JP4141363B2 - Valve control device - Google Patents

Description

  The present invention provides a valve body including a spool that is movable in a forward direction output position moved in a forward direction from a neutral position that has been biased to return, and a reverse direction output position that has been moved in a reverse direction from the neutral position, and the spool A forward pressure operating unit to which an operating fluid is supplied for moving in the forward direction, a reverse pressure operating unit to which an operating fluid is supplied to move the spool in the reverse direction, and the forward rotating A pair of pressure operation units and a reverse pressure operation unit that can be switched between a supply state for supplying the working fluid and a discharge state for discharging the working fluid and that is urged to return to the discharge state. And a control means for controlling the pair of solenoid valves by supplying a pulse current to output a working fluid from the valve body, wherein the control means includes a positive output position of the spool and Reverse In order to change adjust the flow rate of the working fluid output by the position adjustment in the output position, about said that the valve control device is configured to change adjusts the duty ratio of each solenoid valve for supplying the pulse current.

  The valve control device having the above configuration is configured to change and adjust the flow rate of the working fluid output from the valve body by changing and adjusting the duty ratio for the solenoid valve. Conventionally, the duty ratio of the pulse current is set in a state corresponding to the flow rate of the working fluid required to be output from the valve body, and the pulse current is set to the solenoid valve. Is supplied to the solenoid valve with a pulse current having a duty ratio set from the supply start time (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 9-210189

  In the above conventional configuration, in the state where the spool of the valve body is in the neutral position, a pulse current is supplied to each solenoid valve at a duty ratio on the high output side close to, for example, 100%. In such a case, since the working fluid having a large flow rate for high output is supplied to the pressure operation unit for normal rotation or the pressure operation unit for reverse rotation, the spool is quickly operated, and the spool is moved to the positive direction output position. And it is possible to make the flow rate of the working fluid output when operated to the reverse direction output position to a desired flow rate as quickly as possible.

  However, for example, when the target flow rate of the working fluid to be output from the valve body is set to a small value, the solenoid valve is driven with a pulse current having a low output duty ratio from the state where the spool is in the neutral position. In this case, when the spool is operated to the forward direction output position and the reverse direction output position after the supply of the pulse current to the solenoid valve is started, the flow rate of the working fluid output from the valve body is set to a desired flow rate. There was a disadvantage that there was a time lag before making it happen.

  In other words, in this state where the spool is in the neutral position, the working fluid in the forward pressure operating portion or the reverse pressure operating portion is discharged, and the low output side When driving a solenoid valve with a pulse current having a duty ratio, since the supply amount per unit time of the working fluid supplied to the pressure operation unit is small, the pulse current is started to be supplied to the solenoid valve. Until the pressure operation section is filled with the working fluid and the spool is operated to move against the return biasing force, a slight delay occurs, and the flow rate of the working fluid output from the valve body is set to a desired flow rate. There may be a time delay between the two. In addition, since the supply amount of the working fluid per unit time is small, the operating pressure in the pressure operating section by the working fluid causes the spool that is stationary at the neutral position to the forward output position or the reverse output position. There may be a slight time delay before the pressure increases to start moving toward

  An object of the present invention is to provide a valve control device capable of switching to a state in which a valve main body outputs a working fluid having a desired flow rate with as little time delay as possible after supplying a pulse current to an electromagnetic valve. There is in point to do.

  A first characteristic configuration of the present invention is a valve main body provided with a spool that is movable in a forward direction output position moved in a forward direction from a neutral position that is biased to return and in a reverse direction output position moved in a reverse direction from the neutral position. And a forward pressure operating part to which an operating fluid is supplied to move the spool in the forward direction, and a reverse pressure operating part to be supplied with an operating fluid to move the spool in the reverse direction. And can be switched between a supply state in which the working fluid is supplied to each of the forward rotation pressure operation unit and the reverse pressure operation unit and a discharge state in which the operation fluid is discharged, and the discharge state can be restored. And a control means for controlling the pair of solenoid valves by supplying a pulse current to output a working fluid from the valve body, the control means comprising: Forward direction A valve control device configured to change and adjust the duty ratio of the pulse current supplied to each electromagnetic valve in order to change and adjust the flow rate of the working fluid output by position adjustment at the position and the reverse output position. In the state where the spool of the valve body is in the neutral position and the control means supplies a pulse current with a duty ratio for low output to each solenoid valve, before the start of supply, This is because it is configured to supply an initial pulse current corresponding to the duty ratio on the high output side.

  According to the first characteristic configuration, in the state where the spool of the valve body is in the neutral position, the duty ratio for low output is set as the duty ratio corresponding to the output value of the working fluid to be output from the valve body When the pulse current is supplied to the solenoid valve, the initial pulse current corresponding to the duty ratio on the high output side is supplied before the supply of the pulse current having the low output duty ratio is started. That is, before the pulse current is supplied with the duty ratio for low output and the working fluid with the low output flow rate is supplied to the pressure operation unit for normal rotation or the pressure operation unit for reverse rotation, the initial value is applied to the solenoid valve. As a result, the high-output working fluid having a larger flow rate is supplied to the forward pressure operating portion or the reverse pressure operating portion.

  As a result, by supplying the initial pulse current, the time from when the pulse current is started to be supplied to the solenoid valve until the operating fluid is filled in the pressure operation section and the spool is operated to move against the return biasing force. The time required to increase the pressure required to start moving the spool that is stationary at the neutral position toward the forward output position or the reverse output position is reduced. It becomes possible to do. In other words, a delay until the working fluid with a desired flow rate is output by adjusting the position of the spool at the forward direction output position or the reverse direction output position based on the pulse current having a low output duty ratio supplied thereafter. Time can be reduced.

