WO2002006704A1

WO2002006704A1 - Hydraulic continuously variable transmission and working machine vehicle

Info

Publication number: WO2002006704A1
Application number: PCT/JP2001/005215
Authority: WO
Inventors: Shuji Shiozaki; Takeshi Oouchida; Hiroshi Matsuyama; Kunihiko Sakamoto; Takeaki Nozaki; Yukio Kubota
Original assignee: Yanmar Diesel Engine Co., Ltd.
Priority date: 2000-07-14
Filing date: 2001-06-19
Publication date: 2002-01-24
Also published as: AU2001274547A1

Abstract

A hydraulic continuously variable transmission, wherein a first hydraulic device of variable displacement type operates first plungers by a plunger contact part, the output rotating part of a second hydraulic device performs a relative or a synchronous rotation relative to an input rotation by the contact thereof with second plungers, a cylinder block is rotated about the axis thereof, the first plunger chamber of the cylinder block is formed by storing the first plungers in first plunger holes and the second plunger chamber of the cylinder block is formed by storing the second plungers in second plunger holes, a closed hydraulic circuit having first and second oil chambers circulates hydraulic oil between the first and second plunger chambers, the areas where the first plunger chamber communicates with the first oil chamber and the second oil chamber while the cylinder block is rotated one turn about the axis thereof are provided and the areas where the second plunger chamber communicates with the first oil chamber and the second oil chamber while the output rotating part is rotated one turn relative to the cylinder block about the axis thereof are provided, and the stroke volume of the first hydraulic device has a range exceeding the stroke volume of the second hydraulic device.

Description

Specification

Hydraulic continuously variable transmission and work equipment vehicle

The present invention relates to a hydraulic continuously variable transmission that can be widely used for various machines such as industrial machines and vehicles, and a work implement vehicle equipped with the transmission. Background art

Conventionally, as a continuously variable transmission using a fluid pump and a motor, a hydraulic transmission

(HST) is known. However, although this device is excellent in continuously variable transmission, it is known that it is not always good in terms of transmission efficiency, and the applicable speed range is not satisfactory. The reason for the lower transmission efficiency is that the hydraulic pump (fluid pump) and the hydraulic motor (fluid motor) are generally provided separately in the HST, and the driving force is transmitted only through the flow of hydraulic oil. This is because the oil leakage from the valve plate and the sliding torque in each mechanism increase. FIG. 14 shows a conventional example in which HST is used as a continuously variable transmission. The variable displacement hydraulic pump P1 and the fixed displacement hydraulic motor Ml constituting the HST form a closed hydraulic circuit. That is, the hydraulic oil discharged from the hydraulic pump P 1 is sent to the hydraulic motor Ml, and after the hydraulic motor Ml is operated by the pressure of the hydraulic oil, the hydraulic oil is again supplied to the hydraulic pump P 1 via the hydraulic closed circuit. Have been back to one. The output shaft of the engine EG is connected to the hydraulic pump P1. An auxiliary transmission mechanism F1 is provided between the output shaft of the hydraulic motor Ml and a final reduction gear (not shown). As shown in FIG. 14, the sub-transmission mechanism F 1 includes gear trains G 1, G 2, G 3 for the first speed sub-speed, the second speed sub-speed and the third speed sub-speed, and is not shown. The shift lever allows manual shifting. FIG. 15 shows the relationship between the stroke volume of the variable displacement hydraulic pump P1 in the continuously variable transmission of FIG. 14 and the output rotation speed Nout per unit time on the output shaft of the auxiliary transmission mechanism F1. FIG. Here, the stroke volume refers to the amount of hydraulic oil exchanged per rotation of the hydraulic pump P1. According to this characteristic diagram, when the stroke volume of the hydraulic pump P1 changes from VMmax to one VMmax, the output rotation speed shown in FIG. Note that the output rotation speed Nout is a boundary of 0, which means that the + side indicates forward running and the one side indicates reverse running. In addition, + and-of the stroke volume mean the flow direction of the hydraulic oil in the hydraulic closed circuit. VMmax indicates the maximum stroke volume. In addition to the HST, a conventional hydraulic continuously variable transmission shown in FIG. 16 is also known. This device includes a variable displacement hydraulic pump P2 and a variable displacement hydraulic motor M2. The hydraulic pump P2 and the hydraulic motor M2 form a closed hydraulic circuit. That is, the hydraulic oil discharged from the hydraulic pump P 2 is pumped to the hydraulic motor M 2, and after the hydraulic motor M 2 is operated by the hydraulic oil, the hydraulic oil is again supplied to the hydraulic pump P 2 via the hydraulic closed circuit. The two have been to go back. The output shaft of the engine EG is connected to the hydraulic pump P2, and a reduction mechanism Ga is provided between the output shaft of the hydraulic motor M2 and a final reduction device (not shown). In this device, forward / backward switching can be performed by operating a shift lever (not shown). Fig. 17 shows the stroke volume per 1 'rotation of the hydraulic pump P2 and the hydraulic motor M2 in the continuously variable transmission shown in Fig. 16 and the output rotation speed Nmrt per unit time on the output shaft of the reduction mechanism Ga. FIG. 4 is a characteristic diagram showing a relationship between According to this characteristic diagram, when the output rotation speed Nout is 0, the stroke volume VP of the hydraulic pump P2 is 0, and the stroke volume of the hydraulic motor M2 is V Mmax (constant). See dashed line). In this case, since VP = 0, no hydraulic oil is discharged, and thus the rotational force is not transmitted from the continuously variable transmission to the output shaft, and therefore, the output rotational speed Nout becomes zero. When the output rotation speed Nout is between 0 and NE, the stroke volume VP of the hydraulic pump P 2 changes linearly from 0 to VMmax as shown by the solid line in FIG. 17, while the hydraulic motor M 2 Is constant at VMmax. Similarly, when the output rotation speed Nout is between 0 and 1 NE, the stroke capacity of the hydraulic pump P 2 changes linearly from 0 to 1 VMmax, while the stroke volume VM of the hydraulic motor M 2 is 1 VMmax Is constant. Therefore, when the output rotation speed Nout is from -NE to NE, the oil amount (per rotation) discharged by the hydraulic pump P2 is the oil amount discharged (returned) by the hydraulic motor M2 (per rotation). Or) equal to VM. Therefore, the output shaft speed (output rotation speed) increases in proportion to the discharge oil amount VP of the hydraulic pump P2. Further, when the output rotation speed Nout is between NE and 2 NE, the stroke capacity of the hydraulic pump P2 is fixed at VMmax, while the stroke capacity of the hydraulic motor M2 changes linearly from VMmax to 0.5 VMmax. are doing. Similarly, when the output rotation speed Nout is between −NE and 12 NE, the stroke volume of the hydraulic pump P 2 is fixed at one VMmax, while the stroke volume of the hydraulic motor M 2 is one VMmax force, It changes linearly to 0.5 VMmax. In this case, assuming that the rotation speed of the hydraulic pump P2 is NP and the rotation speed of the hydraulic motor M2 is NM, the following equation is established.

NP X VMmax = NMX 0-5 VMmax

Therefore,

NM = 2NP

And the variable displacement hydraulic motor M2 rotates twice as fast as the variable displacement hydraulic pump P2.

