JP2002021996A - Shift control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out automatic shift of a transmission in a midway of a transmission system from an engine to a driving part, without being accompanied with a shift shock. SOLUTION: An agricultural working vehicle is provided with a main transmission 8a and a subsidiary transmission 8b in a midway of the transmission system from the engine E to driving wheels 82. This working vehicle comprises: an angular acceleration control valve 1 which reduce line pressure P0 when an angular acceleration more than a predetermined value is generated at an output side of the main transmission 8a; and a throttle part 7 which changes a throttle opening based on a gear stage of the subsidiary transmission 8b and further reduces an output oil pressure of the angular acceleration control valve 1. Upon automatic shift in which the gear stage of the main transmission 8a of hydraulic clutch type is changed over in order to appropriately hold engine speed of the engine E, pilot pressure Pf whose pressure is adjusted by the angular acceleration control valve 1 and the throttle part 7 is supplied to a pressure reducing valve 83, the line pressure P0 is reduced by an operation of the pressure reducing valve 83, and the reduced line pressure is used as oil pressure for engaging of the hydraulic clutch of the corresponding gear stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device which is mounted on, for example, an agricultural work vehicle such as an agricultural tractor or the like, and which performs automatic shifting to obtain optimum driving performance during work traveling.

[0002]

2. Description of the Related Art In an agricultural work vehicle such as an agricultural tractor, which is provided with an engine as a drive source for traveling and driving a working machine, and transmits the rotation of the engine to traveling devices such as wheels and crawlers, the vehicle travels. In order to obtain good driving performance during work traveling with a work machine pulled to the rear, it is desirable to keep the engine rotation speed in an appropriate speed range near the rotation speed at which maximum power or torque is generated. Is done.

[0003] The rotational speed of the engine is adjusted by the driver's throttle operation. However, the rotational speed of the engine during work traveling varies greatly depending on the load applied to the work machine, so that an appropriate speed range is maintained. To do so, in addition to the throttle operation, it is often necessary to perform a shift (deceleration or speed-up) operation of a transmission arranged in the middle of the transmission system from the engine to the traveling device. However, the driver during the work traveling needs to perform many works including monitoring of the work state of the work machine, and there is a possibility that the speed adjustment operation of the engine may be neglected.

Therefore, conventionally, there has been provided a shift control device which detects the rotational speed of the engine during work traveling and automatically switches the shift speed of the transmission when the detected speed is out of an appropriate speed range. 2. Description of the Related Art Agricultural work vehicles have been put to practical use, in which a proper speed range is always maintained during running so that good work can be performed under maximum power or maximum torque.

[0005] In an agricultural work vehicle, the transmission system from the engine to the traveling device is provided with a main transmission capable of switching gear stages by selectively engaging and disengaging respective hydraulic clutches. The shift control is performed with the hydraulic clutch of the main transmission as a control target.

However, when such a shift operation is simply performed, the load applied to the traveling device and the towing work machine due to loss of the transmission torque from the engine after the hydraulic clutch corresponding to the current gear position is disconnected. As a result, the vehicle speed suddenly increases due to the return of the transmission torque accompanying the engagement of the hydraulic clutch at the corresponding speed, particularly when switching to the speed increasing speed side, and the driver is uncomfortable when shifting to the speed increasing speed. There is a problem of experiencing a shock, and various shift control devices aiming to reduce such shift shock have been proposed.

Many of the conventional proposals detect the acceleration of a vehicle with an acceleration sensor as disclosed in Japanese Patent Application Laid-Open Nos. 62-231841, 2-168068, and based on the detection result. By controlling the opening and closing of the solenoid valve and using the oil pressure continuously or stepwise adjusted by the solenoid valve as the engagement oil pressure, the engagement of the hydraulic clutch after the gear shifting operation is gently generated. It was made. However, these configurations require the acceleration sensor and control means for controlling the opening and closing of the solenoid valve based on the detection result of the acceleration sensor, which complicates the configuration of the control system and causes external electromagnetic noise and the like. There is a possibility that malfunction of the acceleration sensor and the control means may occur due to the influence of the disturbance, and there is a problem that reliability is lacking.

Under such circumstances, the applicant of the present application can mechanically generate a hydraulic pressure according to the acceleration of the vehicle without relying on electric means, and use this hydraulic pressure for engagement of the hydraulic clutch after shifting. Japanese Patent Application Laid-Open No. H11-82713 proposes a shift control device capable of performing a shift without a shift shock by using the shift control.

This device comprises a rotating shaft mechanically connected to an output side of the transmission, a rotating plate which rotates integrally with the rotating shaft, and a flywheel which is fitted to the rotating shaft so as to be relatively rotatable. A variable torsion spring that connects the flywheel and the rotary plate, and forms a variable throttle that is opened when a predetermined amount of relative rotation occurs between the flywheel and the rotary shaft on a fitting circumference of the flywheel and the rotary shaft. Then, using an angular acceleration control valve configured by arranging fixed throttles having a predetermined throttle area in series, the angular acceleration control valve is disposed downstream of the variable throttle in the middle of a hydraulic circuit connecting a hydraulic source and a low-pressure section. The line pressure generated on the discharge side of the hydraulic pressure source is reduced by a pressure reducing valve that operates as a pilot pressure using a hydraulic pressure generated between the fixed throttle and the variable throttle. For engaging with the hydraulic clutch It is obtained by a feed Kyusuru configured as a hydraulic.

