JP2002089655A - Hydraulic continuously variable transmission and transmission for working machine vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic continuously variable transmission device capable of generating a wide range of continuously variable change as well in the speed increase as decrease and thereby establishing a high total efficiency. SOLUTION: A first hydraulic device 100 and a second hydraulic device 200 equipped with a yoke 37 are combined and have a cylinder block 24 in common. A hydraulic closed circuit is provided for circulation of a lubricating oil between the first plunger chamber R1 and second plunger chamber R2, and the arrangement of this continuously variable transmission device includes a division in which the first plunger chamber R1 is in communication with the first oil chamber 53 while the cylinder block 24 rotates one turn round the axis and a division having a communication with the second oil chamber 54, and further a division in which the second plunger chamber R2 is in communication with the first oil chamber 53 while the yoke 37 rotates one turn with respect to the cylinder block 24 round the axis and a division having a communication with the second oil chamber 54, whrein the constitution contains a range in which the stroke capacity of the first hydraulic device 100 exceeds the stroke capacity of the second hydraulic device 200.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic continuously variable transmission and a transmission for a working machine vehicle that can be widely used in various industrial fields such as industrial machines and vehicles.

[0002]

2. Description of the Related Art Conventionally, a hydraulic transmission (HST) has been known as a continuously variable transmission using a fluid pump / motor. However, although this device is excellent in continuously variable transmission, it is known that the transmission efficiency is not always good, and the speed range is not satisfactory.
The reason that the transmission efficiency is low is that the HST is generally provided with a hydraulic pump (fluid pump) and a hydraulic motor (fluid motor) separately, and the driving force is transmitted only through the flow of hydraulic oil. This is because oil leakage from the plate portion and sliding torque are large.

FIG. 14 shows an example in which the HST is used as a continuously variable transmission. A hydraulic closed circuit is formed between the variable displacement hydraulic pump P1 constituting the HST and the fixed displacement hydraulic motor M1. That is, the hydraulic oil discharged from the variable displacement hydraulic pump P1 is sent out to the fixed displacement hydraulic motor M1, and after the fixed displacement hydraulic motor M1 is operated by the pressure of the working oil, the variable displacement hydraulic motor M1 is again transmitted via the hydraulic closed circuit. It returns to the pump P1. The output shaft of the engine EG is connected to the variable displacement hydraulic pump P1, and an auxiliary transmission mechanism F1 is provided between the output shaft of the fixed displacement hydraulic motor M1 and a final reduction device (not shown). In FIG. 14, the sub-transmission mechanism F1 includes gear trains G1, G2, and G3 for the first-speed sub-speed, the second-speed sub-speed, and the third-speed sub-speed, respectively.
The shift can be done manually.

FIG. 15 shows the stroke volume of the variable displacement hydraulic pump P1 in the continuously variable transmission shown in FIG. 14 (the amount of hydraulic oil exchanged per rotation of the variable displacement hydraulic pump P1 per rotation) and the auxiliary transmission mechanism. FIG. 8 is a characteristic diagram of an output rotation speed Nout (an output rotation speed per unit time; hereinafter, the same applies to other output rotation speeds) on an output shaft of F1. According to this characteristic diagram, when the stroke volume of the hydraulic pump P1 changes from VMmax to -VMmax, the output rotational speed shown in FIG. Note that the output rotation speed Nout has a boundary of 0, and the + side indicates forward traveling and the − side indicates reverse traveling. Further, + and-of the stroke volume mean the directions in which the hydraulic oil flows in the closed hydraulic circuit. V
Mmax indicates the maximum stroke volume.

[0005] In addition to the above-mentioned example of using the HST, an example of a hydraulic stepless transmission is known as shown in FIG. This configuration includes a variable displacement hydraulic pump P2 and a variable displacement hydraulic motor M2, and a closed hydraulic circuit is formed between the variable displacement hydraulic pump P2 and the variable displacement hydraulic motor M2. That is, the hydraulic oil discharged from the variable displacement hydraulic pump P2 is pressure-fed to the variable displacement hydraulic motor M2, and after the variable displacement hydraulic motor M2 is actuated by the working oil, the variable displacement hydraulic pump P2 is again transmitted via the hydraulic closed circuit. Have been to return to. The output shaft of the engine EG is connected to the variable displacement hydraulic pump P2, and a reduction mechanism Ga is provided between the output shaft of the variable displacement hydraulic motor M2 and a final reduction device (not shown). In this example, by switching a shift lever (not shown),
You can switch back and forth.

FIG. 17 shows one of the variable displacement hydraulic pump P2 and the variable displacement hydraulic motor M2 in the continuously variable transmission shown in FIG.
Pump / motor stroke volume per rotation and reduction mechanism Ga
FIG. 5 is a characteristic diagram of an output rotation speed Nout at the output shaft of FIG.

This characteristic diagram shows that when the output rotation speed Nout is 0, the stroke volume VP of the variable displacement hydraulic pump P2 is 0, and the stroke volume of the variable displacement hydraulic motor M2 is VMmax (constant). ing. In this case, VP =
Since it is 0, no hydraulic oil is discharged, so that the rotational force is not transmitted, and therefore Nout becomes 0.

While the output rotational speed Nout is between 0 and NE, the stroke volume VP of the variable displacement hydraulic pump P1 is linearly changed from 0 to VMmax, while the stroke volume VM of the variable displacement hydraulic motor M2 is , VMmax.

Similarly, when the output rotational speed Nout is 0 to -N
Until E, the stroke volume of the variable displacement hydraulic pump P1 is
The stroke volume VM of the variable displacement hydraulic motor M2 is constant at VMmax, while linearly changing from 0 to -VMmax.

In this case, while the output rotational speed Nout is between -NE and NE, the amount of oil (per revolution) VP discharged by the variable displacement hydraulic pump P2 = the oil discharged (returned) by the variable displacement hydraulic motor M2. (Per revolution) VM. Therefore, the speed (output rotation speed) increases in proportion to VP.

The output rotation speed Nout is changed from NE to 2N.
Until E, the stroke volume of the variable displacement hydraulic pump P2 is fixed at VMmax, while the stroke volume of the variable displacement hydraulic motor M2 is linearly changed from VMmax to 0.5 VMmax.

Similarly, when the output rotation speed Nout is between -NE and -2NE, the stroke volume of the variable displacement hydraulic pump P2 is fixed at -VMmax, while the stroke volume of the variable displacement hydraulic motor M2 is- It is linearly changed from VMmax to -0.5 VMmax.

In this case, the rotation speed of the variable displacement hydraulic pump P2 is NP, and the rotation speed of the variable displacement hydraulic motor M2 is NM.
Then, since NP × VMmax = NM × 0.5VMmax, NM = 2NP, and the variable displacement hydraulic motor M2 rotates twice as much as the variable displacement hydraulic pump P2.

According to this characteristic diagram, when the stroke volume of the pump changes as shown in FIG. 17, output speeds from -2NE to 2NE are obtained. The total efficiency (total transmission efficiency) of the continuously variable transmission of the HST shown in FIG. 14 or the continuously variable transmission shown in FIG. 16 will be described with reference to FIG. In the case of HST, the 1st speed sub-shift stage (HST
Sub 1 (1)), 2nd sub speed (HST sub 2 in the figure)
(2)) As shown in FIG. 18, the third-speed sub-gear ratio (HST sub-gear 3 (3) in FIG. 18) has an overall efficiency of about 0.8 at any of the gear stages due to oil leakage. This is the best value.

On the other hand, the continuously variable transmission shown in FIG.
Is shown in (4). In the case of ()) as well, due to oil leakage, the best efficiency is about 0.8. As described above, in the hydraulic continuously variable transmission as shown in FIGS. 14 and 16, in order to obtain a certain output rotational speed, FIGS.
As shown in FIG. 7, it is necessary to circulate the hydraulic oil in the closed hydraulic circuit, which causes oil leakage and lowers the efficiency. Further, since the output rotation speed is obtained only by the circulation of the hydraulic oil, a large amount of oil is inevitably required in the case of high-speed rotation, resulting in an increase in the size of the apparatus.

[0016]

As described above, conventionally, there has been a problem that the efficiency is only about 0.8 which is the best value.

Furthermore, a continuously variable transmission comprising an HST,
When the continuously variable transmission shown in FIG. 16 is mounted on a working machine vehicle such as a tractor or a loader, the working machine vehicle originally has a main working area (main working speed area) in a reverse traveling area or a high speed traveling area. The main working speed range is a running range as shown in FIG. FIG. 19 shows the distribution of the working area of the agricultural work vehicle in particular, with the load torque required for the work machine vehicle on the vertical axis and the traveling speed (speed) required at that time on the horizontal axis. In particular, in the working range where the traveling speed is in the forward range, especially in the range of several km / h to 10 km / h,
It can be seen that the main working speed range of many working machine vehicles is concentrated.