When the stroke volume of the pump P2 is changed as shown in FIG. 17, output rotational speeds from 12NE to 2NE are obtained. Next, 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, each speed stage, that is, 1st speed sub speed (HST ^ (1) in the figure), 2nd speed speed (HS in the diagram) The best value of the total efficiency is about 0.8 due to oil leakage even at the shift of the T-sub 2 (2)) and the 3-speed sub-gear (HST sub 3 (3) in the figure). On the other hand, in the continuously variable transmission shown in Fig. 16 (see (4) in Fig. 18), the best value of the total efficiency is about 0.8 due to the same oil leakage. As described above, in the hydraulic continuously variable transmission shown in FIGS. 14 and 16, it is necessary to circulate the hydraulic oil in the hydraulic closed circuit as shown in FIGS. 15 and 17 in order to obtain a predetermined output speed. This results in oil leaks and reduced efficiency. In addition, since the output rotation speed is obtained only by circulating the hydraulic oil, when high-speed rotation is required, a large amount of oil is inevitably required, resulting in an increase in the size of the device. In addition, the conventional device has a problem that only about 0.8 can be obtained as the best value of the total efficiency. Furthermore, when the continuously variable transmission composed of the HST shown in Fig. 14 and the continuously variable transmission shown in Fig. 16 are mounted on a work implement vehicle such as a tractor or loader, originally, the work implement However, the high-speed running area is not the main working area, and the main working speed area is the running area as shown in Figure 19. Fig. 19 shows the distribution of the working area of agricultural work equipment vehicles, the vertical axis represents the load torque required for the work equipment vehicles, and the horizontal axis represents the traveling speed (speed). It can be seen that the main working speed range of many work equipment vehicles is concentrated in the working range where the traveling speed is in the forward range and about 2 km / h to 10 kmZh. In such a work area, a vehicle equipped with a conventional continuously variable transmission consisting of HST force performs forward traveling and reverse traveling with the output rotational speed being zero. Referring to Fig. 18, when the vehicle speed is centered on 0 km / h, in the case of HST, HST ^ U (1) can only cover up to 2-4 kmZh at the time of forward running, and eventually HST sub 2 The shift is switched to (2). In the area shown in Fig. 18 (approximately 2 kmZh to 10 km / h), the HST sub 2 (2) shift switching causes the device to operate in a state where the overall efficiency is lower than 0.8. Will have to be used. In other words, it is not a preferable use condition from the viewpoint of overall efficiency. In order to solve such a problem regarding the overall efficiency, it is necessary to increase the overall capacity of the pump and motor of the HST shown in Fig. 14 and the continuously variable transmission shown in Fig. 16 (see (4) in Fig. 18). it is also conceivable to, but if the problems force ^s that increasing the size I spoon even entire continuously variable transmission. Also, in the continuously variable transmission shown in Fig. 16 (see (4) in Fig. 18), as shown in Fig. 18, in the range of approximately 2 kmZh to 10 km / h, the total efficiency is 0. It is inevitable to use it in a state lower than 0.5 to 0.7, which is not a preferable use state from the viewpoint of overall efficiency. An object of the present invention is to, when the discharge amount of hydraulic oil from a first hydraulic device of a variable displacement type is zero, connect an input side and an output side of a hydraulic continuously variable transmission via a second hydraulic device. By the direct connection, it is possible to obtain a wide range of continuously variable transmissions in both the low speed and the deceleration centering on the direct connection. Transmission is provided. Further, another object of the present invention is to provide an output of the hydraulic continuously variable transmission through a variable displacement differential hydraulic device when the discharge amount of hydraulic oil from the variable displacement hydraulic device is zero. By directly connecting to the side, it is possible to obtain a wide range of continuously variable transmissions for both speed increase and deceleration centering on this direct connection, and to provide a transmission system for work equipment vehicles with high overall efficiency in the work area. That is to say. Disclosure of the invention

In order to solve the above-mentioned problem, a hydraulic continuously variable transmission according to a first aspect of the present invention includes a first plunger and a plunger contact portion, and a variable plunger that operates the first plunger by the contact portion. A capacity-type first hydraulic device and a second hydraulic device having a second plunger and having an output rotating portion that performs relative or synchronous rotation with respect to input rotation by contact with the second plunger. Have. Also, the continuously variable transmission has a cylinder block, The latch hook is configured to rotate around an axis by input rotation, and stores the first and second plungers, respectively. The cylinder block has a first plunger hole and a second plunger hole. The first plunger chamber is formed by storing the first plunger in the first plunger hole. The second plunger chamber is formed by housing the second plunger in the second plunger hole. The continuously variable transmission has a hydraulic closed circuit, the closed circuit includes a first oil chamber and a second oil chamber, and circulates hydraulic oil between the first plunger chamber and the second plunger chamber. While the cylinder block makes one rotation about the axis, a section in which the first plunger chamber communicates with the first oil chamber and a section in which the first plunger chamber communicates with the second oil chamber are respectively set, and the output rotating section is formed. A section in which the second plunger chamber communicates with the first oil chamber and a section in which it communicates with the second oil chamber during one rotation around the axis with respect to the cylinder block are respectively set. There is a range in which the stroke volume of the first hydraulic device exceeds the stroke volume of the second hydraulic device. 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 for storing the plunger. Further, 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 plunger. The first oil chamber is an oil chamber that exchanges hydraulic oil with the first and second plunger chambers, and the second oil chamber is a second oil chamber that exchanges hydraulic oil with the first plunger chamber and the second plunger chamber. One oil chamber is a separate oil chamber. The hydraulic closed circuit includes at least four oil chambers including a first plunger chamber, a first oil chamber, a second plunger chamber, and a second oil chamber, and circulates hydraulic oil formed by these oil chambers and the like. Means road. The stroke volume of the first hydraulic device means that the plunger chamber of the first hydraulic device is in the first oil chamber and the second oil chamber during one rotation of the cylinder block around the axis (during one stroke). Means the amount of hydraulic oil that is transferred. The stroke volume of the second hydraulic device means that the plunger chamber of the second hydraulic device has the first hydraulic chamber and the second hydraulic chamber during one rotation of the output rotating part around the axis with respect to the cylinder block (during one stroke). The amount of hydraulic oil exchanged with the oil chamber. Since the first hydraulic device is a variable displacement type, the plunger contact portion may not act on the first plunger. 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 rotary 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. Also, when the plunger contact portion acts on the first plunger of the first hydraulic device, the hydraulic oil in the first plunger chamber circulates in the hydraulic closed circuit while the cylinder block makes one rotation around the axis. I do. When hydraulic oil is sucked into the second plunger chamber of the second hydraulic device during this circulation, the second plunger is operated by the hydraulic oil, and imparts rotation to the output rotary unit. Then, in a 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 rotation speed higher than the input rotation by the second plunger of the second hydraulic device. Therefore, 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 double speed of 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. During the rotation of the cylinder block by one rotation around the axis, compared with the section in which the first plunger chamber communicates with the first oil chamber, the output rotating section has one rotation around the axis with respect to the cylinder block. It is desirable that the section where the second plunger chamber communicates with the first oil chamber during rotation becomes smaller. In this case, the stroke volume of the second hydraulic device becomes smaller than the stroke volume of the first hydraulic device. Accordingly, the amount of hydraulic oil that the second hydraulic device transfers to and from the first oil chamber during one stroke is smaller than the amount of hydraulic oil that the first hydraulic device transfers to and from the first oil chamber during one stroke. Become. As a result, the operation of the second plunger of the second hydraulic device during one stroke becomes faster, and the output rotation unit rotates accordingly. It is preferable that the continuously variable transmission further includes a first distribution valve and a first application member that imparts reciprocating motion to the first distribution valve. The first applying member applies reciprocating motion in the axial direction to the first distribution valve while the cylinder block rotates once around the axis, and performs the first reciprocating motion in accordance with the axial reciprocation of the first distribution valve. One plunger chamber communicates with the first oil chamber and the second oil chamber. The continuously variable transmission preferably further includes a second distribution valve and a second imparting member that imparts reciprocating motion to the second distribution valve. The force S is desirably used. On the other hand, reciprocation in the axial direction is applied to the second distribution valve during one rotation around the axis, and the second plunger chamber becomes the first oil chamber and the second oil chamber according to the reciprocation of the second distribution valve in the axial direction. Communicates with the second oil chamber. The first distributing valve is reciprocally supported by the cylinder block along the axial direction of the cylinder block, and the first applying member is arranged so as to face the first end of the cylinder block. It is desirable to include a first cam disposed around the axis of the first cam. The second distribution valve is reciprocally supported by the cylinder block along the axial direction of the cylinder block, and the second applying member is blocked by the cylinder so as to face the second end of the cylinder block. It is desirable to include a second cam disposed around the axis of the second cam. It is preferable that the second applying member is displaceable in the axial direction of the cylinder block, and is capable of being held at a displaced position. Preferably, the second cam is displaceable in the axial direction of the cylinder block, and is capable of being held at a displaced position. The above-described hydraulic continuously variable transmission is applicable to a working machine vehicle. In this case, it is desirable that the rotation speed of the output rotation unit when the hydraulic oil does not circulate through the hydraulic closed circuit be included in the main working speed range of the work equipment vehicle. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a sectional view of a continuously variable transmission according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the continuously variable transmission shown in FIG. 1 on the first hydraulic device side.

