Hydraulic control system for slurry stirring

Abstract

The hydraulic control system comprises an oil tank, a pair of oil cylinders, an automatic control loop, a manual control loop and a pump set, wherein the automatic control loop, the manual control loop and the pump set independently correspond to the oil cylinders respectively. The output end of the pump set is connected with the oil cylinder through an automatic control loop and a manual control loop which are connected in parallel. The automatic control loop is suitable for automatically adjusting the oil supply amount flowing to the oil cylinder according to the state of the oil cylinder. The manual control loop is suitable for adjusting the oil supply amount flowing to the oil cylinder according to the autonomously-controlled loop conduction state. The automatic control loop and the manual control loop are not conducted at the same time; the two pump sets are connected through a switching loop, so that when one pump set breaks down, the other pump set supplies oil to the two oil cylinders at the same time through the switching loop. The slurry raking device has the beneficial effects that the action state of the slurry raking head can be adjusted manually or automatically according to different conditions of slurry, so that the working efficiency and flexibility of the slurry raking head can be effectively improved.

Description

Technical Field

[0001] The present application relates to the field of hydraulic technology, and in particular to a hydraulic control system for slurry stirring. Background Art

[0002] In the manufacturing process of specific industrial products, the slurry system often needs to be left standing or stored in a sedimentation tank or storage tank. When production is required, the stationary or stored slurry needs to be sucked up by a slurry suction pump before entering the next process. Since the slurry's standing time varies, the degree of sedimentation or nodules of the slurry may vary; in order to avoid clogging of the slurry suction pump when the slurry is absorbed, the traditional method is to stir the slurry in the sedimentation tank manually or by machine to ensure the uniformity of the slurry. However, the traditional method has the following main problems when stirring the slurry: the efficiency of the manual method is relatively low; the machine stirring generally uses an electric-driven stirring head, which has a relatively small driving force and the stirring head is prone to clogging; at the same time, it cannot be flexibly adjusted for different mud thicknesses and materials. Utility Model Content

[0003] One of the objectives of the present application is to provide a hydraulic control system for slurry stirring that can solve at least one of the defects in the above-mentioned background technology.

[0004] In order to achieve at least one of the above-mentioned purposes, the technical solution adopted in the present application is: a hydraulic control system for slurry stirring, comprising a fuel tank, a pair of oil cylinders, and an automatic control circuit, a manual control circuit and a pump group independently corresponding to each of the oil cylinders; each of the oil cylinders drives a rake head to stir the sedimentation slurry; the input end of the pump group extends to the oil tank, and the output end of the pump group is connected to the oil cylinder through the automatic control circuit and the manual control circuit connected in parallel; the pump group is suitable for supplying oil to the oil cylinder, and the automatic control circuit is suitable for automatically adjusting the oil supply amount flowing to the oil cylinder according to the state of the oil cylinder; the manual control circuit is suitable for adjusting the oil supply amount flowing to the oil cylinder according to the conduction state of the autonomous control circuit; the automatic control circuit and the manual control circuit are not connected at the same time; the two pump groups are connected by a switching circuit, so that when one of the pump groups fails, the other pump group supplies oil to the two cylinders at the same time through the switching circuit.

[0005] Preferably, the automatic control circuit includes a proportional pressure reducing valve and a second electro-hydraulic reversing valve; the control pressure of the proportional pressure reducing valve is controlled by the state of the oil cylinder, and the first branch formed by the proportional pressure reducing valve and the second electro-hydraulic reversing valve in series is connected between the output end of the pump group and the rodless chamber of the oil cylinder; a second branch is formed between the rod chamber of the oil cylinder and the pump group through the manual control circuit whose input end is in a cut-off state, and the proportional pressure reducing valve is also connected to the oil tank through a third branch; the pump group supplies oil to the rodless chamber of the oil cylinder through the first branch to drive the oil cylinder forward, and at this time a differential circuit is formed between the rodless chamber and the rod chamber of the oil cylinder; the pump group provides back pressure to the rod chamber of the oil cylinder through the second branch, and then the oil cylinder returns oil and contracts through the first branch and the third branch.

[0006] Preferably, the proportional pressure reducing valve adopts a pilot control structure; the automatic control circuit also includes a proportional overflow valve, the input end of the proportional overflow valve is connected to the midpoint of the first branch and / or the inlet of the proportional overflow valve, the output end of the proportional overflow valve is connected to the oil tank, and the input end of the proportional overflow valve is also connected to the control end of the proportional pressure reducing valve; the opening of the proportional overflow valve is controlled according to the comparison between the displacement feedback signal of the oil cylinder or the input pressure signal and the set value, thereby controlling the pilot end pressure of the proportional pressure reducing valve.

[0007] Preferably, the automatic control circuit further includes a second shuttle valve, which is connected in parallel to the proportional pressure reducing valve via two input ends, and the output end of the second shuttle valve is connected to the input end of the proportional relief valve.

[0008] Preferably, the manual control circuit includes a third electro-hydraulic reversing valve, a hydraulically controlled one-way valve and a pair of one-way throttle valves; the oil inlet of the third electro-hydraulic reversing valve is connected to the pump group, and the oil return port of the third electro-hydraulic reversing valve is connected to the oil tank and the pump group; the connecting end of the third electro-hydraulic reversing valve is connected to the rodless chamber and the rod chamber of the oil cylinder through two pipelines installed with the one-way throttle valve, the hydraulically controlled one-way valve is installed on the pipeline connecting the third electro-hydraulic reversing valve to the rodless chamber of the oil cylinder, and the control end of the hydraulically controlled one-way valve is connected to another pipeline; the third electro-hydraulic reversing valve is in an oil inlet cut-off state when the automatic control circuit is working, at this time, the oil return port of the third electro-hydraulic reversing valve cooperates with the oil cylinder to form the second branch; the energized state of the third electro-hydraulic reversing valve is controlled by a manual input signal to control the extension and retraction of the oil cylinder; the one-way throttle valve controls the extension and retraction speed of the oil cylinder by adjusting the opening.

