Plow depth control method, system and tractor

Abstract

The present invention discloses a plow depth control method, system and tractor in the field of tractor technology. The plow depth control method includes determining a plow depth request value according to an input plow tool position setting value; determining a converted plow depth value according to an input force position ratio setting value, an actual plow tool position value and a force value; and finely controlling the plow depth according to different deviation ranges between the plow depth request value and the converted plow depth value. At the same time, active intervention control is performed when the load resistance of the plow tool suddenly changes, and the plow tool is forced into the soil to be smoothly controlled in hardened terrain. The present invention can take into account both "operation efficiency" and "operation quality" when the tractor performs plow depth operation, and realizes engine load stability control, load mutation safety control and plow tool forced into the soil to be smoothly controlled, so that the tractor can run efficiently and smoothly.

Description

Technical Field

[0001] The present invention belongs to the technical field of tractors, and in particular relates to a plow depth control method, system and tractor. Background Art

[0002] As a power platform, the tractor connects different machines with the help of suspension mechanism to realize different field operations. The plow is a frequently used machine. It is usually required that the tractor ensures "operation efficiency" on the one hand and "operation quality" on the other hand during the plowing process, and the plowing process is energy-saving. The operation efficiency is usually guaranteed by the tractor's operating speed and the engine load is uniform and not stalled, while the operation quality is usually guaranteed by the tillage depth and the uniformity of the plow depth. At present, there are different control modes in the suspension control, such as floating control, position control, and force control. The floating control mainly follows the plow with the floating wheel to follow the terrain. The uniformity of the plow depth and the stability of the engine load are determined by the height of the terrain and whether the soil is uniform; the position control keeps the plow and the tractor body in a fixed relative position. For relatively flat terrain, the uniformity is good, but for uneven terrain, it is easy to find that some terrain cannot be plowed. At the same time, for terrain with uneven soil, the engine load is unstable; in force control, constant resistance control is performed, and the engine load is relatively stable, but for uneven soil, the plow depth varies greatly and deviates greatly from the actual set value.

[0003] The current suspension system in the market is mainly mechanical suspension system, which cannot realize real-time automatic control of plow depth, but only realizes pre-set force control or position control, with complex transmission process, low control accuracy, slow response process, poor plow depth uniformity and engine stability; some electro-hydraulic suspension systems are based on position control, with auxiliary force value as the boundary, and only lift the plow. When the terrain is uneven and the tractor body is relatively high, the plow follows the tractor to rise, the overall plow depth becomes shallower, or even cannot be plowed. The existing control scheme cannot take into account both "operation efficiency" and "operation quality". Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a plow depth control method, system and tractor, which can take into account both "operation efficiency" and "operation quality" when the tractor performs plow depth operation, and realize engine load stability control, load mutation safety control and plow tool strong pressure into the soil stable control, so that the tractor can run efficiently and smoothly.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, a plow depth control method is provided, comprising: determining a plow depth request value according to an input plow tool position setting value; determining a converted plow depth value according to an input force position ratio setting value, the actual plow tool position and the force value; performing fine plow depth control according to a deviation between the plow depth request value and the converted plow depth value, and at the same time, performing active dry flameout prevention control when the load resistance of the plow tool suddenly changes, and controlling the plow tool to be pressed into the soil smoothly on hard and compacted terrain.

[0007] Furthermore, the plowing depth request value is obtained by the following method:

[0008] H depth_set =AB*H position_set； (1)

[0009] Among them, H depth_set is the plowing depth request value, A is the maximum plowing depth of the plow, B is the conversion coefficient from the plowing position setting to the plowing depth setting, H position_set Set the knob setting for the plow position.

[0010] Furthermore, the converted plowing depth value is obtained by the following method:

[0011] H real =a(AB*H position_real )+(1-a)F draft_real / C (2)

[0012] H real is the conversion plow depth value, a is the comprehensive weight ratio coefficient set by the force position ratio setting knob, H position_real F is the actual plow position value collected by the position sensor; draft_real is the actual force value collected by the force sensor, and C is the conversion coefficient between force value and plow depth.