According to this configuration, when an angular acceleration occurs on the output side of the transmission, the angular acceleration is caused between the flywheel and the rotating plate with the torsion of the torsion spring connecting the two. When the relative angular displacement corresponding to the above occurs and the relative angular displacement reaches a predetermined amount, the variable throttle inside the angular acceleration control valve is opened, and the pilot pressure that decreases in accordance with the opening is applied to the pressure reducing valve. Supplied. As a result, the engagement hydraulic pressure supplied to the hydraulic clutch becomes a hydraulic pressure sufficiently reduced by the operation of the pressure reducing valve in the initial stage of the engagement in which the angular acceleration is large. Is started gently to reduce shift shock. This reduction effect is obtained by the mechanical operation of the angular acceleration control valve and the pressure reducing valve, and is controlled by an electric device as disclosed in Japanese Patent Application Laid-Open Nos. 62-231841 and 2-168068. No special control means is required,
Reliable operation can be performed with a simple configuration.

[0011]

However, Japanese Patent Laid-Open No. 11-8
In the transmission control device proposed in No. 2713, the degree of pressure reduction of the hydraulic pressure for engagement of the hydraulic clutch is determined by the mechanical characteristics of the angular acceleration control valve configured as described above, more specifically, the inertia of the flywheel, While being uniquely determined by the spring constant of the torsion spring and the size of the variable throttle, the agricultural work vehicle to be controlled is provided with a manually-changeable sub-transmission in addition to the main transmission, and outputs when the speed is changed. When the angular acceleration control valve is designed by assuming the angular acceleration that occurs at the time of switching at a specific gear, the angular acceleration generated on the side of the auxiliary transmission changes depending on the gear position of the auxiliary transmission. At the time of switching at the stage, there is a possibility that the initial engagement hydraulic pressure is too high and a satisfactory effect of reducing the engagement shock may not be obtained, and conversely, the initial engagement hydraulic pressure is too low and the Needless time In addition, there is a problem that the burnout of the clutch plate of the hydraulic clutch is promoted and the durability is reduced.

[0012] These problems can be solved by selectively using a plurality of angular acceleration control valves designed for each gear position. As described above, the angular acceleration control valve has a rotating plate, a flywheel, a torsion valve, and a torsion control valve. A mechanical element including many components such as springs, and the use of a plurality of angular acceleration control valves complicates the overall configuration of the shift control device.

[0013] The above problem is not limited to the above-mentioned agricultural work vehicle, and is not limited to the shift control of various work vehicles in which the traveling device and the work device are driven by a common engine. This also occurs in a shift control performed on a screw as a drive unit for a trolling operation performed to keep the small boat at a predetermined position on the sea against the tide.

The present invention has been made in view of such circumstances, and by a small improvement of the shift control device proposed in Japanese Patent Application Laid-Open No. H11-82713, a shift shock generated at the time of shift switching is controlled by the drive state. Accordingly, it is an object of the present invention to provide a shift control device capable of effectively reducing the speed regardless of the above, and capable of stably performing driving under favorable conditions while appropriately maintaining the rotation speed of the engine.

[0015]

According to a first aspect of the present invention, there is provided a speed change control device which is capable of automatically changing gear speeds in the middle of a transmission system from an engine to a drive unit by engaging and disengaging respective hydraulic clutches. A main transmission, and a subtransmission that can manually switch gear stages. The hydraulic clutch is used to maintain a rotation speed of the engine that fluctuates according to a load of the drive unit in a predetermined speed range. In a shift control device that selectively engages and performs a shift control operation of switching a shift speed of the main transmission, a hydraulic pressure that reduces a line pressure when an angular acceleration equal to or more than a predetermined value is generated on an output side of the main transmission. An angular acceleration control valve to be generated, a means for detecting a shift speed of the auxiliary transmission, a throttle means for changing a throttle opening based on a detection result of the means, and reducing a hydraulic pressure generated by the angular acceleration control valve, Before the pressure is reduced by the throttle means The hydraulic pressure generated angular acceleration control valve operates as a pilot pressure, the line pressure and vacuum, characterized by comprising a pressure reducing valve for generating a hydraulic pressure for engagement of the hydraulic clutch.

According to the present invention, in addition to the angular acceleration control valve which operates to reduce the line pressure when an angular acceleration equal to or more than a predetermined value is generated on the output side of the main transmission, means for detecting the gear position of the auxiliary transmission is provided. And a throttle means for changing the throttle opening based on the detection result of the means, wherein the hydraulic pressure generated by the angular acceleration control valve is adjusted according to the throttle opening of the throttle means, that is, the current gear position in the auxiliary transmission. The hydraulic pressure is used as the pilot pressure of the pressure reducing valve to generate the hydraulic pressure for engagement of the hydraulic clutch, and the shift shock generated when shifting the speed of the main transmission is changed regardless of the drive state at that time. Effectively reduce.

Further, the transmission control apparatus according to the second invention is characterized in that
A throttle means in the invention, a fixed throttle separately provided in the middle of a plurality of bypass oil passages that bypass the outlet side of the angular acceleration control valve to the low pressure portion, and an on-off valve for opening and closing the bypass oil passages separately. It is characterized by having.

In the present invention, a plurality of bypass oil passages each having a separate fixed throttle and an on-off valve are arranged in parallel, and throttle means for changing the total throttle area by selectively opening and closing the on-off valve is provided. The change of the aperture area based on the result of the detection of the shift speed is easily realized by simple on / off control.

Further, the speed change control device according to the third invention has a first
The throttle means in the invention includes an electromagnetic relief valve interposed in the middle of a bypass oil passage that bypasses an outlet side of the angular acceleration control valve to a low pressure portion, and means for changing a relief pressure of the electromagnetic relief valve. It is characterized by.