[0009] Preferably, the rodless chamber and rod chamber of the oil cylinder are connected to the manual control circuit and the automatic control circuit respectively through a balancing circuit; the balancing circuit is used to balance the pressure of the rodless chamber and rod chamber of the oil cylinder, and form a differential circuit when the automatic control circuit is working.

[0010] Preferably, the balancing circuit includes a counterbalancing valve, a one-way valve and a pair of overflow valves; the counterbalancing valve and the pair of overflow valves are connected in parallel to the rodless chamber and the rod chamber of the cylinder; the pressure relief directions of the two overflow valves are opposite, the control end of the counterbalancing valve is connected to the rod chamber of the cylinder, and the one-way valve is installed in the rod chamber of the cylinder; the counterbalancing valve is suitable for forming a differential circuit to drive the cylinder to extend when the pressure in the rodless chamber of the cylinder is greater than the back pressure; the counterbalancing valve is suitable for forming a differential circuit to drive the cylinder to contract when the pressure in the rodless chamber of the cylinder is less than the back pressure.

[0011] Preferably, the pump group includes a first oil pump and a second oil pump; the first oil pump is suitable for supplying oil to the manual control circuit and the automatic control circuit, thereby driving the oil cylinder to extend and retract; the second oil pump is suitable for supplying oil to the second branch formed by the manual control circuit, thereby providing back pressure for the oil cylinder; the output ends of the first oil pumps corresponding to the two pump groups are connected through the switching circuit.

[0012] Preferably, the switching circuit includes a first electro-hydraulic reversing valve and a first shuttle valve; the first electro-hydraulic reversing valve is connected to the output ends of the first oil pumps corresponding to the two pump groups respectively; the first shuttle valve is connected in parallel to the first electro-hydraulic reversing valve through two input ends, and the output end of the first shuttle valve is connected to the control end of the first electro-hydraulic reversing valve; the first shuttle valve is in a cut-off state when the two first oil pumps are working normally, so that the first electro-hydraulic reversing valve is in a natural cut-off state; when one of the first oil pumps fails, the first shuttle valve controls the first electro-hydraulic reversing valve to switch according to the pressure difference at the input end, so that both of the oil cylinders are supplied with oil through the first oil pump that is not faulty.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] The hydraulic drive mode is adopted for the pulp rake head, which can provide sufficient driving force; and the action state of the pulp rake head can be adjusted manually or automatically according to the different conditions of the pulp, thereby effectively improving the working efficiency and flexibility of the pulp rake head. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the overall control logic of this application.

[0016] Figure 2 This is a schematic diagram of the hydraulic structure corresponding to a single cylinder in this application.

[0017] Figure 3 Schematic diagram of the hydraulic structure of the pump group in this application.

[0018] Figure 4 Schematic diagram of the hydraulic structure of the switching circuit in this application.

[0019] Figure 5 This is a schematic diagram of the hydraulic structure of the automatic control circuit and the manual control circuit in this application.

[0020] Figure 6 Schematic diagram of the hydraulic structure of the balancing circuit in this application.

[0021] In the figure: oil tank 1, pump group 2, plunger pump 21, gear pump 22, switching circuit 3, first electro-hydraulic reversing valve 31, first shuttle valve 32, automatic control circuit 4, proportional pressure reducing valve 41, proportional relief valve 42, second shuttle valve 43, second electro-hydraulic reversing valve 44, manual control circuit 5, third electro-hydraulic reversing valve 51, hydraulically controlled one-way valve 52, one-way throttle valve 53, first relief valve 54, balancing circuit 6, high-pressure stop valve 61, second relief valve 62, one-way valve 63, counterbalancing valve 64, third relief valve 65, oil cylinder 7, accumulator 8. DETAILED DESCRIPTION

[0022] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that, in the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like are intended to mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0023] In the description of this application, it should be noted that for directional words, such as the terms "center", "horizontal", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and so on, the directions and positional relationships indicated are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of this application.

[0024] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0025] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0026] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0027] The terms "comprises" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units expressly listed, but may include other steps or units not expressly listed or inherent to such process, method, product or apparatus.

[0028] One of the preferred embodiments of this application is as follows: Figure 1 and Figure 2As shown, a hydraulic control system for slurry stirring includes an oil tank 1, a pair of oil cylinders 7, and an automatic control circuit 4, a manual control circuit 5, and a pump group 2 corresponding to each oil cylinder 7. The oil cylinder 7 is used to drive the rake head for stirring the sedimentation slurry to move, and the oil tank 1 is used to provide oil for the movement of the oil cylinder 7 and to return the oil to the oil cylinder 7. The input end of the pump group 2 extends to the oil tank 1, and the output end of the pump group 2 is connected to the oil cylinder 7 through the automatic control circuit 4 and the manual control circuit 5 connected in parallel. The two pump groups 2 are connected through a switching circuit 3, so that when one of the pump groups 2 fails, the other pump group 2 can drive and control the two oil cylinders 7 at the same time through the switching circuit 3, thereby ensuring the stable operation of the entire hydraulic control system.