In this work area, in a vehicle equipped with the conventional HST continuously variable transmission, forward traveling and reverse traveling are performed mainly when the output rotational speed is zero. Referring to FIG. 18, when the vehicle speed is centered on 0 km / h,
In the case of the HST, the HST sub 1 (1) can cover only a few km / h at most in the case of forward running, and eventually switches to the HST sub 2 (2). However, in the range (several km / h to 10 km / h) shown in FIG. 18 due to the shift switching of the HST sub 2 (2), the HST sub 2 (2) must be used in a state where the total efficiency is lower than 0.8. Will not be. That is, it is not a preferable use state from the viewpoint of overall efficiency.

On the premise that such total efficiency is low and that the circulation of hydraulic oil is always required to obtain the output rotational speed, the solution is to use the HST or the NUT shown in FIG. Although it is conceivable to increase the overall capacity of the pump and the motor of the stepped transmission (indicated by (4) in FIG. 18), there is a problem that the entire continuously variable transmission also becomes large.

Also, in the continuously variable transmission shown in FIG. 16, as shown in FIG. 18, in the range of several km / h to 10 km / h, the total efficiency is lower than 0.5 to 0.7. ,
It has to be used, which is not a preferable use state from the viewpoint of overall efficiency.

An object of the present invention is to directly connect an input side and an output side of a hydraulic continuously variable transmission via a second hydraulic device when a discharge amount from a variable displacement first hydraulic device is zero. Accordingly, it is possible to obtain a wide range of continuously variable transmissions in both the speed-up and the deceleration centering on the direct connection, and therefore, it is an object of the present invention to provide a hydraulic continuously variable transmission with high overall efficiency in a work area. .

It is another object of the present invention to provide a hydraulic stepless transmission having an input side and an output side via a variable displacement type differential hydraulic device when the discharge amount from the variable displacement type hydraulic device is zero. With the direct connection, it is possible to obtain a wide range of continuously variable transmissions for both speed increase and deceleration centering on the direct connection, and to provide a transmission for a work machine vehicle with high overall efficiency in a work area. I have.

[0023]

According to a first aspect of the present invention, there is provided a first plunger having a first plunger and a plunger contact portion, the first plunger being protruded and inserted by the contact portion. A first hydraulic device of a variable displacement type, and a second hydraulic device provided with a second plunger, and provided with an output rotation unit that performs either relative or synchronous rotation with respect to the input rotation by abutment of the second plunger. Combination, a cylinder block for accommodating both plungers is shared, the cylinder block is configured to rotate around an axis by input rotation, and a first plunger hole and a second plunger hole are provided in the cylinder block. Is stored in the first plunger hole to form a first plunger chamber, and the second plunger is stored in the second plunger hole to form a second plunger chamber.
A hydraulic closed circuit for circulating hydraulic oil between the plunger chamber and the second plunger chamber is provided, and a first oil chamber and a second oil chamber are provided in the circuit.
The plunger chamber has a section communicating with the first oil chamber and a section communicating with the second oil chamber, and the second plunger chamber is connected to the first oil chamber while the output rotation unit makes one rotation around the axis with respect to the cylinder block. A hydraulic continuously variable transmission having a section communicating with the chamber and a section communicating with the second oil chamber, wherein the stroke volume of the first hydraulic device is greater than the stroke volume of the second hydraulic device. The gist of the present invention is a hydraulic continuously variable transmission provided with:

In the present specification, the first plunger chamber refers to a space formed by a plunger of the first hydraulic device and a plunger hole of a cylinder block that houses the plunger. The second plunger chamber refers to a space formed by a plunger of the second hydraulic device and a plunger hole of a cylinder block that houses the plungers.

Further, the first oil chamber is composed of the first plunger chamber and the second plunger chamber.
The second oil chamber refers to an oil chamber that exchanges hydraulic oil with the plunger chamber, and the second oil chamber is a separate oil chamber from the first plunger chamber and the first oil chamber that exchanges hydraulic oil with the second plunger chamber. The hydraulic closed circuit includes a first plunger chamber, a first oil chamber, a second plunger chamber,
It includes at least four oil chambers of the second oil chamber, and refers to a hydraulic oil circulation path formed by these oil chambers and the like.

The stroke volume of the first hydraulic device is determined during one rotation of the cylinder block around the axis (during one stroke).
It refers to the amount of hydraulic oil that the plunger chamber of the first hydraulic device exchanges with the first oil chamber and the second oil chamber. The stroke volume of the second hydraulic device is
The amount of hydraulic oil that the plunger chamber of the second hydraulic device exchanges with the first oil chamber and the second oil chamber while the output rotation unit makes one rotation around the axis with respect to the cylinder block (during one stroke). .

According to a second aspect of the present invention, in the hydraulic continuously variable transmission according to the first aspect, the first plunger chamber communicates with the first oil chamber while the cylinder block makes one rotation around the axis. The section in which the second plunger chamber communicates with the first oil chamber while the output rotation unit makes one rotation around the axis with respect to the cylinder block is reduced.

According to a third aspect of the present invention, in the hydraulic stepless transmission according to the first aspect, a section in which the first plunger chamber communicates with the second oil chamber while the cylinder block makes one rotation around the axis. In comparison, while the output rotation unit makes one rotation around the axis with respect to the cylinder block, the second plunger chamber is in the second position.
The section communicating with the oil chamber is reduced.

According to a fourth aspect of the present invention, in the hydraulic continuously variable transmission according to the second aspect, a first distribution valve is provided, and a first application member for reciprocating the first distribution valve is provided. Imparts axial reciprocation to the distribution valve while the cylinder block makes one rotation around the axis. The first reciprocating motion of the distribution valve causes the first plunger chamber to move into the first oil chamber and the second oil chamber. A second distributing valve, a second imparting member for imparting reciprocating motion to the second distributing valve, and the output rotating portion makes one rotation about the axis with respect to the cylinder block. A reciprocating motion in the axial direction is applied to the distributing valve therebetween, so that the second plunger chamber communicates with the first oil chamber and the second oil chamber by the reciprocating motion in the axial direction of the distributing valve. Is displaced in the axial direction and is held at the displaced position.

The invention according to claim 5 is the invention according to claims 1 to 4.
The transmission of a working machine vehicle using any of the hydraulic stepless transmissions described in the above, wherein the rotation speed of the output rotating unit when the hydraulic oil does not circulate through the hydraulic closed circuit is the main working speed of the working machine vehicle. The present invention is directed to a transmission for a working machine vehicle, which is configured to be included in a region.

(Operation) According to the first aspect of the present invention,
A cylinder block of the first hydraulic device and the second hydraulic device is shared, and a closed hydraulic circuit in which hydraulic oil circulates between the first hydraulic device and the second hydraulic device is formed in the cylinder block.
In addition, the input block rotates the cylinder block about its axis.

Since the first hydraulic device is of a variable displacement type, the plunger contact portion may not give the first plunger a projecting action. That is, when the hydraulic oil does not circulate in the hydraulic closed circuit, the plunger of the second hydraulic device is in contact with the output rotating unit without performing a stroke operation. Therefore, the output rotation unit rotates integrally with the cylinder block. At this time, since the rotation (number) of the cylinder block is the same as the input rotation (number), the output rotation unit rotates synchronously with the input rotation.

In the case where the plunger abutting portion gives a projecting action to the first plunger of the first hydraulic device, the hydraulic oil in the first plunger chamber is rotated while the cylinder block makes one rotation around the axis. Circulates through a closed hydraulic circuit. When hydraulic oil is sucked into the second plunger chamber of the second hydraulic device during this circulation, the second plunger protrudes with the hydraulic oil and imparts rotation to the output rotary unit.

In the range where the stroke volume of the first hydraulic device exceeds the stroke volume of the second hydraulic device, the output rotating section is given a higher rotational speed than the input rotation by the second plunger of the second hydraulic device. If the rotation provided by the output rotation unit is in the same direction as the input rotation, the present apparatus obtains a rotation exceeding the double speed of the input rotation as the output rotation.

When the rotation given to the output rotation unit is in the opposite direction to the input rotation, the present device can obtain a rotation in the opposite direction to the input rotation as the output rotation. According to the second aspect of the present invention, while the output rotation unit makes one rotation around the axis with respect to the cylinder block, the second plunger chamber is in the first position.
The section communicating with the oil chamber is made smaller than the section where the first plunger chamber communicates with the first oil chamber. Thus, in the hydraulic continuously variable transmission, the stroke volume of the second hydraulic device is smaller than the stroke volume of the first hydraulic device 100.

Accordingly, compared with the amount of hydraulic oil that the first hydraulic device transfers to and from the first oil chamber during one stroke, the operation that the second hydraulic device transfers to and from the first oil chamber during one stroke. The amount of oil decreases. As a result, the protrusion of the second plunger of the second hydraulic device during one stroke is accelerated, and the output rotation unit rotates accordingly.

According to the third aspect of the present invention, the section in which the second plunger chamber communicates with the second oil chamber while the output rotating section makes one rotation around the axis with respect to the cylinder block is defined by the cylinder block. The first plunger chamber is smaller than a section in which the first plunger chamber communicates with the second oil chamber during one rotation around the axis.
Thus, in the hydraulic continuously variable transmission, the stroke volume of the second hydraulic device is smaller than the stroke volume of the first hydraulic device 100.