[0013] Further, the plowing depth control according to the different deviation ranges between the plowing depth request value and the converted plowing depth value includes: setting the deviation e between the plowing depth request value and the converted plowing depth value = H real -H depth_set, set the control boundary of e to [m1, n1], m1 is a negative value, n1 is a positive value, m1 and n1 are respectively a certain set proportion value of the plowing depth request value; when e<0, the conversion plowing depth value is less than the plowing depth request value, when e≤m1, the descending proportional valve is controlled to act, and its current control process is: set m2 to be less than the control boundary m1 value, set the deviation e in the interval [m2, m1], the descending proportional valve current setting interval is [f1, f2], when e≤m2, the current is set to f2; when m2<e<m1, the current is set by looking up the table in the corresponding deviation interval according to the interpolation method, when e=m1, the current is set to f1, when e>m1, the current of the descending proportional valve is controlled to return to zero; when e>0, the conversion plowing depth value is greater than the plowing depth request value, then the ascending proportional valve is controlled to act, and its current control process is: set the boundary value n3, and 0<n3<n1, then when e is in the interval [n3, n1] When the value is greater than or equal to n1, the unloading valve is controlled to close, so that the hydraulic oil output by the hydraulic pump is unloaded through the differential compensation valve; when e≥n1, the rising proportional valve is controlled to perform the plowing action, n2 is set to be greater than the control boundary n1 value, and when the deviation e is set in the interval [n1, n2], the current setting interval of the rising proportional valve is [h1, h2], that is, when e=n1, the current is set to h1, when e≥n2, the current is set to h2, when n1<e<n2, the current is set in the corresponding interval according to the interpolation method, that is, the larger the deviation, the larger the current input to the rising proportional valve; when the deviation e decreases from the interval value of [n3, n1] to less than n3 within a certain time T1, the unloading valve is controlled to close, or when e is maintained at the interval value of [n3, n1] within a certain time T2, the unloading valve is controlled to close. After the T2 time is maintained, when the deviation e≥n1 again, the unloading valve and the rising proportional valve are directly controlled to be energized synchronously to perform the plowing action.

[0014] Furthermore, the active flameout prevention control when the load resistance of the plow suddenly changes includes: calculating the maximum traction driving capacity F of the tractor in this state according to the engine speed information and the current gearbox gear information. max , set F lim1 <F lim2 <F lim3 <F max For different boundary values, F lim1、 F lim2、 F lim3 The maximum driving capacity at the current speed is represented by different proportions: When the force value collected by the force sensor increases to F lim1 , and the force value increase rate is less than k1, the unloading valve is controlled to close; when the force value continues to increase to F lim2 When the proportional valve is controlled to rise, the force value is set at [F lim2 , F lim3], the corresponding current output of the proportional valve is controlled to be [h1, h2], and the plow rises until the force value drops to F lim2 Below, the current of the rising proportional valve and the unloading valve is controlled to return to zero; when the force value collected by the force sensor increases to F lim1 , and the force value increase rate is greater than k1, the unloading valve and the rising proportional valve are controlled to be energized at the same time, and the rising proportional valve current is set to h1. Within a certain period of time T3, if the force value increases to F lim2 , and the rate of force increase is still greater than k1, then the force value is [F lim2 , F lim3 ] interval, the control current is output according to [h3, h2], where h1<h3<h2; or when the internal force value is still less than F within a certain period of time T3 lim2 , and the rate of force increase is still greater than k1, then the force value is [F lim1 , F lim2 ] interval, the current of the rising proportional valve is controlled according to the output control of [h1, h3]. The corresponding current of the real-time force value in the process is determined by the interpolation method; or the force value is still less than F within a certain period of time T3. lim2 , and the rate of change of force increase is less than k1, controlling the current of the rising proportional valve and the unloading valve to return to zero.

[0015] Furthermore, the described control of the plow being forced into the soil smoothly on compacted hard terrain includes: for compacted hard terrain, when the controller receives a descent mode trigger signal and a high-pressure mode trigger signal, the controller first controls the descent proportional valve to lower the plow according to the descent speed setting knob setting value, and when the pressure value collected by the force sensor is close to G1, it is determined that the plow is close to the ground, and the unloading valve and the high-pressure switch valve are controlled to be energized; when the collected pressure value is close to the [0, G2] interval, G2<G1, then the ascending proportional valve is controlled to be energized, and the hydraulic oil output by the hydraulic pump passes through the ascending proportional valve and the high-pressure switch valve and enters the rod chamber of the suspension cylinder, and the plow is forced into the soil under the pressure set by the relief valve until the plow reaches the set depth, and the high-pressure mode is actively exited.

