JP2019107955A - Working vehicle - Google Patents

Abstract

To allow an engine to be activated with less malfunction with respect to a working vehicle equipped with a safety mechanism for an engine activation device.SOLUTION: A working vehicle is equipped with a key switch 58 for activating an engine 5 and pressure sensors 57A and 57B for respectively detecting an operating oil pressure in a duct 53A on an advance high pressure side and that in a duct 53B on a reverse high pressure side. When detected pressure Ph1 and Ph2 of the pressure sensors 57A and 57B do not exceed a preset reference value α, the engine 5 is allowed to be activated by the key switch 58.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a work vehicle such as an agricultural tractor, and more particularly to an engine starter.

  Conventionally, a safety mechanism is provided in a tractor engine starting device. That is, a clutch sensor that detects the disengagement state of the clutch pedal, a shift sensor that detects the neutral state of the shift lever, a traveling system sensor that detects the neutral state of the HST travel operation pedal, and PTO that detects the disengagement state of the PTO lever A sensor is connected to an engine start switch, and it is comprised so that an engine start can be performed when all are in a detection state (patent document 1).

JP 2001-206096 A

  According to Patent Document 1, it is safe to prevent accidental travel or PTO drive by engine start, but it is safe to start the engine by detecting sensors or switches of position information of mechanical switching means of levers and pedals. Because there is a malfunction due to contamination or damage due to aging.

  SUMMARY OF THE INVENTION In view of the above, the present invention provides an engine start-up safety device with few malfunctions.

  In view of the above, the present invention takes the following technical measures.

  According to the first aspect of the invention, when the power transmission device 6 of the traveling vehicle body 1 is provided with the hydraulic stepless transmission 7 and the movable swash plate 38 is driven to the forward side, the hydraulic fluid discharged from the hydraulic pump 36 The motor output shaft is circulated so that the hydraulic oil sucked into the hydraulic motor 37 via the pipe line 53A which becomes high pressure and discharged from the hydraulic motor 37 is sucked through the pipe line 53B to the hydraulic pump 36 and interlocks with the hydraulic motor 37 When the movable swash plate 38 is driven in the backward direction, the hydraulic fluid discharged from the hydraulic pump 36 is drawn into the hydraulic motor 37 through the conduit 53B which is high in pressure. The hydraulic fluid discharged from the hydraulic motor 37 is circulated so as to be sucked into the hydraulic pump 36 through the conduit 53A, and the engine 5 is started in the working vehicle configured to rotate the motor output shaft 37a backward. A switch 58 and pressure sensors 57A and 57B for detecting hydraulic fluid pressure in the forward high-pressure side pipe line 53A and the reverse high-pressure side pipe line 53B, respectively. The detection pressures Ph1 and Ph2 of the pressure sensors 57A and 57B are set in advance. When it does not exceed the reference value α, the engine 5 can be started by the key switch 58.

  Therefore, when the hydraulic fluid pressure is equal to or higher than the reference value α, the engine 5 does not start even if the movable swash plate 38 is on the forward side or the reverse side, and the vehicle body 1 can not start.

  The invention according to claim 2 includes the PTO hydraulic clutch 43 according to the invention according to claim 1, and a pressure sensor 64 is provided in a pipeline 63 from the PTO control valve 61 to the hydraulic clutch piston 42a. When the detected pressure Pp of the hydraulic oil does not exceed the preset reference value β, the engine 5 can be started by the key switch 58.

  As a result, even if the engine start conditions of the pressure sensors 57A and 57B of HST 7 are satisfied, the engine 5 does not start when there is a residual pressure of the PTO hydraulic clutch 43.

  According to the invention described in claim 1, when the hydraulic fluid pressure is equal to or higher than the reference value α, the engine 5 does not start even if the movable swash plate 38 is on the forward side or the reverse side, and the vehicle body 1 unexpectedly starts Can be prevented. Further, since the pressure sensors 57A and 57B attached to the conduits 53A and 53B are detected, there is little possibility of damage due to contamination or aging, and the neutral state of the HST 7 can be stably detected.