FIG. 3 is a cross-sectional view of a main part of the continuously variable transmission shown in FIG. 1 on the second hydraulic device side.

FIG. 4 is a cross-sectional view taken along the line 414 of FIG.

Fig. 5 is a sectional view taken along line 5-5 in Fig. 1.

Fig. 6 (a) is a sectional view taken along line 6-6 in Fig. 1, and Fig. 6 (b) is an explanatory view showing the operation of the contact portion. Fig. 7 is a sectional view taken along the line 7-7 in Fig. 4.

Figure 8 is a plan view of the shifter.

FIG. 9 is a conceptual diagram of the continuously variable transmission shown in FIG.

FIG. 10 is a characteristic diagram showing a relationship between a stroke volume of a hydraulic device and an output rotation speed in the continuously variable transmission of FIG.

FIG. 11 is an explanatory view showing the operation of a plurality of cams for operating the distribution valve.

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

FIG. 13 is an explanatory diagram showing a change in the opening area of the motor port with respect to the rotation angle of the cam in FIG. 11.

Figure 14 is a conceptual diagram of a conventional continuously variable transmission consisting of HST.

FIG. 15 is a characteristic diagram showing the relationship between the pump / motor stroke volume and the output rotation speed of the apparatus in FIG.

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

FIG. 17 is a characteristic diagram showing the relationship between the pump Z motor stroke volume and the output rotation speed of the apparatus in FIG.

Fig. 18 is a characteristic diagram showing the relationship between vehicle speed and overall efficiency of a vehicle equipped with a conventional continuously variable transmission consisting of HST.

Figure 19 is a distribution diagram showing the relationship between vehicle speed and load torque of various work vehicles. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment in which the present invention is embodied in a hydraulic continuously variable transmission used for traveling of a farm work machine vehicle will be described in detail with reference to FIGS. 1 to 13. FIG. 1 is a sectional view of a hydraulic continuously variable transmission (hereinafter referred to as a continuously variable transmission) T. As shown in FIG. 1, the continuously variable transmission T is housed in a power unit case 11 of an agricultural work vehicle. The continuously variable transmission T includes a first hydraulic device 100 and a second hydraulic device 200 that forms a hydraulic closed circuit together with the first hydraulic device 100. As shown in FIG. 9, the input shaft 12 of the continuously variable transmission T is connected to the crankshaft of the engine EG, and the output gear 39 connected to the yoke 37 located on the output side of the device T is It is connected to an input gear 10 connected to a final deceleration device (not shown). The first hydraulic device 100 corresponds to a variable displacement hydraulic device, and the second hydraulic device 200 corresponds to a differential hydraulic device. As shown in FIGS. 1 and 2, the first 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. The second end is rotatably supported by a side wall of the case 11 via a radial bearing 15. This input shaft is also the PTO shaft (power takeoff shaft). A holder 16 is fixed to the inner surface of the support plate 13. Through holes 13 a and 16 a through which the input shaft 12 passes are formed in the support plate 13 and the holder 16, respectively. The bearing receiving hole 18 is formed in the support plate 13 and the holder 16 by enlarging the diameter of the opposite part of the two through holes 13 a and 16 a. In the bearing housing hole 18, the input shaft 12 is supported by a conical roller bearing 19. A sleeve 20 having a large-diameter portion 20a and a small-diameter portion 20b is passed through the input shaft 12 adjacent to the conical roller bearing 19, and the small-diameter portion 20b Is inserted into the inner ring 19 b of the conical roller bearing 19. Then, the nut 21 screwed to the input shaft 12 is tightened from the outside to the inside (the right side in FIG. 1), so that the outer ring 1 of the conical roller bearing 19 is passed through the sleeve 20. 9a is in contact with the enlarged bottom surface and the peripheral surface of the through hole 16a of the through hole 16a in the bearing housing hole 18 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 locked in a state of contact with the locking ring 22 engaged with the peripheral surface of the input shaft 12. A seal member 23 is disposed in the small diameter portion of the through hole 13a. The bearing portion 14 includes a conical roller bearing 19, a sleeve 20, and a nut 21. The first hydraulic device 100 is slidably disposed on a cylinder block 24 and a cylinder block 24 which are integrally connected to the input shaft 12 and the input shaft 12 by press-fitting. A cradle 27 including a plurality of first plungers 34 and a swash plate surface 26 abutting on the first plunger 34 is provided. The cradle 27 is supported in contact with the holder 16 on the back side thereof, and the input shaft 12 passes through the cradle 27. In FIGS. 1 and 2, the cradle 27 and the holder 16 are shown separated for convenience of explanation. The swash plate surface 26 corresponds to the plunger contact portion of the first variable displacement hydraulic device of the present invention. As shown in FIG. 2, the opposing surfaces E 1 and E 2 where the cradle 27 and the holder 16 abut each other are centered on the trunnion axis TR 1 orthogonal to the axis O of the cylinder block 24. It has a semi-cylindrical surface. As a result, the cradle 27 can be tilted about the trunnion axis TR1. Here, according to the position of the cradle 27, a plurality of lines α, β, γ that are orthogonal to the swash plate surface 26 and pass through the trunnion axis TR1 are assumed. The angle between these lines α, β, γ and the axis Ο is set to 0. Note that] 3 coincides with axis Ο. In FIGS. 1 and 2, the position of the cradle 27, that is, the position of the swash plate surface 26 is distinguished by the lines α and y. When the swash plate surface 26 is arranged at the position specified by the line, the swash plate surface 26 is orthogonal to the axis O, and the swash plate surface 26 is arranged at an upright position (not shown). In addition, the position of the swash plate surface 26 specified by the lines α and γ is positive or negative with respect to the time when the swash plate surface 26 is placed in the upright position (clockwise in FIGS. The direction is defined as positive, and the counterclockwise direction is defined as negative). Accordingly, the swash plate surface 26 shown in FIG. 1 and FIG. 2 shows a state where the swash plate surface 26 is arranged at the position specified by the line, and the tilt angle is the maximum. In the present embodiment, the cradle 27 tilts to the negative side as shown in FIGS. 1 and 2 when Nout> NE with the output rotational speed Nout2 NE shown in FIG. Cradle 27 tilts to the positive side. The positions Q ;, β, and γ used in the following description indicate a negative maximum tilt angle position, an upright position, and a positive maximum tilt angle position on the swash plate surface 26, respectively. In the cylinder block 24, a plurality of first cylinder holes 33 are arranged in a ring around the center of rotation, and extend in parallel with the axis 〇. The first cylinder hole 33 is open to the holder 16 side. A first plunger 34 is slidably disposed in each first cylinder hole 33. In the present embodiment, the space formed by the first plunger 34 accommodated in each first cylinder hole 33 and the first cylinder hole 33 corresponds to the first plunger chamber R1. A steel ball 34 a is rotatably fitted to the tip of each first plunger 34, and each first plunger 34 is provided with a steel ball 34 a and a steel ball 34 a attached thereto. It is in contact with the swash plate surface 26 through 35. The swash plate surface 26 in the inclined state reciprocates each first plunger 34 with the rotation of the cylinder block 24, and gives each first plunger 34 an action of a suction and discharge stroke. Each of the first cylinder holes 33 corresponds to a first plunger hole. The second hydraulic device 200 is a cylindrical yoke having a plurality of plungers 44 slidably disposed on the cylinder block 24 and a rotary swash plate surface 36 abutting against each plunger 44. 3 and 7 are provided. A boss plate 40 is rotatably supported at an end of the input shaft 12 on the second hydraulic device 200 side 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. Each of the plungers 44 corresponds to a second plunger, and the yoke 37 corresponds to an output rotating unit. The yoke 37 is fixed to the boss plate 40 by bolts 41. rotation The swash plate surface 36 is provided on the side surface of the yoke 37 facing the cylinder block 24. When a plane including the trunnion axis TR 2 and the trunnion axis TR 2 orthogonal to the axis 〇 of the cylinder block 24 is imagined, the rotary swash plate surface 36 is aligned with the axis O around the trunnion axis TR 2. It is formed so as to be parallel to the virtual plane inclined at a constant angle with respect to the virtual plane. An enlarged diameter portion 37a is formed on the inner peripheral surface of the yoke 37 on the output gear 39 side. In the enlarged diameter portion 37a, the input shaft 12 is provided with a conical roller bearing 29. Supported by Then, the nut 31 screwed to the input shaft 12 is tightened from the output gear 39 side to the cylinder block 24 side so that the outer ring 29 a of the conical roller bearing 29 becomes the enlarged portion 3. It is in contact with the step bottom of 7a. Further, the inner ring 29 b of the conical roller bearing 29 is locked in a state of contact with the locking ring 32 engaged with the circumferential groove 12 a of the input shaft 12. In the cylinder block 24, the same number of the second plunger holes 43 as the first plunger holes 33 are arranged in an annular shape around the center of rotation, and extend in parallel with the axis O. . The second plunger hole 43 corresponds to the second plunger hole. The second plunger hole 43 is arranged concentrically with the pitch circle of the first plunger hole 33 and on a pitch circle having a diameter larger than the pitch circle. In addition, each second plunger hole 43 is shifted from the first plunger hole 33 by 1 Z2 pitch in the circumferential direction of the cylinder block 24 so that the second plunger hole 43 is located between the first plunger holes 33 adjacent to each other. (See Figures 4 and 5). When hydraulic oil flows into the first and second cylinder holes 33 and 43 and pushes out the plungers 34 and 44 of the first hydraulic device 100 and the second hydraulic device 200 in the axial direction. The thrust force acts on the swash plate surface 26 and the rotating swash plate surface 36, and a radial component force acts on the swash plate surface 26 and the rotating swash plate surface 36 in addition to the thrust direction. The swash plate surface 26 and the rotating swash plate surface 36 are supported on the input shaft 12 via conical roller bearings 19 and 29 which are both radial and thrust load bearings. For this reason, the input shaft 12 is pulled by the thrust load and bent by the radial load. Thrust load and radial load only by deformation of input shaft 1 and 2 Because the weight can be absorbed, vibration is not transmitted to the case 11. Therefore, noise due to the vibration of the surface of the case 11 can be reduced. Further, the second plunger hole 43 is arranged so as to overlap with the first plunger hole 33 in the longitudinal direction (the direction of the axis O of the cylinder block 24) as shown in FIG. , And open to the yoke 37 side. A plunger 44 is rotatably disposed in each second plunger hole 43, and a steel ball 44a is rotatably fitted at the tip thereof. In the present embodiment, the space formed by the plunger 44 housed in the second plunger hole 43 and the second plunger hole 43 corresponds to the second plunger chamber R2. Each plunger 44 is in contact with the rotating swash plate surface 36 via a steel ball 44 4a and a shoe 45 to which the steel ball 44a is attached. With the relative rotation between the rotating swash plate surface 36 and the cylinder block 24