In the present invention, a bypass oil passage having a single electromagnetic relief valve is formed on the outlet side of the angular acceleration control valve, and the change of the throttle area based on the result of the detection of the shift speed is changed by the relief of the electromagnetic relief valve. It is easily realized by changing the pressure.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a hydraulic circuit diagram showing a transmission control device according to the present invention, together with a configuration of a traveling transmission system of an agricultural work vehicle provided with the same.

[0022] figure E is an engine, the output of the engine E is mainly clutch C, main transmission 8a (gear ratio i _m), auxiliary transmission 8b (transmission ratio i _n), and a final reduction gear 81 Drive wheel
The agricultural work vehicle (not shown) travels by being transmitted to the drive wheel 82 and rotating the drive wheel 82.

The sub-transmission 8b is a known gear-type transmission configured to change the meshing relationship of the transmission gears by manual operation of the sub-transmission lever 14 schematically shown in the upper part of the figure to realize different gears. This shift operation is performed by interrupting the transmission from the engine E by disengaging the main clutch C by depressing a clutch pedal (not shown).

The main transmission 8a includes, as disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 9-177957 filed by the present applicant, a plurality of speed-change gears loosely fitted to a driven shaft and hydraulic pressures attached to the respective speed-change gears. And a hydraulic clutch type shift mechanism configured to selectively engage these hydraulic clutches by supply and discharge of hydraulic oil and to couple a corresponding shift gear to a driven shaft to realize a corresponding shift speed. Machine.

The shift speed of the main transmission 8a is switched by a line pressure P generated on the discharge side of a hydraulic pump P serving as a hydraulic pressure source.
₀ is selectively supplied to each other hydraulic clutch via the pressure reducing valve 83 and the shift operation valve 84. The shift operation valve 84 is
As shown in the figure, a five-position switching type directional switching valve having three forward switching positions, one reverse switching position, and a neutral position, the spool of which is attached to the main transmission. By realizing each of the above-mentioned switching positions by moving operation with the lever 15, the switching between the three forward speeds and the one reverse speed is performed. The operation of the main transmission lever 15 can be performed manually by a driver holding the main transmission lever 15 and automatically performed by the operation of a transmission actuator 9a (see FIG. 5) attached to the main transmission lever 15 as described later. I'm getting it.

[0026] The pressure reducing valve 83, when switching gear of the main transmission 8a manual or automatic, and reduces the line pressure P ₀ which is generated on the discharge side of the hydraulic pump P, hydraulic engage a corresponding hydraulic clutch The pressure guide circuit 85 is provided to reduce the shift shock caused by the sudden engagement.
It has a known configuration that a large degree of the reduced pressure with a decrease of the pilot pressure P _f applied via.

The conductive pressure circuit 85 inside the pilot pressure P _f, the output side of the main transmission 8a to be controlled, in the figure, below the angular acceleration control valve 1 in conjunction rotation with the output shaft 80 of the auxiliary transmission 8b an act of, by a change in the throttle resistance which is performed as described below in the throttle portion 7 which is arranged in the angular acceleration control valve 1, the line pressure P ₀ are no so as to obtain in vacuo.

FIG. 2 is a side sectional view showing the configuration of the angular acceleration control valve 1. As shown in FIG. As shown in the figure, the angular acceleration control valve 1 has a rotary shaft 3 rotatably supported around its axis in a cylindrical hollow portion inside a fixed housing 2. The rotating shaft 3 is supported at both ends by a pair of ball bearings 20, 21 fixedly fitted in the fixed housing 2 at positions separated by an appropriate length in the axial direction, and between the ball bearings 20, 21. Is fitted with a cylindrical oil guide cylinder 4.

Both ends of the rotating shaft 3 are projected outside the fixed housing 2, and a spur gear 30 is integrally formed at one projected end. As shown in FIG. 1, the spur gear 30 meshes with a spur gear 31 fitted on an output shaft 80 of the auxiliary transmission 8b, and the rotating shaft 3 is connected to the spur gear 31 via the spur gear 31 and the spur gear 30. The output shaft 80 is rotated around the shaft in response to the transmitted rotation.

The other protruding end of the rotary shaft 3 is covered by a cover cap 22 coaxially fixed to the outer surface of the fixed housing 2 on the same side, and is fitted to the axial center of the cover cap 22. The flywheel 5 and the rotary disk 6 are mounted between the ball bearings 23 and the ball bearings 21 at positions supported by the ball bearings 23.

The flywheel 5, which has a thick disk shape and has a large inertia, is supported by ball bearings 50, 51 fitted on the rotary shaft 3 so as to be relatively rotatable coaxially with the rotary shaft 3. ing. The rotating disk 6 is a disk having an outer shape substantially equal to that of the flywheel 5. The rotating disk 6 restricts rotation in the circumferential direction by engagement with a spline formed on the outer periphery of the end of the rotating shaft 3, and the ball bearing It is clamped from both sides by the ball bearing 23 and the ball bearing 51, and is attached while restraining the movement in a certain direction by restraining the movement in the axial direction, so that it rotates with the rotation of the rotating shaft 3.

On the surface of the flywheel 5 facing the rotating disk 6, a recess 52 having an appropriate width in the radial direction is formed over the entire circumference. The flywheel 5 of the rotating disk 6
An annular support ring 61 is protruded on the surface facing the
The support ring 61 has an appropriate gap inside and outside the
Intruded inside 52.

The support ring 61 has an annular friction ring 62.
Are externally held. The friction ring 62 is engaged with the support ring 61 by an engagement pin 63, restricts rotation in the circumferential direction, and is mounted to allow movement in the axial direction. One end face of the friction ring 62 is pressed and urged by a coil spring 64 interposed between the one end face of the friction ring 62 and the side face of the rotating disk 6 opposed thereto. The end face is pressed against the side surface of the flywheel 5. The flywheel 5 and the rotating disk 6 are connected via a torsion spring 65 disposed inside the support ring 61, and a relative angular displacement between the two is allowed by the torsion of the torsion spring 65. It has been done.