  Accordingly, it has become possible to provide a valve control device that allows the valve body to switch to a state in which a working fluid having a desired flow rate is output in a state where time delay is as small as possible after the pulse current starts to be supplied to the solenoid valve. .

  The second characteristic configuration of the present invention is that the control means is configured to supply a pulse current having a duty ratio of 100% as the initial pulse current.

  According to the second characteristic configuration, since the pulse current having a duty ratio of 100%, which is the maximum value in the range in which the duty ratio can be adjusted, is supplied as the initial pulse current, the duty ratio for low output is supplied. Before the pulse current is supplied and the working fluid having the flow rate for low output is supplied, the working fluid set to the highest flow rate for high output is supplied to the pressure operating unit for normal rotation or the pressure operating unit for reverse rotation. Therefore, after the supply of the pulse current to the electromagnetic valve is started, it is possible to switch to a state in which the valve main body outputs a working fluid having a desired flow rate as quickly as possible.

  According to a third feature configuration of the present invention, in addition to the first feature configuration or the second feature configuration, the control unit supplies pulses to the electromagnetic valves in a state where the spool of the valve body is in the neutral position. When the current duty ratio is larger than a set value, a pulse current having a duty ratio of 100% is supplied as the initial pulse current, and each solenoid valve is supplied to each solenoid valve in a state where the spool of the valve body is in the neutral position. When the duty ratio of the pulse current to be supplied is smaller than a set value, the pulse current having a duty ratio smaller than 100% is supplied as the initial pulse current.

  According to the third characteristic configuration, when the duty ratio of the pulse current supplied to the solenoid valve is larger than a set value, a pulse current having a duty ratio of 100% is supplied as the initial pulse current. As described in the configuration, before the pulsed current is supplied at the low output duty ratio and the low output flow rate is supplied, the working fluid set to the highest flow rate for the high output is positive. Since the pressure is supplied to the diverting pressure operating section or the reverse pressure operating section, the valve body outputs a working fluid at a desired flow rate in as short a time as possible after the pulse current starts to be supplied to the solenoid valve. It is possible to switch.

  When the duty ratio of the pulse current supplied to the solenoid valve is smaller than the set value, a pulse current having a duty ratio smaller than 100% is supplied as the initial pulse current. In this way, when setting a duty ratio smaller than the set value and outputting a small flow rate from the valve body, if a pulse current with a duty ratio of 100% is supplied as the initial pulse current, Positioning is difficult to adjust, such as overshooting over a desired flow rate (small flow rate) when adjusting the position of the spool in the forward or reverse output position because too much working fluid is supplied. There is a risk of becoming something. Therefore, in such a case, by supplying a pulse current having a duty ratio smaller than 100% as an initial pulse current, an appropriate flow rate adjustment is performed even when a small flow rate is output from the valve body. It becomes possible.

  According to a fourth feature configuration of the present invention, in addition to any one of the first feature configuration to the third feature configuration, the control means is configured so that the control pulse signal is an off signal after the on signal is output first. And the control pulse signal is output as the pulse current in an inverted state, and the first pulse is commanded as a pulse with a zero duty ratio as the control pulse signal. Thereafter, the output of a pulse current having a duty ratio to be supplied to each electromagnetic valve is instructed as a pulse in a reversed state.

  When the fourth feature configuration is described with reference to the drawings, FIG. 11 shows a time chart for a pulse current to be supplied to the electromagnetic valve. FIG. 11 (a) shows a control pulse signal commanded by the control means, and FIG. 11 (b) shows a pulse current output to the solenoid valve. Incidentally, 75% is exemplified as the duty ratio of the pulse current supplied to the solenoid valve in this case. When such a pulse current is supplied, as shown in FIG. 11 (a), the control pulse signal is an off signal after the on signal is first output. The pulse is commanded as a pulse with a zero duty ratio, and thereafter, the pulse is output as a pulse in which the output of a pulse current with a duty ratio of 75% is inverted, that is, a pulse current with a duty ratio of 25%.

Then, the output of the control pulse signal is output as a pulse current with the on / off state inverted. In this manner, as shown in FIG. 11B, a pulse signal with a duty ratio of 100% can be appropriately output as an initial pulse current before a pulse current with a duty ratio of 75%. is there.
Although specific numerical values are illustrated here for easy understanding, the duty ratio of the pulse current is not limited to 75%, and any duty ratio may be set.

  According to a fifth characteristic configuration of the present invention, in addition to any of the first to fourth characteristic configurations, the control means is configured so that an output stop period in which the spool of the valve body is in the neutral position is longer than a set time. The initial pulse current is supplied only when it is continued.

  According to the fifth characteristic configuration, the control means supplies the initial pulse current only when the output stop period in which the spool of the valve body is in the neutral position continues for the set time or longer. That is, when the control means controls the flow rate of the working fluid to be output from the valve body by changing and adjusting the duty ratio for each electromagnetic valve, the target flow rate of the working fluid is, for example, zero and the set flow rate. Each time the target flow rate is switched from zero to a state where the target flow rate is the set flow rate, the initial pulse current as described above is repeatedly generated. If the pressure is supplied, the pulse current becomes excessive and the spool is excessively operated, which may cause a hunting phenomenon.

  Therefore, the configuration is such that the initial pulse current is supplied only when the output stop period in which the spool is in the neutral position continues for a set time or more, so that the pulse current becomes excessive and the spool is excessively operated. It is possible to perform stable control while avoiding the occurrence of hunting due to the above.

