JP2011191228A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working vehicle capable of adding a driving speed difference between right and left traveling devices to the speed of an operating vehicle, and suppressing the manufacturing cost to a low level, concerning a working vehicle which includes a control part for operating the vehicle speed of a traveling machine body having a pair of right and left traveling devices. <P>SOLUTION: The working vehicle includes the traveling machine body 6 which is travelled and driven by the pair of right and left traveling devices 1, 1. The vehicle is provided with each transmission formed by combining a hydraulic pump with a hydraulic motor 30, respectively on each of the right and left traveling devices 1, 1, and with each operation lever for performing speed-change operation of the transmission respectively on each transmission. The working vehicle also has the control unit for operating the vehicle speed of the traveling machine body 6. The vehicle is further provided with each operation position detection means for detecting then operation position of the operation lever, respectively on each of the pair of transmissions, and the control unit operates the vehicle speed of the traveling machine body 6 from the engine rotation frequency and the operation position of the operation lever. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a work vehicle including a control unit that calculates a vehicle speed of a traveling machine body.

  Patent Document 1 comprising a pair of left and right traveling devices and a main transmission lever potentiometer for detecting the operation position of the main transmission lever, and having a control unit for calculating the vehicle speed of the traveling machine body from the engine speed and the operation position of the main transmission lever The work vehicle shown in FIG. 2 is publicly known, and the work vehicle configured as described above cannot take into account the difference in drive speed between the left and right traveling devices, and therefore the vehicle speed of the traveling machine body may not be calculated correctly when turning. On the other hand, a control unit for providing a rotation sensor such as a pickup sensor for detecting the driving speed of the traveling device for each of the left and right traveling devices and calculating the vehicle speed of the traveling machine body based on the detection results of the pair of rotation sensors. The work vehicle shown in Patent Document 2 including the above is well known, and according to the control unit, the vehicle speed of the traveling machine body in consideration of the turning and the like can be calculated.

JP 2003-303021 A JP 2006-84315 A

However, in the work vehicle described in the above document, since the rotation sensor itself provided in each traveling device is expensive, it is difficult to keep the manufacturing cost low, and the rotation sensor is attached to the traveling device that travels on muddy water in the field. It is necessary to take a waterproof measure when it is provided, and it is difficult to keep costs low from this point.
The present invention is a work vehicle including a control unit that calculates a vehicle speed of a traveling machine body having a pair of left and right traveling devices, and a difference in drive speed between the left and right traveling devices can be added to the calculated vehicle speed. It is an object of the present invention to provide a work vehicle that can keep manufacturing costs low.

  In order to solve the above-described problem, a work vehicle according to the present invention firstly includes a traveling machine body 6 that is driven to travel by a pair of left and right traveling devices 1, 1, and a transmission that combines hydraulic pumps 31 </ b> A and 31 </ b> B and a hydraulic motor 30. Is provided for each of the left and right traveling devices 1 and 1, and operating levers 32 </ b> A and 32 </ b> B for shifting the transmission are separately provided for each of the transmissions, and a work vehicle having a control unit that calculates the vehicle speed of the traveling machine body 6. , Operating position detecting means 47A, 47B for detecting the operating positions of the operating levers 32A, 32B are provided for each pair of transmissions, and the control unit determines the traveling machine body from the engine speed and the operating positions of the operating levers 32A, 32B. 6 vehicle speed is calculated.

  Secondly, it includes a sub-transmission device 30 that performs shift switching of the power transmitted to the traveling devices 1 and 1, and a switching means 54 that performs shift switching of the sub-transmission device 30, and the control unit detects the operation position detection unit. Only when the neutral state of each transmission device is detected by 47A and 47B, the shift switching of the auxiliary transmission device 30 is performed via the switching means 54.

  According to the work vehicle of the present invention configured as described above, by detecting the traveling speed of each of the left and right traveling devices from the operation position of the operating lever that operates the transmission and the engine speed, the influence of turning and the like is detected. In addition, the vehicle speed of the traveling aircraft can be calculated in consideration of the above, so it is possible to keep costs low compared to the case where a rotation sensor such as a pick-up sensor is provided for each traveling device to calculate the vehicle speed considering the effects of turning etc. There is an effect that.