4 4 reciprocates and repeats the suction and discharge strokes. Next, a hydraulic closed circuit formed between the first hydraulic device 100 and the second hydraulic device 200 will be described.

A first inner oil chamber 51 and a second inner oil chamber 52, both of which are annular, are formed on inner circumferential surfaces at both axial ends of the cylinder block 24. Also, annular first outer oil chambers 53 and second outer oil chambers 54 are formed at predetermined intervals near both ends in the axial direction of the cylinder block 24, near the outer peripheral side. The first inner oil chamber 51 and the first outer oil chamber 53 are communicated with each other via a plurality of radially extending oil passages 55, and the second inner oil chamber 52 and the second outer oil chamber 5 are connected to each other. 4 is communicated with a plurality of radially extending oil passages 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 has the same number of first valve holes 57 communicating with the first outer oil chamber 53 and the second outer oil chamber 54 as the first plunger hole 33, and the number of cylinder blocks 24. It extends along the axial direction. Also, the cylinder block 24 has the same number of second valve holes 58 communicating with the first outer oil chamber 53 and the second outer oil chamber 54 as the second plunger hole 43, and The block 24 extends along the axial direction of the block 24. 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. In each first valve hole 57, a port U of an oil passage 59 communicating with the corresponding first plunger hole 33 is formed between the first outer oil chamber 53 and the second outer oil chamber 54. Have been. A spool-type first switching valve 60 is slidably disposed in each first valve hole 57. As shown in FIGS. 1 and 2, the first end of the first switching valve 60 is formed on the outer periphery of the holder 16 by the biasing force of the coil spring 63 wound around the first end. It is always in contact with the cam surface 62 of the cam 61. The first switching valve 60 corresponds to a first distribution valve, and the first cam 61 corresponds to a first applying member. FIG. 11 shows a cam profile of the first cam 61. As shown in the figure, the cam surface 62 of the first cam 61 communicates the first switching valve 60 with the port U and the first outer oil chamber 53 around the port closing position n0. It reciprocates between the first opening position n1 and the second opening position n2 for communicating the port U with the second outer oil chamber 54. In the cam surface 6'2, the position for positioning the first switching valve 60 at the first opening position n1 and the second opening position n2 is the stroke of the first switching valve 60 in that region. The cylinder blocks 24 are located on a pair of virtual planes perpendicular to the axis O of the cylinder block 24 so as not to change. In order to move the first switching valve 60 between the first opening position n1 and the second opening position n2, a slope is formed on the cam surface 62. Then, by the operation of the first cam 61, a region H and a region I are set in the first hydraulic device 100 as shown in FIG. In the region H, with the rotation of the cylinder block 24, the first switching valve 60 is moved to the first opening position n1, and the first plunger hole 33, that is, the first plunger chamber R1 Is a section communicating 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 first plunger hole 33, that is, the first plunger chamber R 1 is This section communicates with the second outer oil chamber 54 via the port U. 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 (maximum stroke volume). ). In response to this, the first hydraulic device 100 according to the present embodiment is configured such that the output rotation speed Nout (the rotation speed of the output gear 39) when the input rotation speed of the input shaft 12 is NE is increased from NE to 2NE. The discharge amount of hydraulic oil on the side is set. In the present 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. 11 is 0 ° to 180 °. In the range, the hydraulic oil is sucked into the first plunger hole 33, that is, the first plunger chamber R1 via the port U. In the range of 180 ° to 360 ° (0 °), the hydraulic oil is discharged from the first plunger hole 33 through the port U from the first plunger chamber R1. Conversely, 0 if the swash plate surface 26 tilts forward. In the range of up to 180 °, the operating oil is discharged from the first plunger hole 33, ie, from the first plunger chamber R1 via the port U. In the range of 180 ° to 360 ° (0 °), hydraulic oil is sucked into the first plunger hole 33, that is, the first plunger chamber R1 via the port U. The oil chamber to be discharged and the oil chamber to be suctioned are determined by regions H and I corresponding to the rotation angle range of the cylinder block 24. In each second valve hole 58, a port W of an oil passage 69 communicating with the corresponding second plunger 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. As shown in FIGS. 1 and 2, the first end of the second switching valve 70 is pressed by a coil spring 73 wound around the second switching valve 70, and a second cylindrical valve provided on the outer periphery of the yoke 37. It is always in contact with the cam surface 72 of the cam 71. The second cam 71 corresponds to a second applying member. The second switching valve 70 corresponds to a second distribution valve. The second 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. Further, a pair of keys 74 is integrally fixed to the yoke 37 at positions opposed to each other by 180 degrees so as to be along the axis O direction of the cylinder block 24. Then, a pair of guide grooves 75 provided on the inner peripheral surface of the second cam 71 is fitted to the key 74 so that the second cam 71 is moved in the direction of the axis の of the cylinder block 24. , And is prevented from rotating relative to the yoke 37 in the circumferential direction. As a result, the second cam 71 can rotate integrally with the yoke 37 about the axis O. Also, the inner diameter of the second cam 71 is set smaller than the outer diameter of the boss plate 40, and the second cam 71 can be locked to the boss plate 40. That is, when the second cam 71 is locked to the boss plate 40 and further movement to the output gear 39 side (movement to the right in FIG. 3) is restricted, the second cam 71 Is located at the locking position, and the locking position is the first displacement position Q1 of the second cam 71. As shown in FIG. 6A, a displacement imparting member 76 is rotatably supported on the output gear side end surface of the second cam 71 with respect to the case 11. The displacement applying member 76 includes a contact member 77 that can contact the output gear side end surface of the second cam 71, and a worm gear 78 that is