis 14 speed change shaft 15 Main transmission 35 volts 37 Hollow cylindrical part 43 spline connection 49 first gear 50 Second gear 51 third gear 52 4th gear 53 idler gear 54F, 54R Hydraulic clutch 54a friction disc 54b steel disc 55F, 55R hydraulic oil passage 55L lubrication passage 60F, 60R, 60L Annular oil chamber 61F, 66R hydraulic oil passage 62 openings 63 Control valve device 64 plate member 66 Outer housing member 67 Inner housing member 68 Volts 71F, 71R hydraulic oil port 71L lubricating oil port 72 Hydraulic pump 75 discharge passage 78 Directional switching valve 83 Pressure reducing valve 86 Gradually increasing hydraulic pressure relief valve 88 oil passage 90 Flow control valve 91 Open / close valve 92 pedals

Continuation of the front page (56) Reference JP-A-2-60833 (JP, A) JP-A-3-70630 (JP, A) JP-A-63-312233 (JP, A) JP-A-5-346144 (JP , A) Japanese Unexamined Patent Publication No. 2-199364 (JP, A) Actually open 4-58417 (JP, U) Actually open 6-20943 (JP, U) Actually open 1-91632 (JP, U) Actually open 59-39329 (JP, U) Actual Kaihei 1-171949 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60K 17/04-17/06 F16H 3/00-3 / 78 F16H 57/02

Claims (19)