  Further, the control device includes a sub-transmission device that performs a shift switching of power transmitted to the traveling device, and a switching unit that performs a shift switching of the sub-transmission device, and the control unit detects the neutral state of each transmission device by the operation position detection unit. Only when it is detected, by performing the shift switching of the sub-transmission device via the switching means, it is possible to perform the shift switching of the sub-transmission device at an appropriate timing using the operation position detection means.

1 is an overall perspective view of an agricultural tractor to which a work vehicle of the present invention is applied. It is a top view which shows the control part in a cabin. It is the figure which showed the front panel. It is a perspective view which shows the structure of the mechanical linkage from a travel shift lever to a transmission device, and the mechanical linkage from a steering handle to a transmission device. It is a perspective view which shows the structure of a link mechanism. It is a front view which shows the structure of a link mechanism. It is a block diagram which shows the structure of a control part. It is a characteristic graph which shows the value of the vehicle speed of the traveling body with respect to the operating angle of the operating arm when the engine is rotated at a rated speed and the traveling body is traveling straight. It is a flowchart of the calculation process of the vehicle speed of the traveling body which a control part performs. It is a processing flowchart regarding another embodiment of the vehicle speed calculation which a control part performs.

Embodiments of the present invention will be described below based on the illustrated example.
FIG. 1 is an overall perspective view of an agricultural tractor to which a work vehicle of the present invention is applied. The tractor shown in the figure is provided with an openable / closable bonnet 3 for accommodating an engine (not shown) on the front side of a body frame 2 supported by a pair of left and right crawler type traveling devices 1 and 1 (traveling device). A traveling machine body 6 is configured by erecting a cabin 4 behind the hood 3 of the machine body frame 2, and a working machine (such as a rotary tiller) is provided at the rear of the traveling machine body 6 via a lifting link (not shown). (Not shown) are coupled so as to be able to be driven up and down.

  The left and right crawler type traveling devices 1, 1 include a crawler frame 10 in the front-rear direction, a drive sprocket 8 and an idler wheel 9 that are rotatably supported on the front and rear of the crawler frame 10, and the drive sprocket 8 and idler wheel 9. And a crawler 11 wound around.

  Engine power is transmitted to the drive sprocket 8 via a transmission installed below the cabin 4, thereby driving the vehicle body. Incidentally, in this tractor, the left and right drive sprockets 8 are rotated at the same drive speed to cause the traveling machine body 6 to travel straight, while the left and right drive sprockets 8 are rotated at different drive speeds to turn the vehicle body.

  FIG. 2 is a plan view showing a control unit in the cabin. The steering unit includes a seat 12 on which an operator is seated, a steering handle 13 that is a steering operation tool disposed in front of the seat 12, and a side operation panel 14 that is disposed on the right (right) side of the seat 12 in the traveling direction. And a front panel 16 disposed in front of the steering handle 13 and a parking brake switch 17 disposed on the left side of the steering handle 13, and a floor step serving as a floor surface between the seat 12 and the steering handle 13. 18 is formed.

  The parking brake switch 17 is a push-operated changeover switch that performs an alternate operation, and switches between a travel regulation state in which a parking brake described later is in an on state and a travelable state in which the parking brake is off. Can do.

  The side operation panel 14 includes a travel shift lever 19 that performs a travel shift by a forward / backward swing operation, an auxiliary shift switch 21 (switching operation tool) provided in a grip portion of the travel shift lever 19, and a forward / backward swing operation. Is provided with an accelerator lever 22 for changing the engine speed.

  The auxiliary transmission switch 21 is a push operation type changeover switch that performs an alternate operation, and a later-described control unit switches a later-described traveling motor 30 that functions as an auxiliary transmission device into at least two stages of high speed and low speed.

  FIG. 3 shows the front panel. The front panel 16 is brought into a travel regulation state by a meter 23 that displays an analog display of the engine speed, a liquid crystal panel 24 that is a display unit that digitally displays the vehicle speed (traveling speed) of the traveling machine body 6, and the parking switch 17. A parking lamp 26 that lights up when switched, and a high-speed lamp 27 that lights up when switched to the “high speed” state by the auxiliary transmission switch 21 are provided.