  According to the second aspect of the invention, in addition to the effects of the first aspect, when the pressure detection of the hydraulic oil to the PTO hydraulic clutch 43 is equal to or more than the reference value β, the start of the engine 5 can be restrained, so PTO Unpredictable rotation of the shaft and the rotating part of the attached work machine can be prevented.

It is a side view of a tractor equipped with a work machine. It is a top view of a tractor. It is a motive power conduction diagram in the transmission case of a tractor. FIG. 7 is a plan view of a part of the transmission case showing an operation relationship of the hydraulic stepless transmission mechanism. (A) A plan view of a state in which the hydraulic stepless transmission interlocks with the forward position, (b) A plan view in a state in which the hydraulic stepless transmission interlocks with the neutral position, (c) A hydraulic stepless transmission into the reverse position It is a top view of the state interlocked. It is a control block diagram. It is a hydraulic circuit diagram. It is a perspective view which shows a key switch operation position. It is a flowchart.

  Embodiments of the present invention will be described based on the drawings.

  The tractor T is a work vehicle that works in a field or the like, and has left and right front wheels 2 and 2 provided as steering wheels, and left and right rear wheels 3 provided as driving wheels, and a traveling vehicle body The engine 5 mounted in the bonnet 4 at the front of the vehicle 1, and the power transmission 6 and the like interposed between the left and right front wheels 2, 2 and the left and right rear wheels 3, 3 and the engine 5 are provided.

  As shown in FIG. 3, the power transmission device 6 has a hydraulic stepless transmission 7, an auxiliary transmission 8, and a front wheel acceleration switching mechanism 9. The power transmission device 6 appropriately transmits power generated by the engine 5 to the rear wheels 3 by appropriately shifting the speed by the hydraulic continuously variable transmission 7 and the auxiliary transmission 8. Further, the power transmission 6 can transmit the power generated by the engine 5 and decelerated by the hydraulic stepless transmission 7 and the auxiliary transmission 8 to the front wheels 2 and 2 through the front wheel acceleration switching mechanism 9. It has become.

  The tractor T switches between the four-wheel drive state in which the power of the engine 5 is transmitted to the left and right front wheels 2, 2 and the left and right rear wheels 3, 3, and the two-wheel drive state in which the left and right rear wheels 3, 3 are transmitted. It is possible. In addition, a working machine W such as a rotary can be attached to the rear of the tractor body 1.

  A pilot seat 11 is provided at the center of the traveling vehicle body 1, and a steering handle 12 used for steering the front wheels 2 and 2 is disposed on the upper end side of the steering wheel post 13 in front of the pilot seat 11. Further, on the lower side of the steering wheel post 13 and in the vicinity of the driver's foot, a clutch pedal 15, a brake pedal 16, and an accelerator pedal 17 are installed.

  Further, on the handlebar post 13, a forward / reverse switching lever 20 is disposed which switches the traveling direction of the tractor 1 during traveling by forward and reverse. The forward / backward switching lever 20 is turned forward for moving the tractor forward, and is turned backward for moving the tractor T backward, thereby switching between forward and reverse travel of the traveling vehicle 1 by power from the engine 5 It is a thing.

  Further, the forward / reverse switching lever 20 has a neutral position between the forward position and the reverse position, and this neutral position is a position at which the traveling vehicle body 1 can be prevented from advancing forward or backward. It has become. In the forward / reverse switching lever 20, the operating position (forward position, reverse position, neutral position) of the forward / reverse switching lever 20 is detected by the forward / reverse lever position detection sensor 21. That is, the forward / reverse lever position detection sensor 21 detects the operation position of the forward / reverse switching lever 20. The forward / reverse lever position detection sensor 21 outputs the detection result to the controller C.

  Further, on the left side of the cockpit 11, there is a PTO output for driving a working machine mounted on the rear of the traveling vehicle 1, the main transmission lever 25 for performing an operation related to shifting during traveling of the traveling vehicle 1, the auxiliary transmission lever 26 and A PTO clutch lever 27 for driving and disengaging the shaft 10 is disposed. The main shift lever 25 is for shifting the hydraulic stepless transmission 7 from first gear to eighth gear. The auxiliary transmission lever 26 shifts the auxiliary transmission 8 at three speeds, low speed, medium speed, and high speed, of the traveling speed of the traveling vehicle body 1. The low and medium speeds at which the auxiliary shift lever 26 shifts changes the working travel speed range where the vehicle travels when working in the field, and the high speeds at which the auxiliary shift lever 26 shifts changes between the fields It has a road speed zone where you can drive on the road.