The outer peripheral surface of the rotary disk 6 has a tooth surface on which a predetermined number of teeth are formed, and faces the inside of a sensor seat 24 formed through the peripheral wall of the cover cap 22. The rotation of the rotating shaft 3 is performed by a magneto-electric type rotation sensor (axle-equivalent rotation sensor 11) attached to the sensor seat 24, as shown by a two-dot chain line in the figure, with the number of teeth on the outer periphery of the rotating disk 6 as a medium. It can be detected.

When the rotary shaft 3 rotates, the flywheel 5 supported by the rotary shaft 3 via the ball bearings 50 and 51 has a rotary disk 6 which rotates integrally with the rotary shaft 3. By the pressing of the held friction ring 62, a frictional resistance acts in the same direction as the rotation direction of the rotating disk 6 and the rotating shaft 3, and the flywheel 5 operates in a steady state in which the rotating shaft 3 maintains a substantially constant rotation speed. During the rotation, the rotating disk 6 and the rotating shaft 3 follow and rotate at the same speed by the action of the frictional resistance.

On the other hand, the rotation speed of the rotating shaft 3 fluctuates,
When an angular acceleration occurs, the flywheel 5 tries to maintain the current rotational speed by its own inertia, and the relative angle with the torsion of the torsion spring 65 between the rotating shaft 3 and the rotating disk 6 rotating integrally. Displacement occurs. This relative angular displacement is
Of the torsion spring 65 and the torsion restoring force of the torsion spring 65, the flywheel 5 and the rotating disc 6
And a relative angular displacement corresponding to the magnitude of the angular acceleration of the rotating shaft 3 is generated.

As shown in FIG. 2, at the axis of the rotating shaft 3,
An oil guide hole 32 is formed, and in the middle of the oil guide hole 32,
A fixed aperture is fitted and fixed with an aperture ring with a small aperture.
Are formed. On both sides of the fitting position, oil supply holes 35 and oil supply holes 36 penetrating through the rotating shaft 3 in the radial direction communicate with respective annular grooves formed around the outer periphery of the rotating shaft 3. The oil guide cylinder 4 is connected to an oil supply hole 25 and an oil supply hole 26 formed in the fixed housing 2 through communication holes 40 and 41 formed at corresponding positions of the oil guide cylinder 4.

The leading end portion 39 of the oil guide hole 32 reaching the fitting portion with the flywheel 5 is communicated with the outer peripheral surface of the rotating shaft 3 by an oil guide hole 37 continuously connected radially outward. The inner peripheral surface of the flywheel 5 fitted to the communication position communicates with the arrangement chamber of the ball bearing 51 that supports one side of the flywheel 5 by a drain groove 53 formed at a predetermined position in the circumferential direction. The variable throttle 38 is constituted by the drain long groove 53 and the oil guide hole 37.

FIG. 3A is a cross-sectional view of the fitting portion of the rotary shaft 3 and the flywheel 5 at the position where the variable throttle 38 is configured. As shown in the drawing, the oil guide hole 37 and the drain groove 53 are formed at positions opposed to each other in the radial direction in a steady state where the relative angular displacement θ of the flywheel 5 with respect to the rotating shaft 3 does not occur. is a magnitude corresponding to the angular acceleration preset in both the forward and reverse directions (= θ _r =
When θ _f ) is reached and the direction of the oil guide holes 37 becomes as shown by the broken lines in the figure, they communicate with each other and the variable throttle 38 is opened.

The upstream side of the fixed throttle 34 is provided with the oil supply hole 2.
5, the communication hole 40, and is connected to the discharge side of the hydraulic source serving as a hydraulic pump P through the oil supply hole 35, the line pressure P ₀ of the hydraulic pump P is generated has been introduced. Further, the downstream side of the variable throttle 38 communicated with the inside of the cover cap 22 by the drain long groove 53 is set in a low pressure state by the oil drain hole 27 formed in the fixed housing 2 so as to communicate with the lower part of the cover cap 22. It is communicated with the kept oil tank T.

With the above arrangement, when the variable throttle 38 is in the open state, the line pressure P ₀ introduced into the oil guide hole 32 is reduced by passing through the fixed throttle 34 and guided to the tip portion 39, and The pressure is reduced by passing through a variable throttle 38 formed by the hole 37 and the drain groove 53, and flows into the installation room of the ball bearings 50 and 51, lubricating the ball bearings 50 and 51 and staying in the cover cap 22. Thereafter, the oil is discharged to the oil tank T through the oil drain hole 27.

At this time, the oil feed hole 26 communicating between the fixed throttle 34 and the variable throttle 38 has a hydraulic pressure P after passing through the fixed throttle 34.
₁ can be taken out. This output oil pressure P ₁ is maintained at a constant pressure substantially equal to the line pressure P ₀ while the angular acceleration of the rotary shaft 3 is small and the variable throttle 38 is in the closed state, and the angular acceleration increases. , The downstream variable throttle 38 is opened and decreases rapidly. FIG. 3B shows the rotating shaft 3.
The relationship between the relative angular displacement θ of the flywheel 5 and the output oil pressure P ₁ is shown.

The output oil pressure P showing such a change mode
₁ is taken out of the fixed housing 2 through the oil feed hole 36, the communication hole 41 and the oil feed hole 26, and as shown in FIG.
The pressure is further regulated in accordance with the open / close state of the throttle unit 7 provided in parallel with the angular acceleration control valve 1, and the pressure reducing valve is
The pilot pressure P _f applied to 83.