[0016] In the second aspect, a plow depth control system is provided, including a hydraulic pump, the outlet of the hydraulic pump is respectively connected to the inlet of the unloading valve, the inlet of the differential compensation valve and the inlet of the rising proportional valve, and then connected to the rodless chamber of the suspension cylinder through the high-pressure switch valve, and the rodless chamber of the suspension cylinder is connected to the descending proportional valve; the rod chamber of the suspension cylinder is provided with an overflow valve; a force sensor, a position sensor, a descending speed setting knob, a descending mode trigger button, a force position ratio setting knob, a plow position setting knob, and a high-pressure mode trigger button are respectively connected to the input end of the controller; the output end of the controller is respectively electrically connected to the control ends of the rising proportional valve, the descending proportional valve, the high-pressure switch valve, and the unloading valve; the controller also collects the gear information of the gearbox and the speed information of the engine, and performs plow depth control according to the plow depth control method described in the first aspect.

[0017] Furthermore, the force sensor is used to obtain real-time force status information of the plow, the position sensor is used to obtain real-time position information of the plow, the descent speed setting knob is used to set the speed of the plow descent process, the descent mode trigger button is used to trigger the descent of the plow, the force position ratio setting knob is used to set the force position weight information of the tillage process, the plow position setting knob is used to set the plow position, and the high pressure mode trigger button is used to trigger the high pressure mode of the plow into the soil during the operation process.

[0018] Furthermore, a one-way valve is provided between the high-pressure switch valve and the rodless chamber of the suspension oil cylinder.

[0019] According to a third aspect, a tractor is provided, wherein the tractor is equipped with the plow depth control system according to the second aspect.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention performs fine control of the plowing depth according to different deviation ranges between the plowing depth request value and the converted plowing depth value. At the same time, it performs active intervention control when the load resistance suddenly changes, and performs stable control of the plow tool's strong pressure into the soil on hardened terrain. It can take into account both "operation efficiency" and "operation quality" when the tractor performs plowing depth operation, and realizes engine load stability control and load sudden change safety control, so that the tractor can run efficiently and smoothly;

[0022] (2) The present invention solves the problem of large variations in plow depth during the tillage process. Different plow depth deviation ranges are set to control different current sizes, and fine plow depth control is performed. At the same time, timely response is given in advance according to the deviation range, so as to achieve uniform control of the plow depth during the tractor operation process.

[0023] (3) The present invention solves the problem of uneven engine load caused by large resistance changes during the tillage process, and achieves stable control of engine load;

[0024] (4) The present invention solves the problem of a sudden increase in resistance during the tillage process, which may cause damage to the tractor plow or engine stalling. Different plow adjustment methods are corresponding to different resistance mutation conditions, which avoids a large plow adjustment range and realizes safety controls such as load sudden engine stalling prevention control and plow protection.

[0025] (5) The present invention solves the problem of large impact of the plow caused by powered descent during the tillage process and causing the tractor body to shake. The actual action intervention point of the strong pressure working condition is controlled by means of a force sensor, so as to achieve stable control of the plow's strong pressure into the soil.

[0026] (6) In the present invention, during the non-regulation process, the hydraulic oil is directly unloaded instead of being unloaded through the differential compensation valve, which can reduce the heat generation of the quantitative pump load sensitive system during the tillage process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the system principle of a plow depth control system provided by an embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of plow depth deviation during plow depth control in an embodiment of the present invention;

[0029] In the figure: 1. Hydraulic pump; 2. Unloading valve; 3. Fixed differential compensation valve; 4. Rising proportional valve; 5. Lowering proportional valve; 6. High-pressure switch valve; 7. One-way valve; 8. Overflow valve; 9. Suspension cylinder; 10. Force sensor; 11. Position sensor; 12. Controller; 13. Engine speed information; 14. Transmission gear information; 15. Lowering speed setting knob; 16. Lowering mode trigger button; 17. Force-position ratio setting knob; 18. Plow position setting knob; 19. High-pressure mode trigger button. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0031] Embodiment 1:

[0032] A plow depth control method comprises: determining a plow depth request value according to an input plow tool position setting value; determining a converted plow depth value according to an input force position ratio setting value, an actual plow tool position value and a force value; performing fine plow depth control according to different deviation ranges between the plow depth request value and the converted plow depth value, and at the same time, performing active intervention safety control when the load resistance of the plow tool suddenly changes, and performing stable control on the plow tool by strong pressure into the soil on hard and compacted terrain.