  Hereinafter, the case where the valve control device according to the present invention is applied to a combine as a work vehicle will be described with reference to the drawings.

  FIG. 1 shows an overall side view of a combine that is an example of a work vehicle. The combine is set at the front of a traveling machine body 2 that is driven by a pair of left and right crawler type traveling devices 1R and 1L. A threshing device 4 that cuts the straw and conveys it backwards is connected so as to be able to move up and down, and the threshing device 4 that receives the harvested cereal mash from the cutting and transportation device 3 and performs threshing / sorting processing to the traveling machine body 2 and threshing It is comprised by mounting the grain tank 5 which stores the grain from the apparatus 4, and forming the boarding operation part 6 in the front location of the grain tank 5. FIG.

Next, the transmission structure of this combine is demonstrated.
As shown in FIG. 2, a continuously variable transmission 7 for linear shift capable of changing the traveling speed in a straight traveling state, and an operation capable of varying the traveling speed of the traveling device located on the turning center side during turning traveling. Transmission system 8 and a transmission case 9 to which power from the continuously variable transmissions 7 and 8 is input and power to the left and right traveling devices 1R and 1L is output. Has been. The continuously variable transmission 7 for linear shift and the continuously variable transmission 8 for turning operation are variable hydraulic pumps 7A and 8A driven by power from an engine mounted on a combine body, and the variable hydraulic pump thereof. It is constituted by a hydrostatic continuously variable transmission (HST) having a well-known structure constituted by a pair of hydraulic motors 7B and 8B that are rotationally driven by oil supplied from 7A and 8A. Incidentally, the power of the engine is transmitted to the transmission shaft 12 of the variable hydraulic pumps 7A and 8A via the transmission belt 10 and the transmission pulley 11.

The transmission case 9 has an output shaft 20 of the continuously variable transmission 7 for linear transmission and an output shaft 21 of the continuously variable transmission 8 for turning operation inserted therein. The power from the output shafts 20 and 21 is transmitted to the pair of left and right traveling devices 1R and 1L, while the power of the continuously variable transmission 7 for linear shift is transmitted to the cutting and conveying device 3. A pair of large and small output gears 20a, 20b for sub-shifting and an output gear 20c for driving the cutting unit are fixed to the output shaft 20 of the continuously variable transmission 7 for linear shift.
The sub-transmission shaft 22 supports a sub-transmission small-diameter gear 22a and a large-diameter gear 22b that are always meshed with the output gears 20a and 20b, and is relatively rotatably supported. A sub-shift gear shift gear 22d that rotates integrally with the transmission shaft 22 is slidably fitted in the axial direction. A sub-transmission device is configured in which the sub-shift gear 22d is slid and operated so that it can be shifted in two steps. An output gear 22e is fixed to the auxiliary transmission shaft 22, and a center gear 24 provided integrally with the support shaft 23 is provided in a state where the output gear 22e is always meshed with the output gear 22e.

  The support shaft 23 is switched on the left and right sides on either side of the center gear 24 so that the power transmitted through the center gear 24 can be input from either of the continuously variable transmissions 7, 8. A flexible transmission path switching mechanism is provided. The transmission path switching mechanism includes a pair of left and right multi-plate friction clutches 25 and 25 each having an outer peripheral gear portion 25 a linked to the transmission system of the continuously variable transmission 8 for turning operation on the outer peripheral portion, and the center gear 24. It is composed of a pair of left and right meshing clutches 27, 27 formed between both side surfaces and the shift gear 26 facing the both side surfaces. The left and right shift gears 26 can be shifted in the direction of the rotation axis, and can be switched between a state in which the meshing clutch 27 is engaged and a state in which the multi-plate friction clutch 25 is in pressure contact and enters transmission, In a state where the pair of left and right meshing clutches 27 and 27 mesh with each other, the left and right friction clutches 25 and 25 are in a disengaged state. That is, when the clutches 27 and 27 are engaged with each other and the left and right shift gears 26 are both engaged with the center gear 24, the left and right traveling devices 1R and 1L are driven at the same speed in the same direction via the shift gear 26. Go straight.

  The left and right shift gears 26, 26 are shifted by the steering hydraulic cylinders 30 </ b> R, 30 </ b> L against the pressing force of the pressing springs 29, 29, so that the meshing clutches 27, 27 are operated to turn the friction clutch 25. 25, and the steering hydraulic cylinders 30R and 30L are operated by switching the solenoid valves 32 and 33 as shown in FIG. . When one of the left and right shift gears 26 is in the engaged state of the friction clutch 25, the traveling device interlocked with the shift gear 26 is in a state where the transmission power of the continuously variable transmission 8 for turning operation is transmitted.

  Transmission gears 21a and 21b are fixed to both ends of the output shaft 21 of the continuously variable transmission 8 for turning operation, and the outer peripheral gear portions of the friction clutches 25 and 25 are respectively attached to the transmission gears 21a and 21b. 25a and 25a are meshed. When one of the left and right shift gears 26, 26 is shifted to the side where the meshing with the center gear 24 is disengaged, the friction clutch 25 on the side to which the shift gear 26 has moved is brought into a pressed state, and the friction clutch 25. Then, the power of the continuously variable transmission 8 for turning operation is transmitted to the shift gear 26, and is transmitted from the shift gear 26 to one of the traveling devices via the relay gear 34 and the final gear 35, so that the aircraft turns. The shift gear 26 is configured to mesh with the relay gear 34 of the transmission system to the traveling device at all times, even when meshed with the center gear 24 and when being operated to the entry side of the friction clutch 25.