As shown in FIG. 1, each of the three throttle oil passages for bypassing between the fixed throttle 34 and the variable throttle 38 of the angular acceleration control valve 1 to the oil tank T is provided with a fixed throttle. 70, 71, 72 and on-off valves 73, 74, 75 are provided.

Each of the fixed throttles 70, 71, 72 has a throttle area that increases in this order, and the corresponding on-off valves 73, 74, 75
Is selectively opened, the fixed aperture 34 and the variable aperture
38, an oil flow is generated that returns to the oil tank T via each of the bypass oil passages in a state where the throttle resistance according to the area of the corresponding fixed throttle 70, 71, 72 is applied. It is.

[0046] branch position of the bypass fluid passage, the output pressure P ₁ of the operation of the angular acceleration control valve 1 is obtained by reducing the pressure of the line pressure P ₀ have been taken out, the output hydraulic pressure P _1, the when closing valve 73, 74 and 75 is opened, it is further reduced pressure in response to the occurrence of the bypass oil flow to the oil tank T, transmitted to the conductive pressure circuit 85 which is branched at the same position as the pilot pressure P _f Is done.

The vacuum degree during the opening of the on-off valve 73, 74, 75 may vary according to the size of the aperture area of the corresponding fixed stop 70, 71, 72, the pilot pressure P _f, the fixed throttle large area When the on-off valve 75 corresponding to 72 is opened, the pressure becomes low, and when the on-off valve 73 corresponding to the small-area fixed throttle 70 is opened, the pressure becomes high when the on-off valve 73 is opened. Intermediate pressure is reached when 74 is released. Further, when all of the on-off valve 73, 74, 75 is in the closed state, the pilot pressure P _f, the output oil pressure P of the angular acceleration control valve 1
It is equal to ₁ (P _f = P ₁₎ the maximum pressure.

[0048] Thus, the pilot pressure P _f sent via the conductive pressure circuit 85 during the operation of the angular acceleration control valve 1, the operation of the throttle portion 7 and, more specifically, the on-off valve 73, 74 and 75 the opening and closing operations, are pressure is adjusted in four steps the output hydraulic pressure P ₁ of the angular acceleration control valve 1 as the highest pressure. This change is realized as described later according to the gear position of the sub-transmission 8b provided in parallel with the main transmission 8a to be controlled. Incidentally, by opening the on-off valve 73, 74, 75 by suitably combining, is susceptible to pressure regulating pilot pressure P _f in addition multistage, the pressure regulating step, the auxiliary transmission 8b It suffices that the same number of gear stages exist. In the following description, the on-off valves 73, 74, and 75 are individually opened and closed, and the pilot pressure P is set in accordance with the four gear stages realized in the auxiliary transmission 8b. A configuration in which _f is regulated in four stages will be described.

FIG. 4 is a plan view showing an example of the configuration of the sub-transmission lever 14 for switching the gear position of the sub-transmission 8b. The sub-transmission lever 14 can be moved along an H-shaped guide groove 16 and has four transmission positions (I to I in the figure) respectively set at both ends of the lateral sides of the H-shape. (Position indicated by IV), it is possible to switch to the corresponding gear. The gear position of the current sub transmission 8b for thus switching the auxiliary transmission switch LW ₁ ~LW ₄ which are respectively distributing the shift position of the I~IV is turned on in contact with a portion of the auxiliary shift lever 14 This is to be detected.

FIG. 5 is a plan view showing a configuration example of the main shift lever 15 for switching the gear position of the main transmission 8a. The main shift lever 15 can be moved along a guide groove 17 which is formed by connecting two vertical sides by a horizontal side and bending into a crank shape. One shift position (position shown as A to C in the drawing) and a neutral position (position shown as N in the drawing), and one shift position for reverse set at the end of the short vertical side Position (the position shown as R in the figure) to thereby control the shift operation valve.
By moving the spool 84 to the corresponding position, it is possible to realize three forward speeds and one reverse speed.

The switching of the three forward speeds in the main transmission 8a can be automatically performed by the operation of the speed change actuator 9a in addition to the manual operation. The speed change actuator 9a can be constituted by a hydraulic cylinder having its output rod engaged near the base of the main speed change lever 15 as shown in the figure. The guide groove 17 is moved along the long vertical side, and is positioned at the shift positions A to C set along the vertical side. These shift position A, B, and are each and C, Yes by arranging the main speed change switch SW ₁ to SW ₃ for turning on the contact between a portion of the main shift lever 15, the by advancing and retracting operation of the shift actuator 9a shift position a, B, realization of C, the main speed change switch SW ₁ to SW ₃
Is turned on and off in a stepwise and reliable manner. Further, the engagement between the main transmission lever 15 and the transmission actuator 9a is released by moving the main transmission lever 15 along the lateral side of the guide groove 17, and the movement of the main transmission lever 15 to the reverse position R is It can only be done manually.

FIG. 6 is a block diagram showing the configuration of the control system of the speed change control device according to the present invention. In the figure, reference numeral 9 denotes a shift control unit using a microprocessor. An input side of the shift control unit 9 includes an engine rotation sensor 10 for detecting the number of revolutions of the engine E, and an output side of the main transmission 8a ( Auxiliary transmission
An output signal of the axle-equivalent rotation sensor 11 for detecting the rotation speed of the output shaft 80) of 8b is provided. These rotation sensors
Reference numerals 10 and 11 are shown in FIG.
As shown in FIG. 2, the sensor seat 24 of the angular acceleration control valve 1
A magneto-electric rotation sensor mounted as shown in FIG.