[0029] It should be noted that the stirring of the sedimentation slurry can be a single rake slurry head structure or a double rake slurry head structure. In order to improve the stirring efficiency, a double rake slurry head structure is generally used. The two rake slurry heads are arranged opposite to each other and the rake stirring of the sedimentation slurry is achieved by simultaneously approaching and biting. The movement of the two rake slurry heads is driven and controlled by an independent oil cylinder 7, that is, Figure 1 As shown, each rake head has its own independent oil cylinder 7, balancing circuit 6, manual control circuit 5, automatic control circuit 4, and pump unit 2. The two rake heads operate synchronously; if one rake head fails, the entire slurry mixing process will be disrupted. Therefore, a switching circuit 3 connects the two pump units 2 corresponding to the two rake heads, ensuring that if one pump unit 2 fails, the system will be inoperative.

[0030] When the rake head needs to rake and stir the settled slurry, the pump group 2 can be started and output the pressurized oil used to drive the oil cylinder 7 to operate. There are two paths for the pressurized oil to flow to the oil cylinder 7: one is to flow to the oil cylinder 7 through the automatic control circuit 4, and the other is to flow to the oil cylinder 7 through the manual control circuit 5. Among them, the automatic control circuit 4 can automatically adjust the oil supply to the oil cylinder 7 according to the state of the oil cylinder 7, thereby controlling the extension and retraction direction and speed of the oil cylinder 7; the manual control circuit 5 can adjust the oil supply to the oil cylinder 7 according to the conduction state of the autonomous control circuit, thereby controlling the extension and retraction direction and speed of the oil cylinder 7.

[0031] It should be noted that the specific structure and operating principle of the rake head are well known to those skilled in the art and will not be elaborated on in detail here. The rake head operates similarly to the bucket of an excavator. The extension of the oil cylinder 7 controls the distance and angle of the rake head's downward rotation, during which the rake head rakes the settled slurry. The retraction of the oil cylinder 7 controls the angle and distance of the rake head's upward rotation, during which the rake head resets after completing a raking motion, preparing for the next raking motion.

[0032] It is understandable that the precipitated slurry may be in a sludge-like state or in a hard, agglomerated state, depending on the slurry material. For sludge-like precipitated slurries, the load force on the rake head during raking and stirring is small and can be considered constant; however, for agglomerated precipitated slurries, the load force on the rake head during raking and stirring is uneven and generally large. Traditional methods for raking and stirring different precipitated slurries generally use a constant control loop that adapts to larger loads. This results in the need for raking and stirring slurries that are sludge-like or agglomerated.

[0033] To accommodate sedimentation slurries in different states, this embodiment employs an automatic control circuit 4 and a manual control circuit 5 for the control circuit of the oil cylinder 7. The automatic control circuit 4 automatically adjusts the oil supply from the pump assembly 2 to the oil cylinder 7 based on the state information of the oil cylinder 7 under different loads, thereby flexibly controlling the expansion and contraction amount and speed of the oil cylinder 7, that is, the raking force and raking speed of the raking head. The manual control circuit 5 autonomously controls the oil cylinder 7 with a constant oil supply, thereby controlling the oil cylinder 7 to drive the raking head to move at a constant expansion and contraction amount and speed. Specifically, for silty sedimentation slurries or other sedimentation slurries with lower hardness, this embodiment can control the oil cylinder 7 to drive the raking head to rake and stir through the manual control circuit 5; for sedimentation slurries that may agglomerate, this embodiment can control the oil cylinder 7 to drive the raking head to rake and stir through the automatic control circuit 4.

[0034] It's important to note that due to the different control methods of automatic control circuit 4 and manual control circuit 5, they are not simultaneously active during use; that is, cylinder 7 can only operate under the control of one of the control circuits. Furthermore, manual control circuit 5 does not necessarily mean that the entire circuit is manually controlled by a staff member. Rather, the target raking force and raking speed of the raking head, namely the operating pressure and extension and retraction speed of cylinder 7, are manually and autonomously set. The retraction and reversing of cylinder 7 are automatically controlled by the program based on the set values. For ease of understanding, the specific implementations of automatic control circuit 4 and manual control circuit 5 will be described in detail below.

[0035] In this embodiment, there are many specific structures of the automatic control loop 4 that can realize the above functions. For the sake of easy understanding, the following will be described in detail using one of the structures. Figure 2 and Figure 5As shown, the automatic control circuit 4 includes a proportional pressure-reducing valve 41 and a second electro-hydraulic reversing valve 44. The control pressure of the proportional pressure-reducing valve 41 is controlled by the state of the oil cylinder 7. The proportional pressure-reducing valve 41 and the second electro-hydraulic reversing valve 44 are connected in series to form a first branch connected between the output end of the pump group 2 and the rodless chamber of the oil cylinder 7. At the same time, a second branch is formed between the rod chamber of the oil cylinder 7 and the pump group 2 via the manual control circuit 5 with its input in the closed state. The proportional pressure-reducing valve 41 is connected to the oil tank 1 via a third branch.