  Further, on the right side of the control seat 11, a position lever 28 for adjusting the height of the working machine is disposed. The lift arm 29 interlocking with the elevating cylinder is vertically interlocked by the longitudinal operation of the position lever 28, and the work machine W coupled via the three-point link mechanism P is interlocked vertically.

  Next, the power transmission device 6 in the transmission case 30 constituting the traveling vehicle body 1 will be described based on FIG. The rotation of the output shaft of the engine 5 is transmitted to the input shaft 32 of the transmission case 30 via the main clutch 31 which is interrupted by the clutch pedal 15. The rotation of the input shaft 32 is accelerated by the speed increasing gears 33 and 34 and transmitted to the input shaft 35 of the hydraulic continuously variable transmission 7.

  The hydraulic continuously variable transmission (HST) 7 is a hydrostatic continuously variable transmission, and is composed of a variable displacement hydraulic pump 36 and a fixed displacement hydraulic motor 37. The rotation of the hydraulic motor 37 is changed by changing the inclination. The inclination of the movable swash plate 38 is changed by the hydraulic cylinder mechanism 40 which operates by detecting the movement of the main shift lever 25 and the forward / reverse switching lever 20, and the rotation of the motor output shaft 37a of the hydraulic motor 37 is shifted. The rotation of the pump output shaft 36 a directly linked to the hydraulic pump 36 is the same as the rotation speed of the input shaft 35.

  The rotation of the pump output shaft 36a is transmitted to the PTO intermediate shaft 44 through the PTO positive / reverse clutch 42 and the PTO hydraulic clutch 43, and further transmitted to the PTO output shaft 10 through the PTO transmission 45 and the outside of the transmission case 30. It is taken out to drive a working machine W such as a rotary.

  The motor output shaft 37 a of the hydraulic motor 37 drives the front and rear wheels 2 and 3 through the auxiliary transmission 8, and further drives the front wheel 2 from the auxiliary transmission 8 through the front wheel acceleration switching mechanism 9.

  The HST 7 is shifted by the main shift lever 25. The main shift lever 25 is provided so as to be operable around the base end and lightly engaged at a plurality of locations (for example, eight locations) and rotatably supported so that the gear can be sensed in multiple (for example, eight) stages. . The rotational position of the main shift lever 25 is detected by the main shift lever position detection sensor 25 a, and the detection result is output to the controller C.

  In addition, the tractor T connected with the working machine W is capable of working in the field or traveling on the road, but the field and the road have different appropriate speed regions at the time of traveling There is. For this reason, when the traveling vehicle body 1 travels, the speed range is switched by operating the main shift lever 25 and the sub shift lever 26 according to the traveling state of the traveling place or the like. That is, by operating the main shift lever 25 and the sub shift lever 26, the speed range during traveling is switched.

  For example, when working in a field, the driver switches the main shift lever 25 to any one of the first gear to the eighth gear according to the speed at the time of work, and Switch to either.

  The position of the main transmission lever 25 is detected by a main transmission lever position detection sensor 25a, and the position of the auxiliary transmission lever 26 is detected by an auxiliary transmission lever detection sensor 26a. The controller C switches the HST 7 to the gear selected by the main shift lever 25 by controlling the rod 40 a of the hydraulic cylinder mechanism 40 according to the detection result from the main shift lever position detection sensor 25 a.

  The HST 7 is provided with a trunnion shaft 46 connected to the movable swash plate 38 and a neutral holding mechanism 48 for holding the trunnion arm 47 in a neutral position. The trunnion shaft 46 and the trunnion arm 47 and the movable swash plate 38 interlock with each other, and the rotational angle (position) of the trunnion shaft 46 and the trunnion arm 47 and the inclination angle of the movable swash plate 38 change correspondingly. .