integrally connected to the contact member 77 via a shaft 78a. It is composed of As shown in FIG. 6 (b), the abutment body 77 is composed of a pair of arms 79, 80 extending on both sides of the shaft 78a of the worm gear 78, and the clockwise direction of the worm gear 78. Alternatively, one of the arms 79 and 80 abuts on the output gear side end face of the second cam 71 by the counterclockwise rotation. In this embodiment, when the worm gear 78 rotates clockwise in FIG. 6B, the arm 80 comes into contact with the end face on the output gear side of the second cam 71 and is positioned at the reference position Q 0. The second cam 71 to the second displacement position Q2. Also, in FIG. 6 (b), when the arm 79 rotates counterclockwise, the second cam 71 is moved from the reference position Q0 to the first displacement position Q. Move to 1. A worm shaft 81 rotatably supported by the case 11 is combined with the worm gear 78. The worm shaft 81 is operatively connected to a not-shown actuator. When the actuator is in the neutral position and is not operated, the contact body 77 contacts the second cam 71 to position the second cam 71 at the reference position Q0. Then, based on the rotation of the actuator in the forward or reverse direction and the amount of the rotation, the amount of rotation of the worm gear 78, and thus the amount of movement between the reference position Q0 and the first displacement position Q1, and the reference The amount of movement between the position Q 0 and the second displacement position Q 2 has been determined. The holding mechanism is constituted by the worm gear 78 and the worm shaft 81. The actuator, the worm shaft 81, the worm gear 78, and the contact member 77 constitute a variable mechanism. FIG. 11 shows a cam blower nozzle of the second cam 71. In FIG. 11, the relative position between the cam surface 62 and the cam surface 72 changes because the second cam 71 rotates together with the yoke 37, but for convenience of explanation, they are combined into one. Is shown. Then, based on the relative rotation of the yoke 37 with respect to the cylinder block 24, an area J and an area K are set in the second hydraulic device 200 by the action of the second cam 71. The region J is a section in which the second plunger hole 43 communicates with the second outside oil chamber 54 via the port W by the second switching valve 70 displaced by the cam surface 72. The area K is a section in which the second plunger hole 43 force, that is, the second plunger chamber R 2 communicates with the first outer oil chamber 53 via the port W. For example, when the swash plate surface 26 tilts to the negative side as shown in FIG. 1 or FIG. 2, the second cam 71 (shown in the reference position Q 0) shown in FIG. Hydraulic oil is sucked into the second plunger hole 43, ie, the second plunger chamber R2, through the port W in the range of 0 ° to 180 ° in the relative rotation angle around the axis. — Similarly, when the swash plate surface 26 is tilted to the negative side as shown in FIG. 1 or FIG. 2, the second plunger hole 43 is provided when the relative rotation angle is in the range of 180 ° to 360 ° (0 °). That is, hydraulic oil is discharged from the second plunger chamber R2 through the port W. Conversely, when the swash plate surface 26 is tilted to the positive side, when the relative rotation angle is in the range of 0 ° to 180 °, the port W is opened from the second plunger hole 43, that is, from the second plunger chamber R2. Hydraulic oil is drained through. In the range of 180 ° to 360 ° (0 °), hydraulic oil is sucked into the second plunger hole 43, that is, into the second plunger chamber R2 via the port W. The oil chamber to be discharged and the oil chamber to be suctioned are determined by the regions J and K corresponding to the rotation angle range. FIG. 12 shows the second cam 71 and the second cam 71 when the second switching valve 70 is switched by the action of the second 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 cylinder block 24 is shown. FIG. 13 shows the relative rotation angle between the second cam 71 and the cylinder block 24 and the opening by the second switching valve 70 when communicating with the first outer oil chamber 53 or the second outer oil chamber 54. FIG. 4 is a characteristic diagram of the present embodiment showing a relationship with an opening area of a port W. The plus (+) side indicates the opening area when the port W communicates with the first outside oil chamber 53, and the minus (1) side indicates the opening area when the port W communicates with the second outside oil chamber 54. .

(When the second cam 71 is located at the reference position Q 0)

When the second cam 71 is located at the reference position Q0, that is, when 0≤Nout≤2NE in FIG. 10, the port W is in the range from 0 ° to 180 ° as shown in FIGS. In the range from 180 ° to 360 ° (0 °), it is communicated with the first outer oil chamber 53. In the present embodiment, when the second cam 71 is located at the reference position Q 0, the port W is opened when the port W communicates with the first outer oil chamber 53 and when the port W communicates with the second outer oil chamber 54. Sections are the same as each other So that the cam surface 72 is set.

(When the second cam 72 is located in the first displacement section Q1 to Q0)

When the second cam 71 is located on the first displacement position Q1 side, that is, in FIG. 10, when 2 NE and Nout, the port W is connected as shown in FIGS. 12 and 13. That is, the second plunger chamber R2 communicates with the second outer oil chamber 54 up to a predetermined angle (for example, about 3 degrees) to 150 °, and the second plunger chamber R2 has a second angle from 150 ° to the predetermined angle. 1Communicated with the outer oil chamber 53. That is, the area J is set such that the area (opening section) becomes narrower than when the second cam 71 is located at the reference position Q0, and conversely, the area of the second cam 71 becomes wider so that the area K becomes wider. Surface 72 is set. In this way, by changing the regions J and K, the communication section (region) with the second outer oil chamber 54 in one stroke of the second hydraulic device 200 (force) is applied to the first hydraulic device 100. It is smaller than the communication section (area I) with the second outer oil chamber 54 in one stroke. That is, the yoke 37 is compared with the region I (section) where the first plunger chamber R1 communicates with the second outer oil chamber 54 while the cylinder hook 24 makes one rotation around the axis. During 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. Therefore, compared to 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 The distribution of the areas J and K is set so that the amount of hydraulic oil transferred to and from the chamber 54 decreases, and finally the stroke volume at the first displacement position Q1 decreases to 0.5 VMmax.