As a result, the operation of the second hydraulic device to and from the second oil chamber during one stroke is compared with the amount of hydraulic oil to and from the second hydraulic chamber during one stroke by the first hydraulic device. The amount of oil decreases. As a result, the protrusion of the second plunger of the second hydraulic device during one stroke is accelerated, and the output rotation unit rotates accordingly.

According to the fourth aspect of the present invention, the first imparting member imparts axial reciprocation to the first distribution valve while the cylinder block makes one rotation around the axis, and the first imparting member is provided with the first distribution member. The first plunger chamber communicates with the first oil chamber and the second oil chamber by reciprocation in the axial direction.

On the other hand, while the output rotation unit makes one rotation around the axis with respect to the cylinder block, the second application member provides the second rotation.
An axial reciprocation is applied to the distribution valve, and the second plunger chamber communicates with the first oil chamber and the second oil chamber by the axial reciprocation of the distribution valve. The second applying member is displaced in the axial direction and is held at the displaced position.

According to the invention set forth in claim 5, according to claim 1,
The hydraulic continuously variable transmission according to any one of claims 4 to 4, wherein the hydraulic continuously variable transmission is employed in a transmission of a work equipment vehicle, and a rotation speed of an output rotation unit when the hydraulic oil does not circulate in a hydraulic closed circuit is adjusted to a work equipment. Be included in the main working speed range of the vehicle. As a result, the operation described in any one of claims 1 to 4 is obtained in the transmission of the work implement vehicle.

[0042]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a hydraulic continuously variable transmission used as a working machine for traveling of an agricultural work machine vehicle will be described in detail with reference to FIGS. explain.

FIG. 1 is a sectional view of a hydraulic continuously variable transmission (hereinafter referred to as a continuously variable transmission) T, and is a sectional view taken along line EE of FIG. FIG. 2 is a sectional view of a principal part of the continuously variable transmission T on the first hydraulic device side, FIG. 3 is a sectional view of a principal part of the continuously variable transmission T also on the second hydraulic device side, and FIG. A section view,
FIG. 5 is a sectional view taken along line BB of FIG.

As shown in FIG. 1, the continuously variable transmission T is housed in a case 11 of a power unit of an agricultural work machine vehicle. The continuously variable transmission T includes a first hydraulic device 100 and a second hydraulic device 200 that forms a closed hydraulic circuit between the first hydraulic device 100 and the first hydraulic device 100.

The input shaft 12 of the continuously variable transmission T is connected to the crankshaft of the engine EG as shown in FIG. 9, and an output gear 39 connected to a yoke 37, which is an output side, is connected to a final reduction gear (not shown). The input gear 10 is engaged with the input gear 10.

The first hydraulic device 100 corresponds to a variable displacement type hydraulic device, and the second hydraulic device 200 corresponds to a differential hydraulic device. One end of the input shaft 12 of the continuously variable transmission T is rotatably supported via a bearing portion 14 on a support plate 13 provided on the case 11, and the other end is provided on a side wall of the case 11 via a radial bearing 15. And is rotatably supported by a PTO shaft. A holder 16 is fixed to an inner surface of the support plate 13. The support plate 13 and the holder 16 have through holes 13 through which the input shaft 12 passes.
a, 16a are formed, and the diameter of the opposite part of the through holes 13a, 16a is increased to form a bearing housing hole 18.

In the bearing housing hole 18, the input shaft 1
2 is supported by a conical roller bearing 19. A sleeve 20 having a large-diameter portion 20a and a small-diameter portion 20b is inserted through the input shaft 12 adjacent to the conical roller bearing 19, and the small-diameter portion 20b is formed on the inner ring 19b of the conical roller bearing 19.
Is inserted inside. Then, by tightening the nut 21 screwed to the input shaft 12 from the outside to the inside (to the right in FIG. 1), the outer ring 19 a of the conical roller bearing 19 is inserted into the bearing storage hole 18 through the sleeve 20. Of the through hole 16a and the inner peripheral surface of the enlarged diameter portion of the through hole 13a. The end surface of the small diameter portion 20 b of the sleeve 20 is abutted and locked to a locking ring 22 engaged with the peripheral surface of the input shaft 12. A seal member 23 is disposed at the small diameter portion of the through hole 13a.

The bearing section 14 comprises a conical roller bearing 19, a sleeve 20 and a nut 21. First
The hydraulic device 100 includes an input shaft 12 and a cylinder block 2 integrally connected to the input shaft 12 by press-fitting.
4. A cradle 27 including a plurality of plungers 34 slidably disposed on the cylinder block 24 and a swash plate surface 26 that comes into contact with the plungers 34.
The cradle 27 is supported on the back side of the holder 16 and the input shaft 12 is penetrated therethrough. In FIGS. 1 and 2, the cradle 27 and the holder 16 are illustrated separately for convenience of explanation.

The swash plate surface 26 corresponds to the plunger contact portion of the variable displacement type first hydraulic device of the present invention. Further, the plunger 34 corresponds to a first plunger. As shown in FIG. 2, the opposing surface E where the cradle 27 and the holder 16 contact each other
Reference numerals 1 and E2 each have a semi-cylindrical surface centered on a trunnion axis TR1 orthogonal to the axis O of the cylinder block 24. As a result, the cradle 27 moves to the trunnion axis TR1.
It is possible to tilt around. Here, assuming lines α, β, γ that are orthogonal to the swash plate surface 26 and pass through the trunnion axis TR1, these lines α, β, γ (hereinafter, referred to as
The angle formed by the axis O and α, β, γ) is θ. Β coincides with the axis O.

In FIG. 1 and FIG. 2, the swash plate surface 26 is shown with the aforementioned α, β, and γ according to the position thereof. β is a position when the swash plate surface 26 is located at the upright position. Α and γ are opposite to each other when the swash plate surface 26 is in the upright position (positive in the clockwise direction and negative in the counterclockwise direction in FIGS. 1 and 2). This is the position of the maximum tilt angle tilted at the same angle θ in the direction.

In this embodiment, the output rotation speed Nout shown in FIG.
= NE, tilts to the negative side when Nout> NE as shown in FIGS. 1 and 2, and tilts to the positive side when Nout <NE. Note that the swash plate surface 26 shown in FIGS. 1 and 2 is in a state of being tilted at the maximum tilt angle when located at the α position.

In the following description, the α, β, and γ positions are referred to as a negative maximum tilt angle position, an upright position, and a positive maximum tilt angle position on the swash plate surface 26, respectively. The cylinder block 24 has a plurality of cylinder holes 33 around its rotation center.
Are arranged in a ring shape and extend parallel to the axis O. The cylinder hole 33 has an opening formed on the holder 16 side. A plunger 34 is slidably disposed in each cylinder hole 33. In this embodiment, the cylinder hole 3
The space formed by the plunger 34 and the cylinder hole 33 housed in 3 corresponds to the first plunger chamber R1. A steel ball 34a is rotatably fitted to the tip of the plunger 34, and the plunger 34 includes the steel ball 34a and the steel ball 34.
a is in contact with the swash plate surface 26 via a shoe 35 to which a is attached. The swash plate surface 26 in the inclined state is
The plunger 34 is reciprocated with the rotation of
The function of the discharge stroke is given.

The cylinder hole 33 corresponds to a first plunger hole. The second hydraulic device 200 includes a plurality of plungers 4 slidably disposed on the cylinder block 24.
4 and a cylindrical yoke 37 having a rotating swash plate surface 36 that comes into contact with the plunger 44. A boss plate 4 is provided at the end of the input shaft 12 on the second hydraulic device 200 side.
0 is rotatably supported via a bearing 38. The boss plate 40 is formed in a substantially disk shape. An output gear 39 is fixed to the boss portion 40a of the boss plate 40.

The plunger 44 corresponds to a second plunger, and the yoke 37 corresponds to an output rotating unit. The yoke 37 is connected and fixed to the boss plate 40 by bolts 41. The rotating swash plate surface 36 is provided on a side surface of the yoke 37 facing the cylinder block 24. The rotation swash plate surface 36 is constant with respect to the axis O about the trunnion axis TR2 when a trunnion axis TR2 orthogonal to the axis O of the cylinder block 24 and a plane (virtual plane) including the trunnion axis TR2 are imagined. It is formed so as to be parallel to the virtual plane inclined at an angle.

The output gear 3 on the inner peripheral surface of the yoke 37
On the 9th side, an enlarged diameter portion 37a is formed.
Inside, the input shaft 12 is supported by a conical roller bearing 29. By tightening the nut 31 screwed to the input shaft 12 from the output gear 39 side to the cylinder block 24 side, the outer ring 29a of the conical roller bearing 29 is in contact with the step bottom surface of the enlarged diameter portion 37a. The inner ring 29b of the conical roller bearing 29 is abutted and locked on a locking ring 32 engaged with the peripheral groove 12a of the input shaft 12.

In the cylinder block 24, the same number of cylinder holes 43 as the cylinder holes 33 are arranged annularly around the center of rotation, and extend in parallel with the axis O. The cylinder hole 43 corresponds to a second plunger hole. The cylinder hole 43 is concentric with the pitch circle of the cylinder hole 33 and is arranged on a pitch circle having a diameter larger than the pitch circle. The cylinder block 2 is positioned so that each cylinder hole 43 is located between the cylinder holes 33 adjacent to each other.
In the circumferential direction of No. 4, the cylinder hole 33 is シ リ ン ダ of each other.
They are arranged shifted by a pitch (see FIGS. 4 and 5).