(57) [Claims] [Claim 1 further comprising a partition wall (1a) in the middle, a front housing (1) that the are open rear end, Yes to open the front end, the mission that is connected to the rear end of the front housing case (2), the bearing is fixedly installed to the front Haujin grayed frame (4)
And is supported by the partition wall while penetrating the partition wall.
Performing the driving shaft (7), and this at the rear of the drive shaft arranged raw shaft concentric output shaft which had been supported by the bearing frame (10), a speed change transmission between these driving shaft and the output shaft to be at least one with a hydraulic clutch type first transmission (12) that is disposed in the front housing, is supported on the partition wall and the bearing frame between the above-mentioned partition wall and the bearing frame as First transmission (1) having an intermediate shaft (11) of
And 2), the drive shaft front end are being supported respectively on the bearing frame (13) and a transmission shaft (14), the mission to perform speed change transmission between the drive shaft (13) and a transmission shaft (14) in transmission structure of the tractor with a second transmission that is disposed within the case and (15), said first transmission (12) has a plurality hydraulic clutch (54
F, 54R) , and the plurality of hydraulic clutches (54F, 5R
4R) are all arranged on the drive shaft (7), and the bearing frame (4) is located behind the front housing (1) .
Fixedly installed in the front housing (1) from
The rear end of the drive shaft can be supported via the output shaft.
And the bearing frame (4) is fixedly installed.
The bearing frame to the front housing (1) of
The mission case can be connected to surround (4).
A transmission structure characterized by being said to be Noh . 2. The bearing frame (4) comprises a plurality of inwardly directed bosses (1) protruding from the rear end of the front housing (1).
Transmission structure according to claim 1, characterized in that it has a plurality of outward projections (4a) mounted on b). 3. A first gear (49) in which the first transmission (12) is loosely fitted and installed on a driving shaft (7), and fixedly installed on the intermediate shaft (11) by the first gear. A second gear (50) rotationally driven, a third gear (51) fixedly installed on the intermediate shaft (11), and a third gear fixedly installed on the output shaft (10) and rotationally driven by the third gear. A fourth gear (52) is provided, and the first gear (4
9. The transmission according to claim 1, further comprising a first hydraulic clutch (54R) for connecting 9) to the drive shaft and a second hydraulic clutch (54F) for connecting the fourth gear (52) to the drive shaft. Construction. 4. The first gear (49) and the second gear (50) are directly meshed with each other, and the third gear (51) and the fourth gear (52) are attached to the bearing frame (4). The first idler gear (53) that is axially supported meshes with the first gear.
4. The transmission structure according to claim 3, wherein the transmission (12) of FIG. 5. A hollow cylindrical portion for supporting the driving shaft (7).
(37) is integrally formed with the partition wall (1a),
Clutch operating oil passages (55F, 55R) in the shaft (7) and
Create a clutch in the partition wall (1a) for the lubricating oil passage (55L)
Pair with the dynamic oil passage (61F, 61R) and the lubricating oil passage (61L)
The annular oil chambers (60F, 60R, 60L) to be connected
A direction for controlling the operation of the first transmission (12) by forming a partition between the hollow cylindrical portion and the driving shaft.
Control valve device (63) including switching valve (78)
A part of the valve housing (64, 66, 67)
In close contact with one wall surface (1c) of the front housing (1)
Te, is fixedly supported on the front housing, a hydraulic pump driven by said driving shaft (7) (72)
Is attached to the front surface of the partition wall (1a), and the control valve device (6) is provided through an oil passage (75) in the partition wall.
3. The transmission structure according to claim 1, which is connected to 3). 6. The control valve device (63)
Is arranged so as to pass through an opening (62) formed in one side wall of the front housing (1) on the rear side of the partition wall (1a) and to extend inside and outside of the front housing, while the front end of the opening is arranged. Transmission structure according to claim 5, characterized in that a plate member (64) which is in close contact with the outer surface (1c) of the front housing is provided on the valve housing (64, 66, 67). 7. The plate member (64) has a clutch operating oil port (71F, 71R) and a lubricating oil port (71L) opening toward the outer surface (1c) of the front housing (1), The clutch operating oil passages (61F, 61R) and the lubricating oil passage (61) in the partition wall (1a) described above.
L) are the ports (71F, 71R, 71)
L) and the annular oil chamber (60F, 60R, 60L) are formed in a linear passage open at both ends.
Transmission structure. 8. The transmission structure according to claim 6, wherein the directional control valve (78) is mounted inside the valve housing (64, 66, 67) outside the front housing (1). To wherein said control valve device, said hydraulic clutch (54F, 54R) Hydraulic increasing type relief valve for gradually increasing the action hydraulic against the (86), the lubricating oil in a non-engagement state of the hydraulic clutch Road (55L, 61
L) is provided with valve means (90, 91) for lubricating oil supply control for stopping the supply of lubricating oil and starting the supply of lubricating oil from the state where the hydraulic clutch is slip-engaged. The transmission structure according to claim 5 . 10. The valve means (90, 91) is configured to control the supply of lubricating oil in response to an oil pressure applied to the hydraulic clutches (54F, 54R). Transmission structure. 11. A lubricating oil supply passage (88), wherein said valve means is provided in said control valve device (63).
11. The transmission structure according to claim 10, further comprising an opening / closing valve (91) that opens and closes in response to the hydraulic pressure applied to the hydraulic clutches (54F, 54R). 12. The valve means responds to an oil pressure flowing through a lubricating oil supply passage (88) provided in the control valve device (63) with a hydraulic pressure applied to the hydraulic clutches (54F, 54R). 11. The transmission structure according to claim 10, further comprising a flow control valve (90) which is controlled to be changed. 13. A part of the oil from the lubricating oil supply passage (88) when the hydraulic pressure applied to the hydraulic clutches (54F, 54R) by the flow control valve (90) is increased to almost normal hydraulic pressure. The transmission structure according to claim 12, wherein the transmission structure is configured to drain. 14. The hydraulic pressure applied to the hydraulic clutches (54F, 54R) with respect to the lubricating oil supply passage (88) provided in the control valve device (63) by the valve means has a value at which the hydraulic clutch is slip-engaged. And a flow rate control valve (90) for draining a part of the oil from the supply passage when the supply passage is closed to open. 11. The transmission structure according to claim 10. 15. The control valve device includes a hydraulic clutch (54) operated by a pedal (92).
Pressure reducing valve means (83) for reducing the hydraulic pressure applied to the F, 54R) and the lubricating oil passage (55L, 55L, in response to the hydraulic pressure applied to the hydraulic clutch in the disengaged state of the hydraulic clutch).
61L) is provided with valve means (90, 91) for controlling the supply of lubricating oil, which stops the supply of lubricating oil and starts supplying the lubricating oil from the state in which the hydraulic clutch is slip-engaged. The transmission structure according to claim 5 . 16. A lubricating oil supply passage (88) wherein said valve means is provided in said control valve device (63).
The transmission structure according to claim 15, further comprising an opening / closing valve (91) that opens and closes in response to the clutch acting hydraulic pressure. 17. A flow control valve (90) for changing and controlling the amount of oil flowing through a lubricating oil supply passage (88) provided in the control valve device (63) by the valve means in response to the clutch acting hydraulic pressure. 16. The transmission structure according to claim 15, including: 18. The flow control valve (90) is configured to drain a part of oil from the lubricating oil supply passage (88) when the clutch working oil pressure is increased to a substantially normal oil pressure. Paragraph 17 transmission structure. 19. The lubricating oil supply passage (88), wherein the valve means is provided in the control valve device (63).
When the hydraulic clutches (54F, 54R) are slip-engaged, the on-off valve (91) that changes from the closed state to the open state, and when the clutch working hydraulic pressure is increased to almost normal hydraulic pressure, some oil is removed from the lubricating oil supply passage. A transmission structure according to claim 15, comprising a flow control valve (90) for draining.