Next, the structure of the mechanical linkage from the travel shift lever to the transmission device and the mechanical linkage from the steering handle to the transmission device will be described with reference to FIGS.
FIG. 4 is a perspective view showing a configuration of mechanical linkage from the travel shift lever to the transmission and mechanical linkage from the steering handle to the transmission. As shown in the figure, the transmission device includes a work machine transmission case 28 in which a speed change mechanism for shifting engine power is installed on the work machine side and is disposed directly below the floor surface, and a pair of crawler type traveling devices 1, HST (transmission) which is a hydraulic stepless transmission provided separately for each one and attached to the front side of the work machine transmission case 28 so that the engine power is input and the power is transmitted to the HST side etc. A fixed gear case 29 is provided.

  Each HST includes HST pumps 31A and 31B that are hydraulic pumps installed on the upper surface side of the work machine transmission case 28 and a traveling motor 30 that is a hydraulic motor that drives the corresponding drive sprocket 8 of the crawler traveling devices 1 and 1. (Refer to FIG. 1), and the HST performs stepless shift of the power transmitted to the corresponding crawler type traveling devices 1, 1 and performs forward / reverse switching. That is, by this HST, stepless speed change switching is performed, and the traveling body 6 is switched forward and backward.

  Then, hydraulic oil is pumped to the traveling motor 30 side by the HST pumps 31A and 31B driven by engine power input from the gear case 29, whereby the traveling motor 30 is operated to drive the crawler traveling devices 1 and 1. . At this time, by changing the inclination of a swash plate (not shown) provided in the HST pumps 31A and 31B, the amount of hydraulic oil supplied to the traveling motor 30 per unit time can be changed steplessly. By continuously changing the amount of working oil supplied to the motor 30 per unit time, the driving speed of the traveling motor 30 is changed steplessly.

  That is, each HST is configured to change the power transmitted to each corresponding crawler type traveling device 1, 1 steplessly by changing the inclination of the swash plate of the HST pumps 31A, 31B. The tilt change is performed by swinging the operating arms 32A and 32B supported on the side surfaces of the HST pumps 31A and 31B back and forth. The operating arms 32A and 32B supported by the HST pumps 31A and 31B so as to be able to swing back and forth are mechanically connected to the traveling speed change lever 19 and the steering handle 13 described above.

  Specifically, the travel shift lever 19 is connected to the lower side of the linkage unit 34 projecting upward from the front end portion of the floor via the shift operation side link 33, and the shaft is set by the operator's steering operation. A steering handle 13 is connected to the upper end side of the linkage unit 34 via a vertical steering shaft (not shown) that rotates around.

  By a pair of left and right link mechanisms 36A, 36B in the front-rear direction extending forward from the side of each operating arm 32A, 32B in the pair of HST pumps 31A, 31B arranged adjacent to the upper surface of the work machine transmission case 28. The pair of operation arms 37A and 37B provided on the lower side of the speed change operation side link 33 connecting portion of the linkage unit 34 and the above-described pair of operating arms 32A and 32B are connected.

  In other words, the link mechanisms 36A and 36B are provided separately for each pair of HSTs, and the pair of operating arms 32A and 32B for shifting the HST through the pair of link mechanisms 36A and 36B, and the travel speed change lever. 19 and the steering handle 13 are mechanically connected.

  FIG. 5 is a perspective view showing the configuration of the link mechanism, and FIG. 6 is a front view showing the configuration of the link mechanism. As shown in these drawings, the operating arm 32A supported on the front HST pump 31A side, which is the front HST pump 31A, is connected via a proximity side link mechanism 36A which is a link mechanism on the side close to both the HST pumps 31A and 31B. The operating arm 32B supported on the rear HST pump side, which is the rear HST pump 31B, is connected to the front operating arm 37A located on the front side of the pair of operating arms. It is connected to a rear operation arm 37B located on the rear side of the pair of operation arms via a separation side link mechanism 36B which is a link mechanism far from 31A and 31B.

  Each of the link mechanisms 36A, 36B includes a pair of front and rear connecting rods 38A, 38B39A, 39B and connecting links 41A, 41B for connecting the connecting rods, and a front rod which is a front connecting rod. The front end portions of 38A and 38B are rotatably connected to the corresponding operation arms 37A and 37B, and the rear end portions of the rear rods 39A and 39B, which are rear connection rods, are connected to the front end portions of the corresponding operation arms 32A and 32B. The front rods 38A and 38B are connected to each other so that the rear end portions of the front rods 38A and 38B and the front end portions of the rear rods 39A and 39B are connected by corresponding connection links 41A and 41B.