[0033] like Figure 1The figure shows a schematic diagram of a plow depth control system applicable to the plow depth control method described in the present embodiment. The outlet of the hydraulic pump 1 is connected to the inlet of the unloading valve 2, the inlet of the differential compensation valve 3 and the inlet of the rising proportional valve 4, and then connected to the rodless chamber of the suspension cylinder 9 through the strong pressure switch valve 6 and the one-way valve 7. At the same time, the rodless chamber of the suspension cylinder 9 is connected to the descending proportional valve 5; the rod chamber of the suspension cylinder 9 is provided with an overflow valve 8; the force sensor 10 is located at the hinge point between the lower tie rod of the three-point suspension and the tractor, and can collect tension and pressure values. During the tillage process, the tension state information of the plow is obtained in real time. When the plow is off the ground, it is displayed as a pressure value. The plow is in different positions, and the pressure value is different. The force sensor 10 is connected to the input end of the controller 12; the position sensor 11 is concentric with the rotation axis of the lifting arm to obtain the real-time position information of the plow, and communicates with the controller 12. The input end of the controller 12 is connected; the force position ratio setting knob 17 can set the force position weight ratio (0%-100%) of the tillage process; the plow position setting knob 18 sets different plow positions (0-100%), the high pressure mode trigger button 19 can trigger the plow high pressure mode during the operation, the descending mode trigger button 16 triggers the plow descending action, and the descending speed setting knob 15 sets the plow descending process speed (0-100%); the controller 12 obtains the gearbox gear information 14 and the engine speed information 13 in real time, and controls the unloading valve 2, the rising proportional valve 4, the descending proportional valve 5, and the high pressure switch valve 6 according to the tillage process control strategy to achieve the corresponding functions and performance requirements.

[0034] The tillage process control strategy is as follows.

[0035] (1) Plowing depth request:

[0036] H position_set The setting value of the knob 18 is set for the plow position, and its value range is [0%, 100%], corresponding to the entire stroke of the suspension cylinder 9. The controller 12 adjusts the position of the plow according to the setting value H. position_set , convert the requested position of the plow tool to the plow depth, and determine the requested plow depth value. The conversion method is:

[0037] H depth_set =AB*H position_set； (1)

[0038] Among them, H depth_set is the plowing depth request value. When it is 0%, it is the maximum plowing depth request, and the plowing depth value is A. When H position_set Set more than * When 100%, the plowing depth request value defaults to 0, and no actual plowing operation is performed; A is the maximum plowing depth of the plowing tool, B is the conversion coefficient from the plowing tool position setting to the plowing depth setting, H position_set The setting of knob 18 is set for the plough position.

[0039] (2) Change the plowing depth:

[0040] The force position ratio setting knob 17 sets the force position ratio coefficient a during the tillage process to determine the position control or force control influence weight. The controller 12 performs the conversion plow depth value control according to the setting value of the force position ratio setting knob 17, the actual position value of the plow tool, and the force value. The specific control method is:

[0041] H real =a(AB*H position_real )+(1-a)F draft_real / C (2)

[0042] Among them, H real is the conversion plow depth value, a is the comprehensive weight ratio of force position, which is a value in the interval [0%, 100%] and is set by the force position ratio setting knob 17; H position_real The actual plow position value collected by the position sensor 11; F draft_real is the actual force value collected by the force sensor 10, and C is the conversion coefficient between the force value and the plowing depth.

[0043] According to the needs of adapting to tractors with different horsepower, plows and soil resistance terrain, different A, B and C parameters can be adjusted to meet different farming requirements.

[0044] (3) Comprehensive control of force and position:

[0045] The controller 12 performs control according to the different deviation ranges between the plowing depth request value and the converted plowing depth value. Under normal conditions, the unloading valve 2 is normally open, and the hydraulic oil output by the hydraulic pump 1 is directly unloaded through the unloading valve 2, and is not unloaded through the fixed differential compensation valve 3. The pressure loss is reduced, thereby reducing the heat generation of the system. Only when the control pressure switch valve 6 is actuated or the rising proportional valve 4 needs to be actuated, the unloading valve 2 is linked or actuated in advance to ensure that the plow can be actuated in time. The specific method is as follows:

[0046] Set the deviation between the requested plowing depth value and the converted plowing depth value e=H real -H depth_set ,like Figure 2 As shown, the control boundary of e is set to [m1, n1], m1 is a negative value, n1 is a positive value, m1 and n1 are respectively a certain set ratio value of the plowing depth request value, and the reference value ratio is a value in the interval of [-10%, 10%], such as m1=-6%H in the example depth_set , n1=5%H depth_set ;