  The continuously variable transmission 7 for linear shift is configured to be able to perform a stepless speed change operation in the forward direction and the reverse direction from the neutral position, and the riding operation unit 6 has a predetermined direction along the front-rear direction. A main transmission lever 14 is provided that can be swung by manual operation over the front-rear operation range. As shown in FIG. 3, the swash plate 13 of the variable hydraulic pump 7A is linked to the main transmission lever 14 via the hydraulic servo mechanism SV, and the angle of the swash plate 13 is changed based on an operation command of the main transmission lever 14. By doing so, the output state on the hydraulic motor 7B side is changed steplessly. In other words, if there is a manual operation on the main transmission lever 14, the shift operation can be lightly operated by performing an assist operation with the hydraulic operation force by the action of the hydraulic servo mechanism SV. .

  As shown in FIG. 8, when the shift lever 14 is in the neutral range and the neutral state is commanded, the swash plate 13 is in the neutral state and the hydraulic motor 7B does not rotate and is maintained in the stopped state. When the command from 14 is a shift command to the forward speed increasing side or the reverse speed increasing side, the angle of the swash plate 13 is set to the forward rotation direction (forward speed increasing by the hydraulic servo mechanism SV in accordance with the operation command of the main speed change lever 14. Direction) or in the reverse direction (reverse acceleration direction) is tilted by a command amount by the main shift lever 14 by the hydraulic operating force, and the hydraulic motor 7B is driven to rotate in the forward direction or the reverse direction at a speed according to the command. Thus, the speed change operation is performed.

  On the other hand, the continuously variable transmission 8 for turning operation is configured such that the variable speed operation can be performed steplessly in each of the forward rotation direction and the reverse rotation direction, similarly to the continuously variable transmission 7 for linear shift. However, the continuously variable transmission 8 for turning operation does not shift manually, but the swash plate 15 of the variable hydraulic pump 8A is linked to the hydraulic turning operation mechanism 16, and the turning operation mechanism 16 Thus, the output state on the hydraulic motor 8B side is changed by changing the swash plate angle. As shown in FIG. 3, the turning operation mechanism 16 includes a double-acting transmission hydraulic cylinder 17 that is interlocked with the swash plate 15 in the continuously variable transmission 8 for turning operation, and the transmission hydraulic cylinder 17. And a hydraulic pressure control unit VU for performing hydraulic pressure control. The transmission hydraulic cylinder 17 is configured to be urged to return to the neutral position by the urging force of a pair of left and right springs 17a and 17b provided therein.

Next, the configuration of the hydraulic control unit VU will be described.
As shown in FIG. 4, this hydraulic control unit VU is a hydraulic pilot type control as a valve body that controls the hydraulic pressure supply state to drive the shift hydraulic cylinder 17 in the forward rotation direction and the reverse rotation direction from the neutral shift position. A valve 36 is provided. The control valve 36 includes a spool 37 that is movable to a forward output position moved in the forward direction from the neutral position and a reverse output position moved backward from the neutral position, and the spool 37 is returned to the neutral position. A pair of coil springs 38 and 39 as biasing means for biasing is provided.

  In addition, the control valve 36 is moved in the forward direction to the pressure operating unit 40 for forward rotation supplied with hydraulic oil as the working fluid in order to move the spool 37 in the forward direction, and the spool 37 is moved in the reverse direction. Therefore, a reverse pressure operation unit 41 to which hydraulic oil as a working fluid is supplied is provided, and the supply state of the hydraulic oil to each of the forward rotation pressure operation unit 40 and the reverse rotation pressure operation unit 41 is controlled. A pair of pilot pressure control solenoid valves 42 and 43 are provided in a state that can be switched between a supply state for supplying the working fluid and a discharge state for discharging the working fluid, and that is biased back to the discharge state. ing.

  In other words, the pair of pilot pressure control solenoid valves 42 and 43 is supplied from the hydraulic pump as working fluid supplied from a hydraulic pump (not shown) to the pressure operating units 40 and 41 and from the hydraulic pump. The solenoid valve 42 is a two-position switching type solenoid valve that can be switched between two positions, that is, a discharge state in which the supply operation is stopped and the pressure operating sections 40 and 41 are connected to the oil drain passage 44. , 43 is configured to be urged to return to the ejected state by springs 45, 46. By energizing and energizing the solenoids 47, 48, the valve body is operated against the urging force of the springs 45, 46. It is configured to switch to the supply state. Therefore, when the energization is stopped, the pilot pressure control solenoid valves 42 and 43 are always in the discharged state, and the state is maintained.

  The control valve 36 is provided with a pair of output ports OP1 and OP2 that are individually connected to the pair of hydraulic oil chambers 17A and 17B of the hydraulic cylinder 17 for speed change, and the spool 37 is in the forward direction output position. When one of the pair of output ports OP1, OP2 is moved to the input port IP, the other reverse output port OP2 is connected to the discharge port DP. Is moved to the reverse output position, the reverse output port OP2 is connected to the input port IP and the forward output port OP1 is connected to the discharge port DP.

  The spool 37 is configured to be movable to a forward holding position between the neutral position and the forward output position and a backward holding position between the neutral position and the backward output position. The pair of output ports OP1 and OP2 are connected to the discharge port DP in the neutral position, and the pair of output ports OP1 and OP2 are connected to the discharge port DP in the forward holding position and the backward holding position, respectively. The input port IP and the discharge port DP are not connected to each other.

