Hydraulic circuit for adjusting coulter pressure on an agricultural spreading machine

Abstract

The invention relates to a hydraulic circuit (10) for coulter pressure adjustment on an agricultural spreading machine, comprising a first line section (20) which is configured to be connected to a first coulter pressure adjustment cylinder (104) and to supply a hydraulic pressure to the first coulter pressure adjustment cylinder (104), a first pressure limiting valve (22) which is configured to limit the hydraulic pressure in the first line section (20) to a first maximum pressure, a second line section (16) which is configured to be connected to a second coulter pressure adjustment cylinder (106) and to supply a hydraulic pressure to the second coulter pressure adjustment cylinder (106), and a second pressure limiting valve (18) which is configured to limit the hydraulic pressure in the second line section (16) to a second maximum pressure.

Description

[0001] The invention relates to a hydraulic circuit for adjusting the coulter pressure on an agricultural spreading machine according to the preamble of patent claim 1, a hydraulic control block according to the preamble of patent claim 9, an agricultural spreading machine according to the preamble of patent claim 10 and a method for adjusting the coulter pressure on an agricultural spreading machine according to the preamble of patent claim 11.

[0002] Since the coulters of an agricultural spreading machine in the tractor's track penetrate less deeply into the soil than coulters running outside the track due to soil compaction at the same coulter pressure, the coulters running in the track must be subjected to a higher coulter pressure so that the application result is not impaired by soil compaction in the track area. In particular, different placement depths inside and outside the track should be prevented. On agricultural spreading machines, each coulter or group of coulters is usually assigned a coulter pressure adjustment cylinder with which the coulter pressure on the coulter or group of coulters can be changed or adjusted.

[0003] Until now, two separate and independently controllable hydraulic circuits were required to simultaneously implement different coulter pressures on the coulter pressure adjustment cylinders of an agricultural spreading machine. This resulted in twice the flow rate being required to simultaneously generate two different coulter pressures.

[0004] In this context, for example, a solution for applying the same pressure to a group of coulters on a seed drill is known from US Pat. EP 3 106 012 B1 proposes providing two adjustable pressure valves in a hydraulic circuit.

[0005] The object underlying the invention is to reduce the effort required for providing different share pressures on the shares of an agricultural spreading machine.

[0006] The object is achieved by a hydraulic circuit of the type mentioned at the outset, wherein the second maximum pressure to which the second pressure relief valve limits the hydraulic pressure in the second line region depends on the hydraulic pressure in the first line region.

[0007] The hydraulic circuit can be used to provide two different hydraulic pressures with comparatively little effort, which can be used to implement two different coulter pressures. In this way, a higher coulter pressure can be set on the coulter or coulters that run in the compacted tractor track than on the coulters that run outside the tractor track. Because the second maximum pressure is dependent on the hydraulic pressure in the first line section, it is ensured with little effort that the coulters in the track always experience increased pressure, so that soil compaction in the track area is compensated for by the coulter pressure difference. The hydraulic circuit achieves this with a simple design and a small number of cost-effective standard components.

[0008] The agricultural spreading machine can be used to spread seed and / or fertilizer, for example. The agricultural spreading machine can therefore be a seed drill or a fertilizer spreading machine. Furthermore, the agricultural spreading machine can be configured for the combined spreading of seed and fertilizer. The coulters can therefore be seed coulters or fertilizer coulters.

[0009] In a preferred embodiment of the hydraulic circuit according to the invention, the second line section is adjacent to the valve inlet of the second pressure relief valve. Furthermore, the first line section is adjacent to the valve outlet of the second pressure relief valve. The second line section and the first line section of the hydraulic circuit are thus separated from each other by the second pressure relief valve.

[0010] In a further preferred embodiment of the hydraulic circuit according to the invention, the second pressure relief valve is designed to open when an opening pressure applied to the valve inlet is exceeded, wherein the opening pressure is preferably dependent on a spring closing force exerted by a spring of the second pressure relief valve. Preferably, the opening pressure is also dependent on an additional closing force exerted by the hydraulic pressure in the first line region. Because the opening pressure is dependent on the spring closing force and the additional closing force, the second maximum pressure to which the second pressure relief valve limits the hydraulic pressure in the second line region depends, on the one hand, on the spring properties of the valve spring of the second pressure relief valve and, on the other hand, on the hydraulic pressure in the first line region.The spring properties of the valve spring of the second pressure relief valve can be used to determine the difference between the second maximum pressure to which the second pressure relief valve limits the hydraulic pressure in the second line area and the hydraulic pressure in the first line area.