(When the second cam 72 is located in the second displacement section Q0 to Q2)

'When the second cam 71 is located on the second displacement position Q2 side, that is, when the vehicle is moving backward, in FIG. 10, when Nout is less than 0, it is shown in FIGS. 12 and 13. Thus, the port W, that is, the second plunger chamber R2 is communicated with the second outer oil chamber 54 from about 240 degrees to about 240 degrees, and from about 240 degrees to about 34 degrees. Up to 0 degrees, it is communicated with the first outer oil chamber 53. In this way, by changing the areas: T and K, the communication section (area Κ) with the first outer oil chamber 53 in one stroke of the second hydraulic apparatus 200 (the area Κ) force The first hydraulic apparatus 1 It becomes smaller than the communication section (area 外側) with the first outer oil chamber 53 in one stroke of 00. That is, compared to the section (region Η) in which the first plunger chamber R1 communicates with the first outer oil chamber 53 while the cylinder hook 24 makes one rotation around the axis, the yoke 37 is The section (area I) where the second plunger chamber R2 communicates with the first outer oil chamber 53 during one rotation around the axis with respect to the cylinder block 24 becomes smaller. Therefore, compared to the amount of hydraulic oil that the first hydraulic device 100 sends and receives to and from the first outer oil chamber 53 during one stroke, the first hydraulic device 200 The distribution of the areas J and K is set so that the amount of hydraulic oil transferred to and from the chamber 53 decreases, and finally decreases to 0.5 VMmax at the second displacement position Q2. In this embodiment, the first plunger hole 33, the second plunger hole 43, the first outer oil chamber 53, the second outer oil chamber 54, the first valve hole 57, the second valve hole 58, The oil passage 59, the oil passage 69, the port U and the port W constitute a hydraulic closed circuit. As shown in FIGS. 4, 5, and 7, a communication passage 8 is provided between the first outer oil chamber 53 and the second outer oil chamber 54 so as to be along the axis O of the cylinder block 24. 2, 8 3 are formed. In the communication passage 82, a relief valve 85 for opening and closing a valve seat 84 provided on the first outer oil chamber 53 side is provided, and by the action of a coil spring 86 built in the communication passage 82, The valve seat 84 is closed. Then, 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 and the first outer oil chamber 53 is opened. The communication between the second outer oil chambers 54 is established. In the communication passage 83, a relief valve 88 for opening and closing a valve seat 87 provided in the second outer oil chamber 54 is provided. Valve seats 8 and 7 are closed. The hydraulic pressure of the hydraulic oil in the second outer oil chamber 54 is When the panel pressure is higher than the panel pressure of 89, the relief valve 88 opens the valve seat 87 to allow communication between the second outer oil chamber 54 and the first outer 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 has an introduction oil passage 91 in the radial direction corresponding to the large diameter portion 20a of the sleeve 20, and the introduction oil passage 91 has a radius in the large diameter portion 20a. The oil passage 92 and the large-diameter portion 20a are formed in a circumferential groove 93 formed on the outer peripheral surface of the large-diameter portion 20a. The support plate 13 is provided with an oil passage 94 communicating with the circumferential groove 93. The oil passage 94 is filled with hydraulic oil from a charge pump (not shown). In the input shaft 12, a portion facing the first inner oil chamber 51 and the second inner oil chamber 52 is provided with a pair of charge valves 95 (inverted) that open and close a valve seat that can communicate with the shaft hole 90. Stop valve) is located. 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. The charge valve 95 prevents the hydraulic oil from flowing back to the shaft hole 90.

(Action)

Now, the operation of the continuously variable transmission T configured as described above will be described.

For the sake of convenience, the description will be made assuming that the input rotation speed NE applied from the crankshaft of the engine EG to the input shaft 12 is constant.

(When output 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 arranged at the upright position via the cradle 27. In this state, as shown in FIG. 6 (b), the second cam 71 is in contact with the arm 79 of the contact member 77, and the cam surface 72 at this time is the reference surface shown in FIG. It is located at position Q0. In this state, the driving force of the engine EG causes the cylinder block 24 to rotate in the forward direction at the rotational speed NE via the input shaft 12 at a force S, and the swash plate surface 26 has the axis の of the input shaft 12. In a neutral state, standing upright. Therefore, each first plunger 34 of the first hydraulic device 100 is not reciprocated by the swash plate surface 26, and in this state, the operating oil does not circulate in the hydraulic closed circuit. For this reason, on the second hydraulic device 200 side, the protruding end of each plunger 44 abuts and engages with the rotary swash plate surface 36 via the shoe 45 in a state where the plunger 44 cannot perform a stroke movement. Therefore, the cylinder block 24 and the rotary swash plate surface 36 are directly connected to each other, and rotate together. That is, in this state, the input shaft 12 and the output gear 39 are directly connected. The forward rotation imparted to the rotating swash plate surface 36 in this manner is transmitted to the final reduction gear via the yoke 37, the POS plate 40, the output gear 39, and the input gear 10. When the swash plate surface 26 is arranged in the upright position, the stroke volume of the first hydraulic device 100 becomes zero as shown in FIG. 10, and the output rotation speed Nout (the rotation of the output gear 39) Is equal to the input speed NE. In this embodiment, the case where the output rotation speed Nout (the rotation speed of the output gear 39) is the same as the input rotation speed NE is included, that is, the input shaft 12 of the continuously variable transmission T and the output gear are included. The range before and after, including when the vehicle is directly connected to the vehicle 39, is set as the main working speed range of the agricultural work vehicle. For example, as shown in FIG. 19, when the agricultural working machine vehicle according to the present embodiment is a cultivator, the running speed is assumed to be 3 km / h to 8 kmZh in the main working speed range. Within the speed range, the direct connection state is established and the output rotation speed Nout (the rotation speed of the output gear 39) is set to be NE. In the present embodiment, the main working speed range is 3 kmZh to 8 kmZh.

(When the output speed Nout is between NE and 2 NE)

When the shift lever 97 shown in FIG. 8 is operated distally (upward in FIG. 8) with respect to the N position from the intermediate position in the F region, the swash plate surface 26 is moved through the cradle 27. Is tilted to the negative side as shown in FIGS. 1 and 2, and is disposed in the area between the negative maximum tilt angle position and the upright position. In this case, the cylinder block 2 4 is driven through the input shaft 12 by the driving force of the engine EG. Rotates at the rotational speed NE. Then, in the area 1 of the first hydraulic device 100, the hydraulic oil is discharged from the first plunger hole 33 to the second outer oil chamber 54 via the port U. On the other hand, in the region H, the hydraulic oil is sucked from the first outer oil chamber 53 through the port U into the first plunger hole 33. The amount of hydraulic oil circulating in the hydraulic closed circuit increases as the tilt angle of the swash plate surface 26 in the negative direction increases. The hydraulic oil discharged into the second outer oil chamber 54 is sucked into the second plunger hole 43 in the range of 0 ° to 180 ° through the port W. Meanwhile, 180. Hydraulic oil is discharged (discharged) from the second plunger hole 43 in the range of about 360 ° (0 °). As a result, the number of rotations NE at which the cylinder block 24 is driven via the input shaft 12 and the forward direction of the plunger 44 of the second hydraulic device 200 with respect to the rotation swash plate surface 36 of the plunger 44 are increased. The rotation swash plate surface 36 is rotated by the sum with the rotation speed. The forward rotation applied 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 human power gear 10. And performs a speed increasing action. At this time, 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 in FIG. 10 increases from zero to VMmax (maximum stroke volume). In response, the output speed Nout increases from NE to 2 NE.

Note that the stroke volume of the second hydraulic device 200 when the output rotation speed Nout changes from NE to 2 NE remains the maximum stroke volume VMmax.

(When the output speed Nout exceeds 2 NE)

When moving the vehicle forward and at high speed, that is, by operating the shift lever 97 shown in FIG. 8 in the F region further to the distal side (upward in FIG. 8) than the N position, the cradle 27 is moved. The swash plate surface 26 is located at the maximum negative tilt angle position. At this time, the stroke volume of the first hydraulic device 100 remains at the maximum stroke volume VMmax. Then, when the displacement applying member 76 is operated, the second cam 71 located at the reference position Q0 is It moves between the quasi position Q 0 and the first displacement position Q 1. For example, when the second cam 71 is located at the first change position Q1, as shown in FIGS. 12 and 13, the port W is in the range of about 3 degrees to 150 degrees. (2) The outer oil chamber (54) is communicated with the first outer oil chamber (53) in a range of 150 ° to about 3 degrees. That is, the area J is narrower than when the second 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 performs the second outer oil chamber during one stroke. The section communicating with 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 The amount of hydraulic oil exchanged with the outer oil chamber 54 is reduced. For this reason, the amount of hydraulic oil discharged from the first hydraulic device 100 to the second outer oil chamber 54 during one stroke and the second outer oil chamber 5 during the one stroke The number of strokes of the second hydraulic device 200 increases until the first hydraulic device 100 completes one stroke, corresponding to the ratio of the amount of hydraulic oil sucked from step 4. As a result, the second hydraulic device 200 gives the rotation swash plate surface 36 a rotation speed higher than that of NE. Therefore, the output rotation speed Nout is larger than 2 NE due to the rotation speed NE of the cylinder block 24 ^ the sum of the rotation speeds applied by 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 VMraax (maximum stroke volume) as described above, while the stroke volume of the second hydraulic device 200 is Changes from VMmax to 0.5 VMmax. As a result, the output rotation speed Nout increases from 2 NE to 3 NE.