  More specifically, on the inner peripheral surface for sliding of the valve body that slidably supports the spool 37 in the axial direction, the input port oil communicated with the input port IP in the central portion of the spool 37 in the axial direction. A path 49 is formed, and output port oil paths 50 and 51 communicating with the pair of output ports OP1 and OP2 are formed on both outer sides in the axial direction of the input port oil path 49, respectively. Discharge port oil passages 52 and 53 respectively communicating with the discharge port DP are formed on both outer side portions in the axial direction from the pair of output port oil passages 50 and 51, respectively. The output port oil passages 50, 51 and the discharge port oil passages 52, 53 are communicated with the outer periphery of the spool 37, or the output port oil passages 50, 51 are connected to the input port. A pair of communication passages 54 and 55 for communicating with the oil passage 49 are formed.

  In the neutral position as shown in FIG. 4, the communication passages 54 and 55 connect the output port oil passages 50 and 51 and the discharge port oil passages 52 and 53. When the spool 37 is moved in the forward direction by a set amount from this neutral position, the forward direction output position is as shown in FIG. 5 (a). At this forward direction output position, the pair of communication passages 54, 55 One communication passage 54 connects the output port oil passage 50 corresponding to the forward direction output port OP1 and the input port oil passage 49, and the other communication passage 55 is an output port corresponding to the reverse direction output port OP2. The oil passage 51 and the discharge port oil passage 53 are connected. Therefore, the shifting hydraulic cylinder 17 is moved in the forward direction (forward acceleration direction).

  Further, when the spool 37 is moved in the reverse direction by a set amount from the neutral position, a reverse output position as shown in FIG. 5 (b) is obtained, and at this reverse output position, of the pair of communication passages 54, 55. The other communication path 55 connects the output port oil path 51 corresponding to the reverse direction output port OP2 and the input port oil path 49, and the one communication path 54 is an output port corresponding to the forward direction output port OP1. The oil passage 51 and the discharge port oil passage 52 are connected. Therefore, the shifting hydraulic cylinder 17 is operated to move in the reverse direction (reverse acceleration direction).

  When the spool 37 is moved in the positive direction from the neutral position by a small operation amount smaller than the set amount, the positive position is maintained between the neutral position and the positive output position as shown in FIG. Become. In the forward holding position, the pair of communication passages 54 and 55 are connected to the pair of output port oil passages 50 and 51, respectively. Will not be connected to. Therefore, the shift hydraulic cylinder 17 is in a state of maintaining the shift position at that time.

  Then, when the spool 37 is moved in the reverse direction from the neutral position by a small operation amount smaller than the set amount, the reverse direction is maintained between the neutral position and the reverse output position as shown in FIG. Become position. In this reverse direction holding position, as in the forward direction holding position, the pair of communication paths 54 and 55 are connected to the pair of output port oil paths 50 and 51, respectively, but the input port oil path 49 and the discharge port It will be in the state where it is not connected to either of the oil paths 52 and 53. Therefore, the shift hydraulic cylinder 17 is in a state of maintaining the shift position at that time.

  When the shifting operation of the continuously variable transmissions 7 and 8 as described above is added, for example, as shown in FIG. 7, the shifting positions of the swash plates 13 and 15 are in a neutral region having a predetermined width including the neutral position N. For example, the shift output (travel speed) is zero, and when the shift position of the swash plates 13 and 15 is rotated in a predetermined direction from the neutral range, the travel speed in the forward direction is increased steplessly. When the plates 13 and 15 are operated in the direction opposite to the predetermined direction from the neutral zone, the traveling speed in the backward direction is increased steplessly.

  The boarding operation unit 6 is provided with a turning lever 56 as turning command means capable of swinging over a predetermined left and right operation range along the left and right direction from the neutral position. As shown in FIG. A rotation lever sensor 57 composed of a rotary potentiometer for detecting 56 operation positions, and a rotation detected by counting the output rotation speeds of the pair of continuously variable transmissions 7 and 8 by counting the number of teeth of the gear 22e and the gear 21a. Sensors 58 and 59, potentiometer-type shift position sensors 60 and 61 as shift position detecting means for detecting the swash plate angle of each of the continuously variable transmissions 7 and 8, respectively, and turning to switch the turning mode in three stages by dial operation A mode switching operation tool 62 and the like are provided, and based on the input information, the turning operation mechanism 16 and the steering hydraulic cylinders 30R, 30 are provided. Control device H of the microcomputer utilized is provided as a control means for controlling the operation.

  Next, turning control by the control device H will be described. As shown in the flowchart of FIG. 8, for example, when the main transmission lever 14 is operated and the vehicle travels straight, the turning lever 56 moves from the neutral position to the left and right. When the turning operation is performed on either side, if the turning center side, that is, the turning direction is right, the right steering hydraulic cylinder 30R is actuated so that the right traveling device 1R receives the shifting power of the continuously variable transmission 8 for turning. Switch to the state to be transmitted (steps 1 to 4). That is, the traveling device on the turning center side (right side) is driven by the continuously variable transmission 8 for turning, and the traveling device on the side opposite to the turning center side (left side) is driven by the continuously variable transmission 7 for straight travel. Switch to the transmission state. The left and right traveling devices 1R, 1L have the same rotational direction, and the speed ratio of their rotational speeds is the speed ratio corresponding to the turning radius commanded by the turning lever 56, so A target shift position of the transmission is obtained (step 5).