[0011] Furthermore, a hydraulic circuit according to the invention is advantageous in which the second pressure relief valve is designed such that the spring closing force and the additional closing force add up to a total closing force and thus lead to an increased opening pressure. The second pressure relief valve therefore operates according to the principle of closing force addition, wherein the closing force addition takes into account a spring closing force predetermined by the spring properties of the valve spring and an additional closing force predetermined by the hydraulic pressure in the first line region. The hydraulic pressure in the second line region is increased compared to the hydraulic pressure in the first line region by a pressure difference attributable to the spring closing force. The hydraulic pressure in the second line region is increased by a fixed amount. This amount can be set at the factory and / or adjustable by the machine operator.

[0012] Furthermore, a hydraulic circuit according to the invention is advantageous in which the first pressure relief valve and the second pressure relief valve are connected in series. The first line section is preferably delimited by the first pressure relief valve, the second pressure relief valve, and the at least one first share pressure cylinder. The implemented differential pressure circuit is thus implemented by two pressure relief valves connected in series.

[0013] In another preferred embodiment of the hydraulic circuit according to the invention, the second pressure relief valve is mechanically and / or manually adjustable. Preferably, the fluid pressure required to overcome the spring closing force is adjustable. By mechanical and / or manual adjustment, the spring properties of the valve spring and thus the spring closing force influencing the opening pressure can be adjusted. As part of the mechanical and / or manual adjustment of the second pressure relief valve, for example, the preload of the valve spring can be changed. To increase the spring closing force and thus increase the required opening pressure, the preload of the spring can be increased mechanically and / or manually. To decrease the spring closing force and thus reduce the required opening pressure, the preload of the valve spring can be reduced.

[0014] In a further development, the hydraulic circuit according to the invention has an actuating device connected to the second pressure relief valve, by means of which the second pressure relief valve can be adjusted. For example, the preload of the valve spring of the second pressure relief valve can be adjusted via the actuating device. The actuating device can be a handwheel or an adjusting slide, for example. The actuating device can have a scale readable by a machine operator, which indicates the differential pressures to be achieved by the second pressure relief valve between the second maximum pressure, to which the second pressure relief valve limits the hydraulic pressure in the second line section, and the hydraulic pressure in the first line section.

[0015] In another preferred embodiment of the hydraulic circuit according to the invention, the first pressure relief valve is electrically adjustable. If the first pressure relief valve is electrically adjustable, it can be connected to a control device for adjusting the coulter pressure. The coulter pressure generated by the first coulter pressure cylinder can be adjusted via the control device. This also influences the coulter pressure generated by the second coulter pressure adjustment cylinder. The first pressure relief valve can, for example, be a proportional pressure relief valve in which opening pressures can be adjusted proportionally to the solenoid current.

[0016] The object underlying the invention is further achieved by a hydraulic control block of the type mentioned above, wherein the hydraulic circuit of the hydraulic control block according to the invention is designed according to one of the embodiments described above. With regard to the advantages and modifications of the hydraulic control block according to the invention, reference is therefore first made to the advantages and modifications of the hydraulic circuit according to the invention.

[0017] The housing of the hydraulic control block, into which the hydraulic circuit is integrated, can be made of plastic or metal, for example. For example, the housing is an injection-molded plastic housing or an injection-molded aluminum housing.

[0018] The hydraulic control block according to the invention preferably has a first cylinder connection and a second cylinder connection. A first coulter pressure adjustment cylinder can be connected to the first line section via the first cylinder connection. A second coulter pressure adjustment cylinder can be connected to the second line section via the second cylinder connection. Furthermore, the hydraulic control block preferably has an inlet connection and a return connection. Hydraulic fluid from a tractor-side hydraulic source can be introduced into the hydraulic circuit via the inlet connection. Hydraulic fluid from the hydraulic circuit can be supplied to a tractor-side hydraulic tank via the return connection.

[0019] The object underlying the invention is further achieved by an agricultural spreading machine of the type mentioned above, wherein the hydraulic circuit of the spreading machine according to the invention is designed according to one of the embodiments described above or is a component of a previously described hydraulic control block. Regarding the advantages and modifications of the spreading machine according to the invention, reference is made to the advantages and modifications of the hydraulic circuit according to the invention and the hydraulic control block.

[0020] The spreading machine can, for example, be an attachment that can be attached to an agricultural vehicle, in particular a tractor. The agricultural spreading machine can be designed to be carried or pulled by the agricultural vehicle. The agricultural spreading machine can, for example, be a seed drill.

[0021] The object underlying the invention is further achieved by a method of the type mentioned above, wherein the second maximum pressure to which the second pressure-limiting valve limits the hydraulic pressure in the second line region is dependent on the hydraulic pressure in the first line region. The method according to the invention is preferably used for adjusting the coulter pressure on an agricultural spreading machine according to one of the embodiments described above. The adjustment of the coulter pressure is preferably implemented by means of a hydraulic circuit according to one of the embodiments described above.

[0022] With regard to the advantages and modifications of the method according to the invention, reference is made to the advantages and modifications of the agricultural spreading machine according to the invention and the advantages and modifications of the hydraulic circuit according to the invention.

[0023] A preferred embodiment of the invention is explained and described in more detail below with reference to the accompanying drawings. Fig. 1 an embodiment of the hydraulic circuit according to the invention for adjusting the share pressure in a schematic representation.

[0024] The Fig. Figure 1 shows a hydraulic control block 50 of an agricultural spreading machine designed as a seed drill. The hydraulic control block 50 comprises a hydraulic circuit 10 integrated into a housing 52, which serves to adjust the coulter pressure on the agricultural spreading machine.

[0025] The hydraulic control block 50 has an inlet connection 54, which is connected via an inlet line 100 to a hydraulic source 202 of a tractor-side hydraulic unit 200. Hydraulic fluid, for example hydraulic oil, can be introduced from the tractor-side hydraulic source 202 into the hydraulic circuit 10 via the inlet connection 54. The hydraulic control block 50 further comprises a first cylinder connection 56 and a second cylinder connection 58. The first cylinder connection 56 is connected via a connecting line 102 to a first coulter pressure adjustment cylinder 104. The second cylinder connection 58 is connected via a connecting line 106 to a second coulter pressure adjustment cylinder 108. A different hydraulic pressure is provided to the coulter pressure adjustment cylinders 104, 108 via the connecting lines 102, 106, so that the coulter pressure adjustment cylinders 104, 108 generate different coulter pressures on the respective sowing coulters.Since the coulter connected to the coulter pressure adjustment cylinder 108 runs in the tractor's track, a higher coulter pressure is required on this coulter due to the soil compaction caused by the tractor in order to achieve a uniform planting depth across the entire width of the machine. The coulter connected to the coulter pressure adjustment cylinder 104 runs outside the tractor's track and requires a lower coulter pressure due to less soil compaction.

[0026] The hydraulic control block 50 further includes a return port 60. Hydraulic fluid can be discharged from the hydraulic circuit 10 via the return port 60 and the return line 110 and fed to a hydraulic tank 204 of the tractor-side hydraulic unit 200. The return line 110 is also connected to the outlets of the coulter pressure adjustment cylinders 104, 108, so that the hydraulic fluid discharged from the coulter pressure adjustment cylinders 104, 108 is also fed back to the hydraulic tank 204 of the hydraulic unit 200.

[0027] The housing 52 of the hydraulic control block 50 can be made of plastic and / or metal, for example. The housing 52 can be, for example, a plastic injection-molded or aluminum injection-molded housing.

[0028] The hydraulic circuit 10 integrated into the housing 52 has an inlet line 12 connected to the inlet connection 54. Via the inlet line 12 and the throttle 14, the hydraulic fluid enters a line section 16, which is connected to the coulter pressure adjustment cylinder 108 and provides a hydraulic pressure to the coulter pressure adjustment cylinder 108. The line section 16 is the "second line section" within the meaning of the patent claims.

[0029] A pressure relief valve 18 is connected to the line section 16, via which the hydraulic pressure in the line section 16 is limited to a maximum pressure. The pressure relief valve 18 is the "second pressure relief valve" within the meaning of the patent claims.

[0030] The line section 16 is thus located at the valve inlet 24 of the pressure relief valve 18. A line section 20 is located at the valve outlet 26 of the pressure relief valve 18, which is connected to the coulter pressure adjustment cylinder 104 and provides a hydraulic pressure to the coulter pressure cylinder 104. A pressure relief valve 22 limits the hydraulic pressure in the line section 20 to a maximum pressure. The line section 20 is the "first line section" within the meaning of the patent claims. The pressure relief valve 22 is the "first pressure relief valve" within the meaning of the patent claims.

[0031] The maximum pressure to which the pressure relief valve 18 limits the hydraulic pressure in the line area 16 depends on the hydraulic pressure in the line area 20. The pressure relief valve 18 opens when an opening pressure applied to the valve inlet 24 is exceeded, wherein the opening pressure depends on a spring closing force and an additional closing force. The spring closing force is exerted by a valve spring of the pressure relief valve 18. The additional closing force is exerted by the hydraulic pressure in the line area 20. The pressure relief valve 18 is designed such that the spring closing force and the additional closing force add up to a total closing force and thus lead to an increased opening pressure.The pressure relief valves 22, 18 connected in series allow two different hydraulic pressures to be provided with comparatively little effort, which can be used to implement two different coulter pressures. In this way, a higher coulter pressure can be set on the sowing coulter connected to the coulter pressure adjustment cylinder 108, which runs in the compacted tractor track, than on the sowing coulter connected to the coulter pressure adjustment cylinder 104. Thanks to a comparatively simple design with a small number of inexpensive standard components, the coulter pressure adjustment cylinders 104, 108 can be subjected to different hydraulic pressures, so that soil compaction in the area of ​​the tractor's track is compensated for by the coulter pressure difference.

[0032] The hydraulic pressure in line area 16 is thus increased by a fixed amount, which depends on the spring closing force of the valve spring of the pressure relief valve 18. The spring closing force is preset at the factory and can be subsequently adjusted by the machine operator. For this purpose, the pressure relief valve 18 is manually adjustable. By adjusting the pressure relief valve 18, the fluid pressure required to overcome the spring closing force can be set. For this purpose, the pressure relief valve 18 is connected to an actuating device by means of which the pressure relief valve can be adjusted. The actuating device can be, for example, a handwheel or an adjusting slide.

[0033] The pressure relief valve 22 is an electrically adjustable valve. The pressure relief valve 22 is designed as a proportional pressure relief valve, in which opening pressures can be adjusted proportionally to the solenoid current.

[0034] The hydraulic circuit 10 further comprises an outlet line 28, which is connected to the return connection 60. The hydraulic fluid passing through the pressure relief valve 22 can be discharged from the hydraulic control block 50 via the outlet line 28.

[0035] Furthermore, the hydraulic circuit 10 comprises two pressure gauges 30a, 30b, via which the fluid pressures in the line areas 16, 20 can be monitored.

[0036] In an embodiment not shown, the pressure gauge 30b is replaced by a pressure sensor, wherein the signals from this pressure sensor enable control of the hydraulic pressure in the line region 20, i.e., the "first line region." In particular, the signals from the pressure sensor are used to control the pressure relief valve 22, i.e., the "first pressure relief valve," based on a comparison between an actual hydraulic pressure measured by the pressure sensor and a target hydraulic pressure specified by a user. List of reference symbols 10 Hydraulic circuit 12 Inlet line 14 Throttle 16 Management area 18 Pressure relief valve 20 Management area 22 Pressure relief valve 24 valve inlet 26 Valve outlet 28 Outlet line 30a, 30b Pressure gauge 50 hydraulic control block 52 housings 54 Inlet connection 56 cylinder connection 58 cylinder connection 60 return connection 100 supply line 102 connecting cable 104 coulter pressure adjustment cylinder 106 connecting cable 108 coulter pressure adjustment cylinder 110 Return line 200 hydraulic unit 202 Hydraulic source 204 Hydraulic tank

Claims

[1] Hydraulic circuit (10) for adjusting coulter pressure on an agricultural spreading machine, with - a first line section (20) which is designed to be connected to a first coulter pressure adjustment cylinder (104) and to provide a hydraulic pressure to the first coulter pressure adjustment cylinder (104); - a first pressure relief valve (22) which is designed to limit the hydraulic pressure in the first line section (20) to a first maximum pressure; - a second line section (16) which is designed to be connected to a second coulter pressure adjusting cylinder (108) and to supply a hydraulic pressure to the second coulter pressure adjusting cylinder (108); and - a second pressure relief valve (18) which is designed to limit the hydraulic pressure in the second line section (16) to a second maximum pressure; characterized by, that the second maximum pressure to which the second pressure relief valve (18) limits the hydraulic pressure in the second line section (16) depends on the hydraulic pressure in the first line section (20). [2] Hydraulic circuit (10) according to claim 1, characterized by , that the second line section (16) is connected to the valve inlet (24) of the second pressure relief valve (18) and the first line section (20) is connected to the valve outlet (26) of the second pressure relief valve (18). [3] Hydraulic circuit (10) according to claim 1 or 2, characterized by , that the second pressure relief valve (18) is configured to open when an opening pressure applied to the valve inlet (24) is exceeded, wherein the opening pressure is preferably of - a spring closing force exerted by a valve spring of the second pressure relief valve (18), and - depends on an additional closing force exerted by the hydraulic pressure in the first line section (20). [4] Hydraulic circuit (10) according to claim 3, characterized by , that the second pressure relief valve (18) is designed such that the spring closing force and additional closing force add up to a total closing force and thus lead to an increased opening pressure. [5] Hydraulic circuit (10) according to one of the preceding claims, characterized by , that the first pressure relief valve (22) and the second pressure relief valve (18) are connected in series. [6] Hydraulic circuit (10) according to one of the preceding claims, characterized by , that the second pressure relief valve (18) is mechanically and / or manually adjustable. [7] Hydraulic circuit (10) according to claim 6, characterized byan actuating device connected to the second pressure relief valve (18), by means of which the second pressure relief valve (18) can be adjusted. [8] Hydraulic circuit (10) according to one of the preceding claims, characterized by , that the first pressure relief valve (22) is electrically adjustable. [9] Hydraulic control block (50), with - a case (52), and - a hydraulic circuit (10) integrated into the housing (52); characterized by , that the hydraulic circuit (10) is designed according to one of the preceding claims. [10] Agricultural spreading machine, in particular seed drill, with - at least a first share, wherein the share pressure on the first share is adjustable by means of a first share pressure adjusting cylinder (104) of the spreading machine; - at least a second coulter, wherein the coulter pressure on the second coulter is adjustable by means of a second coulter pressure adjusting cylinder (108) of the spreading machine; and - a hydraulic circuit (10) which is connected to the first coulter pressure adjustment cylinder (104) and the second coulter pressure adjustment cylinder (108) and is configured to provide hydraulic pressure to the first coulter pressure adjustment cylinder (104) and the second coulter pressure adjustment cylinder (108); characterized by that the hydraulic circuit (10) is designed according to one of claims 1 to 8 or is part of a hydraulic control block (50) according to claim 9. [11] Method for adjusting the coulter pressure on an agricultural spreading machine, in particular on an agricultural spreading machine according to claim 10, by means of a hydraulic circuit (10), in particular a hydraulic circuit (10) according to any one of claims 1 to 8, comprising the steps: - Limiting the hydraulic pressure in a first line section (20) of the hydraulic circuit (10) by means of a first pressure limiting valve (22) of the hydraulic circuit (10) to a first maximum pressure, wherein the first line section (20) is connected to a first coulter pressure adjusting cylinder (104) and specifies a hydraulic pressure to the first coulter pressure adjusting cylinder (104); - Limiting the hydraulic pressure in a second line section (16) of the hydraulic circuit (10) by means of a second pressure limiting valve (18) of the hydraulic circuit (10) to a second maximum pressure, wherein the second line section (16) is connected to a second coulter pressure adjusting cylinder (108) and specifies a hydraulic pressure to the second coulter pressure adjusting cylinder (108); characterized by, that the second maximum pressure to which the second pressure relief valve (18) limits the hydraulic pressure in the second line section (16) depends on the hydraulic pressure in the first line section (20).

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