When hydraulic fluid flows into the cylinder holes 33 and 43 and pushes the plungers 34 and 44 of the first hydraulic device 100 and the second hydraulic device 200 in the axial direction, the thrust force is reduced to the swash plate surface 26 and the rotation. Working on the swash plate surface 36,
A radial component force acts on the rotary swash plate surface 36 in addition to the thrust direction. The swash plate surface 26 and the rotary swash plate surface 36 are the same conical roller bearing 1 as a radial / thrust load shared bearing.
It is supported by the input shaft 12 via 9, 29. For this reason, the input shaft 12 is pulled by the thrust load and bent by the radial load. However, since the thrust load and the radial load are absorbed only by the deformation of the input shaft 12, the vibration is not transmitted to the case 11, so that the noise caused by the vibration of the surface of the case 11 can be reduced.

Further, the cylinder hole 43 is
As shown in FIG. 1, they are arranged so as to overlap each other in the length direction (the direction of the axis O of the cylinder block 24), and an opening is formed on the yoke 37 side. A plunger 44 is slidably disposed in each cylinder hole 43, and a steel ball 44a is rotatably fitted to the tip of the plunger 44.

In the present embodiment, the space formed by the plunger 44 housed in the cylinder hole 43 and the cylinder hole 43 corresponds to the second plunger chamber R2. Plunger 4
4 is in contact with the rotating swash plate surface 36 via a steel ball 44a and a shoe 45 to which the steel ball 44a is attached. The plunger 44 reciprocates with the relative rotation between the rotary swash plate surface 36 and the cylinder block 24, and repeats the suction and discharge strokes.

The first hydraulic device 100 and the second hydraulic device 2
A hydraulic closed circuit formed between the hydraulic circuit and the hydraulic circuit will be described. On the inner peripheral surface at both axial ends of the cylinder block 24,
Both have a first inner oil chamber 51 and a second inner oil chamber 52 that are annular. Further, annular first outer oil chambers 53 and second outer oil chambers 54 are formed near both ends in the axial direction of the cylinder block 24, respectively. The first inner oil chamber 51 and the first outer oil chamber 53 have a plurality of radially extending oil paths 55, and the second inner oil chamber 52 and the second outer oil chamber 54 have a plurality of radially extending oil paths. It is communicated via 56.

The first outer oil chamber 53 corresponds to a first oil chamber, and the second outer oil chamber 54 corresponds to a second oil chamber. The cylinder block 24 includes the first outer oil chamber 53 and the second outer oil chamber 5.
Four first valve holes 57 communicating with each other extend in the axial direction of the cylinder block 24 in the same number as the number of the cylinder holes 33. A second valve hole 5 communicating the first outer oil chamber 53 and the second outer oil chamber 54 together with the cylinder block 24.
8 are the same number as the cylinder holes 43 and the cylinder block 24
Extending along the axial direction of Each of the first valve holes 57 and each of the second valve holes 58 are arranged so as to be adjacent to each other as shown in FIGS.

Each first valve hole 57 has a port U of an oil passage 59 communicating with the corresponding cylinder hole 33 between the first outer oil chamber 53 and the second outer oil chamber 54.
A spool-type first switching valve 60 is slidably disposed in each first valve hole 57. As shown in FIGS. 1 and 2, one end of the first switching valve 60 is pressed against a cam surface 62 of a cam 61 formed on the outer periphery of the holder 16 by the urging force of a coil spring 63 wound around the periphery thereof. Is always in contact. The first switching valve 60 corresponds to a first distribution valve, and includes a cam 61.
Corresponds to the first applying member.

FIG. 11 shows a cam profile of the cam 61. As shown in FIG. 11, the cam surface 62 of the cam 61 is connected to the port U and the port U with the first switching valve 60 centered on the port closing position n0. It reciprocates between a first opening position n1 for communicating with the first outside oil chamber 53 and a second opening position n2 for communicating between the port U and the second outside oil chamber. Cam surface 62
, The first switching valve 60 is connected to the first opening position n1 and the second
The part to be located at the opening position n2 is located on a pair of virtual planes perpendicular to the axis O of the cylinder block 24 and parallel to each other so that the stroke of the first switching valve 60 does not change in that region. . Also, the cam surface 62 has a slope so that the first switching valve 60 moves between the first opening position n1 and the second opening position n2.

Then, by the cam action of the cam 61,
The first hydraulic device 100 includes a region H as shown in FIG.
An area I is provided. In the region H, as the cylinder block 24 rotates, the first switching valve 60 is moved to the first opening position n.
1 is a section in which the cylinder hole 33, that is, the first plunger chamber R1 communicates with the first outer oil chamber 53 via the port U.

In the region I, the first switching valve 60 is moved to the second opening position n2 with the rotation of the cylinder block 24, and the cylinder hole 33, that is, the first plunger chamber R1 is moved through the port U. Is a section communicating with the second outside oil chamber 54.

When the swash plate surface 26 is displaced from the upright position to the negative maximum tilt angle position, the stroke volume of the first hydraulic device 100 at this time is from 0 to VMmax in FIG.
(Maximum stroke volume), and accordingly, when the input rotation speed of the input shaft 12 is NE, the output rotation speed Nout (the output gear 39)
In this embodiment, the discharge amount of the hydraulic oil on the first hydraulic device 100 side is set so that the speed is increased from NE to 2NE.

In this embodiment, when the swash plate surface 26 is tilted to the negative side as shown in FIG. 1 or FIG. 2, the rotation angle around the axis of the cylinder block 24 shown in FIG.
In the range of 80 °, the cylinder hole 33, that is, the first
Hydraulic oil is sucked into the plunger chamber R1 via the port U. In the range of 180 ° to 360 ° (0 °), hydraulic oil is discharged from the cylinder hole 33, that is, from the first plunger chamber R1 via the port U.

On the other hand, when the swash plate surface 26 is tilted to the positive side, the cylinder hole 33 extends from the cylinder hole 33 within the range of 0 ° to 180 °.
That is, hydraulic oil is discharged from the first plunger chamber R1 via the port U. In the range of 180 ° to 360 ° (0 °), hydraulic oil is sucked into the cylinder hole 33, that is, into the first plunger chamber R1 via the port U. The discharge oil chamber and the suction oil chamber are determined by regions H and I corresponding to the rotation angle range.

In each second valve hole 58, a port W of an oil passage 69 communicating with the corresponding cylinder hole 43 is formed between the first outside oil chamber 53 and the second outside oil chamber 54.
In each second valve hole 58, a spool-type second switching valve 70 is slidably disposed so as to be parallel to the plunger 44. The second switching valve 70 corresponds to a second distribution valve. One end of the second switching valve 70 has a cylindrical cam 7 provided on the outer periphery of the yoke 37 by the urging force of a coil spring 73 wound around the periphery thereof as shown in FIGS.
It is always in contact with one cam surface 72. The cam 71 corresponds to a valve operating mechanism and a contact member, and the cam 71 corresponds to a second applying member.

The cam 71 is slidably fitted to the outer peripheral surface of the yoke 37 in the direction of the axis O of the cylinder block 24. A pair of keys 74 are integrally fixed to the yoke 37 at positions opposite to each other by 180 degrees so as to extend along the direction of the axis O of the cylinder block 24. And cam 7
1 is a key 74 provided with a pair of guide grooves 75 provided on its inner peripheral surface.
Is slidably fitted in the direction of the axis O of the cylinder block 24, and the yoke 37 is
Is not allowed to rotate in the circumferential direction. As a result, the cam 71 can rotate integrally with the yoke 37 about the axis O.

The inner diameter of the cam 71 is made smaller than the outer diameter of the boss plate 40, and the cam 71 can be locked to the boss plate 40. That is, the locking position between the cam 71 and the boss plate 40 is set to the first displacement position Q1 of the cam 71 where the further movement to the output gear 39 side is disabled.

As shown in FIG. 6A, a displacement applying member 76 is rotatably supported on the output gear side end surface of the cam 71 with respect to the case 11. The displacement applying member 76 includes a contact member 77 that can contact the end face of the cam 71 on the output gear side, and a worm gear 78 that is integrally connected to the contact member 77 via a shaft 78a. The contact member 77 is shown in FIG.
As shown in FIG. 7, the worm gear 78 is composed of a pair of arms 79 and 80 with the shaft 78a at the center, and by rotating the worm gear 78 clockwise or counterclockwise,
One of the arms 79 and 80 can be brought into contact with the end face of the cam 71 on the output gear side.

In this embodiment, when the worm gear 78 rotates clockwise in FIG.
0 abuts on the output gear side end surface of the cam 71, and the reference position Q
The cam 71 located at 0 is moved to the second displacement position Q2. In FIG. 6B, the cam 71 is located at the reference position Q0.
The arm 79 that is positioned rotates counterclockwise,
The cam 71 located at the reference position Q0 is moved to the first displacement position Q1.