[0036] When the control pressure of the proportional pressure reducing valve 41 needs to be increased according to the state of the oil cylinder 7, it means that oil needs to be supplied to the rodless chamber of the oil cylinder 7 to drive the oil cylinder 7 to extend and move forward. Then, under the control of the signal, the second electro-hydraulic reversing valve 44 connects the first branch with the rodless chamber of the oil cylinder 7, and then the pump group 2 supplies oil to the rodless chamber of the oil cylinder 7 through the connected first branch to drive the oil cylinder 7 forward; at this time, a differential circuit can be formed between the rodless chamber and the rod chamber of the oil cylinder 7, so that the pressure oil in the rod chamber of the oil cylinder 7 can flow back to the rodless chamber, thereby further ensuring the stability of the forward movement of the oil cylinder 7.

[0037] When the control pressure of the proportional pressure reducing valve 41 needs to be reduced according to the state of the cylinder 7, it means that the cylinder 7 needs to retract and retreat. The pump group 2 can then provide back pressure to the rod chamber of the cylinder 7 through the second branch. At the same time, the second electro-hydraulic reversing valve 44, under signal control, connects the first branch with the rodless chamber of the cylinder 7. Then, the oil in the rodless chamber of the cylinder 7 flows back to the fuel tank 1 along the connected first and third branches, thereby realizing the retreat of the cylinder 7.

[0038] It is understandable that, as can be seen from the foregoing, the extension and forward movement of the oil cylinder 7 drives the rake head to perform rake stirring, and the retraction and backward movement of the oil cylinder 7 drives the rake head to reset. Therefore, when the oil cylinder 7 is retracted, the load force on the rake head is relatively small. At this time, the rake head can be reset by simply providing a small back pressure to the rod chamber of the oil cylinder 7, avoiding excessive driving force causing the rake head to produce a large reset impact. As can be seen from the foregoing, the function of the manual control circuit 5 is to provide the oil cylinder 7 with a constant flow rate to achieve a small load. Therefore, at this time, the manual control circuit 5 can also provide an appropriate back pressure for the automatic control circuit 4 during the retraction process of the oil cylinder 7. In other words, the automatic control circuit 4 only performs adaptive driving force control on the forward direction of the oil cylinder 7.

[0039] It should be noted that the specific structures and working principles of the proportional pressure reducing valve 41 and the second electro-hydraulic reversing valve 44 are well known to those skilled in the art, and therefore will not be elaborated on in detail here. Figure 5As shown, the proportional pressure reducing valve 41 can be a three-way valve, whose inlet is used to connect to the pump group 2, the outlet is used to connect to the inlet of the second electro-hydraulic reversing valve 44, and the oil discharge port is used to connect to the oil tank 1. The second electro-hydraulic reversing valve 44 adopts a two-position four-way valve. For ease of understanding, the control end of the second electro-hydraulic reversing valve 44 can be defined as YV2, and the control end of the proportional pressure reducing valve 41 can be defined as YV3; the second electro-hydraulic reversing valve 44 controls the first branch to be in a cut-off state in a natural state, and the proportional pressure reducing valve 41 is in an inlet and outlet conduction state in a natural state. When the oil cylinder 7 needs to move forward, the control end YV2 is energized to conduct the first branch, and then the oil output by the pump group 2 can enter the rodless chamber of the oil cylinder 7; in this process, the control end YV3 can adjust the control pressure according to the degree of control. When the oil cylinder 7 needs to retreat, the control terminal YV2 continues to be energized to conduct the first branch. At this time, the control terminal YV3 can control the outlet of the proportional pressure reducing valve 41 to be connected to the oil drain port to conduct the third branch. Then, the oil in the rodless chamber of the oil cylinder 7 can flow back to the oil tank 1 along the first branch and the third branch. Figure 5 It can be represented by T, and the rodless chamber and rod chamber of the cylinder 7 are represented by A and B respectively.

[0040] In this embodiment, the proportional pressure reducing valve 41 is the key to the automatic control circuit 4 to achieve adaptive control of the driving force of the oil cylinder 7, that is, the opening of the proportional pressure reducing valve 41 is adaptively controlled by the state of the oil cylinder 7, thereby achieving adaptive adjustment of the control pressure of the proportional pressure reducing valve 41. There are many ways to perform adaptive control of the opening of the proportional pressure reducing valve 41, such as electromagnetic control or hydraulic pilot control; in order to ensure stable control, in this embodiment, the proportional pressure reducing valve 41 preferably adopts a hydraulic pilot control structure. Figure 5 As shown, the automatic control circuit 4 also includes a proportional relief valve 42, the input end of the proportional relief valve 42 is connected to the midpoint of the first branch and / or the inlet of the proportional pressure reducing valve 41, the output end of the proportional relief valve 42 is connected to the oil tank 1, and the input end of the proportional relief valve 42 is also connected to the control end of the proportional pressure reducing valve 41.

[0041] It can be understood that the opening of the proportional relief valve 42 is controlled by the state of the cylinder 7; the state of the cylinder 7 includes the displacement state and the pressure state, etc., and the opening of the proportional relief valve 42 can be controlled according to the comparison between the displacement feedback signal or the input pressure signal of the cylinder 7 and the set value, thereby controlling the pilot end pressure of the proportional pressure reducing valve 41.