(When the output speed Nout is between 0 and NE)

When the shift lever 97 shown in FIG. 8 is operated in the F region to the N position side from the intermediate position in the F region, the swash plate surface 26 tilts forward through the cradle 27. It is located in the area between the positive maximum tilt angle position and the upright position. In this case, the swash plate surface 26 tilts in the forward direction. Therefore, when the cylinder block 24 is rotated via the input shaft 12 by the driving force of the engine EG, the first plunger hole in the region H shown in FIG. From 33, the hydraulic oil is discharged to the first outer oil chamber 53 via the oil passage 59 and the port U. In the region I, the hydraulic oil is sucked into the first plunger hole 33 through the second outer oil chamber 54, 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 forward direction increases.

On the other hand, in the second hydraulic device 200, the hydraulic oil discharged to the first outer oil chamber 53 is sucked into the second plunger hole 43 through the port W. The hydraulic oil from the second plunger hole 43 in the range of 0 ° to 180 ° is discharged to the second outer oil chamber 54. As a result, the “when the output rotation speed Nout exceeds the range between NE and 2 NE and exceeds 2 NE” due to the protrusion and pressing action of the second hydraulic device 200 on the rotating swash plate surface 36 of the plunger 44. The rotation in the opposite direction is applied to the yoke 37. Therefore, the yoke 37, the boss plate 40, and the output gear 39 are rotated by the sum of the rotation speed in the reverse direction and the rotation speed in the forward direction of the cylinder block 24. 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, the stroke volume of the first hydraulic device 100 in FIG.

(The above “1” means that the hydraulic oil is discharged from the port U to the first outer oil chamber 53.) The absolute value increases toward the side, and the output rotation speed Nout accordingly becomes NE Decelerate from to zero. When the output speed Nout changes from NE to zero, the second hydraulic system The stroke volume per revolution of 200 remains at 1 VMmax. (The above “-” means that the hydraulic oil is sucked from the first outer oil chamber 53 via the port W.)

(When the output speed Nout is zero)

When the shift lever 97 is operated to the N position, the swash plate surface 26 is disposed at the maximum positive tilt angle position via the cradle 27. In this case, in the present embodiment, the stroke volume of the first hydraulic device 100 is fixed to one VMmax. As a result, the rotational speed in the opposite direction is balanced with the rotational speed NE at which the cylinder block 24 is driven via the input shaft 12. That is, the sum of the rotational speeds is zero (the output rotational speed Nout is zero). ) And the output gear 39 stops.

(When output speed Nout is less than zero) '

Next, when the shift repeller 97 shown in FIG. 8 is operated to the R region in order to move the vehicle backward, the swash plate surface 26 is disposed at the positive maximum tilt angle position via the cradle 27. At this time, the stroke volume of the first hydraulic device 100 is fixed to one VMmax. Then, the second 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 second cam 71 is located at the second displacement position Q2, as shown in FIGS. 12 and 13, the port W is in the range of about 340 degrees to about 240 degrees. The second outer oil chamber 54 is communicated with the first outer oil chamber 53 in a range of about 240 degrees to about 340 degrees. That is, contrary to the case where the output rotation speed Nout exceeds 2 NE, the area J is expanded and the area K is narrowed compared to when the second cam 71 is located at the reference position Q0. For this reason, compared with the section in which the first hydraulic device 100 communicates with the first outer oil chamber 53 during one stroke, the first outer hydraulic chamber 200 during the one stroke. 53 The section communicating with 3 becomes smaller. Accordingly, compared with the amount of hydraulic oil that the first hydraulic device 100 sends and receives with the first outer oil chamber 53 during one stroke, the first hydraulic device 200 The amount of hydraulic oil exchanged with the outer oil chamber 53 decreases. Therefore, the amount of hydraulic oil discharged from the first hydraulic device 100 to the first outer oil chamber 53 during one stroke and the amount of the hydraulic oil discharged from the second hydraulic device 200 to the first outer oil chamber 53 during one stroke are reduced. The number of strokes of the second hydraulic device 200 increases until the first hydraulic device 100 completes one stroke, corresponding to the ratio of the amount of hydraulic oil sucked from 53. As a result, the second hydraulic device 200 gives the rotating swash plate surface 36 a rotational speed whose absolute value is larger than one NE. Therefore, the output rotation speed Nout is smaller than zero due to the sum of the rotation speed NE of the cylinder block 24 and the applied rotation speed of the second hydraulic device 200. The reverse rotational torque is transmitted to the final reduction gear via the yoke 37, the boss plate 40, the output gear 39, and the input gear 10. In this embodiment, at this time, the stroke volume of the first hydraulic device 100 in FIG. 10 is one VMmax of a fixed amount as described above, while the stroke volume of the second hydraulic device 200 is Is set to change from 1 VMmax to 10.5 VMmax. In addition, the output speed Nout increases from zero in the reverse direction. According to the present embodiment, the following effects can be obtained.