The input of the shift control section 9 is supplied with the outputs of a throttle sensor 12 for detecting the throttle opening of the engine E and a main clutch sensor 13 for detecting the engagement of the main clutch C. On the input side of the shift control unit 9, the auxiliary shift switches LW ₁ to LW ₁ to
LW ₄ is connected, and the shift control unit 9 determines whether the auxiliary transmissions LW _{1 to} LW ₄ are on or off,
The present speed stage in 8b can be recognized. Note in the figure, is shown by the four auxiliary transmission switch LW ₁ ~LW ₄ one block.

[0054] Also, the input side of the transmission control unit 9, the main shift switches SW ₁ ~ to be turned on by the contact with the main shift lever 15
SW ₃ is connected, the shift control unit 9, these on-off state of the main transmission switch SW ₁ to SW _3, forms so as to recognize the shift speed of the main transmission 8a is changed as described below is there. In the figure, three sub speed change switches SW _{1 to} S
The W ₃ is shown by one block.

Further, on the input side of the shift control section 9, a mode switch 18 for switching between manual shift and automatic shift is provided.
Is connected. This mode changeover switch 18 is provided as shown in FIG.
As schematically shown in FIG. 3, a two-position switch type switch disposed on the tip knob of the sub-transmission lever 14 can be used. When this switch is operated to the automatic side, the shift speed of the main transmission 8a is changed. The operation is performed by the above-described operation of the actuator 9a.

On the other hand, the output of the shift control unit 9 is given to a shift actuator 9a for switching the shift speed of the main transmission 8a. The shift actuator 9a receives a shift-up command given from the shift control unit 9 or The advancing / retreating operation is performed in response to the downshift command, so that the shift speed is switched as described above. When the above-described hydraulic cylinder is used as the shift actuator 9a, the output of the shift control unit 9 is supplied to an electromagnetic switching valve provided in a hydraulic feed circuit of the shift actuator 9a to switch the supply direction of the working oil pressure. can do.

Further, the output of the shift control unit 9 is output from the throttle unit 7.
More specifically, the on-off valves 73, 74, and 75 of the throttle unit 7 are respectively provided to the on-off valves 73, 74, and 75, and these on-off valves 73, 74, and 75 respond to an operation command given from the transmission control unit 9. Each is opened and closed individually. The on-off valves 73, 74, 75
For example, it can be configured as a normally-closed electromagnetic valve that is opened in response to energization of the solenoid, and an operation command from the shift control unit 9 is given as a signal for turning on and off the excitation circuit of each other solenoid.

The shift control section 9 has a mode changeover switch 18 connected to the input side, which is switched to an automatic side.
The following procedure is performed on the condition that the throttle opening input from the throttle sensor 12 is equal to or greater than a predetermined opening and that the main clutch C is determined to be in the engaged state by the input from the main clutch sensor 13. Performs a shift control operation for automatic shifting. That is, an automatic shift operation can be realized by switching the mode changeover switch 18 to the automatic side without fixing the throttle lever for the slot operation to an appropriate position, and performing the depression operation of the clutch pedal, without performing the depression operation of the clutch pedal. In addition to switching the mode changeover switch 18 to the manual side, the lock is also released by releasing the fixing of the throttle lever or depressing the clutch pedal.

FIG. 7 is a flowchart showing the operation of the shift control section 9. The shift control unit 9 that has started the shift control operation when the above-described conditions are satisfied captures the output of the engine rotation sensor 10 connected to the input side, and thereby recognizes the current rotation speed N of the engine E (step S).
1), which checks whether it exceeds the upper limit rotational speed N ₁ set in advance (step S2), and then checks whether below the minimum rotational speed N ₂ which is set in advance (step S3).

FIG. 8 is a characteristic diagram showing general output characteristics of engine E. As shown by the solid line in the figure, generating power L of the engine increases with an increase in the rotational speed, the maximum value L _max becomes at a predetermined rotational speed N _3,
After that, it decreases conversely as the rotation speed increases. Further, as shown by the dashed line in the figure, the output torque T of the engine is increased with the increase of the rotational speed, the maximum value T _max in small rotational speed N ₄ than the rotational speed N ₃
, And thereafter decreases with an increase in the rotation speed.

The upper limit rotational speed N ₁ used in the comparison in step S 2 is slightly higher than the rotational speed N _{3 at} which the generated power L of the engine E takes the maximum value L _max , and conversely, the lower limit used in the comparison in step S ₃ rotational speed N _2, the output torque T of the engine E is set slightly lower than the rotational speed N ₄ having the maximum value T _max.

As a result of the determinations in steps S2 and S3, the shift control unit 9 determines that the current rotational speed N of the engine E is N
₂ or more, if the fall in the range of N ₁ or less, the maximum value L of the generating power L and the output torque T is each of the engine E
_max, close to the T _max, current running state of is determined to be proper, the process returns to step S1 without performing also any shift operation, receives the output of the engine rotation sensor 10 again, and repeats the same determination.

[0063] On the other hand, the result of the comparison in the step S2, when the rotational speed N of the engine E is determined to exceed the upper limit speed N _1, the shift control unit 9, the time t ₁ elapses by counting the built-in timer was whether the checked (step S4), and if the same state is continued until time t ₁ has elapsed, it is determined that the rotational speed N of the current engine E is excessive, first, the output-side shift actuator 9a to issue a shift-up command and allowed one-step upshift the gear position of the current situation is recognized by the input from the main transmission switch SW ₁ to SW ₃ with (step S5), and the input from the auxiliary transmission switch LW ₁ ~LW ₄ An open command is issued to the throttle unit 7 in accordance with the current gear position of the recognized sub-transmission 8b, and the on-off valves 73, 74, 75
Is selectively opened to change the aperture resistance of the aperture section 7 (step S6), and a series of operations is completed.