[0042] Specifically, when the oil at the input of proportional relief valve 42 flows back to tank 1 through proportional relief valve 42, the pressure at the input of proportional relief valve 42 exceeds the pressure at the output due to the restricted opening of proportional relief valve 42, causing some oil to flow through the pipeline to the control end of proportional pressure-reducing valve 41. The control end of proportional relief valve 42 can be defined as YV4. When the control pressure of proportional pressure-reducing valve 41 needs to be increased, that is, the opening of proportional pressure-reducing valve 41 needs to be reduced, and cylinder 7 needs to advance, the input current at control end YV4 controls the opening of proportional relief valve 42 based on the state of cylinder 7, thereby increasing the oil flow to the control end of proportional pressure-reducing valve 41 and driving the valve core in the direction of decreasing the opening. Conversely, the opening of proportional relief valve 42 increases, thereby controlling the increase in the opening of proportional pressure-reducing valve 41. Proportional relief valve 42 is electro-hydraulic controlled, and the control end input current is adjusted to adjust the opening based on the detection signal of the sensor installed on cylinder 7.

[0043] It should be noted that in order to ensure that the opening of the proportional pressure reducing valve 41 can be stably controlled, it is necessary to ensure that the pressure at the input end of the proportional relief valve 42 must be greater than the minimum control pressure of the control end of the proportional pressure reducing valve 41. However, during the operation of the first branch, the midpoint pressure may be too low, which may cause the opening control of the proportional pressure reducing valve 41 to fail. Therefore, the input end of the proportional relief valve 42 can be connected to the inlet and outlet positions of the proportional pressure reducing valve 41 respectively. When the pressure is too low at the outlet position of the proportional pressure reducing valve 41, that is, the midpoint position of the first branch, the input end pressure of the proportional relief valve 42 can come from the inlet position of the proportional pressure reducing valve 41; on the contrary, when the oil cylinder 7 is retreating, the inlet pressure of the proportional pressure reducing valve 41 is zero. At this time, the input end pressure of the proportional relief valve 42 can come from the outlet of the proportional pressure reducing valve 41, that is, the midpoint of the first branch.

[0044] In this embodiment, Figure 5 As shown, to achieve adaptive selection of the pressure at the input of proportional relief valve 42, automatic control circuit 4 also includes a second shuttle valve 43. Second shuttle valve 43 is connected in parallel to the inlet and outlet of proportional pressure-reducing valve 41 via its two inputs. The output of second shuttle valve 43 is connected to the input of proportional relief valve 42. The function of second shuttle valve 43 is to output the maximum pressure between the two inputs. The specific structure and operating principles of second shuttle valve 43 and proportional relief valve 42 are well known to those skilled in the art and will not be elaborated here.

[0045] In this embodiment, there are many specific structures of the manual control circuit 5 that can realize the above functions. For the sake of easy understanding, the following will be described in detail using one of the structures. Figure 1 、 Figure 2 and Figure 5As shown, the manual control circuit 5 includes a third electro-hydraulic reversing valve 51, a hydraulically controlled one-way valve 52, and a pair of one-way throttle valves 53. The oil inlet of the third electro-hydraulic reversing valve 51 is connected to the pump group 2, and the oil return port of the third electro-hydraulic reversing valve 51 is connected to the oil tank 1 and the pump group 2. The connecting end of the third electro-hydraulic reversing valve 51 is connected to the rodless chamber and the rod chamber of the oil cylinder 7 respectively through two pipelines equipped with one-way throttle valves 53. The hydraulically controlled one-way valve 52 is installed in the pipeline connecting the third electro-hydraulic reversing valve 51 to the rodless chamber of the oil cylinder 7, and the control end of the hydraulically controlled one-way valve 52 is connected to the other pipeline.

[0046] When the automatic control circuit 4 is working, the third electro-hydraulic reversing valve 51 shall not be energized, and the oil inlet of the third electro-hydraulic reversing valve 51 is in a cut-off state; and the oil return port of the third electro-hydraulic reversing valve 51 can cooperate with the rod chamber of the oil cylinder 7 to form a second branch, so that the pressure output by the pump group 2 can be delivered to the rod chamber of the oil cylinder 7 through the third electro-hydraulic reversing valve 51 and the corresponding pipeline to generate back pressure to drive the oil cylinder 7 to retreat.

[0047] When it is necessary to drive the cylinder 7 to extend and move forward through the manual control circuit 5, the third electro-hydraulic reversing valve 51 can connect the rodless chamber of the cylinder 7 with the output end of the pump group 2 through the power supply of the control end, so that the pressure oil output by the pump group 2 enters the rodless chamber of the cylinder 7; at the same time, the rod chamber of the cylinder 7 is connected to the oil tank 1, so that the oil in the rod chamber of the cylinder 7 flows back to the oil tank 1.

[0048] When it is necessary to drive the cylinder 7 to retract and retreat through the manual control circuit 5, the third electro-hydraulic reversing valve 51 can connect the rod chamber of the cylinder 7 with the output end of the pump group 2 by energizing the control end, so that the pressure oil output by the pump group 2 enters the rod chamber of the cylinder 7. At the same time, the pressure oil can also drive the hydraulically controlled one-way valve 52 connected to the rodless chamber of the cylinder 7 to conduct reverse conduction, and then the rodless chamber of the cylinder 7 can be connected to the oil tank 1, so that the oil in the rodless chamber of the cylinder 7 can flow back to the oil tank 1.