  Both the connection link 41A of the close side link mechanism 36A and the connection link 41B of the separation side link mechanism 36B are attached to the work machine transmission case 28 side and project from the work machine transmission case 28 to the side of the link mechanism side. The left and right fulcrum shafts 44 are rotatably supported.

  The connection link 41A of the proximity side link mechanism 36A includes a rectangular connection arm 40 that rotates about the axis of the support shaft 44, and the front rod 38A of the proximity side link mechanism 36A is provided on the front and back surfaces of the connection arm 40. The rear end portion and the front end portion of the rear rod 39A are connected to each other so as to be rotatable.

  With this configuration, the connecting link 41A moves the rear rod 39A forward by the forward movement of the front rod 38A accompanying the forward swing of the operation arm 37A, and thereby protrudes upward from the proximal end portion toward the distal end portion. While the operating arm 32A is swung forward, the rear rod 39A is moved backward by the rearward movement of the front rod 38A accompanying the backward swinging of the operation arm 37A, and thereby the operating arm 32A is swung rearward.

  The connecting link 41B of the separation-side link mechanism 36B is rotated about the axis of the support shaft 44 and is rotated about the axis of the support shaft 44 and a rectangular upper connection arm 42 protruding upward from the support shaft 44 side. And a lower end connecting arm 43 that protrudes downward from the support shaft 44 side. The rear end portion of the front rod 36B of the separation side link mechanism 36B is rotatably connected to the upper portion of the upper side connecting arm 42. A front end portion of the rear rod 39B of the separation side link mechanism 36B is rotatably connected to a lower portion of the lower side connection arm 43.

  With this configuration, the connecting link 41B moves the rear rod 39B backward by the forward movement of the front rod 38B accompanying the forward swing of the operation arm 37B, and thereby protrudes downward from the proximal end portion toward the distal end portion. While the operating arm 32B is rocked backward, the rear rod 39B is moved forward by the rearward movement of the front rod 38B accompanying the backward rocking of the operation arm 37B, thereby causing the working arm 32B to rock forward.

  As described above, when the travel shift lever 19 is swung from the front / rear neutral position where the HST is in the neutral state to the forward travel side (specifically, the front side), the linkage unit 34 and the link mechanisms 36A and 36B are moved. The operating arms 32A and 32B are swung through the respective HSTs so that each HST is accelerated toward the forward travel side. On the other hand, when the travel shift lever 19 is swung from the front / rear neutral position to the reverse travel side, which is the other front / rear side, The operating arms 32A and 32B are swung through the linkage unit 34 and the link mechanisms 36A and 36B, and each HST is accelerated to the reverse travel side. It should be noted that the speed increase amount of each HST increases as the swing operation amount from the front-rear neutral position increases.

  In addition, when the steering gear 13 is operated to the neutral position so that the vehicle body moves straight when the travel shift lever 19 is swung to a position other than the neutral position, the pair of HSTs have the same gear ratio. Thus, when the pair of operation arms 37A and 37B are operated and the steering handle 13 is steered to the turning side so that the vehicle body turns to the left or right side, the crawler type traveling on the outside of the turning is performed. The operation arm for the crawler type traveling device 1 outside the turn compared to the operation arm 37 for the crawler type traveling device 1 inside the turning so that the device 1 is driven at a higher speed than the crawler type traveling device 1 inside the turning. 37, the forward / backward swing amount from the neutral position increases, but the difference between the swing amounts of the pair of operation arms 37A, 37B differs from the neutral position of the steering handle 13. The larger the operation amount increases.

  Further, by increasing the operation amount from the neutral position of the steering handle 13 by a predetermined amount or more, the crawler type traveling device 1 on the inner side of the turning is driven in reverse with respect to the crawler type traveling device 1 on the outer side of the turning so that the traveling machine body 6 is in place. It is also possible to make a spin turn that turns with almost no forward or backward movement.

  Further, each link mechanism 36A, 36B is provided with a length adjusting mechanism on the connecting rod. By adjusting the length, the swinging position of the operating arms 32A, 32B with respect to the operating position of the steering handle 13 and the travel speed change lever 19 are adjusted. The swinging positions of the operating arms 32A and 32B relative to the operating position can be adjusted separately for the left and right.

  Incidentally, when the traveling speed change lever 19 is swung to the neutral position, even if the steering operation by the steering handle 13 is performed, the operation arm 37A, 37B is held in the front-rear neutral position. It is composed.

  Further, as shown in FIG. 3, a pair of front and rear potentiometers 47A and 47B (operation position detecting means) are provided in the vicinity of the fulcrum shaft on the upper surface side of the work machine transmission case 28 and the front HST pump 31A via a mounting bracket 45. Is supported. The rear potentiometer 47A is mechanically connected to the operating arm 32A of the front HST pump 31A via a potentiometer link 48A, and the swing angle (information on the forward / backward swing position (operation position) of the operating arm 32A is reflected). Hereinafter, the front potentiometer 47B is mechanically connected to the lower connection arm 43 of the separation-side link mechanism 36B via the potentiometer link 48B, so that the rear-side HST pump is detected. The operation angle of the operating arm 32B of 31B is detected.

  That is, potentiometers 47A and 47B for detecting the operating angles of the operating arms 32A and 32B are provided separately for the left and right operating arms 32A and 32B (for each HST), and a pair detected separately by the pair of potentiometers 47A and 47B. The gear ratio of each HST is detected from the operating angles of the operating arms 32A, 32B.

  In this HST, as described above, in addition to performing stepless traveling speed change by adjusting the inclination of the swash plate of the HST pumps 31A and 31B, the inclination of the swash plate of the traveling motor 30 composed of a variable displacement motor is adjusted. The travel shift is also performed. That is, the left and right HST travel motors 30 serve as sub-transmissions that perform travel shifts, and the inclination of the swash plate of the travel motor 30 is changed by expansion and contraction of a sub-transmission cylinder (not shown) formed of a hydraulic cylinder. Specifically, the traveling motor 30 is divided into at least two stages of a “high speed” state in which high speed power is transmitted to the crawler type traveling devices 1, 1 and a “low speed” state in which low speed power is transmitted by the auxiliary transmission cylinder. Switched.

  In addition, a hydraulic parking brake is provided on each of the left and right traveling motors 30. The parking brake is turned on and off by supplying and discharging the working oil. Switch between and.

Next, the configuration of the control unit will be described with reference to FIGS.
FIG. 7 is a block diagram illustrating a configuration of the control unit. The control unit includes a main microcomputer 51 that controls the hydraulic system and the like, a front panel control-side microcomputer 52 that controls various members of the front panel 16, and an engine control microcomputer 53 that is an ECU that controls the engine speed. Then, they are connected to each other by serial communication, and data is transmitted and received between them.

  The main microcomputer 51 mounted on the work vehicle is connected to the input side of the pair of potentiometers 47A and 47B (operation position detecting means), the auxiliary transmission switch 21 and the parking brake switch 17, and the main microcomputer 51. Is input with information about the engine speed from the engine control microcomputer 53 via the front panel control side microcomputer 53.

  On the other hand, on the output side of the main microcomputer 51, there is a sub-transmission switching valve 54 (switching means) for switching the shift of the sub-transmission device composed of a traveling motor by switching the supply and discharge of hydraulic oil to and from the sub-transmission cylinder. A parking brake valve 56 for switching supply / discharge of hydraulic oil to / from the parking brake is connected.

  When the parking brake switch 17 is turned on, the control unit turns on the parking brake by the parking brake valve 56 to switch the traveling body 6 to the travel restricted state, while the parking brake switch 17 is turned off. If so, the parking brake is turned off by the parking brake valve 56 and the traveling machine body 6 is switched to a travelable state.

  Further, the control unit uses the engine rotation speed transmitted from the engine control microcomputer 53 and the operation angles of the operating arms 32A and 32B detected by the potentiometers 47A and 47B, respectively. , 1 is calculated, the vehicle speed of the traveling machine body 6 in consideration of the influence of turning and the like is calculated based on the driving speeds of the left and right crawler type traveling devices 1, 1, and the result is digitally displayed on the liquid crystal panel 24. It is configured to display. Details will be described below. Incidentally, the liquid crystal panel 24 is connected to the main microcomputer 51 and the front panel control side microcomputer 52.