[0047] When e<0, the converted plowing depth value is less than the plowing depth request value. When e≤m1, the controller 12 controls the descending proportional valve 5 to operate. The current control process is as follows: m2 is set to be less than the control boundary m1 value. When the deviation e is set in the interval [m2, m1], the current setting interval of the descending proportional valve 5 is [f1, f2]. When e≤m2, the current is set to f2; when m2<e<m1, the current is set by looking up the table in the corresponding deviation interval according to the interpolation method; when e=m1, the current is set to f1; when e>m1, the controller 12 controls the current of the descending proportional valve 5 to return to zero;

[0048] Further, when e>0, the converted plowing depth value is greater than the requested plowing depth value, and the controller 12 controls the rising proportional valve 4 to act, and its current control process is: set the boundary value n3, and 0<n3<n1, then when e is the interval value of [n3, n1], the controller 12 controls the unloading valve 2 to close, so that the hydraulic oil output by the hydraulic pump 1 is unloaded through the fixed differential compensator 3, and further, when the controller 12 calculates the deviation e≥n1, the controller 12 controls the current of the rising proportional valve 4 to perform the plowing action, and sets n2 to be greater than the control boundary n1 value. When the deviation e is set in the interval [n1, n2], the current setting interval of the rising proportional valve 4 is [h1, h2], that is, When e=n1, the current is set to h1, when e≥n2, the current is set to h2, and when n1<e<n2, the current is set by looking up the table in the corresponding interval according to the interpolation method, that is, the larger the deviation, the larger the current input to the rising proportional valve 4, so that the deviation is reduced quickly; when the deviation e decreases from the [n3, n1] interval value to less than n3 within a certain time T1, the unloading valve is controlled to be closed, or when e is maintained at the [n3, n1] interval value within a certain time T2, the controller 12 controls the unloading valve 2 to be closed, and further, after the T2 time is maintained, when the deviation e≥n1 again, the unloading valve 2 and the rising proportional valve 4 are directly controlled to be energized synchronously to perform the plow lifting action.

[0049] Through different current control in different deviation ranges, precise control and timely response of the plow adjustment process can be achieved, the problem of large changes in plow depth during the tillage process can be solved, and the uniformity of the plow depth during the tractor operation process can be controlled. At the same time, the influence of the force conversion plow depth weight can be incorporated to solve the problem of large changes in resistance during the tillage process, which leads to uneven engine load, and the engine load stability control can be achieved to ensure the uniformity and stability of the tillage process.

[0050] (4) Protection of plows and flameout prevention control:

[0051] Furthermore, based on the integrated force-position control, if the load resistance suddenly increases due to tree roots, stones or hard ground, active intervention is carried out to avoid damage to the plow and prevent the engine from stalling, further protecting the control:

[0052] The controller 12 obtains the engine speed information n转速 According to the engine speed-torque external characteristic curve, determine the maximum torque M corresponding to different speeds max , the controller 12 simultaneously obtains the current gearbox gear information in real time, and determines the maximum wheel side torque M according to the gear ratio of the entire transmission process from the engine to the drive axle. 轮 , and then calculate the maximum traction driving capacity F of the tractor under this state according to the tractor wheel diameter max , set F lim1、 F lim2、 F lim3 (F lim1 <F lim2 <F lim3 <F max ) is limited to different boundary values, F lim1、 F lim2、 F lim3 represents the different proportions of the maximum driving capacity at the current speed. The reference range of the proportion is [60%, 90%]. For example, F lim2 =75% * F max :

[0053] When the force value collected by the force sensor 10 increases to F lim1 , and the force value increase rate is less than k1, the controller 12 controls the unloading valve 2 to close; when the force value continues to increase to F lim2 When the controller 12 controls the rising proportional valve 4 to operate, the setting force is [F lim2 , F lim3 ] interval process, the controller 12 controls the current output of the rising proportional valve 4 to be [h1, h2], and controls the plow to rise until the force value is reduced to F lim2 Below, the current of the rising proportional valve 4 and the unloading valve 2 is controlled to return to zero, and the operation continues according to the comprehensive setting parameters of the corresponding force position;