[0049] It should be noted that the specific structures and working principles of the third electro-hydraulic reversing valve 51, the one-way throttle valve 53, and the hydraulically controlled one-way valve 52 are well known to those skilled in the art. The one-way throttle valve 53 can control the extension and retraction speed of the oil cylinder 7 by adjusting the opening; the hydraulically controlled one-way valve 52 can form a hydraulic lock to ensure that the oil cylinder 7 can maintain a stable position under load. There are many specific types of the third electro-hydraulic reversing valve 51, such as Figure 5As shown, the third electro-hydraulic directional valve 51 is a Y-type, three-position, four-way directional valve; its two control terminals are designated YV5 and YV6. When the cylinder 7 is to be advanced, control terminal YV5 is energized, connecting the output of the pump assembly 2 to the rodless chamber of the cylinder 7 and the fuel tank 1 to the rod chamber of the cylinder 7. When the cylinder 7 is to be retracted, control terminal YV6 is energized, connecting the output of the pump assembly 2 to the rod chamber of the cylinder 7 and the fuel tank 1 to the rodless chamber of the cylinder 7.

[0050] It will be appreciated that to ensure safe operation of the manual control circuit 5, the manual control circuit 5 also includes a first relief valve 54, which is connected in parallel to the oil inlet and return port of the third electro-hydraulic reversing valve 51. In the event of a conduction failure in the manual control circuit 5, the first relief valve 54 returns the pressurized oil output by the pump assembly 2 to the fuel tank 1, thereby ensuring safe operation of the manual control circuit 5. The specific structure and operating principle of the first relief valve 54 are well known to those skilled in the art and will not be elaborated on here.

[0051] In this embodiment, Figure 1 and Figure 2 As shown, the rodless and rodded chambers of the oil cylinder 7 are connected to the manual control circuit 5 and the automatic control circuit 4, respectively, via a balancing circuit 6. The balancing circuit 6 is used to balance the pressures in the rodless and rodded chambers of the oil cylinder 7 and to form a differential circuit when the automatic control circuit 4 is operating. This ensures the safety of the automatic and manual control circuits 4 and 5 in supplying oil to the oil cylinder 7, preventing overloads on the oil cylinder 7. It also ensures the operational stability of the oil cylinder 7 when it encounters sudden load changes.

[0052] Specifically, there are many specific structures of the balancing circuit 6 that can achieve the above functions. For the sake of easy understanding, one of the structures will be described in detail below. Figure 6 As shown, the balancing circuit 6 includes a counterbalance valve 64, a check valve 63, and a pair of relief valves. The counterbalance valve 64 and the pair of relief valves are connected in parallel to the rodless and rod-mounted chambers of the oil cylinder 7; the two relief valves release pressure in opposite directions. The control end of the counterbalance valve 64 is connected to the rod-mounted chamber of the oil cylinder 7, while the check valve 63 is installed in the rod-mounted chamber of the oil cylinder 7. When the pressure in the rodless chamber of the oil cylinder 7 exceeds the back pressure, the counterbalance valve 64 forms a differential circuit to drive the oil cylinder 7 to extend. When the pressure in the rodless chamber of the oil cylinder 7 is less than the back pressure, the counterbalance valve 64 forms a differential circuit to drive the oil cylinder 7 to retract.

[0053] It is understood that the two relief valves are the second relief valve 62 and the third relief valve 65; the second relief valve 62 releases pressure toward the pipeline connected to the rod chamber of the oil cylinder 7, while the third relief valve 65 releases pressure toward the pipeline connected to the rodless chamber of the oil cylinder 7. The second relief valve 62 and the third relief valve 65 can cooperate to form a safety valve group, thereby preventing the oil cylinder 7 from overloading and ensuring the safe operation of the system. That is, if the oil cylinder 7 encounters an overload or other fault during the forward movement, the pressurized oil delivered by the pump group 2 can flow back to the oil tank 1 through the second relief valve 62; similarly, if the oil cylinder 7 encounters an overload or other fault during the backward movement, the pressurized oil delivered by the pump group 2 can flow back to the oil tank 1 through the third relief valve 65.

[0054] It will also be appreciated that the counterbalance valve 64 and the check valve 63 can cooperate to form a differential circuit to balance the back pressure generated by the cylinder 7 and the load acting on the cylinder 7, thereby ensuring that the cylinder 7 reacts quickly and operates smoothly. Specifically, when the load increases (the pressure in the rodless chamber of the cylinder 7 increases), the back pressure decreases, and the counterbalance valve 64 can open to form a differential circuit to enable the cylinder 7 to advance. Conversely, when the load decreases (the pressure in the rodless chamber of the cylinder 7 decreases), the back pressure increases, and the cylinder 7 retreats through the differential circuit to a balanced position.

[0055] It should be noted that the specific structures and working principles of the overflow valve, the counterbalance valve 64 and the one-way valve 63 are well known to those skilled in the art, and therefore will not be elaborated on in detail. Figure 6 As shown, the balancing circuit 6 also includes a pair of high-pressure shutoff valves 61. The high-pressure shutoff valves 61 are installed at the ends of the two pipelines in the balancing circuit 6, away from the oil cylinder 7. The high-pressure shutoff valves 61 can cut off or regulate the pipelines. The specific structure and operating principle of the high-pressure shutoff valves 61 are well known to those skilled in the art and will not be elaborated here.

[0056] In this embodiment, Figure 3 As shown, the pump group 2 includes a first oil pump and a second oil pump; the first oil pump can supply oil to the manual control circuit 5 and the automatic control circuit 4, thereby driving the oil cylinder 7 to extend and retract; the second oil pump can supply oil to the second branch formed by the manual control circuit 5, thereby providing back pressure for the oil cylinder 7. Specifically, Figure 5 As shown, the output end of the first oil pump is connected to the oil inlet of the third electro-hydraulic reversing valve 51 in the manual control circuit 5 and the inlet of the proportional pressure reducing valve 41 in the automatic control circuit 4; the output end of the second oil pump is connected to the oil discharge port of the third electro-hydraulic reversing valve 51 in the manual control circuit 5.

[0057] As can be understood from the foregoing, pump assembly 2 not only needs to normally drive cylinder 7 for extension and retraction, but also needs to provide back pressure for cylinder 7. If both oil supply methods were provided by the same oil pump, a corresponding switching mechanism would have to be designed, which would complicate the system structure and increase the failure rate. Therefore, in this embodiment, two oil pumps are provided: the first oil pump is used to supply oil for the normal operation of cylinder 7, and the second oil pump is used only to provide back pressure for cylinder 7. In this way, different oil pumps only need to be turned on and off according to different working requirements.

[0058] It should be noted that the output pressure requirement of the first oil pump is relatively large, so the first oil pump can preferably use a plunger pump 21; the output pressure requirement of the second oil pump is relatively small, so the second oil pump can preferably use a gear pump 22. The specific structure and working principle of the plunger pump 21 and the gear pump 22 are well known to those skilled in the art, so they will not be elaborated here. For ease of understanding, as Figure 3 As shown, the output pressure of the plunger pump 21 is represented by P1, and the output pressure of the gear pump 22 is represented by P2.

[0059] In this embodiment, there are many specific structures of the switching circuit 3 that can realize the above functions. For the sake of easy understanding, the following will be described in detail using one of the structures. Figure 4 As shown, the switching circuit 3 includes a first electro-hydraulic reversing valve 31 and a first shuttle valve 32; the first electro-hydraulic reversing valve 31 is connected to the output ends of the first oil pumps corresponding to the two pump groups 2 respectively; the first shuttle valve 32 is connected in parallel to the first electro-hydraulic reversing valve 31 through two input ends, and the output end of the first shuttle valve 32 is connected to the control end of the first electro-hydraulic reversing valve 31.

[0060] When both pump groups 2 are operating normally, the output pressures of their corresponding first oil pumps should be consistent. At this time, the first shuttle valve 32 will be in the closed state, causing the first electro-hydraulic reversing valve 31 to be in the natural closed state. When one of the first oil pumps fails, the pressure at the input end of the first shuttle valve 32 corresponding to the failed first oil pump drops to zero. The first shuttle valve 32 can then transmit the pressure at the other input end to the control end of the first electro-hydraulic reversing valve 31 to drive the first electro-hydraulic reversing valve 31 to switch the direction. In other words, the first shuttle valve 32 controls the first electro-hydraulic reversing valve 31 to switch direction according to the pressure difference at the input end, so that both oil cylinders 7 are supplied with oil by the first oil pump that is not faulty.

[0061] It should be noted that the specific structures and operating principles of the first shuttle valve 32 and the first electro-hydraulic reversing valve 31 are well known to those skilled in the art and will not be elaborated upon here. The function of the first shuttle valve 32 is to shut off the first electro-hydraulic reversing valve 31 when the input pressure is balanced and to drive the first electro-hydraulic reversing valve 31 to switch direction when a pressure difference exists between the input and the input. The first electro-hydraulic reversing valve 31 is preferably a two-position, four-way valve, with a control terminal designated as YV1. This terminal controls the movement of the valve core based on the output pressure of the first shuttle valve 32 to achieve switching.

[0062] It should be noted that the switching circuit 3 can only provide the output pressure of the first oil pump to the two oil cylinders 7 at the same time. If both the first oil pump and the second oil pump fail, the switching circuit 3 can only be used when the manual control circuit 5 is working normally; the working pressure of the manual control circuit 5 is relatively low, and the single first oil pump can meet the pressure requirements of the two manual control circuits 5.

[0063] It is understandable that when the first oil pump fails, there may be a delay in the switching process of the switching circuit 3; in order to further ensure the working safety of the hydraulic control system, such as Figure 1 、 Figure 2 and Figure 5 As shown, an accumulator 8 can also be connected in parallel at the connection position of each first oil pump and the manual control circuit 5 and the automatic control circuit 4, so that when the first oil pump of the pump group 2 fails, the accumulator 8 can quickly replenish oil to ensure the stability of the oil circuit; as the output pressure of the accumulator 8 on the faulty side gradually decreases, the switching circuit 3 will gradually open, which can ensure the switching stability of the switching circuit 3.

[0064] The above describes the basic principles, main features, and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-described embodiments. The above-described embodiments and the specification merely illustrate the principles of the present application. Various changes and improvements may be made to the present application without departing from the spirit and scope of the present application. These changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A hydraulic control system for slurry stirring, characterized in that: It includes an oil tank, a pair of oil cylinders, and an automatic control circuit, a manual control circuit and a pump group independently corresponding to each of the oil cylinders; Each of the oil cylinders drives a rake head to stir the sedimentation slurry; The input end of the pump group extends to the oil tank, and the output end of the pump group is connected to the oil cylinder through the automatic control circuit and the manual control circuit connected in parallel; The pump group is adapted to supply oil to the oil cylinder, the automatic control circuit is adapted to automatically adjust the oil supply amount to the oil cylinder according to the state of the oil cylinder; the manual control circuit is adapted to adjust the oil supply amount to the oil cylinder according to the conduction state of the autonomous control circuit; the automatic control circuit and the manual control circuit are not conducted at the same time; The two pump groups are connected via a switching circuit, so that when one of the pump groups fails, the other pump group supplies oil to the two oil cylinders at the same time through the switching circuit.