  The trunnion arm 47 is displaceable between a forward position (FIG. 5 (a)), a neutral position (FIG. 5 (b)) and a reverse position (FIG. 5 (c)). The HST 7 outputs the power of the engine 5 as a force for advancing the traveling vehicle body 1 when the trunnion arm 47 is in the forward position, and outputs it as a force for reversing the traveling vehicle 1 when the trunnion arm 47 is in the reverse position. When the trunnion arm 47 is positioned at the neutral position, it does not output the traveling vehicle 1 as a force for advancing or reversing.

  The trunnion arm 47 is driven by the hydraulic cylinder mechanism 40. The hydraulic cylinder mechanism 40 is configured such that the moving speed of the trunnion arm 47 changes in accordance with the operation speed of the hydraulic cylinder mechanism 40 that drives the trunnion arm 47. That is, as the operating speed of the hydraulic cylinder 40 is increased, the moving speed of the trunnion arm 47 is increased. The hydraulic cylinder mechanism 40 is configured such that hydraulic oil is supplied from the pump to one or the other of the double acting cylinder portion via the control valve 49, but the control valve 49 includes a pair of solenoids 49a and 49b, The hydraulic cylinder mechanism 40 is operated on the extension side on the basis of the pulse signal to the solenoid 49a and on the reduction side on the basis of the pulse signal of the other solenoid 49b.

  The neutral holding mechanism 48 fixes the cam plate 50 to the trunnion shaft 46 on the upper surface of the HST 7, and presses the roller 51 appropriately biased against the peripheral cam portion of the cam plate 50. The roller 51 is urged so as to be lowered into the recess 50a of the cam portion, and the trunnion shaft 46 and the trunnion arm 47 are configured to return to the neutral position (shown in FIG. 5B).

  One end of a trunnion arm 47 is rotatably connected to the cam plate 50, and the other end of the trunnion arm 47 is connected to a piston rod 40 a of the hydraulic cylinder mechanism 40 via a link 52. Therefore, when the hydraulic cylinder mechanism 40 is expanded and contracted, the trunnion shaft 46 is rotated via the link 52, the trunnion arm 47 and the cam plate 50 so that the HST 7 can be shifted. Further, the HST 7 is provided with a trunnion arm angle sensor 47a that detects the rotation angle of the trunnion shaft 46, that is, the trunnion arm 47.

  As described above, the forward and reverse switching control and speed control by HST 7 are input with the position signal of the forward and reverse switching lever 20 and the position signal of the main shift lever 25, and these input signals are integrated to calculate the designated speed signal. The speed signal is output to the solenoids 49a and 49b of the control valve 49 based on the calculation result of the controller C to control the hydraulic cylinder mechanism 40 to the extension side or the shortening side, thereby the trunnion arm 47, the trunnion shaft 46 and the movable oblique The plate 38 is driven and controlled.

  When the forward command signal is output from the controller C and the movable swash plate 38 is driven to the forward side, the hydraulic fluid discharged from the hydraulic pump 36 is drawn into the hydraulic motor 37 through the conduit 53A, and then the hydraulic motor 37 The hydraulic fluid discharged therefrom is drawn into the hydraulic pump 36 through the conduit 53B and circulated, so that the motor output shaft 37a interlocked with the hydraulic motor 37 rotates forward. On the other hand, when the movable swash plate 38 is driven to the reverse side, the hydraulic oil discharged from the hydraulic pump 36 is drawn into the hydraulic motor 37 through the pipe line 53B and the hydraulic oil discharged from the hydraulic motor 37 and the pipe line 53A Then, it is sucked into the hydraulic pump 36 and circulated. In this case, the motor output shaft 37a rotates backward. Reference numerals 54a and 54b denote neutral valves for smoothing the oil pressure in the return side pipe, 55a and 55b denote supply throttle valves, and 56 denotes a relief valve.