  FIG. 8 is a characteristic graph showing the value of the vehicle speed of the traveling machine body with respect to the operating angle of the operating arm when the engine is rotated at a rated speed and the traveling machine body travels straight. In the present tractor, when the value of the operation angle (θ) detected by the potentiometers 47A and 47B is smaller than the neutral maximum angle (Nmax) and larger than the neutral minimum angle (Nmin) (in the neutral range), HST is in a neutral state. That is, when the operation angle (θ) is smaller than the neutral maximum angle (Nmax) and larger than the neutral minimum angle (Nmin), the swing position of the traveling speed change lever 19 that swings the operating arms 32A and 32B is neutral. Position.

  Further, when the value of the operation angle (θ) is equal to or greater than the neutral maximum angle (Nmax) and equal to or less than the forward maximum acceleration angle (Fmax), the HST is the operation amount (from the neutral maximum angle of the operating arms 32A and 32B). The speed is increased to the forward side in proportion to θ−Nmax). When the operating angle (θ) becomes the same as the forward maximum acceleration angle (Fmax), the HST is maximized to the forward side, and when the operating angle (θ) becomes larger than that, the HST is increased. Is held in a state where the speed is increased to the maximum on the forward side.

  On the other hand, when the value of the operation angle (θ) is equal to or smaller than the neutral minimum angle (Nmin) and equal to or greater than the reverse maximum acceleration angle (Bmax), the HST is the amount of operation from the neutral minimum angle of the operating arms 32A and 32B ( Nmin−θ), the speed is increased to the reverse side. When the operating angle (θ) becomes the same as the reverse maximum acceleration angle (Bmax), the HST is maximum accelerated to the reverse side, and when the operating angle (θ) becomes smaller than that, the HST Is held in a state of being accelerated to the reverse side to the maximum extent.

  Further, when the control unit detects a switching operation by the auxiliary transmission switch 21, the auxiliary transmission valve 54 is used to change from the "low speed" to the "high speed" or "high speed" of the left and right auxiliary transmission devices including the travel motor 30. ”To“ low speed ”, since the vehicle speed of the traveling vehicle body 6 changes even when the gear ratio of the HST is the same depending on whether it is in the“ high speed ”state or the“ low speed ”state (specifically, The slope of the slope portion of the characteristic graph shown in FIG. 8 changes), and the switching state of the left and right auxiliary transmissions is also used for calculating the vehicle speed of the traveling machine body 6.

Next, calculation of the vehicle speed of the traveling machine body by the control unit will be described based on FIG.
FIG. 9 is a flowchart of the calculation processing of the vehicle speed of the traveling machine performed by the control unit. When the calculation processing flow of the vehicle speed of the traveling machine body 6 is started, the control unit proceeds to step S1. In step S1, the engine speed (E) is detected from information from the engine control side microcomputer 53, and the process proceeds to step S2.

  In step S2, the left shift position (L), which is the operating angle (θ) of the HST side operating arm 32A that transmits power to the left crawler type traveling device 1, is detected by the potentiometer 32A, and the process proceeds to step S3. In step S3, the engine speed (E), the left shift position (L) detected in step S2 and the transmission gear ratio (k) of the auxiliary transmission are used, and from the characteristic graph of FIG. A travel speed (VL) that is the drive speed of the travel device 1 is calculated, and the process proceeds to step S4.

  In step S4, the right shift position (R), which is the operation angle (θ) of the HST side operating arm 32B that transmits power to the right crawler type traveling device 1, is detected by the potentiometer 47B, and the process proceeds to step S5. In step S5, the engine speed (E), the right shift position (R) detected in step S4, and the gear ratio (k) of the auxiliary transmission are used, and from the characteristic graph of FIG. A travel speed (VR) that is the drive speed of the travel device 1 is calculated, and the process proceeds to step S6.

  In step S6, the average value of the traveling speeds (VL, VR) that are the driving speeds of the left and right crawler type traveling devices 1, 1 is calculated, and the calculated value is set as the vehicle speed of the traveling machine body 6 and the process proceeds to step S7.

  In step S7, the on / off state of the parking brake switch 17 is detected, and when the parking brake switch 17 is in the off state and the traveling machine body 6 is switched to the travelable state, the process proceeds to step S8 and the liquid crystal panel 24 is turned on. After displaying the vehicle speed of the traveling machine body 6 calculated in step S6, the process returns to step S1. In step S7, when the parking brake switch 17 is in the on state and the traveling machine body 6 is switched to the travel regulation state, it is considered that the traveling machine body 6 is stopped and the vehicle speed is zero. The vehicle speed is not displayed on the liquid crystal panel 24, and the process returns to step S1.

  According to the tractor configured as described above, it is not necessary to perform waterproofing processing, and the tractor itself has the traveling speed of the left and right crawler type traveling devices 1 and 1 using a potentiometer that is less expensive than the rotation sensor. Since the driving speed is calculated separately and the vehicle speed of the traveling machine body 6 is calculated based on the calculation result, it becomes possible to know a more accurate vehicle speed considering the influence of turning and the like.

Next, another embodiment of the vehicle speed calculation performed by the control unit will be described with reference to FIG.
FIG. 10 is a process flow diagram regarding another embodiment of the vehicle speed calculation performed by the control unit. When the flow of the process for detecting the stop state is started, the control unit proceeds to step S11. In step S11, the switching state of both auxiliary transmissions is determined from the output signal to the auxiliary transmission switching valve 54, etc., and if the auxiliary transmission is switched to "low speed", the process proceeds to step S12 while " If it is switched to “high speed”, the process proceeds to step S13.

  In step S12, the speed ratio (kl) at the time of “low speed” of the auxiliary transmission is substituted for the speed ratio (k), and the process proceeds to step S14, while in step S13, “ Substitute the gear ratio (kh) for "high speed" and proceed to step S14. Incidentally, the gear ratio (kl) at the time of “low speed” and the gear ratio (kh) at the time of “high speed” specifically mean the proportionality constant (slope) of the proportional portion in the characteristic graph of FIG.

  In step S14, the right shift position (R) described above is detected by the potentiometer 47B, and it is identified whether or not the value of the right shift position (R) is within the neutral range described above. On the other hand, the process proceeds to step S15. In step S18, since HST is in the neutral state, 0 is substituted for the drive speed (VR) of the crawler type traveling device 1 on the right side, and the process proceeds to step S19.

  In step S15, it is identified whether the value of the right shift position (R) is equal to or greater than the neutral maximum angle (Nmax) or equal to or less than the neutral minimum angle (Nmin). If there is, the process proceeds to step S16, and if it is equal to or smaller than the neutral minimum angle (Nmin), the process proceeds to step S17.

  In step S16, the operation amount (R−Nmax) from the neutral maximum angle is sequentially multiplied by the speed ratio (k) and the engine speed (E), thereby driving the driving speed (VR of the right crawler type traveling device). ) And the process proceeds to step S19. When the value of the right shift position (R) is larger than the forward maximum acceleration angle (Fmax), the transmission ratio (k) is changed to the forward maximum acceleration angle (Fmax−Nmax) from the neutral maximum angle. A value obtained by sequentially multiplying the engine speed (E) and the driving speed (VR) of the crawler type traveling device on the right side.

  In step S17, the operation amount (Nmin−R) from the neutral minimum angle of the operating arm 32B is sequentially multiplied by the speed ratio (k), the engine speed (E), and minus one (−1). The drive speed (VR) of the crawler type traveling device on the right side is calculated, and the process proceeds to step S19. Incidentally, in step S18, the drive speed (VR) becomes a negative value of 0 or less, which means that the right crawler type traveling device 1 is driven in reverse. When the value of the right shift position (R) is smaller than the reverse maximum acceleration angle (Bmax), the transmission ratio (k) is changed from the neutral maximum angle to the reverse maximum acceleration angle (Nmin−Bmax). Then, the value obtained by sequentially multiplying the engine speed (E) and minus one (−1) is defined as the drive speed (VR) of the crawler type traveling device 1 on the right side.

  In step S19, the left shift position (L) described above is detected by the potentiometer 47A, and it is identified whether or not the value of the left shift position (L) is within the neutral range described above. On the other hand, the process proceeds to step S20. In step S23, since HST is in the neutral state, 0 is substituted for the drive speed (VL) of the left crawler type traveling device 1, and the process proceeds to step S24.

  In step S20, it is identified whether the value of the left shift position (L) is greater than or equal to the neutral maximum angle (Nmax) or less than or equal to the neutral minimum angle (Nmin), and greater than or equal to the neutral maximum angle (Nmax). If there is, the process proceeds to step S21, and if it is equal to or smaller than the neutral minimum angle (Nmin), the process proceeds to step S22.