The continuously variable transmission according to the present embodiment shares a cylinder hook 24 of the first hydraulic device 100 and the second hydraulic device 200 and has the first hydraulic device 100 in the cylinder block 24. A hydraulic closed circuit in which hydraulic oil circulates between the second hydraulic device 200 and the second hydraulic device 200 is formed, and the rotation is driven by the engine EG. As a result, the driving force from the engine EG is transmitted to the rotary swash plate surface 36 of the second hydraulic device 200 even when the hydraulic oil does not circulate in the hydraulic closed circuit. That is, the input shaft 12 (input side) of the continuously variable transmission T and the output gear 39 (output side) are directly connected. A wide range of continuously variable transmissions including both the low speed side and the deceleration side can be obtained centering on such a direct connection state. From this, it is possible to obtain the high operability of switching between forward and reverse by only operating the shift lever 97 and covering a wide shift range from the highest speed of forward to the highest speed of reverse. By making the second hydraulic device 200 a variable displacement type, the speed change range is expanded to a forward high-speed range and a reverse range, and a gear mechanism (reverser) for switching between forward and backward can be omitted. In the present embodiment, the first hydraulic device 100 operates according to the displacement of the tilt angle of the swash plate surface 26. Also, when the swash plate surface 26 is at the maximum positive / negative tilt angle position, the second hydraulic device 200, as shown in FIGS. The section communicating with the second outer oil chamber 54 can be narrowed. Therefore, the stroke volume of the second hydraulic device 200 can be made relatively smaller than 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, the rotation speed greater than NE or one NE is applied to the rotating swash plate surface 36 by the projecting and pressing action of the plunger 44 of the second hydraulic device 200. Therefore, the continuously variable transmission T can obtain a forward high-speed region exceeding 2 NE and a reverse traveling region below the opening. In the present embodiment, the continuously variable transmission is a continuously variable transmission used for traveling of agricultural work vehicle. As a result, the above-described operational effects can be obtained when the agricultural work machine vehicle travels. In the present embodiment, the shift range when the hydraulic oil discharge amount of the first hydraulic device 100 is zero is set within the main working speed range of the work machine. That is, when the output rotation speed Nout (the rotation speed of the output gear 39) is the same as the input rotation speed NE, that is, when the input shaft 12 and the output gear 39 of the continuously variable transmission are connected. The range before and after, including the direct connection state, was set as the main working speed range of this agricultural machine vehicle. As shown in Fig. 19, when the agricultural work vehicle of the present embodiment is a cultivator, the traveling speed is assumed to be approximately 2 km / h to 8 km / h as the traveling speed range of the main working speed range. Within, the direct connection state is obtained and output The rotation speed Nout (the rotation speed of the output gear 39) was set to be NE. As a result, in the main working speed range, the hydraulic oil does not flow through the hydraulic closed circuit, and oil leakage in the hydraulic closed circuit is suppressed. As a result, transmission efficiency is enhanced, energy loss in the main working speed range can be reduced, and highly efficient farming can be performed. (5) in FIG. 18 shows the characteristics of the relationship between the total efficiency (total transmission efficiency) and the vehicle speed in the present embodiment. As shown in the figure, in the present embodiment, it can be seen that an extremely high overall efficiency can be obtained as compared with other conventional HST sub-shifts, sub-seconds, and sub-three shifts. In particular, in the main work speed range, the overall efficiency is also high, indicating that efficient work can be performed. In the present embodiment, the second hydraulic device 200 is actuated by a plunger group 44 and a plunger group 44 inserted into the plurality of second plunger holes 43 in the cylinder block 24. A rotary swash plate surface 36 that rotates relative to or synchronously with the cylinder block 24, a second switching valve 70 group that controls the suction and discharge of hydraulic oil to and from each second plunger hole 43, The 2 switching valve 70 group is constituted by a second cam 71 (valve operating mechanism) that operates according to the rotation of the cylinder block 24. The second cam 71 is provided with a worm shaft 81, a worm gear 78, and an abutting member 77 (variable mechanism). The operation of the variable mechanism causes the second hydraulic device 200 to perform one stroke. During this time, the section communicating with the first outer oil chamber 53 or the second outer oil chamber 54 is changed. As a result, the stroke capacity of the second hydraulic device 200 can be changed, and the capacity can be varied. In the present embodiment, the second switching valve 70 is constituted by a timing spool provided in parallel with each plunger 44, and the second cam 71 is rotated integrally with the rotary swash plate surface 36. In addition, a timing cam is provided so as to be displaceable along the axis of the cylinder block 24. As a result, the second cam 71 rotates integrally with the rotary swash plate surface 36 and is displaced along the axis of the cylinder block 24. As a result of the second switching valve 70 being displaced by the action of the second cam 71, the suction / discharge timing of the second switching valve 70 can be changed. In the present embodiment, the second cam 71 is provided with a base in the axial direction of the cylinder block 24. The worm gear 78 and the worm shaft 81 are provided so as to be displaceable between the quasi position QO, the first displacement position Ql, and the second displacement position Q2, and hold the second cam 71 at the displaced position. Holding mechanism). For this reason, the second cam 71 can be held at each position, and a stable action can be given to the second switching valve # 0 at each position. At the first displacement position Q1, the boss plate 40 functions as a stopper. Therefore, a stable cam action can be provided to the second switching valve 70. The above embodiment may be modified as follows.

In both embodiments, the traveling speed in the main working speed range is about 2 kmZl! It is not limited to ~ 8 kmZh. In the case of agricultural work equipment vehicles other than cultivators, for example, tractors, sub-soilers, disc mowers, etc., there is a main working speed range according to the work equipment vehicle, so the input side and output side of the continuously variable transmission are directly connected. If the condition is set according to the main working speed range, work can be performed with high efficiency. A configuration in which the stroke volume of the first hydraulic device 100 exceeds the maximum stroke volume VMmax of the second hydraulic device 200 may be adopted. In this case, instead of changing the stroke volume of the second hydraulic device 200 from VMmax to 0.5 V Mmax to realize a forward high-speed range exceeding 2 NE and a reverse range below zero, the second The stroke volume of the first hydraulic device 100 may be changed to a range exceeding VMmax while the stroke volume of the hydraulic device 200 is maintained at VMmax-constant. Specifically, the tilt angle of the swash plate surface 26 of the first hydraulic device 100 is larger than the tilt angle of the rotary swash plate surface 36 of the second hydraulic device 200. I do. In this case, the second hydraulic device 200 does not require a variable mechanism and a holding mechanism for the second cam 71. 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. Or, the plunger 4 4 may be protruded and immersed in the radial direction.

Claims

The scope of the claims

1. A variable displacement first hydraulic device comprising a first plunger and a plunger contact portion, and the first plunger being operated by the contact portion;

A second hydraulic device having a second plunger, and having an output rotating unit that performs relative or synchronous rotation with respect to the input rotation by contact with the second plunger;

A cylinder block which is configured to rotate around the axis by input rotation and stores the first and second plungers respectively, and the first and second plunger holes are provided in the cylinder block. Is provided, and

A first plunger chamber formed by storing the first plunger in the first plunger hole;

A second plunger chamber formed by storing the second plunger in the second plunger hole;

A hydraulic closed circuit including a first oil chamber and a second oil chamber, and for circulating hydraulic oil between the first plunger chamber and the second plunger chamber;

While the cylinder block makes one rotation around the axis, a section in which the first plunger chamber communicates with the first oil chamber and a section in which the second plunger communicates with the second oil chamber are set. The section where the second plunger chamber communicates with the first oil chamber and the section where the second hydraulic chamber communicates with each other during one rotation about the axis with respect to the oil pressure are set, and the stroke capacity of the first hydraulic device is set. A hydraulic continuously variable transmission having a range exceeding the stroke volume of the second hydraulic device.

2. The hydraulic continuously variable transmission according to claim 1, wherein the output rotation is smaller than a section in which the first plunger chamber communicates with the first oil chamber while the cylinder block makes one rotation around the axis. The hydraulic system is characterized in that the section where the second plunger chamber communicates with the first oil chamber becomes smaller while the section makes one rotation around the axis with respect to the cylinder block.

3. The hydraulic continuously variable transmission according to claim 1, wherein the output rotation is smaller than that of the section in which the first plunger chamber communicates with the second oil chamber while the cylinder block makes one rotation around the axis. The hydraulic system is characterized in that the section where the second plunger chamber communicates with the second oil chamber becomes smaller while the part makes one rotation around the axis with respect to the cylinder block.

4. The hydraulic continuously variable transmission according to claim 2 or claim 3 further comprises:

A first distributing valve and a first imparting member for imparting a reciprocating motion to the first distributing valve, wherein the first imparting member is provided while the cylinder block makes one rotation around the axis; The first plunger chamber communicates with the first oil chamber and the second oil chamber in accordance with the axial reciprocation of the first distribution valve.

A second distributing valve and a second imparting member for imparting a reciprocating motion to the second distributing valve, wherein the second imparting member rotates the output rotary unit one rotation about the axis with respect to the cylinder block. Hydraulic pressure that imparts axial reciprocation to the second distribution valve so that the second plunger chamber communicates with the first and second oil chambers in accordance with the axial reciprocation of the second distribution valve. Type continuously variable transmission.

5. The hydraulic continuously variable transmission according to claim 4, wherein the first distribution valve is reciprocally supported by the cylinder block along an axial direction of the cylinder block, and the first applying member is a cylinder block. A hydraulic continuously variable transmission comprising a first cam disposed around the axis of the cylinder block so as to face the first end of the gear.

6. The hydraulic continuously variable transmission according to claim 4, wherein the second distribution valve is reciprocally supported by the cylinder block along the axial direction of the cylinder block, and the second applying member is a cylinder block. A hydraulic continuously variable transmission including a second cam disposed around the axis of the cylinder block so as to face the second end of the block.

7. The hydraulic continuously variable transmission according to claim 6, wherein the second applying member is displaceable in an axial direction of the cylinder block, and is capable of being held at a displaced position. Continuously variable transmission.

8. The hydraulic continuously variable transmission according to claim 6, wherein the second cam is a cylinder professional. A hydraulic continuously variable transmission that is capable of being displaced in the axial direction of the rack and being held at the displaced position.

9. A work vehicle equipped with the hydraulic continuously variable transmission according to any one of claims 1 to 8, wherein the rotation of the output rotation unit when the hydraulic oil does not circulate through the hydraulic closed circuit. A work implement vehicle, wherein the speed is included in a main work speed range of the work implement vehicle.