2. The hydraulic control system for slurry stirring according to claim 1, characterized in that: The automatic control circuit includes a proportional pressure reducing valve and a second electro-hydraulic reversing valve; The control pressure of the proportional pressure reducing valve is controlled by the state of the oil cylinder. The first branch formed by the series connection of the proportional pressure reducing valve and the second electro-hydraulic reversing valve is connected between the output end of the pump group and the rodless chamber of the oil cylinder; the second branch is formed between the rod chamber of the oil cylinder and the pump group through the manual control circuit with the input end in the cut-off state. The proportional pressure reducing valve is also connected to the oil tank through a third branch. The pump group supplies oil to the rodless chamber of the cylinder through the first branch to drive the cylinder forward. At this time, a differential circuit is formed between the rodless chamber and the rod chamber of the cylinder; the pump group provides back pressure to the rod chamber of the cylinder through the second branch, and then the cylinder returns oil and contracts through the first branch and the third branch.

3. The hydraulic control system for slurry stirring according to claim 2, characterized in that: The proportional pressure reducing valve adopts a pilot control structure; The automatic control circuit further comprises a proportional relief valve, wherein an input end of the proportional relief valve is connected to the midpoint of the first branch and / or an inlet of the proportional relief valve, an output end of the proportional relief valve is connected to the oil tank, and an input end of the proportional relief valve is also connected to a control end of the proportional pressure reducing valve; The opening of the proportional relief valve is controlled according to the comparison between the displacement feedback signal or the input pressure signal of the oil cylinder and the set value, thereby controlling the pilot end pressure of the proportional pressure reducing valve.

4. The hydraulic control system for slurry stirring according to claim 3, characterized in that: The automatic control circuit further includes a second shuttle valve, which is connected in parallel to the proportional pressure reducing valve via two input ends, and an output end of the second shuttle valve is connected to an input end of the proportional relief valve.

5. The hydraulic control system for slurry stirring according to claim 2, characterized in that: The manual control circuit includes a third electro-hydraulic reversing valve, a hydraulically controlled one-way valve and a pair of one-way throttle valves; The oil inlet of the third electro-hydraulic reversing valve is connected to the pump group, and the oil return port of the third electro-hydraulic reversing valve is connected to the oil tank and the pump group; the connecting end of the third electro-hydraulic reversing valve is respectively connected to the rodless chamber and the rod chamber of the oil cylinder through two pipelines installed with the one-way throttle valve, the hydraulically controlled one-way valve is installed in the pipeline connecting the third electro-hydraulic reversing valve to the rodless chamber of the oil cylinder, and the control end of the hydraulically controlled one-way valve is connected to another pipeline; The third electro-hydraulic reversing valve is in an oil inlet cut-off state when the automatic control circuit is operating. At this time, the oil return port of the third electro-hydraulic reversing valve cooperates with the oil cylinder to form the second branch; Controlling the energized state of the third electro-hydraulic reversing valve by manually inputting a signal to control the extension and retraction of the oil cylinder; The one-way throttle valve controls the extension and contraction speed of the oil cylinder by adjusting the opening degree.

6. The hydraulic control system for slurry stirring according to claim 5, characterized in that: The rodless chamber and rod chamber of the oil cylinder are connected to the manual control circuit and the automatic control circuit respectively through a balancing circuit; the balancing circuit is used to balance the pressure of the rodless chamber and rod chamber of the oil cylinder and form a differential circuit when the automatic control circuit is working.

7. The hydraulic control system for slurry stirring according to claim 6, characterized in that: The balancing circuit includes a counterbalance valve, a one-way valve and a pair of relief valves; The counterbalance valve and the pair of relief valves are connected in parallel to the rodless chamber and the rod chamber of the oil cylinder; the pressure relief directions of the two relief valves are opposite, the control end of the counterbalance valve is connected to the rod chamber of the oil cylinder, and the one-way valve is installed in the rod chamber of the oil cylinder; The counterbalancing valve is suitable for forming a differential circuit to drive the cylinder to extend when the rodless chamber pressure of the cylinder is greater than the back pressure; the counterbalancing valve is suitable for forming a differential circuit to drive the cylinder to retract when the rodless chamber pressure of the cylinder is less than the back pressure.

8. The hydraulic control system for slurry stirring according to any one of claims 2 to 7, characterized in that: The pump group includes a first oil pump and a second oil pump; the first oil pump is suitable for supplying oil to the manual control circuit and the automatic control circuit, thereby driving the oil cylinder to extend and retract; the second oil pump is suitable for supplying oil to the second branch formed by the manual control circuit, thereby providing back pressure for the oil cylinder; the output ends of the first oil pumps corresponding to the two pump groups are connected through the switching circuit.

9. The hydraulic control system for slurry stirring according to claim 8, characterized in that: The switching circuit includes a first electro-hydraulic reversing valve and a first shuttle valve; The first electro-hydraulic reversing valve is connected to the output ends of the first oil pumps respectively corresponding to the two pump groups; The first shuttle valve is connected in parallel to the first electro-hydraulic reversing valve via two input ends, and the output end of the first shuttle valve is connected to the control end of the first electro-hydraulic reversing valve; The first shuttle valve is in a cut-off state when the two first oil pumps are working normally, so that the first electro-hydraulic reversing valve is in a natural cut-off state; When one of the first oil pumps fails, the first shuttle valve controls the first electro-hydraulic directional valve to switch direction according to the pressure difference at the input end, so that both of the oil cylinders are supplied with oil through the first oil pump that is not faulty.

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