  In step S21, the operation amount (L-Nmax) from the neutral maximum angle is sequentially multiplied by the speed ratio (k) and the engine speed (E), thereby driving the driving speed (VL) of the left crawler type traveling device. ) And the process proceeds to step S24. When the value of the left shift position (L) is larger than the forward maximum acceleration angle (Fmax), the transmission ratio (k) is changed to the forward maximum acceleration angle (Fmax−Nmax) from the neutral maximum angle. A value obtained by sequentially multiplying the engine speed (E) and the driving speed (VL) of the left crawler type traveling device.

  In step S22, the operation amount (Nmin-L) from the neutral minimum angle of the operating arm 32A is sequentially multiplied by the gear ratio (k), the engine speed (E), and minus one (-1). Then, the driving speed (VL) of the left crawler type traveling device 1 is calculated, and the process proceeds to Step S24. Incidentally, in step S22, the driving speed (VL) becomes a negative value of 0 or less, which means that the left crawler type traveling device 1 is driven in reverse. When the value of the left shift position (L) is smaller than the reverse maximum acceleration angle (Bmax), the transmission ratio (k) is changed from the neutral maximum angle to the reverse maximum acceleration angle (Nmin−Bmax). Then, the value obtained by sequentially multiplying the engine speed (E) and minus one (−1) is defined as the driving speed (VL) of the left crawler type traveling device.

  In step S24, the vehicle speed (V) of the traveling machine body 6 is calculated by calculating the average value of the calculated traveling speeds (VR, VL) of the left and right crawler type traveling devices 1, 1, and the process proceeds to step S25.

  In step S25, it is identified whether or not both the left and right crawler type traveling devices 1 and 1 are stopped. If both are stopped, the process proceeds to step S26, but not so. If so, the process proceeds to step S27. In step S26, "TRUE" is substituted for the discriminant variable (N), and the process returns to step S11. In step S27, “FALSE” is substituted for the discriminant variable (N), and the process returns to step S11.

  The control unit calculates the vehicle speed (V) of the traveling machine body 6 as described above. When the vehicle speed (V) is 0 and “FALSE” is substituted for the discrimination variable (N), The control unit can identify that the traveling machine body 6 is not in a stopped state but is in a spin-turning state on the spot. In this way, it is possible to correctly detect the traveling state.

  By the way, in this tractor, when the switching operation of the auxiliary transmission switch 21 is detected, only when the stop of the traveling machine body is identified, the auxiliary transmission is changed from “high speed” to “low speed” or from “low speed”. The control unit may be configured to switch to “high speed”. This makes it possible to perform shift switching of the auxiliary transmission device at an appropriate timing. Incidentally, the case where the stop of the traveling machine body 6 is identified means that, in the example of FIG. 10, the neutral state of both HSTs is detected by the potentiometers 47A and 47B, or the engine speed (E) is This is the case when it is zero.

1 Crawler type traveling device (traveling device)
6 traveling machine body 30 traveling motor (hydraulic motor, auxiliary transmission)
31 HST pump (hydraulic pump)
32 Actuation lever 47 Potentiometer (operation position detection means)
54 Sub-transmission switching valve (switching means)

Claims (2)

  A traveling machine body (6) that is driven to travel by a pair of left and right traveling devices (1, 1) is provided, and a transmission that combines a hydraulic pump (31A, 31B) and a hydraulic motor (30) is connected to the left and right traveling devices (1, 1). ) Are provided for each of the transmissions and actuating levers (32A, 32B) for shifting the transmission are provided for each of the transmissions, and are operated in a work vehicle having a control unit for calculating the vehicle speed of the traveling machine body (6). Operation position detecting means (47A, 47B) for detecting the operation position of the lever (32A, 32B) is provided for each pair of transmissions, and the control unit controls the engine speed and the operation position of the operating lever (32A, 32B). Work vehicle for calculating the vehicle speed of the traveling machine body (6).   A sub-transmission device (30) that performs a shift switching of power transmitted to the travel device (1, 1), and a switching means (54) that performs a shift switching of the sub-transmission device (30). 2. The operation according to claim 1, wherein the shift of the auxiliary transmission (30) is switched via the switching means (54) only when the neutral state of each transmission is detected by the operation position detection means (47A, 47B). vehicle.

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