A worm shaft 81 rotatably supported by the case 11 is meshed with the worm gear 78. The worm shaft 81 is operatively connected to an actuator (not shown). When the actuator is in the neutral position and is not operated, the contact member 77 contacts the cam 71 to position the cam 71 at the reference position Q0. The amount of rotation of the worm gear 78, that is, the amount of movement between the reference position Q0 and the first displacement position Q1, and the amount of movement between the reference position Q0 and the second displacement position Q2 are determined by the forward and reverse rotation of the actuator and the amount of rotation. Has been determined.

The worm gear 78 and the worm shaft 81 constitute a holding mechanism. The actuator, the worm shaft 81, the worm gear 78, and the contact member 77 constitute a variable mechanism.

FIG. 11 shows a cam profile of the cam 71. In FIG. 11, the relative position between the cam surface 62 and the cam surface 72 changes because the cam 71 rotates together with the yoke 37, but they are shown together for convenience of explanation.

Then, the yoke 37 is connected to the cylinder block 2.
The region J and the region K are imparted to the second hydraulic device 200 by the cam action of the cam 71 due to the relative rotation with the region 4.

The area J is the second area displaced by the cam surface 72.
This is a section where the cylinder hole 43 communicates with the second outside oil chamber 54 via the port W by the switching valve 70. Also, the area K
Means that the cylinder hole 43 has the second plunger chamber R
A section 2 communicates with the first outside oil chamber 53 via the port W.

For example, as shown in FIG. 1 or FIG.
Is tilted to the negative side, the cylinder hole 43 in the range of 0 ° to 180 ° relative to the cam 71 (when located at the reference position Q0) shown in FIG. That is, the second plunger chamber R2
Hydraulic oil is sucked through the port W.

In this case, 180 ° to 360 °
In the range of (0 °), from the cylinder hole 43, that is,
Hydraulic oil is discharged from the second plunger chamber R2 via the port W. Conversely, when the swash plate surface 26 is tilted forward,
In the range of 0 ° to 180 °, hydraulic oil is discharged from the cylinder hole 43, that is, from the second plunger chamber R2 via the port W. In the range of 180 ° to 360 ° (0 °), the cylinder plunger 43 is moved to the cylinder hole 43.
Hydraulic oil is sucked into port 2 through port W. The oil chamber to be discharged and the oil chamber to be sucked are determined by regions J and K corresponding to the rotation angle range.

FIG. 12 shows the cam 71 and the cylinder when the second switching valve 70 is switched by the cam action of the cam 71 and the port W communicates with the first outer oil chamber 53 and the second outer oil chamber 54, respectively. The relative rotation angle range of the block 24 is shown. FIG. 13 shows the cam 71 and the cylinder block 2.
4 is a characteristic diagram of the present embodiment showing the relationship between the relative rotation angle of the fourth and the opening area of the port W opened by the second switching valve 70 when communicating with the first outside oil chamber 53 or the second outside oil chamber 54. It is. The plus (+) side indicates the opening area when communicating with the first outer oil chamber 53, and the minus (-) side indicates the opening area when communicating with the second outer oil chamber 54.

(When Located at Reference Position Q0) Cam 71
Are located at the reference position Q0, that is, in FIG. 10, when 0 ≦ Nout ≦ 2NE, FIGS.
As shown in the figure, the port W is communicated with the second outer oil chamber 54 from 0 ° to 180 °, and is communicated with the first outer oil chamber 53 from 180 ° to 360 ° (0 °).

In the present embodiment, when located at the reference position Q0, the opening sections of the port W when communicating with the first outer oil chamber 53 and when communicating with the second outer oil chamber 54 are the same as each other. The cam surface 72 is set so as to be as follows.

When the cam 71 is located on the first displacement position Q1 side, that is, when 2NE <Nout in FIG. 10, FIG. 12 and FIG. As shown in FIG. 13, the port W, that is, the second plunger chamber R2 is communicated with the second outer oil chamber 54 up to several degrees to 150 degrees, and the first plunger chamber R2 is up to 150 degrees to several degrees.
It communicates with the outer oil chamber 53. That is, in the region J, the cam surface 72 of the cam 71 is set so that the region (opening section) is narrower than when the cam 71 is located at the reference position Q0, and conversely, the region K is widened.

As described above, by changing the regions J and K, the section (region J) communicating with the second outside oil chamber 54 in one stroke of the second hydraulic device 200 becomes one of the first hydraulic device 100. It becomes smaller than a section (region I) communicating with the second outer oil chamber 54 in the stroke. That is, the region I (section) where the first plunger chamber R1 communicates with the second outer oil chamber 54 while the cylinder block 24 makes one rotation around the axis.
While the yoke 37 makes one rotation around the axis with respect to the cylinder block 24, the area J (section) where the second plunger chamber R2 communicates with the second outer oil chamber 54 becomes smaller.

Accordingly, compared with the amount of hydraulic oil that the first hydraulic device 100 transfers to and from the second outer oil chamber 54 during one stroke, the second hydraulic device 200 Room 5
The distribution of the areas J and K is set so that the amount of hydraulic oil exchanged with the number 4 becomes smaller and finally becomes 0.5 VMmax with respect to VMmax at the position of Q1.

(When Positioned at Second Displacement Positions Q0 to Q2) When the cam 71 is located on the second displacement position Q2 side,
In the case of so-called reverse travel, in FIG. 10, if Nout <0, as shown in FIGS. 12 and 13, the port W, that is, the second plunger chamber R2 is filled with the second outer oil from 340 degrees to 240 degrees. Communicated with room 54, 240 degrees to 340
The fluid is communicated to the first outer oil chamber 53 up to several degrees.

As described above, by changing the regions J and K, the section (region K) communicating with the first outside oil chamber 53 in one stroke of the second hydraulic device 200 becomes one of the first hydraulic device 100. It becomes smaller than a section (area H) communicating with the first outer oil chamber 53 in the stroke. That is, a section (area H) in which the first plunger chamber R1 communicates with the first outer oil chamber 53 while the cylinder block 24 makes one rotation around the axis.
The section (region K) where the second plunger chamber R2 communicates with the first outer oil chamber 53 while the yoke 37 makes one rotation around the axis with respect to the cylinder block 24 becomes smaller.

Accordingly, compared with the amount of hydraulic oil that the first hydraulic device 100 exchanges with the first outer oil chamber 53 during one stroke, the second hydraulic device 200 sets the first outer oil during one stroke. Room 5
The distribution of the areas J and K is set so that the amount of hydraulic oil exchanged with 3 becomes smaller and finally becomes 0.5 VMmax with respect to VMmax at the position of Q2.

In this embodiment, the cylinder hole 33, the cylinder hole 43, the first outer oil chamber 53, the second outer oil chamber 54, the first
The valve hole 57, the second valve hole 58, the oil passage 59, the oil passage 69, the port U and the port W form a closed hydraulic circuit.

The first outer oil chamber 53 and the second outer oil chamber 54
4, 5, and 7, communication passages 82 and 83 are formed along the axis O of the cylinder block 24. As shown in FIG. A relief valve 85 for opening and closing a valve seat 84 provided on the first outer oil chamber 53 side is provided in the communication passage 82, and the valve seat 84 is closed by a coil spring 86 provided in the communication passage 82. I have. When the hydraulic pressure of the operating oil in the first outer oil chamber 53 is higher than the spring pressure of the coil spring 86, the relief valve 85 opens the valve seat 84 to open the first outer oil chamber 53 and the second outer oil chamber. Communication is made between 54.

A relief valve 88 for opening and closing a valve seat 87 provided in the second outer oil chamber 54 is provided in the communication passage 83, and the valve seat 87 is closed by a coil spring 89 provided in the communication passage 83. are doing. When the hydraulic pressure of the operating oil in the second outer oil chamber 54 is higher than the spring pressure of the coil spring 89, the relief valve 88 opens the valve seat 87 and the second
The outside oil chamber 54 communicates with the first outside oil chamber 53.

A shaft hole 90 is formed in the input shaft 12 along the axis O in order to charge the hydraulic closed circuit with hydraulic oil. The shaft hole 90 is formed in the large diameter portion 20 a of the sleeve 20.
, An introduction oil passage 91 is provided in the radial direction, and the introduction oil passage 91 is an oil passage 92 formed in the large diameter portion 20a in the radial direction and a circumferential groove formed on the outer peripheral surface of the large diameter portion 20a. 93. The support plate 13 is provided with an oil passage 94 communicating with the circumferential groove 93, and the oil passage 94 is filled with hydraulic oil from a charge pump (not shown).

In the input shaft 12, a pair of charge valves 95 (check valves) for opening and closing a valve seat that can communicate with the shaft hole 90 is provided at a portion facing the first inner oil chamber 51 and the second inner oil chamber 52. Is arranged. The charge valve 95 opens until the hydraulic pressure of the hydraulic closed circuit reaches the charge pressure in the shaft hole 90, and supplies the hydraulic oil in the shaft hole 90 to the hydraulic closed circuit. or,
The charge valve 95 prevents the hydraulic oil from flowing back to the shaft hole 90.

(Operation) The operation of the continuously variable transmission T configured as described above will be described. For convenience of explanation,
The description will be made assuming that the input rotation speed NE given from the crankshaft of the engine EG to the input shaft 12 is constant.

(When the output rotational speed Nout is NE) When the shift lever 97 shown in FIG. 8 is operated to a position near the middle in the F region, the swash plate surface 26 is positioned through the cradle 27 to the upright position.

In this state, the cam 71 is in contact with the arm 79 of the contact member 77, and the cam surface 72 at this time is located at the reference position Q0 shown in FIG. In this state, the cylinder block 24 rotates in the forward direction by the driving force of the engine EG via the input shaft 12 at NE, but
The swash plate surface 26 is in a neutral position in an upright position with respect to the axis O of the input shaft 12. The plunger 34 of the first hydraulic device 100 is not reciprocated by the swash plate surface 26. Therefore, in this state, the operating oil does not circulate in the hydraulic closed circuit. Therefore, on the second hydraulic device 200 side, the protruding end of each plunger 44 abuts on the rotary swash plate surface 36 via the shoe 45 in a state where the plunger 44 cannot perform the stroke movement. 36 is directly connected, and rotates integrally. That is, this state is caused by the input shaft 12 and the output gear 3
9 is directly connected. The forward rotation given to the rotating swash plate surface 36 is transmitted to the final reduction gear via the yoke 37, the boss plate 40, the output gear 39, and the input gear 10.

When the swash plate surface 26 is located at the upright position, the stroke volume of the first hydraulic device 100 becomes zero as shown in FIG. 10, and the output rotational speed Nout (the rotational speed of the output gear 39). Is the input rotational speed NE.

In this embodiment, the output speed N
out (the rotation speed of the output gear 39) includes the same rotation speed as the input rotation speed NE, that is, before and after including when the input shaft 12 of the continuously variable transmission T and the output gear 39 are directly connected. The range is set to the main working speed range of this agricultural work machine vehicle. For example, as shown in FIG. 19, when the agricultural working machine vehicle of this embodiment is a cultivator, the traveling speed is several km / h to 8 km.
/ H is the running speed range of the main working speed range,
Within this traveling speed range, the output rotation speed Nout (the rotation speed of the output gear 39) is set to NE so that the direct connection state is established. In the present embodiment, the main working speed range is 3 km / h to 8 km / h.

(When the output rotational speed Nout is between NE and 2NE) When the shift lever 97 shown in FIG. , The swash plate surface 26 is tilted to the negative side as shown in FIGS. 1 and 2 to be positioned in a region between the negative maximum tilt angle position and the upright position.

In this case, the cylinder block 24 rotates at NE through the input shaft 12 by the driving force of the engine EG. Then, in the region I of the first hydraulic device 100, the operating oil flows from the cylinder hole 33 through the port U to the second outer oil chamber 54.
Is discharged to

Then, in the region H, the operating oil is sucked from the first outer oil chamber 53 into the cylinder hole 33 through the port U. The amount of hydraulic oil circulating through the closed hydraulic circuit is determined by the swash plate surface 2.
6 increases as the tilt angle in the negative direction increases.

The hydraulic oil discharged into the second outer oil chamber 54 is
Via the port W, it is sucked into the cylinder hole 43 in the range of 0 ° to 180 °. On the other hand, 180 ° to 360 ° (0
The working oil is discharged (discharged) from the cylinder hole 43 in the range of (°).

As a result, the rotational speed NE at which the cylinder block 24 is driven via the input shaft 12 and the second hydraulic device 2
00 and the number of rotations in the forward direction by the pressing action of the plunger 44 against the rotating swash plate surface 36, the rotation swash plate surface 36
Is rotated. The forward rotation imparted to the rotating swash plate surface 36 is transmitted as a forward rotation to the final reduction gear via the yoke 37, the boss plate 40, the output gear 39, and the input gear 10, thereby increasing the speed. .

At this time, when the swash plate surface 26 is displaced from the upright position to the negative maximum tilt angle position, the first
The stroke volume of the hydraulic device 100 increases from 0 to VMmax (maximum stroke volume), and accordingly, the output rotation speed Nout becomes NE.
From 2 to NE.

The output rotation speed Nout is changed from NE to 2NE.
, The stroke volume of the second hydraulic device 200 remains at the maximum stroke volume VMmax. (When the output rotation speed Nout exceeds 2 NE) When it is desired to increase the forward speed, that is, when the shift lever 97 shown in FIG. Through the swash plate surface 26
At the maximum negative tilt angle position.

At this time, the stroke volume VP of the first hydraulic device 100 remains at the maximum stroke volume VMmax. Then, an actuator (not shown) is operated to move the cam 71 located at the reference position Q0 between the reference position Q0 and the first displacement position Q1.

For example, when the cam 71 is located at the first displacement position Q1, as shown in FIG. 12 and FIG.
A few degrees to 150 ° communicate with the second outer oil chamber 54,
From 50 ° to several degrees, it is communicated with the first outer oil chamber 53. That is, the area J (area) is smaller in the area J than when the cam 71 is located at the reference position Q0.

Therefore, compared to the section in which the first hydraulic device 100 communicates with the second outer oil chamber 54 during one stroke, the second hydraulic device 200 communicates with the second outer oil chamber 54 during one stroke. The communicating section becomes smaller. Accordingly, the first hydraulic device 10
The amount of hydraulic oil that the second hydraulic device 200 transfers to and from the second outer oil chamber 54 during one stroke is smaller than the amount of hydraulic oil that is transferred to and from the second outer oil chamber 54 during one stroke. . For this reason, the first hydraulic device 100 is operated during one stroke by the second outer oil chamber 5.
4 and the amount of hydraulic oil sucked from the second outside oil chamber 54 by the second hydraulic device 200 during one stroke until the first hydraulic device 100 completes one stroke. Then, the number of strokes of the second hydraulic device 200 increases.

As a result, the second hydraulic device 200 gives the rotation swash plate surface 36 a rotation speed higher than NE. Therefore,
The output rotation speed Nout is larger than 2NE due to the sum of NE and the applied rotation speed of the second hydraulic device 200.

The rotational torque applied to the rotary swash plate surface 36 is transmitted to the final reduction gear via the yoke 37, the boss plate 40, the output gear 39, and the input gear 10. At this time, in FIG. 10, the stroke volume of the first hydraulic device 100 is a fixed amount of VMmax (maximum stroke volume) as described above.
The stroke volume of the second hydraulic device 200 is 0.5 VMm from VMmax.
changes to ax. As a result, the output rotation speed Nout is 2 NE
From 3 to NE.

(In the case where the output rotation speed Nout is between 0 and NE) When the shift lever 97 shown in FIG.
When the swash plate surface 26 is operated to the N position side from the intermediate position, the swash plate surface 26 is tilted to the positive side via the cradle 27 to be positioned in a region between the positive maximum tilt angle position and the upright position.

In this case, since the swash plate surface 26 tilts in the forward direction, when the cylinder block 24 rotates via the input shaft 12 by the driving force of the engine EG, the first hydraulic device 10
At 0, the hydraulic oil is discharged from the cylinder hole 33 to the first outer oil chamber 53 via the oil passage 59 and the port U in a region H shown in FIG.

In the region I, hydraulic oil is sucked from the second outer oil chamber 54 into the cylinder hole 33 via the port U and the oil passage 59. The amount of hydraulic oil circulating in the hydraulic closed circuit increases as the tilt angle of the swash plate surface 26 in the positive direction increases.

On the other hand, in the second hydraulic device 200, the hydraulic oil discharged to the first outside oil chamber 53 is received in the cylinder hole 43 through the port W. The hydraulic oil from the cylinder hole 43 in the range of 0 ° to 180 ° is supplied to the second outer oil chamber 54.
Is discharged to

As a result, the projecting and pressing action of the plunger 44 of the second hydraulic device 200 against the rotary swash plate surface 36 causes the output rotation speed Nout to be in a direction opposite to that in the case where the output rotation speed Nout is between NE and 2NE and exceeds 2NE. Give rotation. Therefore, the yoke 37, the boss plate 40, and the output gear 3 are determined by the sum of the rotational speed in the reverse direction and the rotational speed in the forward direction of the cylinder block 24.
9 is rotated. Since the sum of the rotation speeds at this time is the rotation speed in the forward direction reduced by the rotation speed in the reverse direction, the output rotation speed Nout is smaller than “when the output rotation speed Nout is NE”.

In this embodiment, at this time, when the swash plate surface 26 is displaced from the upright position to the positive maximum tilt angle position side,
In FIG. 10, the stroke volume of the first hydraulic device 100 is from 0 to −VMmax (the “−” indicates the port U to the first outer oil chamber 53).
Is discharged. ), And the output rotational speed Nout is accordingly reduced from NE to 0.

Note that the output rotation speed Nout at this time is NE
, The stroke volume per rotation of the second hydraulic device 200 at the time of the change from 0 to 0 remains at −VMmax. (The "-" means that the oil is sucked from the first outer oil chamber 53 through the port W.) (When the output speed Nout is 0)
When the swash plate 7 is operated to the N position, the swash plate surface 26 is positioned at the maximum positive tilt angle position via the cradle 27.

In this case, in the present embodiment, the first hydraulic device 1
The stroke volume of 00 is fixed at -VMmax. As a result, the rotational speed in the opposite direction and the cylinder block 24
And the number of revolutions NE driven via the motor 2 is balanced, that is, the sum of the number of revolutions is 0 (the output number of revolutions Nout is 0),
The output gear 39 stops.

Next, when it is desired to move backward, that is, when the shift lever 97 shown in FIG. 8 is operated to the R region, the swash plate surface 26 is positively moved via the cradle 27. Position at the maximum tilt angle position. At this time, the stroke volume of the first hydraulic device 100 is fixed at -VMmax. Then, the cam 71 located at the reference position Q0 is moved between the reference position Q0 and the second displacement position Q2.

For example, when the cam 71 is located at the second displacement position Q2, as shown in FIG. 12 and FIG.
From 340 degrees to 240 degrees is communicated with the second outside oil chamber 54, and from 240 degrees to 340 degrees is the first outside oil chamber 53.
Is communicated to. That is, contrary to the case where the distance exceeds 2 NE, the area J is wider and the area K is narrower in the area J than when the cam 71 is located at the reference position Q0.

Therefore, compared to the section in which the first hydraulic device 100 communicates with the first outer oil chamber 53 during one stroke, the second hydraulic device 200 communicates with the first outer oil chamber 53 during one stroke. The communicating section becomes smaller. Accordingly, the first hydraulic device 10
The amount of hydraulic oil that the second hydraulic device 200 transfers to and from the first outer oil chamber 53 during one stroke is smaller than the amount of hydraulic oil that is transferred to and from the first outer oil chamber 53 during one stroke. . For this reason, the first hydraulic device 100 operates the first outer oil chamber 5 during one stroke.
3 and the second hydraulic device 200 corresponds to the ratio of the amount of hydraulic oil suctioned from the first outer oil chamber 53 during one stroke by the first hydraulic device 100 until the first hydraulic device 100 completes one stroke. Then, the number of strokes of the second hydraulic device 200 increases.

As a result, the second hydraulic device 200 gives the rotation swash plate surface 36 a rotation speed greater than -NE. Therefore, the output rotation speed Nout becomes smaller than 0 due to the sum of NE and the applied rotation speed of the second hydraulic device 200.

The rotational torque in the reverse direction is applied to the yoke 37,
The power is transmitted to the final reduction gear via the boss plate 40, the output gear 39, and the input gear 10. In this embodiment, at this time, in FIG. 10, the stroke volume of the first hydraulic device 100 is -VMmax of a fixed amount as described above, while the stroke volume of the second hydraulic device 200 is -VMmax to -0. It is set to change to 0.5 VMmax. In addition, the output rotational speed Nout increases in the reverse direction from 0 accordingly.

According to the present embodiment, the following effects can be obtained. (1) The continuously variable transmission according to the present embodiment includes a first hydraulic device 1
00 and the cylinder block 24 of the second hydraulic device 200, forming a closed hydraulic circuit in which hydraulic oil circulates between the first hydraulic device 100 and the second hydraulic device 200 in the cylinder block 24. It is configured to be driven to rotate.

As a result, even if the hydraulic oil does not circulate in the hydraulic closed circuit, the driving force from the engine EG is applied to the second hydraulic device 20.
0 is transmitted to the rotating swash plate surface 36. That is, the input shaft 12 (input side) of the continuously variable transmission T and the output gear 39 (output side) are directly connected. Focusing on this direct connection state,
A wide range of continuously variable transmission including both the speed increasing side and the decelerating side can be obtained.

Therefore, the shift lever 97
By lever operation, high operability can be obtained in which forward or backward switching can be performed, and a wide shift range can be covered from the highest speed of forward movement to the highest speed of reverse movement.

[0128] By setting the second hydraulic device 200 to have a variable capacity, the speed change range can be extended to a forward high-speed range and a reverse range, and a gear mechanism (reverser) for switching between forward and backward can be omitted.

(2) In the present embodiment, the first hydraulic device 1
00 is a swash plate surface 26 having a range of maximum positive and negative tilt angles.
It operates according to the displacement of the tilt angle. Further, when the swash plate surface 26 forms the maximum positive and negative tilt angles, the second hydraulic device 200 operates the first outer oil chamber 53 or the second outer oil chamber 5 in one rotation of the cylinder block as shown in FIGS.
Since the section communicating with 4 can be narrowed, its stroke volume can be made relatively small with respect to the stroke volume of the first hydraulic device 100.

When the stroke volume of the second hydraulic device 200 is smaller than the stroke volume of the first hydraulic device 100, the reciprocating speed of the plunger 44 increases. For this reason,
By the protruding pressing action of the plunger 44 of the second hydraulic device 200, the rotation swash plate surface 36 is given a rotation larger than NE or -NE. It is possible to obtain a lower reverse range.

(3) In this embodiment, the continuously variable transmission is a continuously variable transmission used for traveling of the agricultural work vehicle. As a result, the operation and effect (1) or (2) can be achieved when the agricultural work machine vehicle travels.

(4) In the present embodiment, the first hydraulic device 1
The shift range when the hydraulic oil discharge amount of 00 was 0 was set within the main working speed range of the working machine. That is, the output rotation speed Nout
(The rotation speed of the output gear 39) includes the same rotation speed as the input rotation speed NE, that is, the range before and after including the case where the input shaft 12 of the continuously variable transmission T and the output gear 39 are directly connected. Was set in the main working speed region of this agricultural work machine vehicle.
As shown in FIG. 19, when the agricultural working machine vehicle of the present embodiment is a cultivator, the traveling speed is set to be several km / h to 8 km / h as the traveling speed range of the main working speed range. The output rotation speed N is set so as to be in the directly connected state.
out (the number of revolutions of the output gear 39) was set to NE. As a result, in the main working speed range, the hydraulic oil does not flow through the hydraulic closed circuit, so that oil leakage in the hydraulic closed circuit is suppressed, transmission efficiency is increased, and energy loss in the main working speed range can be reduced. Very efficient agricultural work can be performed.

FIG. 18 shows the characteristics of the relationship between the total efficiency (total transmission efficiency) and the vehicle speed in the case of this embodiment (indicated by (5) in FIG. 18). As shown in the figure, in the case of the present embodiment, it can be seen that the total efficiency is extremely high compared with the other conventional HST sub-first, sub-second, and sub-third shifts. . In particular, in the main operation speed region, the overall efficiency is also high, and it can be seen that efficient operation can be obtained.

(5) In the present embodiment, the second hydraulic device 2
00 denotes a plurality of cylinder holes 4 in the cylinder block 24.
3 (second plunger hole), and a rotating swash plate surface 36 which is operated by the plungers 44 and rotates relative to or synchronously with respect to the cylinder block 24.
A second switching valve 70 (valve) group for controlling suction and discharge of hydraulic oil to and from each cylinder hole 43; and a cam 71 that operates the second switching valve 70 group in accordance with the rotation of the cylinder block 24.
(Valve operating mechanism). Further, the cam 71 is provided with a worm shaft 81, a worm gear 78, and an abutment body 77 (variable mechanism), and the operation of the variable mechanism allows the second hydraulic device 200 to move the first outside oil chamber during one stroke. The section communicating with 53 or the second outer oil chamber 54 is changed.

As a result, the stroke capacity of the second hydraulic device 200 is changed by the operation of the variable mechanism, and the capacity can be changed. (6) In the present embodiment, the second switching valve 70 is a timing spool provided in parallel with each plunger 44, the cam 71 rotates integrally with the rotary swash plate surface 36, and the axis of the cylinder block 24. The timing cam is arranged so as to be freely displaceable along. As a result, the cam 71
The cylinder block 24 rotates integrally with the rotating swash plate surface 36.
Along the axis of. The second switching valve 70 includes a cam 71
As a result, the suction and discharge timing of the second switching valve 70 can be changed.

(7) In the present embodiment, the cam 71 is positioned at the reference position Q in the axial direction of the cylinder block 24.
A worm gear 78 for holding the cam 71 at the displaced position, and a worm shaft 81 (holding mechanism) are provided so as to be freely displaceable between the position 0, the first displacement position Q1, and the second displacement position Q2.

For this reason, the cam 71 is particularly positioned at the first displacement position Q.
If it is located at any one of the first and second displacement positions Q2, it can be held at that position. A stable cam action can be imparted to the second switching valve 70 at each position of the cam 71.

At the first displacement position Q1, the boss plate 40 functions as a stopper. Therefore, even at the first displacement position Q1, a stable cam action can be provided to the second switching valve 70.

Note that the above embodiment may be modified as follows. 1) In both of the above embodiments, the main working speed range is a running speed of several km / h to 8 km / h, but the main working speed range is not limited to this running speed range. In the case of agricultural work equipment vehicles other than cultivators, for example, tractors, subsoilers, disk mowers, etc., since there is a main work speed range according to the work equipment vehicle, the direct connection state of the input side and output side of the continuously variable transmission is changed. If the setting is made in accordance with the main operation speed range, the operation can be performed with high efficiency.

2) Stroke volume VP of first hydraulic device 100
Has a range exceeding the maximum stroke volume VMmax of the second hydraulic device 200, and achieves a forward high-speed range exceeding 2NE and a reverse range below 0 by the second hydraulic device 200.
Instead of changing the stroke volume of the second hydraulic device 200 from VMmax to 0.5 VMmax, the stroke volume of the second hydraulic device 200 may be kept constant at VMmax, and VP may be changed to a range exceeding VMmax.

In this case, specifically, the second hydraulic device 20
0 than the tilt angle of the rotating swash plate surface 36 of the first hydraulic device 10.
The swash plate 26 has a range in which the tilt angle of the swash plate surface 26 becomes large. In this case, in the second hydraulic device 200,
The variable mechanism and the holding mechanism of the cam 71 become unnecessary.

Also in this case, the stroke volume of the second hydraulic device can be made smaller than the stroke volume of the first hydraulic device 100.
Further, the stroke capacity of the first hydraulic device and the stroke volume of the second hydraulic device can be made equal, and the effect of claim 1 can be obtained.

Furthermore, the first hydraulic device 100 or
At least one of the second hydraulic devices 200 is
Alternatively, the plunger 44 may be of a radial type that protrudes in the radial direction.

[0144]

As described in detail above, in the hydraulic stepless transmission according to the first aspect, when the discharge amount from the variable displacement type first hydraulic device is 0, the hydraulic continuously variable transmission is connected via the second hydraulic device. By directly connecting the input side and output side of the hydraulic continuously variable transmission,
A wide range of continuously variable transmission can be obtained for both speed increase and deceleration centering on this direct connection. Therefore, a hydraulic continuously variable transmission with high overall efficiency in the work area is obtained.

That is, even when the hydraulic oil does not circulate in the hydraulic closed circuit, the input rotation can be transmitted to the output rotation unit. Further, by circulating the hydraulic oil through the hydraulic closed circuit, the present device can change the rotation speed before and after the input rotation as a base point.

In the range where the stroke volume of the first hydraulic device exceeds the stroke volume of the second hydraulic device, the output rotating section is given a higher rotational speed than the input rotation by the second plunger of the second hydraulic device. When the rotation given to the output rotation unit is in the same direction as the input rotation, the present device can obtain a rotation exceeding the input rotation as the output rotation.
Further, when the rotation given to the output rotation unit is in the opposite direction to the input rotation, the present device can obtain a rotation in the opposite direction to the input rotation as the output rotation.

In the hydraulic stepless transmission according to the second and third aspects, the stroke volume of the second hydraulic device is reduced by the first hydraulic device 1.
The stroke capacity of the first hydraulic device and the stroke volume of the second hydraulic device can be made equal to each other, and the effect of claim 1 can be obtained.

The hydraulic stepless transmission according to claim 4 is
The stroke volume of the second hydraulic device can be made smaller than the stroke volume of the first hydraulic device only by displacing the second applying member in the axial direction.

In the transmission for a working machine vehicle according to the fifth aspect, the output rotation can be obtained in the speed range without the hydraulic oil circulating through the hydraulic closed circuit. And the work efficiency of the work equipment vehicle can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a continuously variable transmission according to an embodiment of the present invention, and is a cross-sectional view taken along line EE of FIG.

FIG. 2 is a sectional view of a main part of the continuously variable transmission on a first hydraulic device side.

FIG. 3 is a sectional view of a principal part of the continuously variable transmission on the side of a second hydraulic device.

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is a sectional view taken along line AA of FIG. 1;

6A is a cross-sectional view taken along the line CC of FIG. 1, and FIG. 6B is an explanatory view showing an operation of a contact portion.

FIG. 7 is a sectional view taken along line DD of FIG. 4;

FIG. 8 is a plan view of a shifter.

FIG. 9 is a conceptual diagram of a continuously variable transmission according to the embodiment.

FIG. 10 is a characteristic diagram similarly showing a stroke volume and an output rotation speed of the hydraulic device.

FIG. 11 is an explanatory view showing the cam action of the cams 61 and 71.

FIG. 12 is an explanatory diagram showing a timing at which a motor port is opened by a cam action.

FIG. 13 is an explanatory diagram showing a change in an opening area of a motor port with respect to a rotation angle of a cam 71.

FIG. 14 is a conceptual diagram of a continuously variable transmission including a conventional HST.

FIG. 15 is a characteristic diagram similarly showing a pump / motor stroke volume and an output rotation speed.

FIG. 16 is a conceptual diagram of another conventional hydraulic continuously variable transmission.

FIG. 17 is a characteristic diagram similarly showing a pump / motor stroke capacity and an output rotation speed.

FIG. 18 is a characteristic diagram showing a relationship between vehicle speed and overall efficiency.

FIG. 19 is a distribution diagram showing a relationship between vehicle speed and load torque of various work vehicles.

[Explanation of symbols]

R1 ... first plunger room, R2 ... second plunger room, 2
4 ... Cylinder block, 26 ... Swash plate surface (plunger contact portion), 33 ... Cylinder hole (1st plunger hole), 34 ...
Plunger (first plunger), 36: rotating swash plate surface (rotating swash plate), 37: yoke (output rotating part), 43: cylinder hole (second plunger hole), 44: plunger (second plunger), 53 ... First outer oil chamber (first oil chamber), 54 ...
2nd outside oil chamber (2nd oil chamber), 60 ... 1st switching valve (1st distribution valve), 61 ... cam (1st provision member), 70 ... 2nd switching valve (valve and 2nd distribution valve), 71: cam (valve operating mechanism, abutting member and second applying member), 81: worm shaft (holding mechanism together with worm gear 78, worm shaft 8)
1. A variable mechanism is configured together with the worm gear 78, the contact body 77, and the actuator. ), 100: first hydraulic device, 200: second hydraulic device.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hiroshi Matsuyama 1-32 Chayacho, Kita-ku, Osaka, Osaka Prefecture Inside Yanmar Diesel Co., Ltd. (72) Norihiko Sakamoto 1-32 Chayacho, Kita-ku, Osaka, Osaka Yanmar Diesel Co., Ltd. (72) Inventor Goro Nozaki 1-32, Chayacho, Kita-ku, Osaka, Osaka Yanmar Diesel Co., Ltd. (72) Yukio Kubota 1-32, Chayacho, Kita-ku, Osaka, Japan Yanmaー Agricultural Machinery Co., Ltd.

Claims (5)

[Claims] 1. A variable displacement type first hydraulic device comprising a first plunger and a plunger contact portion, wherein the first plunger projects and retreats by the contact portion, and a second plunger.
Combination with a second hydraulic device provided with an output rotating unit that performs either relative rotation or synchronous rotation with respect to input rotation by abutment of a second plunger, sharing a cylinder block for housing both plungers, Is configured to rotate around an axis by an input rotation, a first plunger hole and a second plunger hole are provided in the same cylinder block, and the first plunger is housed in the first plunger hole to form a first plunger chamber, The second plunger is housed in the second plunger hole to form a second plunger chamber, and a hydraulic closed circuit for circulating hydraulic oil between the first plunger chamber and the second plunger chamber is provided. A second oil chamber is provided, and the first plunger chamber has a section communicating with the first oil chamber and a section communicating with the second oil chamber while the cylinder block makes one rotation around the axis. A hydraulic continuously variable transmission configured to have a section in which the second plunger chamber communicates with the first oil chamber and a section in which the second plunger chamber communicates with the first oil chamber during one rotation around the axis with respect to the cylinder block. A hydraulic continuously variable transmission having a configuration in which the stroke volume of the first hydraulic device exceeds the stroke volume of the second hydraulic device. 2. The hydraulic continuously variable transmission according to claim 1, wherein the first plunger chamber communicates with the first oil chamber while the cylinder block makes one rotation around the axis.
A hydraulic continuously variable transmission, wherein a section in which the second plunger chamber communicates with the first oil chamber is reduced while the output rotation unit makes one rotation around the axis with respect to the cylinder block. 3. The hydraulic continuously variable transmission according to claim 2, wherein the output of the first plunger chamber is smaller than that of a section in which the first plunger chamber communicates with the second oil chamber while the cylinder block makes one rotation around the axis. A hydraulic continuously variable transmission, wherein a section in which the second plunger chamber communicates with the second oil chamber is reduced while the rotating portion makes one rotation around the axis with respect to the cylinder block. 4. The hydraulic continuously variable transmission according to claim 2, further comprising a first distribution valve, a first provision member for reciprocating the first distribution valve, While the cylinder block makes one rotation around the axis, reciprocation in the axial direction is applied to the distribution valve, and the first plunger chamber becomes the first oil chamber and the second oil chamber by the axial reciprocation of the distribution valve. A second distributing valve, a second imparting member for imparting reciprocating motion to the second distributing valve, and the second distributing valve is connected to the cylinder block while the output rotating unit makes one rotation about the axis with respect to the cylinder block. And the second plunger chamber communicates with the first oil chamber and the second oil chamber by the axial reciprocation of the distribution valve. A continuously variable hydraulic transmission characterized by being displaced in the axial direction and held at the displaced position. Place. 5. A transmission for a working machine vehicle using the hydraulic continuously variable transmission according to claim 1, wherein the hydraulic oil is not circulated in a hydraulic closed circuit. A transmission for a work implement vehicle, wherein the rotation speed of the output rotation unit is included in a main work speed range of the work implement vehicle.