[0054] When the force value collected by the force sensor 10 increases to F lim1 , and the force value increase rate is greater than k1, the controller 12 controls the unloading valve 2 and the rising proportional valve 4 to be electrically actuated at the same time, and sets the current of the rising proportional valve 4 to h1. Within a certain time T3, if the force value increases to F lim2 , and the rate of force increase is still greater than k1, then the force value is [F lim2 , F lim3 ] interval, the controller 12 controls the current to be output according to [h3, h2], where h1<h3<h2; or when the internal force value is still less than F for a certain period of time T3 lim2 , and the rate of force increase is still greater than k1, then the force value is [F lim1 , F lim2] interval, the controller 12 controls the current of the rising proportional valve 4 to output control according to [h1, h3]. The real-time force value corresponding to the current in the process is determined by looking up the table according to the interpolation method; or when the force value is still less than F within a certain period of time T3 lim2 , and the rate of change of force increase is less than k1, the controller 12 controls the current of the rising proportional valve 4 and the unloading valve 2 to return to zero.

[0055] The present invention solves the problem of sudden increase of resistance during tillage process, which may cause damage to tractor plow or engine stalling, and realizes safe control of load mutation.

[0056] (5) The plow is pressed into the soil with force, reducing the impact of the plow entering the soil:

[0057] For compacted terrain or hard soil, strong pressure is required to push the plow into the soil. In order to prevent the plow from hitting the ground at a fast speed and causing damage to the plow when it falls under the combined action of power and gravity, and causing impact on the tractor body, the plow's entry into the soil is smoothly controlled. The smooth control method is as follows: when the plow descent trigger button 16 and the strong pressure mode trigger button 19 are activated, the plow descends at the speed preset by the descent speed setting knob 15, and the controller 12 monitors the force value changes of the force sensor 10 in real time (the force sensor collects the force value as pressure when the plow is off the ground). When the pressure value collected by the force sensor 10 is close to G1, it is judged that the plow is The plow is already close to the ground. At this time, the controller 12 controls the unloading valve 2 and the high-pressure switch valve 6 to be energized. When the pressure value collected by the force sensor 10 is close to the [0, G2] interval (G2<G1), the controller 12 controls the rising proportional valve 4 to be energized, and the hydraulic pump 1 outputs the hydraulic oil through the rising proportional valve 4 and the high-pressure switch valve 6 and then enters the rod chamber of the suspension cylinder 9, and the plow is forced into the soil at the set pressure of the overflow valve 8. When the set depth is reached, the high-pressure mode is actively exited. This method avoids the strong impact caused by the plow when the plow power + gravity is superimposed and falls, which causes the shaking of the tractor body, and realizes the smooth control of the plow being forced into the soil.

[0058] The hydraulic pump in the present invention adopts a fixed displacement pump mode, and can also adopt a variable displacement pump mode, and the present invention can reduce the heat generation of the fixed displacement pump load sensitive system during the tillage process and achieve system thermal balance. The functional principles of the rising proportional valve, the falling proportional valve, and the high-pressure switch valve can all be fine-tuned, and the rod cavity overflow valve adopts an adjustable and non-adjustable mode. The high-pressure mode button is a self-locking form, and can also adopt a self-reset mode; the deviation control interval and the corresponding set current can be fine-tuned according to the situation; the torque setting ratio can be adjusted accordingly according to different engine characteristics; at the same time, the high-pressure switch valve can be cancelled, which means it does not have a high-pressure function, and the corresponding oil cylinder is a single-acting oil cylinder, which still does not affect the realization of some functions and strategies. All tractor plow depth control methods and systems formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

[0059] Embodiment 2:

[0060] Based on the plow depth control method described in Example 1, this embodiment provides a plow depth control system, such as Figure 1 As shown, it includes a hydraulic pump 1, the outlet of the hydraulic pump 1 is respectively connected to the inlet of the unloading valve 2, the inlet of the differential compensation valve 3 and the inlet of the rising proportional valve 4, and then connected to the rodless chamber of the suspension cylinder 9 through the high-pressure switch valve 6, and a one-way valve 7 is also arranged between the high-pressure switch valve 6 and the rodless chamber of the suspension cylinder 9; at the same time, the rodless chamber of the suspension cylinder 9 is connected to the descending proportional valve 5; the rod chamber of the suspension cylinder 9 is provided with an overflow valve 8; a force sensor 10, a position sensor 11, a descending speed setting knob 15, a descending mode trigger button 16, a force position ratio setting knob 17, a plow position setting knob 18, and a high-pressure mode trigger button 19 are respectively connected to the input end of the controller 12; the force sensor 10 is used to real-timely control the position of the plough during the tillage process. Obtain the force state information of the plow; the position sensor 11 is used to obtain the real-time position information of the plow; the descent speed setting knob 15 is used to set the speed of the plow descent process; the descent mode trigger button 16 is used to trigger the plow descent; the force position ratio setting knob 17 is used to set the force position weight information of the tillage process; the plow position setting knob 18 is used to set different plow positions; the high pressure mode trigger button 19 is used to trigger the high pressure mode of the plow into the soil during the operation; the output end of the controller 12 is electrically connected to the control ends of the rising proportional valve 4, the descending proportional valve 5, and the high pressure switch valve 6 respectively; the controller 12 also collects the gear information of the gearbox and the speed information of the engine, and performs plow depth control according to the plow depth control method described in Example 1.