  The processing for obtaining the target shift position will be described. As shown in FIG. 8, the relationship between the amount of movement of the turning lever 56 away from the straight command position in the turning command operation area and the speed ratio corresponding to the turning radius is shown. It is determined and stored as a relationship corresponding to a quadratic function. On the other hand, the target shift of the continuously variable transmission 8 for turning is determined from the detected swash plate angle value of the continuously variable transmission 7 for straight travel detected by the shift position sensor 60 and the function having the relationship shown in FIG. The position, that is, the target swash plate position is obtained. Then, the operation of the turning operation mechanism 16 is controlled so that the speed change position of the continuously variable transmission 8 for turning detected by the speed change position sensor 60 becomes the target speed change position (steps 6 to 8). . The speed change position of the continuously variable transmission 7 for linear shift is adjusted by manual operation with respect to the shift lever 14.

  If the relationship shown in FIG. 9 is further described, a line L1 in FIG. 9 indicates the speed of the continuously variable transmission on the straight-ahead side as a reference. Line L2 shows the change in the target rotation speed in the slow turning mode, line L3 shows the change in the target rotation speed in the trust turning mode, and line L4 shows the change in the target rotation speed in the super turning turn mode, The turning mode designated by the turning mode switching operation tool 62 is selected. In other words, in the gentle turning mode indicated by the line L2, when the turning lever 56 is operated to the maximum operating position, the turning side traveling device is about 1/3 of the traveling speed V of the opposite side traveling device. A change characteristic of the speed ratio of the left and right traveling apparatuses 1R and 1L with respect to the operation position of the turning lever 56 is set in advance so as to be decelerated to the speed. In the belief turning mode indicated by the line L3, when the turning lever 56 is operated to the maximum operating position, the operation position of the turning lever 56 is decelerated until the traveling speed of the turning side traveling device becomes zero. The speed ratio of the left and right traveling devices 1R, 1L is preset. Also, in the super turning mode indicated by the line L4, when the turning lever 56 is operated to the maximum operating position, the running speed of the turning side traveling device rotates in the opposite direction to the drive rotation direction of the opposite side traveling device. The speed ratio of the left and right traveling apparatuses 1R and 1L with respect to the operation position of the turning lever 56 is set in advance so that the speed is the same as the speed of the opposite traveling apparatus.

Next, a process for controlling the operation of the hydraulic control unit VU will be described.
Control is performed when the spool 37 is operated to the forward output position and the reverse output position by changing and adjusting the duty ratio of the pulse current supplied to the pilot pressure control solenoid valves 42 and 43 by the control device H. The flow rate of the working fluid output from the output ports OP1 and OP2 of the valve 36, that is, the flow rate of the hydraulic fluid supplied to the hydraulic cylinder 17 for speed change can be changed and adjusted.

  Specifically, the duty ratio of the pulse current supplied to each solenoid valve 42, 43, that is, the ON time with respect to the cycle T among the cycle T of the pulse signal that repeats the ON state and the OFF state at every fixed cycle T. By changing and adjusting the ratio, the oil pressure as the fluid pressure that changes according to the duty ratio and the return biasing force to the neutral position by the springs 38 and 39 with respect to the spool 37 are balanced. The position adjustment is performed at the forward direction output position and the backward direction output position, and the flow rate of hydraulic oil supplied to the hydraulic cylinder 17 can be adjusted. As shown in FIG. 10, the relationship between the duty ratio and the flow rate is set in advance so that the hydraulic oil flow rate increases as the duty ratio increases. Further, as apparent from this figure, when the duty ratio is low, the hydraulic oil flow rate does not flow. By adjusting the duty ratio to about 30%, the spool 37 is held in the reverse holding position or The position can be adjusted to the forward holding position.

  Then, when the control device H supplies a low output duty ratio, for example, a pulse current of about 40 to 80 percent, to the electromagnetic valves 42 and 43 in a state where the spool 37 is in the neutral position, Before the start of supply, an initial pulse current corresponding to the duty ratio on the high output side is supplied. Specifically, when the duty ratio of the pulse current supplied to each solenoid valve 42, 43 is larger than the set value (50%) in the state where the spool 37 is in the neutral position, the duty of 100% is used as the initial pulse current. When the duty ratio of the pulse current supplied to each solenoid valve 42, 43 is smaller than the set value (50%) in the state where the spool 37 is in the neutral position, the initial pulse is supplied. As a current, a duty ratio smaller than 100%, for example, a pulse current of 80% is supplied.

  The control device H is configured to supply the initial pulse current only when the output stop period in which the spool 37 is in the neutral position continues for a set time or longer. Specifically, when a command with a duty ratio of zero percent is continuously generated while a time longer than the time corresponding to 10 cycles of the pulse signal has elapsed, it is output at a duty ratio for driving the cylinder thereafter. The initial pulse current is supplied when the operation is performed.

  The control device H is configured to execute processing as follows as a specific configuration of signal processing when outputting a pulse current. That is, the control pulse signal is commanded in a form that becomes an off signal after the on signal is output first, and is configured to output as a pulse current in a state where the output of the control pulse signal is inverted, and As a control pulse signal, the first pulse is commanded as a pulse with a duty ratio of zero percent, and thereafter, a pulse in a state where the output of the pulse current of the duty ratio to be supplied to each of the solenoid valves 42 and 43 is inverted. Is configured to command.

  In other words, when supplying the pulse current PU2 having the low output duty ratio to the solenoid valves 42 and 43, 100% of the pulse current PU1 is supplied as the initial pulse current. A pulse current as shown in FIG. 11 (b) is supplied. FIG. 11 illustrates a case where a pulse current having a duty ratio of 75% is supplied as a low output duty ratio.