  By the way, the working oil pressure in the pipe 53A is high on the forward side, and the working pressure in the pipe 53B constituting the circulation pipe is low. Conversely, on the reverse side, the working oil pressure in the conduit 53B is high, and the working pressure in the conduit 53A is low. In addition, such a state continues even while the engine 5 is stopped. For this reason, when starting the engine 5, there is a risk of a sudden start on the forward side or the reverse side. Therefore, the pressure sensors 57A and 57B are incorporated in the pipelines 53A and 53B, respectively, so that the pressure of the hydraulic pressure in each pipeline can be detected, and the detection signal is transmitted to the controller C. When the forward / backward switching lever 20 is operated forward or backward, the pipelines 53A and 53B forming the circulation pipeline are connected to the pipeline 53A or 53B corresponding to the hydraulic fluid discharge side from the hydraulic pump 36. A high pressure condition is exhibited, that is, the conduit 53A is on the forward high pressure side, and the conduit 53B is on the reverse high pressure side.

  When the pressure sensor 57A or 57B exceeds the reference value α stored in advance by the input of the pressure information, the controller C determines that the forward / reverse switching lever 20 is operated in the forward or reverse direction and is not in the neutral position. The engine start by the switch 58 is controlled. When both pressure sensors 57A and 57A detect the reference value α or less, the engine can be started by the key switch 58.

  As described above, the PTO clutch turns on the mechanical PTO positive / reverse clutch 42 that switches from the neutral position to the normal rotation side or the reverse rotation side based on the longitudinal operation of the PTO lever 27, and the PTO switch 60 to control PTO. It consists of a PTO hydraulic clutch 43 which is engaged when the solenoid 61a of the valve 61 is excited. Among the above, in the PTO hydraulic clutch 43, hydraulic oil is supplied to the hydraulic clutch piston 43a, and the clutch disc 43b is brought into pressure contact with a fixed wall surface so that the clutch 43 is engaged. The PTO switch 60 is switched ON or OFF. When the PTO switch 60 is turned OFF, the solenoid 61a is de-energized, and the hydraulic oil in the hydraulic clutch piston 43a is discharged and the clutch is disengaged. Further, a pressure sensor 64 is provided in a conduit 63 from the PTO control valve 61 to the clutch piston 43a. The detected pressure Pp information is sent to the controller C. The controller C compares this value with the reference value β stored in advance by the input of the detected pressure Pp, and when it exceeds the reference value β, determines that the PTO hydraulic clutch 43 is in the ON state, and prevents engine start by the key switch 58 Are configured to When the pressure sensor 64 detects the reference value β or less, it is determined that the clutch is disengaged, and the engine can be started by the key switch 58.

  Although the key switch 58 is inserted into the switch insertion hole and operated to rotate, the "stop", "operation", "remaining heat" and "start" are operated in the order of "stop" position where the engine It can be stopped and the key switch 58 can be inserted and removed, and the "Operating" position is the position during engine rotation. When the "remaining" position is preheated for several seconds and operated to the "starting" position, the engine starts. , Automatically return to the "drive" position. Further, at the above-mentioned "operation" position, each part is in the energized state, and each part of the sensor and switches are activated.

  The engine start control will be described based on the flowchart of FIG. When the key switch 58 is operated to the "drive" position (S101), the power is turned on, sensor detection and the like are performed, and the depression operation of the clutch pedal 15 is determined (S102). Then, the HST pressure sensors 57A and 57B are read, and the detected pressure Ph1 of the conduit 53A side pressure sensor 57A and the detected pressure Ph2 of the conduit 53B side pressure sensor 57B are compared with the reference value α set and stored in advance (S103 to S105 And HST7 is determined to be a neutral position when neither exceeds the reference value α. The forward / backward switching lever 20 is on the forward side when the detected pressure Ph1 is higher than the reference value α, and the forward / backward switching lever 20 is on the reverse side when the detected pressure Ph2 is higher than the reference value α. It returns (S106).

  If YES in S104 and S105, the PTO pressure sensor 64 is further read, and the detected pressure Pp is compared with a preset reference value β (S107, S108). If the reference value β is not exceeded, the PTO clutch 42 is turned off. It is determined that the condition is If it is the reference value β or more, the PTO hydraulic clutch 43 is engaged, that is, since the PTO switch 60 is in the ON position, the PTO switch 60 is turned off (S109). In the case of YES in S108, the engine 5 is started when the key switch 58 is operated to the "start" position. When either the HST pressure sensor 57A or 57B or the PTO pressure sensor 64 exhibits a reference value or more, engine start is restrained even if the key switch 58 is operated to the "start" position.