[0061] Embodiment three:

[0062] Based on the plow depth control system described in the second embodiment, this embodiment provides a tractor, wherein the tractor is equipped with the plow depth control system described in the second embodiment.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A plow depth control method, characterized in that: include: Determine the plowing depth request value according to the input plow position setting value; Determine the conversion plowing depth value according to the input force position ratio setting value, the actual position value of the plow tool and the force value; The plowing depth is precisely controlled according to the deviation between the plowing depth request value and the converted plowing depth value. At the same time, active intervention control is performed when the load resistance of the plow changes suddenly, and the plow is pressed into the soil smoothly on hard and compacted terrain. The active intervention control when the load resistance of the plow changes suddenly includes: According to the engine speed information and the current gearbox gear information, the maximum traction driving capacity F of the tractor in this state is determined. max , set F lim1 <F lim2 <F lim3 <F max For different boundary values, F lim1、 F lim2、 F lim3 The different proportions of the maximum driving capacity at the current speed: When the force value collected by the force sensor increases to F lim1 , and the force value increase rate is less than k1, the unloading valve is controlled to close; when the force value continues to increase to F lim2 When the proportional valve is controlled to rise, the force value is set at [F lim2 , F lim3 ], the corresponding current output of the proportional valve is controlled to be [h1, h2], the current corresponding to the real-time force value is determined by interpolation, and the plow rises until the force value drops to F lim2 Below, the current of the rising proportional valve and the unloading valve are controlled to return to zero; When the force value collected by the force sensor increases to F lim1 , and the force value increase rate is greater than k1, the unloading valve and the rising proportional valve are controlled to be electrically actuated at the same time, and the rising proportional valve current is set to h1. Within a certain time T3, if the force value increases to F lim2 , and the rate of force increase is still greater than k1, then the force value is [F lim2 , F lim3 ] interval, the rising proportional valve current is controlled to be output in the interval [h3, h2], where h1<h3<h2; or when the internal force value is still less than F within a certain period of time T3 lim2 , and the rate of force increase is still greater than k1, then the force value is [F lim1 , F lim2 ] interval, the current of the rising proportional valve is controlled according to the output control of [h1, h3]. The corresponding current of the real-time force value in the process is determined by the interpolation method; or the force value is still less than F within a certain period of time T3. lim2 , and the rate of change of force increase is less than k1, controlling the current of the rising proportional valve and the unloading valve to return to zero.

2. The plowing depth control method according to claim 1, characterized in that: The plowing depth request value is obtained by the following method: H depth_set =A-B*H position_set； (1) Among them, H depth_set is the plowing depth request value, A is the maximum plowing depth of the plow, B is the conversion coefficient from the plowing position setting to the plowing depth setting, H position_set Set the knob setting for the plow position.

3. The plowing depth control method according to claim 1, characterized in that: The converted plow depth value is obtained by the following method: H real =a(A-B*H position_real )+(1-a)F draft_real / C (2) H real is the conversion plow depth value, a is the force position comprehensive weight ratio coefficient set by the force position ratio setting knob, H position_real F is the actual plow position value collected by the position sensor; draft_real is the actual force value collected by the force sensor, and C is the conversion coefficient between force value and plow depth.

4. The plowing depth control method according to claim 1, characterized in that: The plowing depth control according to the deviation between the plowing depth request value and the converted plowing depth value comprises: Set the deviation between the requested plowing depth value and the converted plowing depth value e=H real -H depth_set , set the control boundary of e to [m1, n1], m1 is a negative value, n1 is a positive value, and m1 and n1 are respectively a set proportion value of the plowing depth request value; When e<0, the converted plowing depth value is less than the plowing depth request value. When e≤m1, the descending proportional valve is controlled to act. The current control process is as follows: m2 is set to be less than the control boundary m1 value. When the deviation e is set in the interval [m2, m1], the descending proportional valve current setting interval is [f1, f2]. When e≤m2, the current is set to f2. When m2<e<m1, the current is set in the corresponding deviation interval according to the interpolation method. When e=m1, the current is set to f1. When e>m1, the current of the descending proportional valve is controlled to return to zero. When e>0, the converted plowing depth value is greater than the plowing depth request value, and the rising proportional valve is controlled to act. The current control process is: set the boundary value n3, and 0<n3<n1, then when e is the interval value of [n3, n1], the unloading valve is controlled to close, so that the hydraulic oil output by the hydraulic pump is unloaded through the fixed differential compensation valve; when e≥n1, the rising proportional valve is controlled to perform the plowing action, and n2 is set to be greater than the control boundary n1 value. When the deviation e is set in the interval of [n1, n2], the current setting interval of the rising proportional valve is [h1, h2]. That is, when e=n1, the current is set to h1, when e≥n2, the current is set to h2, and when n1<e<n2, the current is set in the corresponding interval by interpolation method; when the deviation e decreases from the interval value of [n3, n1] to less than n3 within a certain time T1, the unloading valve is controlled to be closed; or when the deviation e remains in the interval value of [n3, n1] within a certain time T2, the unloading valve is controlled to be closed. After T2 time, when the deviation e≥n1 again, the unloading valve and the rising proportional valve are directly controlled to be energized synchronously to perform the plow lifting action.

5. The plowing depth control method according to claim 1, characterized in that: The method of controlling the plow to be pressed firmly into the soil and to be stable on the hard and compacted terrain includes: For hardened terrain, when the controller receives the descent mode trigger signal and the high-pressure mode trigger signal, the controller first controls the descent proportional valve to lower the plow according to the descent speed setting knob setting value. When the pressure value collected by the force sensor is close to G1, it is judged that the plow is close to the ground, and the unloading valve and the high-pressure switch valve are controlled to be energized. When the collected pressure value is close to the [0, G2] interval, G2<G1, the ascending proportional valve is controlled to be energized, and the hydraulic oil output by the hydraulic pump passes through the ascending proportional valve and the high-pressure switch valve into the rod chamber of the suspension cylinder. The plow is forced into the soil under the pressure set by the relief valve until the plow reaches the set depth, and the high-pressure mode is automatically exited.

6. A plow depth control system, characterized in that: The invention comprises a hydraulic pump (1), wherein the outlet of the hydraulic pump (1) is respectively connected to the inlet of the unloading valve (2), the inlet of the differential compensation valve (3) and the inlet of the rising proportional valve (4), and then connected to the rodless chamber of the suspension cylinder (9) through the strong pressure switch valve (6), and the rodless chamber of the suspension cylinder (9) is connected to the descending proportional valve (5); the rod chamber of the suspension cylinder (9) is provided with an overflow valve (8); a force sensor (10), a position sensor (11), a descending speed setting knob (15), a descending mode trigger button (16), a force position ratio setting knob (17), a plow position setting knob (18) and a strong pressure mode trigger button (19) are respectively connected to the input end of the controller (12); The output end of the controller (12) is electrically connected to the control ends of the ascending proportional valve (4), the descending proportional valve (5), the strong pressure switch valve (6), and the unloading valve (2) respectively; The controller (12) also collects gear information of the transmission and speed information of the engine, and performs plowing depth control according to the plowing depth control method according to any one of claims 1 to 5.

7. The plowing depth control system according to claim 6, characterized in that: The force sensor (10) is used to obtain real-time force status information of the plow. The position sensor (11) is used to obtain the real-time position information of the plow. The descending speed setting knob (15) is used to set the speed of the plow descending process. The descending mode trigger button (16) is used to trigger the plough to descend. The force ratio setting knob (17) is used to set the force weight information of the tillage process. The plough position setting knob (18) is used to set the plough position. The strong pressure mode trigger button (19) is used to trigger the strong pressure mode of the plow during operation.

8. The plowing depth control system according to claim 6, characterized in that: A one-way valve (7) is also provided between the high-pressure switch valve (6) and the rodless chamber of the suspension oil cylinder (9).

9. A tractor, characterized in that: The tractor is equipped with the plow depth control system according to claim 6.

Images