  In this case, as a configuration in which the control pulse signal is output as a pulse current as it is as a configuration in which the control pulse signal is commanded in the form of an off signal after the on signal is first output as the control pulse signal, FIG. If the first pulse of the pulse current having a duty ratio of 75% as shown in (a) is changed to 100% as the initial pulse current, the off-time is eliminated between the pulse and the next pulse, and as a result The pulse becomes 175% (see FIG. 12B). If such a long pulse is supplied, the flow rate of the hydraulic oil is excessively increased, and there is a possibility that the flow rate corresponding to the duty ratio of 75% becomes temporarily excessive.

  Therefore, when the control device H supplies a pulse current having a duty ratio of 75% as shown in FIG. 11B, an ON signal is generated as a control pulse signal as shown in FIG. It is a form in which an off signal is output after being output first, but the first pulse is commanded as a pulse with a zero duty ratio, and thereafter, a pulse in a state where the output of a pulse current with a duty ratio of 75% is inverted, that is, The pulse current is output as a pulse current in a state where the on / off state of the output of the control pulse signal is inverted. As a result, as shown in FIG. 11B, a pulse signal having a duty ratio of 100% can be appropriately output as an initial pulse current before a pulse current having a duty ratio of 75%.

  FIGS. 13 and 14 show the case where the initial pulse current corresponding to the duty ratio on the high output side as described above is supplied and the case where such initial pulse current is not supplied. The experimental data by this applicant are shown. That is, FIG. 13 shows an oblique view of the continuously variable transmission 8 for turning when the pulse current set with a duty ratio of 60% is supplied to the solenoid valves 42 and 43 and the initial pulse current is not supplied. Data such as the detected value (L5) of the angle of the plate 15, the charge pressure (L6) inside the pressure operating units 40 and 41 to which the hydraulic oil is supplied, the load pressure (L7) in the hydraulic oil chamber of the hydraulic cylinder 17 for shifting, etc. The change with the passage of time is shown. Further, FIG. 14 shows the change with time of similar data when the initial pulse current PU1 of 100% is output, and the operation of the shift hydraulic cylinder 17 is performed quickly. It has been shown that

  For example, when shifting the continuously variable transmission 8 for turning in the forward acceleration direction in accordance with the operation of the turning lever 56, the operation when performing the shifting operation of the continuously variable transmission 8 for turning is described. The spool 37 in the control valve 36 is moved to the forward output position. Specifically, a pulse current that repeatedly turns on and off is supplied to the solenoid 47 in the solenoid valve 42 for pilot pressure control with respect to the pressure operating unit 40 for forward rotation, and the duty ratio is changed. adjust. The duty ratio to be a target at that time is a position at which the gear shift operation speed increases as the deviation between the operation position of the swash plate 15 of the continuously variable transmission 8 for turning and the target gear shift position increases. It is set according to the deviation. By supplying the pulse current in this manner, the spool 37 is moved against the biasing force of the spring 39 and moved to the forward output position to output the hydraulic oil flow rate corresponding to the duty ratio from the output port OP1. is there. When shifting the continuously variable transmission 8 for turning in the reverse speed increasing direction, the spool 37 in the control valve 36 is moved to the reverse output position. At this time, the pilot pressure applied to the pressure operating unit 41 for reverse rotation is operated. The control solenoid valve 43 is similarly controlled.

  Then, when the speed change position of the continuously variable transmission 8 for turning reaches the target speed change position by the speed increasing operation, the spool 37 is moved to the forward holding position. That is, the duty ratio of the pulse current with respect to the solenoid 47 is changed and adjusted so as to become a holding duty ratio, that is, 30%. As a result, the electromagnetic force of the solenoid 47 and the biasing force of the spring 39 are balanced, and the spool 37 is held at that position, and the shifting hydraulic cylinder 17 holds the shifting position at that time. Note that the same processing is performed for the operation at the forward holding position even when the holding is performed at the backward holding position.

  When returning the turning continuously variable transmission 8 to the neutral position, when the solenoids 47 and 48 for the pilot pressure control solenoid valves 42 and 43 are switched to the non-energized state, the spool 37 Return to the neutral position by the biasing force. In this neutral position, the hydraulic oil chambers 17A and 17B of the transmission hydraulic cylinder 17 are both in an oil drained state, and the transmission hydraulic cylinder 17 has the urging force of the springs 17a and 17b and the continuously variable transmission for turning. The swash plate 15 is restored to the neutral position by the neutral restoring force.

  Then, as shown in FIG. 8, when the turning lever 56 is in the neutral position, a speed synchronization process for straight traveling is executed (step 9). In this speed synchronization process, the left and right steering hydraulic cylinders 30R and 30L are not operated, so there is no function for shifting the traveling speed of the traveling device by automatic control. Based on the detection information of each of the rotation sensors 58 and 59, the continuously variable transmission 8 for turning is constantly rotated in the same direction as the rotation direction of the continuously variable transmission 7 at an output rotational speed substantially the same as the output rotational speed. A process of shifting the swash plate 15 is performed.

[Another embodiment]
Hereinafter, other embodiments are listed.

(1) In the above embodiment, when the duty ratio of the pulse current supplied to the solenoid valve is larger than a set value, the control device applies a pulse current having a duty ratio of 100% as one pulse current for the initial period. When the duty ratio of the pulse current that is supplied and supplied to the solenoid valve is smaller than the set value, the pulse current of 80% as the duty ratio smaller than 100% is supplied as one pulse current as the initial pulse current. Although what was comprised is illustrated, it may comprise as follows not only in such a structure.

  As the initial pulse current, a pulse current having a constant duty ratio, for example, a pulse current having a duty ratio of 100%, or a lower pulse ratio, for example, an intermediate pulse current of 90 to 100% is supplied. You may do it.

  When the duty ratio of the pulse current supplied to the solenoid valve is smaller than a set value, the initial pulse current is set to a duty ratio smaller than 80% as a duty ratio smaller than 100%, or from 80% A larger duty ratio may be set.

  Instead of supplying only one pulse as the initial pulse current, a plurality of pulses may be output.

(2) In the above embodiment, the control means commands the control pulse signal in the form of the off signal after the on signal is output first, and the output of the control pulse signal is inverted. The first pulse corresponding to the initial pulse current is commanded as a pulse with a zero duty ratio as the control pulse signal, and is then output to each solenoid valve. Although the configuration is such that the output of the pulse current having the duty ratio to be supplied is commanded as an inverted pulse, it may be configured as follows instead of such a configuration.

  That is, as the control pulse signal, the control pulse signal is instructed in the form of the off signal after the on signal is output first, and is output as it is as the pulse current, and corresponds to the initial pulse current. The first pulse is a pulse signal corresponding to a duty ratio (for example, 100%) on the high output side, and the subsequent pulse signal is supplied to each solenoid valve in a form that becomes an on signal after the off signal is first output. A control pulse signal having a power duty ratio (for example, 75%) may be commanded and output as a pulse current without being inverted.

(3) In the embodiment described above, the initial pulse current is supplied only when the output stop period in which the spool is in the neutral position continues for a set time or longer. The time set for the period is exemplified, but the configuration is not limited to this, and the set time is not limited to 10 periods of the pulse signal, and a longer time may be set. You may make it set any one of the period for 10 periods.

(4) In the above embodiment, the control valve is configured as a hydraulic pilot operation type in a state in which the spool is moved by the pilot hydraulic pressure, and is used as a working fluid for the forward pressure operation portion and the reverse pressure operation portion. However, it is not limited to supplying hydraulic oil, but may be operated using other fluids, such as one operated by air pressure.

(5) In the above-described embodiment, the valve control device is applied to a speed change operation device that performs a speed change operation on a continuously variable transmission for turning. However, the valve control device includes a pulse current for the electromagnetic valve. As long as the flow rate of the working fluid from the valve body to the operation target such as a hydraulic cylinder is adjusted by changing the duty ratio, the present invention can be applied to any device without being limited to the speed change device. For example, it is good also as a structure which adjusts the flow volume with respect to the raising / lowering hydraulic cylinder for operating a working device up / down.

(6) In the above embodiment, the combine is exemplified as the work vehicle provided with the valve control device. However, the combine is not limited to the combine, and may be a tractor or other agricultural work machine or a construction work vehicle.

Combine side view Schematic configuration diagram showing transmission structure Control block diagram Diagram showing the configuration of a neutral hydraulic control unit The figure which shows the structure of the hydraulic control unit of a shift operation state The figure which shows the structure of the hydraulic control unit of a shift position holding state The figure which shows the relationship between the shift position and the shift output Flow chart of control operation The figure which shows the relationship between the operation position of the turning lever and the speed ratio Graph showing the relationship between duty ratio and flow rate Diagram showing pulse current Diagram showing a comparative example of pulse current Figure showing experimental data Figure showing experimental data

Explanation of symbols

36 Valve body 37 Spool 40, 41 Pressure operation part 42, 43 Solenoid valve H Control means PU1 Initial pulse current

Claims (5)

A valve body including a spool that is movable to a forward output position moved in the forward direction from the neutral position that has been urged and a reverse output position moved in the reverse direction from the neutral position, and the spool is moved in the forward direction. A pressure operating part for forward rotation supplied with a working fluid for operating the pressure, a pressure operating part for reverse rotation supplied with an operating fluid for moving the spool in the reverse direction, and the pressure operating part for forward rotation A pair of solenoid valves that can be switched between a supply state for supplying the working fluid to each of the pressure operating sections for reverse rotation and a discharge state for discharging the working fluid, and urged to return to the discharge state; Control means for controlling the pair of solenoid valves by supplying a pulse current to output a working fluid from the valve body,
The control means is
The duty ratio of the pulse current supplied to each solenoid valve is changed and adjusted in order to change and adjust the flow rate of the working fluid output by adjusting the position of the spool at the forward output position and the reverse output position. A valve control device comprising:
The control means is
In the state where the spool of the valve body is in the neutral position, when supplying a pulse current with a duty ratio for low output to each solenoid valve, it corresponds to the duty ratio on the high output side before starting the supply. A valve control device configured to supply an initial pulse current. The control means is
The valve control device according to claim 1, wherein a pulse current having a duty ratio of 100 percent is supplied as the initial pulse current. The control means is
When the duty ratio of the pulse current supplied to each solenoid valve is larger than a set value when the spool of the valve body is in the neutral position, a pulse current having a duty ratio of 100% is used as the initial pulse current. Supply
When the duty ratio of the pulse current supplied to each solenoid valve is smaller than a set value when the spool of the valve body is in the neutral position, the duty ratio is smaller than 100% as the initial pulse current. The valve control device according to claim 1, wherein the valve control device is configured to supply a pulsating current. The control means is
The control pulse signal is commanded in a form that is turned off after the on signal is output first, and is configured to output the pulse current in a state where the output of the control pulse signal is inverted, and
As the control pulse signal, the first pulse is commanded as a pulse with a zero duty ratio, and thereafter, the pulse current output of the duty ratio to be supplied to each solenoid valve is commanded as a pulse in an inverted state. The valve control device according to any one of claims 1 to 3, wherein the valve control device is configured.   The control means is configured to supply the initial pulse current only when an output stop period in which the spool of the valve body is in the neutral position continues for a set time or longer. The valve control apparatus of any one of -4.

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