  In the embodiment of FIG. 9, the engine start is held on the basis of the determination of the PTO pressure sensor 64 in addition to the HST pressure sensors 57A and 57B, but only the HST pressure sensors 57A and 57B may be determined, or Only the PTO pressure sensor 64 may be determined. Furthermore, a sensor 65 for detecting depression of the clutch pedal 15 may be disposed, and a configuration capable of starting the engine 5 in the detection state of the sensor 65 may be added.

  The hydraulic system for supplying the hydraulic fluid to the hydraulic cylinder mechanism 40 is, as shown in FIG. 7, a main pump 70 used for control of the working machine W and control of traveling, and a sub pump for delivering hydraulic oil for HST 7 and power steering 71. It has 72. The hydraulic oil of the hydraulic cylinder mechanism 40 for rotating the trunnion shaft 46 is supplied from the sub pump 72 to the control valve 49 for trunnion control, so the operating pressure is stable. The hydraulic oil from the sub pump 72 is supplied to the power steering 71, and then supplied to the HST 7 through the relief valve 73 and the oil cooler 74.

  Further, the hydraulic oil from the main pump 70 adjusts the hydraulic pressure by the main relief valve 75 to control the main clutch 31 through the travel valve 76, and controls the left and right brake cylinders 79L and 79R through the brake valve 78, and The branched hydraulic oil is sent to control related to the working machine W.

  The hydraulic fluid to the working machine W relationship is sent to the horizontal cylinder 81 and the elevating cylinder 82 by the diverting valve 80. The horizontal cylinder 81 is controlled by a horizontal valve 83, the elevating cylinder 82 is controlled by an electrohydraulic valve 84 and a slow return check valve 85, and hydraulic oil is returned to the inside of the transmission case 30 through the safety relief valve 86.

1 traveling vehicle body 5 engine 6 power transmission 7 hydraulic stepless transmission (HST)
36 hydraulic pump 37 hydraulic motor 37a motor output shaft 38 movable swash plate 42 PTO clutch 43 PTO hydraulic clutch 43a hydraulic clutch piston 53A pipe 53B pipe 57A pressure sensor 57B pressure sensor 58 key switch 61 PTO control valve 63 pipe Ph1 detected pressure Ph2 Detection pressure Pp Detection pressure α Reference value β Reference value

Claims (2)

  The power transmission device (6) of the traveling vehicle body (1) is equipped with a hydraulic stepless transmission (7), and when the movable swash plate (38) is driven forward, hydraulic oil discharged from the hydraulic pump (36) Is drawn into the hydraulic motor (37) through the high pressure line (53A), and the hydraulic fluid discharged from the hydraulic motor (37) is drawn into the hydraulic pump (36) through the line (53B) And the motor output shaft (37a) interlocked with the hydraulic motor (37) is rotated forward, and when the movable swash plate (38) is driven backward, the hydraulic pump (36) ) Is discharged to the hydraulic motor (37) via the pipe line (53B) which becomes high pressure, and the hydraulic oil discharged from the hydraulic motor (37) is transmitted via the pipe line (53A) Circulating so as to be sucked into the hydraulic pump (36) In a working vehicle configured to rotate a motor output shaft (37a) to a reverse side, a key switch (58) for starting an engine (5), the forward high pressure side pipe (53A) and the reverse high pressure side pipe And pressure sensors (57A, 57B) for respectively detecting the hydraulic fluid pressure in the passage (53B), and the detection pressures (Ph1, Ph2) of the pressure sensors (57A, 57B) exceed a preset reference value (α) A working vehicle characterized in that the key switch (58) enables starting of the engine (5) when the key switch (58) does not exist. A pressure sensor (64) is provided in a conduit (63) from the PTO control valve (61) to the hydraulic clutch piston (42a) including a PTO hydraulic clutch (43), and the pressure detected for hydraulic fluid for the PTO clutch (42) The work vehicle according to claim 1, wherein the engine (5) can be started by the key switch (58) when Pp) does not exceed a preset reference value (β).

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