When it is determined that the rotation speed N of the engine E is lower than the lower limit speed N ₂ as a result of the comparison in step S 3, the transmission control unit 9 has elapsed the time t ₂ by counting the time of the built-in timer. whether the checked (step S7), and if the same state is continued until time t ₂ has elapsed, it is determined that the rotational speed N of the current engine E is too small, the shift down speed change actuator 9a of the output side Issues a command,
The gear of the main transmission 8a recognized by the input from the main transmission switch SW ₁ to SW ₃ allowed to one step downshift with (step S8), and the sub is recognized by the input from the auxiliary transmission switch LW ₁ ~LW ₄ An opening command is issued to the throttle unit 7 in accordance with the current gear position of the transmission 8b, and the opening / closing valves 73, 74, and 75 are selectively opened to change the throttle resistance of the throttle unit 7 (step S9). Finish the operation.

After the operation of step S6 or S9 is completed, the shift control unit 9 sets the. It is determined whether or not switching to the manual mode has been performed by each of the above-described operations (step S10). If the automatic mode is continued, the process returns to step S1 to repeat the same operation.

[0066] or more agricultural work vehicle by the operation of the shift control unit 9, rotational speed of the engine E, the upper limit speed N ₁ or less, there is a lower limit speed N ₂ or more proper speed range, the engine E
However, the vehicle travels while maintaining a desirable driving state near the maximum power _Lmax or the maximum torque _Tmax , and good driving performance can be obtained during work traveling performed by pulling the work implement.

The main transmission 8a according to a command from the transmission control unit 9
Upshifting and downshifting are performed by pushing and pulling the main shift lever 15 by the operation of the shift actuator 9a to move the spool of the shift operation valve 84, and to supply hydraulic pressure to the hydraulic clutch corresponding to the previous shift stage. After stopping and disengaging the hydraulic clutch, the procedure is started by starting the hydraulic pressure supply to the hydraulic clutch corresponding to the next shift speed and engaging the hydraulic clutch. During this procedure, the final hydraulic pressure for engaging the hydraulic clutch reduces the line pressure P ₀ according to the angular acceleration generated on the output side of the auxiliary transmission 8b by the operation of the angular acceleration control valve 1, and reducing valve pilot pressure P _f obtained by vacuum in accordance with the throttle resistance applied in accordance with the opening and closing of the valve 73, 74, 75 in the throttle section 7 acts
Generated by 83 operations.

The agricultural work vehicle during work traveling is subjected to the road surface resistance of the drive wheels 82 and the traction resistance of the work implement. When the gear is switched in this state, the gear corresponding to the previous gear is applied. With the disconnection of the hydraulic clutch, the vehicle speed decreases due to the loss of transmission torque from the engine, and the rotation speed of the output side of the main transmission 8a, that is, the output shaft 80 of the auxiliary transmission 8b, decreases. The degree of such a decrease in the rotational speed differs depending on the vehicle speed before switching, that is, depending on the speed of the auxiliary transmission 8b.
Generally, the higher the shift speed before the changeover is, the higher the speed is.

In the present invention, when the rotational speed of the output shaft 80 decreases, the angular acceleration control valve 1 operates according to the occurrence of the angular acceleration of the output shaft 80, and the output at which the line pressure P ₀ is reduced is output. The oil pressure P ₁ is taken out, and the output oil pressure P ₁
Is reduced by the operation of the throttle section 7, and a pilot pressure _Pf is generated. As described above, the degree of pressure reduction in the throttle unit 7 depends on which of the on-off valves 73, 74, and 75 is opened, and whether or not these valves are opened depends on whether the sub-transmission 8b Determined by the column.

Therefore, when the gear is at the lowest speed I, the on-off valve 75 corresponding to the fixed throttle 72 having a large area is opened, and when the gear is in the gear II, the on-off valve 74 is opened. If each of the valves 73, 74 is opened, and all of the on-off valves 73, 74, 75 are closed when in the highest gear IV,
The pilot pressure P _f, when the angular acceleration equal to or greater than a predetermined said output shaft 80 is generated, becomes lower as the gear position of the sub-transmission 8b is on the low speed side, such pilot pressure P
The operation of the pressure reducing valve 83 in accordance with the feed of _f generates the hydraulic pressure for engaging the hydraulic clutches for realizing the respective gears of the main transmission 8a, so that the re-engagement of these hydraulic clutches starts smoothly. Is done. Figure 9 is a diagram showing the relationship between the opening and closing state of the opening and closing valve 73, 74, 75 the pilot pressure P _f.

In this engaged state, the output speed of the main transmission 8a increases in a constant acceleration state and converges due to transmission via the hydraulic clutch which is half-engaged inside the main transmission 8a. , Until the angular acceleration becomes zero and the variable throttle 38 of the angular acceleration control valve 1 is closed. Therefore, the speed change operation of the main transmission 8a can be reliably performed without causing unpleasant shift shock. At this time, hydraulic engagement of the hydraulic clutch, because they give by the operation of the pressure reducing valve 83 in accordance with the action of the pilot pressure P _f, it is possible to secure a sufficient amount of hydraulic oil, high responsiveness Is obtained.

In the above-described embodiment, the throttle section is provided with the fixed throttles 70, 71, 72 having different throttle areas, and the on-off valves 73, 74, 75 for opening and closing the bypass oil passage in which these are provided. Although the diaphragm 7 is configured, the aperture section can be realized by another configuration.

FIG. 10 is a hydraulic circuit diagram showing another embodiment of the shift control device according to the present invention having a throttle portion 7 of another configuration. The throttle unit 7 in the figure includes an electromagnetic relief valve 77 in the middle of a single bypass oil passage 76 that bypasses the fixed throttle 34 and the variable throttle 38 of the angular acceleration control valve 1 to the oil tank T. By changing the relief pressure of the electromagnetic relief valve 77, the output oil pressure P1 of the angular acceleration control valve ₁ is reduced,
Pressure guiding circuit 85 branched at the same position as the bypass oil passage 76
And it has a configuration for transmitting a pilot pressure P _f in.
The configuration of the other parts is the same as that shown in FIG. 1, and the corresponding components are denoted by the same reference numerals, and description thereof will be omitted.

According to this configuration, a single valve (electromagnetic relief valve 77) is controlled so that a smooth shift with little shift shock is possible. There is a problem that the stepwise opening control of 77 is required, and the configuration of the control system becomes slightly complicated.

In the above embodiment, an example of application to an agricultural work vehicle has been described. However, the present invention can be applied to shift control of a work vehicle for various works other than farm work. Needless to say, the present invention is also widely applied to a shift control in which a shift stage of a hydraulic clutch type transmission arranged in a transmission system from an engine to a screw as a drive unit is switched in a boat such as a fishing boat. be able to.

[0076]

As described above in detail, in the transmission control apparatus according to the first aspect of the present invention, when an angular acceleration equal to or more than a predetermined value is generated on the output side of the main transmission, the hydraulic pressure generated by the operation of the angular acceleration control valve is provided. Is further reduced by throttle means for changing the throttle area based on the result of detection of the gear position of the auxiliary transmission, and is used as pilot pressure of a pressure reducing valve that generates hydraulic pressure for engagement of the shift hydraulic clutch of the main transmission. Therefore, for example, a shift shock generated at the time of shift switching performed during work traveling in an agricultural work vehicle can be effectively reduced regardless of the state before shifting, and can be controlled to a constant acceleration, and the engine can be controlled. It is possible to stably perform work traveling under good conditions with proper rotation speed, and reduce wear of the clutch plate of the hydraulic clutch for shifting, and durability It can be improved.

Further, in the transmission control apparatus according to the second aspect of the present invention, a plurality of bypass oil passages each having a separate fixed throttle and an on-off valve and bypassing the outlet side of the angular acceleration control valve to the low pressure section are further provided. In the shift control device according to the above, each of the throttle means for changing the throttle area based on the detection result of the shift speed by an electromagnetic relief valve arranged in the middle of a bypass oil passage that bypasses the outlet side of the angular acceleration control valve to the low pressure portion. With this configuration, the present invention provides excellent effects, such as reduction of shift shock accompanying shift change can be realized with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a transmission control device according to the present invention.

FIG. 2 is a side sectional view showing a configuration of an angular acceleration control valve.

FIG. 3 is a transverse cross-sectional view of a fitting portion of a rotary shaft and a flywheel.

FIG. 4 is a plan view showing a configuration example of a sub-transmission lever.

FIG. 5 is a plan view showing a configuration example of a main transmission lever.

FIG. 6 is a block diagram showing a configuration of a control system of the transmission control device according to the present invention.

FIG. 7 is a flowchart showing an operation content of a shift control unit.

FIG. 8 is a characteristic diagram showing output characteristics of an engine.

FIG. 9 is a diagram showing a relationship between an open / close state of an on-off valve and a pilot pressure.

FIG. 10 is a hydraulic circuit diagram showing another embodiment of the shift control device according to the present invention.

[Explanation of symbols]

Reference Signs List 1 angular acceleration control valve 7 throttle section 8a main transmission 8b sub transmission 9 transmission control section 9a transmission actuator 10 engine rotation sensor 14 auxiliary transmission lever 15 main transmission lever 70, 71, 72 fixed throttle 73, 74, 75 opening / closing valve 76 Bypass oil passage 77 Electromagnetic relief valve 83 Pressure reducing valve E Engine P Hydraulic pump R Shift lever CW ₁ -CW ₄ Sub-shift switch LW ₁ -LW ₄ Sub-shift switch

Claims (3)

[Claims] 1. A main transmission capable of automatically changing gear positions by engaging and disengaging respective hydraulic clutches in a transmission system from an engine to a drive unit, and a subtransmission capable of manually changing gear positions. Gears for selectively engaging and disengaging the hydraulic clutch to change the gear position of the main transmission in order to maintain a rotation speed of the engine that fluctuates according to a load of the drive unit in a predetermined speed range. A shift control device that performs a control operation, wherein when an angular acceleration equal to or more than a predetermined value is generated at an output side of the main transmission, an angular acceleration control valve that generates a hydraulic pressure that reduces a line pressure, and detects a shift speed of the auxiliary transmission. Means for changing the opening degree of the throttle based on the detection result of the means to reduce the hydraulic pressure generated by the angular acceleration control valve; and controlling the hydraulic pressure generated by the angular acceleration control valve reduced by the throttle means by a pilot. Works as pressure , Shift control device, characterized in that the line pressure and vacuum; and a pressure reducing valve for generating a hydraulic pressure for engagement of the hydraulic clutch. 2. The throttle device according to claim 1, wherein the throttle means includes a fixed throttle separately provided in the middle of a plurality of bypass oil passages for bypassing an outlet side of the angular acceleration control valve to a low-pressure portion, and individually opens and closes the bypass oil passages. The shift control device according to claim 1, further comprising an on-off valve that performs the operation. 3. An electromagnetic relief valve interposed in the middle of a bypass oil passage that bypasses an outlet side of the angular acceleration control valve to a low pressure section, and a means for changing a relief pressure of the electromagnetic relief valve. The shift control device according to claim 1, further comprising: