A forklift clamping enabling system and control method

Abstract

This invention discloses a forklift clamping enabling system and control method, relating to the field of hydraulic drive technology. Specifically, a forklift clamping enabling system and control method for driving the action of an attachment cylinder includes: a main oil circuit with a main oil circuit shut-off valve connected in series inside; and an attachment oil supply circuit connected in parallel with the main oil circuit shut-off valve, with an attachment directional valve connected in series inside, the oil switching port of the attachment directional valve being connected to the oil switching port of the attachment cylinder. When the main oil circuit shut-off valve is open, the high-pressure end and the low-pressure end of the attachment oil supply circuit are connected. This forklift clamping enabling system and control method, by setting a main oil circuit shut-off valve in the main oil circuit, achieves anti-misoperation of the attachment cylinder and avoids the attachment oil supply circuit from bearing high pressure, reducing the pressure requirements of the oil circuit and valve body, thereby reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of hydraulic drive technology, and more specifically, to a forklift clamping enabling system. Furthermore, this invention also relates to a forklift control method based on the aforementioned forklift clamping enabling system. Background Technology

[0002] Existing forklifts typically control the mast and attachment movements of the forklift by operating a multi-way directional valve via a lever. These movements generally include lifting and lowering, tilting forward and backward, and other attachment movements. Conventional multi-way valves do not have solenoid valves and lack safety features.

[0003] At present, there are many laws and regulations that involve safety functions, such as driver-in-place safety functions and attachment clamping enable functions. There are many ways to achieve these safety functions, such as using an electro-proportional multi-way valve and implementing it through logic control by a controller; adding a solenoid valve to a mechanical valve and then controlling it through electronic control logic to achieve driver-in-place safety functions; and designing a mechanical valve system with a mechanical lock structure to achieve attachment enable functions.

[0004] However, using an electro-proportional multi-way valve in conjunction with a controller for logic control is costly; while using a mechanical lock structure to enable attachments is low-cost, it is structurally complex, difficult to assemble, and complicated to operate.

[0005] For example, when installing clamping attachments (such as paper roll clamps) on a forklift, there is often a safety hazard caused by operator error, which can lead to the attachment releasing the goods and causing them to fall.

[0006] To address this issue, the relevant technical document CN203382457U discloses a forklift attachment safety self-locking device, which involves connecting a normally closed solenoid valve in series in the attachment oil supply line. The solenoid valve is controlled to open and close by an enable switch. When the solenoid valve is open, high-pressure oil can enter the attachment cylinder through the attachment reversing valve and drive the attachment cylinder to move. When the solenoid valve is closed, the high-pressure oil cannot enter the attachment cylinder after passing through the attachment reversing valve, so that the attachment reversing valve and the oil supply line are subjected to high pressure.

[0007] Therefore, how to provide a forklift clamping enabling system and control method that can prevent goods from falling due to misoperation, has a simple structure, is easy to operate, and has little impact on the internal oil circuit pressure is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a forklift clamping enabling system, which, by setting a main oil circuit shut-off valve in the main oil circuit, realizes the prevention of misoperation of the attachment cylinder and avoids the frequent generation of high pressure in the attachment oil supply circuit, saves energy consumption, reduces the pressure requirements of the oil circuit and valve body, and thus reduces production costs.

[0009] Another objective of this invention is to provide a forklift control method based on the aforementioned forklift clamping enable system, which can solve the same technical problem and achieve the same objective.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A forklift clamping enabling system for driving the action of an attachment cylinder includes:

[0012] The main oil circuit is internally connected to a main oil circuit shut-off valve.

[0013] The attachment oil supply circuit is connected in parallel with the main oil circuit shut-off valve. An attachment directional valve is connected in series inside the attachment oil supply circuit. The oil change port of the attachment directional valve is connected to the oil change port of the attachment cylinder. When the main oil circuit shut-off valve is turned on, the high-pressure end and the low-pressure end of the attachment oil supply circuit are connected.

[0014] Preferably, the main oil circuit shut-off valve is a normally open two-position two-way solenoid valve, and the two oil change ports of the main oil circuit shut-off valve are respectively connected to the high-pressure end and the low-pressure end of the main oil circuit.

[0015] Preferably, it also includes an enable switch; when the enable switch is triggered, the main oil circuit shut-off valve is in the closed state.

[0016] Preferred options also include:

[0017] An enable switch is located within the control mechanism of the attachment reversing valve;

[0018] A micro switch is used to detect the working position of the attachment directional valve. When the attachment directional valve is in a non-intermediate position, the micro switch is triggered. When the triggering states of the enable switch and the micro switch are consistent, the main oil circuit shut-off valve is energized and in the off state.

[0019] Preferably, the micro switch and the enable switch are connected in series with a single-pole double-control relay, and the two sets of relays are electrically connected to the main oil circuit shut-off valve in the form of a double-control circuit.

[0020] Preferably, the attachment directional valve is a three-position six-way directional valve or a three-position four-way directional valve. When the valve stem of the attachment directional valve is in one of the end positions, the micro switch is in the triggered state; when the attachment directional valve is in the middle position or the other end position, the micro switch is in the non-triggered state.

[0021] Preferably, the enable switch is located at the attachment control handle for controlling the movement of the attachment directional valve stem.

[0022] Preferably, the main oil circuit shut-off valve includes:

[0023] A pilot-operated two-position two-way valve is connected in series in the main oil line;

[0024] The pilot oil circuit of the pilot-operated two-position two-way valve is connected to the low-pressure end of the main oil circuit through the main oil circuit solenoid valve; when the main oil circuit solenoid valve is in the conducting state, the main oil circuit shut-off valve is in the conducting state.

[0025] Preferably, the main oil circuit solenoid valve is a normally open two-position two-way solenoid valve.

[0026] Preferably, the oil inlet of the attachment cylinder during its retraction stroke is connected to the low-pressure end of the main oil circuit via a pilot-operated overflow valve.

[0027] A forklift control method based on the above-mentioned forklift clamping enable system includes the following actions:

[0028] Obtain the execution signal;

[0029] When the execution signal is to shut off the main oil circuit shut-off valve and control the attachment reversing valve to be in the open position, the attachment cylinder is controlled to move.

[0030] When the execution signal is to shut off the main oil circuit shut-off valve and control the attachment reversing valve to be in the shut-off position, the attachment cylinder is controlled not to move.

[0031] When the execution signal is to turn on the main oil circuit shut-off valve and control the attachment directional valve to be in the open or closed position, the attachment cylinder is controlled not to move.

[0032] The forklift clamping enabling system provided by this invention has at least the following advantages compared with the prior art:

[0033] 1. A main oil circuit shut-off valve is installed on the main oil circuit, and the attachment oil supply circuit is arranged in parallel with the main oil circuit shut-off valve. The attachment oil supply circuit is controlled by the on / off control of the main oil circuit shut-off valve. That is, when the main oil circuit shut-off valve is in the closed state, the attachment oil supply circuit can supply oil normally. When the main oil circuit shut-off valve is in the open state, the attachment oil supply circuit is in the non-supply state. At this time, the high pressure end and the low pressure end of the attachment oil supply circuit are directly connected to release the high pressure oil. Even if the attachment oil supply circuit is misoperated, it will not cause the attachment cylinder to move, reducing production hazards.

[0034] 2. At the same time, the main oil circuit shut-off valve is used for direct conduction. In the event of misoperation, the high-pressure end of the attachment oil supply circuit can be directly depressurized, reducing the pressure build-up in the attachment reversing valve and attachment oil supply circuit, and reducing oil leakage problems.

[0035] The forklift control method provided by this invention has the same beneficial effects. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the hydraulic circuit principle of the forklift clamping enabling system provided by the present invention.

[0038] Figure 2 This is a schematic diagram of the attachment control handle provided by the present invention;

[0039] Figure 3 This is a schematic diagram of the connection circuit between the enable switch and the micro switch provided by the present invention.

[0040] Figures 1-3 middle:

[0041] In the diagram: 1. Attachment directional valve; 2. Main oil circuit shut-off valve; 201. Pilot-operated two-position two-way valve; 202. Main oil circuit solenoid valve; 3. Enable switch; 4. Pilot-operated relief valve; 5. Micro switch; 6. Attachment cylinder; 7. Attachment control handle. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] The core of this invention is to provide a forklift clamping enabling system. By setting a main oil circuit shut-off valve in the main oil circuit, the system can prevent misoperation of the attachment cylinder and avoid the attachment oil supply circuit from bearing high pressure, thereby reducing the pressure requirements of the oil circuit and valve body and thus reducing production costs.

[0044] Please refer to Figures 1-3 A forklift clamping enabling system for driving the action of attachment cylinder 6, comprising:

[0045] Main oil circuit, with a main oil circuit shut-off valve 2 connected in series inside the main oil circuit;

[0046] The attachment oil supply circuit is connected in parallel with the main oil circuit shut-off valve 2. The attachment oil supply circuit is internally connected with the attachment reversing valve 1, and the oil change port of the attachment reversing valve 1 is connected to the oil change port of the attachment cylinder 6. When the main oil circuit shut-off valve 2 is turned on, the high pressure end and the low pressure end of the attachment oil supply circuit are connected.

[0047] like Figure 1 As shown, during operation, P1 and P2 are oil inlets, i.e., high-pressure ends; P3 and T are oil return ports, i.e., low-pressure ends.

[0048] Taking a three-position six-way directional valve as the attachment directional valve 1 as an example, when the valve core is in the neutral position, P1 and T are directly connected, and the attachment is in a stationary state.

[0049] When the valve core moves to the right, i.e., to the left end position, P1 and T are cut off, b2 and c1 are connected, and b1 and c2 are connected. When the main oil circuit shut-off valve 2 is in the cut-off state, high-pressure oil enters through port P2, flows through b2 and c1 in sequence, and enters the right chamber of the attachment cylinder 6, pushing the attachment cylinder 6 to extend, thus realizing the release action. If the main oil circuit shut-off valve 2 is in the connected state, according to the principle of high-pressure oil flowing to lower pressure, the high-pressure oil enters through P2 and flows to T through the main oil circuit shut-off valve 2. With the cooperation of the check valve installed at the oil inlet of the attachment reversing valve 1, the oil pressure in the attachment cylinder is constant, and the attachment cylinder 6 does not move. That is, when the main oil circuit shut-off valve 2 is in the connected state, even if the valve core of the attachment reversing valve 1 is operated to the right, the attachment cylinder 6 will not move, thus avoiding attachment release caused by misoperation.

[0050] When the valve core moves to the left, i.e., to the right end, P1 and T are cut off, b2 and b1 are connected, and c1 and c2 are connected. When the main oil circuit shut-off valve 2 is in the cut-off state, the high-pressure oil flows from P2 through b2 and b1 into the left chamber of the attachment cylinder 6, and the attachment cylinder 6 contracts to achieve the attachment clamping action. If the main oil circuit shut-off valve 2 is in the connected state, according to the principle of high-pressure oil flowing to lower pressure, the high-pressure oil enters from P2 and flows to T through the main oil circuit shut-off valve 2. With the cooperation of the check valve installed at the oil inlet of the attachment reversing valve 1, the oil pressure in the attachment cylinder is constant, and the attachment cylinder 6 does not move. That is, when the main oil circuit shut-off valve 2 is in the connected state, even if the valve core of the attachment reversing valve 1 is moved to the left, the attachment cylinder 6 will not move, thus avoiding attachment clamping caused by misoperation.

[0051] The operation of the hydraulic cylinders of the above attachments is shown in the table below:

[0052]

[0053] In summary, by controlling the on / off state of the main oil circuit shut-off valve 2, the enable control of the attachment oil supply circuit can be realized. That is, when the main oil circuit shut-off valve 2 is in the open state, the attachment cylinder 6 does not move and is uncontrolled. When the main oil circuit shut-off valve 2 is in the closed state, the attachment cylinder 6 is controlled to move.

[0054] When designing the oil circuit, the main oil circuit shut-off valve 2 can be made of various valves, such as gate valves, butterfly valves, stop valves, etc. However, in the hydraulic oil circuit, solenoid valves are preferred.

[0055] For example, in some embodiments, the main oil circuit shut-off valve 2 is a normally open two-position two-way solenoid valve, and the two oil change ports of the main oil circuit shut-off valve are respectively connected to the high-pressure end and the low-pressure end of the main oil circuit.

[0056] By keeping the main oil circuit shut-off valve 2 in the normally open state, the attachment cylinder 6 is protected against misoperation. That is, when the main oil circuit shut-off valve 2 is not reversed, the operating mechanism controls the attachment reversing valve 1 to operate and cannot control the attachment cylinder 6. Only when the main oil circuit shut-off valve 2 is reversed and in the cut-off state can the operating mechanism control the attachment reversing valve 1 to operate and complete the control of the attachment cylinder 6.

[0057] To enhance ease of operation, some embodiments also include an enable switch 3; when the enable switch 3 is triggered, the main oil circuit shut-off valve 2 is in the off state.

[0058] That is, by adding an enable switch 3 in the control mechanism, the main oil circuit cut-off valve 2 is directly controlled. When the enable switch 3 is triggered, the main oil circuit cut-off valve 2 is in the cut-off state and the attachment cylinder 6 is in the controllable state. When the enable switch 3 is not triggered, the main oil circuit cut-off valve 2 is in the conduction state and the attachment cylinder 6 is in the uncontrollable state.

[0059] The control attachment cylinder's actions are shown in the table below:

[0060]

[0061] In forklifts and other engineering machinery equipped with attachments, the enable switch 3 can be installed in multiple locations, such as on the control handle, etc. Figure 2 As shown, during operation, the enable switch 3 must be pressed simultaneously; otherwise, it will be considered a misoperation, and the attachment cylinder 6 will not perform any action. Alternatively, the output of the driver's seat sensing system can be used as the enable switch 3. That is, when the seat sensing system senses the driver, the attachment cylinder 6 is controllable, and vice versa. Or, the above two arrangements can be combined, that is, the driver sensing system and the enable switch 3 located on the operating handle are electrically connected to the main oil circuit cut-off valve 2 in the form of an AND gate circuit. That is, when the driver sensing system senses the driver and the enable switch 3 is triggered, the attachment cylinder 6 is controllable. If either of the above two conditions is missing, the attachment cylinder 6 is uncontrollable.

[0062] The specific control logic is shown in the table below:

[0063]

[0064] In other embodiments, it also includes:

[0065] Enable switch 3 is located in the control mechanism of the attachment reversing valve 1;

[0066] Microswitch 5 is used to detect the working position of attachment directional valve 1. When attachment directional valve 1 is in a non-intermediate position, microswitch 5 is triggered. When the triggering states of enable switch 3 and microswitch 5 are consistent, the main oil circuit shut-off valve 2 is energized and in the off state.

[0067] In practical use, multiple sets of attachment cylinders 6 are often used in combination and controlled individually, resulting in multiple operating levers. For example, these levers control the raising and lowering of forklift attachments, the adjustment of tilt angles, and the clamping and releasing of grippers. Generally, only the attachment cylinder 6 that controls clamping and releasing is enabled. Therefore, the enable switch 3 is set in the operating lever for clamping and releasing the gripper. However, if the enable switch 3 is not pressed, the main oil circuit shut-off valve 2 is in the conducting state, and the other operating levers without enable switches 3 are ineffective. Therefore, to solve the above problem, microswitches 5 are set at both ends of the attachment directional valve 1 that controls clamping and releasing the gripper. The microswitches 5 and the enable switch 3 are electrically connected to the main oil circuit shut-off valve 2 via an XOR gate circuit. That is, when the microswitches 5 are in the middle position and the enable switch 3 is not triggered, the main oil circuit shut-off valve 2 is also in the closed state, which does not affect the control of other attachments and will not cause other operating levers to fail.

[0068] Furthermore, when the valve core of the attachment directional valve 1, which controls the clamping and release of the fixture, moves to both ends, it triggers the micro switch 5. At the same time, when the enable switch 3 is triggered, the main oil circuit shut-off valve 2 is energized and cut off, and the attachment cylinder 6 is controlled. If the enable switch 3 is not triggered at this time, the main oil circuit shut-off valve 2 will not be energized and the attachment cylinder 6 will not be controlled, thus avoiding misoperation of the control lever for clamping and releasing the fixture.

[0069] The specific control logic is shown in the table below:

[0070]

[0071] At the same time, the seat sensing system can be combined with the above-mentioned XOR gate circuit to form an AND gate circuit and then electrically connected to the main oil circuit cut-off valve 2. That is, when the seat sensing system does not sense the driver, the main oil circuit cut-off valve 2 is always in the conducting state, and all cylinders are in an uncontrollable state. Only when the driver sensing system senses the driver can the cylinders be controlled according to the above logic.

[0072] In some embodiments, the XOR gate circuit is replaced by the following structure, such as... Figure 3 As shown, specifically: micro switch 5 and enable switch 3 are connected in series with single-pole double-control relays, and the two sets of relays are electrically connected to the main oil circuit shut-off valve 2 in the form of a double-control circuit.

[0073] That is, when the triggering states of micro switch 5 and enable switch 3 are the same, the main oil circuit shut-off valve 2 can be energized and in the cut-off state, and the attachment cylinder 6 can be in the controllable state. When micro switch 5 and enable switch 3 are in different triggering states, the attachment cylinder 6 is uncontrollable.

[0074] Similarly, the output of the seat sensing system can be used as a switch and connected in series with the dual-control circuit to achieve the same control effect as in the previous embodiment.

[0075] In other embodiments, such as Figure 1 As shown, the attachment directional valve 1 is a three-position six-way directional valve or a three-position four-way directional valve. When the valve stem of the attachment directional valve 1 is in one of the end positions, the micro switch 5 is in the triggered state; when the attachment directional valve 1 is in the middle position or the other end position, the micro switch 5 is in the non-triggered state.

[0076] That is, a micro switch 5 is set only at one end of the valve stem of the attachment reversing valve 1. Generally speaking, the clamp attachment is mainly set to enable control during the release process, that is, to avoid the workpiece being released due to misoperation. Therefore, in combination with this embodiment, the micro switch 5 is set at the left end, that is, the enable switch 3 needs to be triggered only when releasing, and the enable switch 3 does not need to be triggered for other operations in order to perform control.

[0077] The specific control logic is shown in the table below:

[0078]

[0079] Furthermore, to facilitate the simultaneous triggering of the enable switch 3 when operating the control lever, the enable switch 3 is located at the attachment control handle 7, which controls the valve stem movement of the attachment directional valve 1, such as... Figure 2 As shown.

[0080] Therefore, in some embodiments, the main oil circuit shut-off valve 2 includes:

[0081] A pilot-operated two-position two-way valve 201 is connected in series in the main oil line;

[0082] The pilot oil circuit of the pilot oil circuit of the pilot-operated two-position two-way valve 201 is connected to the low-pressure end of the main oil circuit through the main oil circuit solenoid valve 202; when the main oil circuit solenoid valve 202 is in the conducting state, the main oil circuit shut-off valve 2 is in the conducting state.

[0083] In actual use, the oil pressure in the main oil circuit is relatively high, so the driving force required to directly drive the main oil circuit shut-off valve 2 is relatively large. Therefore, a pilot-operated two-position two-way valve 201 is connected in series in the main oil circuit. Then, the pilot oil circuit and the low-pressure end of the main oil circuit are controlled by the main oil circuit solenoid valve 202 to realize the switching of the pilot-operated two-position two-way valve 201, thereby realizing the on-off control of the main oil circuit. That is, when the solenoid valve is in the non-main oil circuit, the driving force required is relatively small.

[0084] Furthermore, the main oil circuit solenoid valve 202 is a normally open two-position two-way solenoid valve. That is, when the main oil circuit solenoid valve 202 is not energized, it is in a normally open state, and consequently, the pilot-operated two-position two-way valve 201 is in a normally open state. When the main oil circuit solenoid valve 202 is not energized, it is in a closed state, and consequently, the pilot-operated two-position two-way valve 201 is also in a closed state.

[0085] Furthermore, the oil inlet of the attachment cylinder 6 during its retraction stroke is connected to the low-pressure end of the main oil circuit via a pilot-operated relief valve 4.

[0086] like Figure 1 As shown, when the attachment reversing valve 1 is in the right position, the oil inlet of the attachment cylinder 6 during its contraction stroke is connected to the high-pressure end of the main oil circuit, i.e., b2 and b1 are connected, and P2 is connected to the left chamber of the attachment cylinder 6. At this time, the attachment cylinder 6 contracts, and the attachment performs a clamping action. When the clamping force exceeds the set threshold, the pilot-operated relief valve 4 opens, allowing some high-pressure oil to be released through the pilot-operated relief valve 4, thus preventing the clamping force from continuously increasing and causing damage to the workpiece held by the fixture. The setting of the clamping force threshold is determined by the conduction pressure of the pilot-operated relief valve 4, making overall adjustment convenient and suitable for clamping different workpieces.

[0087] In addition to the forklift clamping enabling system disclosed in the above embodiments, the present invention also provides a forklift control method based on the above forklift clamping enabling system, including the following actions:

[0088] Obtain the execution signal;

[0089] When the execution signal is to shut off the main oil circuit shut-off valve 2 and control the attachment reversing valve 1 to be in the open position, the attachment cylinder 6 is controlled to move.

[0090] When the execution signal is to shut off the main oil circuit shut-off valve 2 and control the attachment reversing valve 1 to be in the shut-off position, the attachment cylinder 6 will not operate.

[0091] When the execution signal is to open the main oil circuit shut-off valve 2 and control the attachment directional valve 1 to be in the open or closed position, the attachment cylinder 6 will not operate.

[0092] The above execution signals come from enable switch 3, micro switch 5, and seat sensing system. The relationship between the triggering state of enable switch 3, micro switch 5, and seat sensing system, the cut-off and conduction state of main oil circuit cut-off valve 2, and the end position of attachment directional valve 1 is described in the embodiment and will not be repeated here.

[0093] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0094] The forklift clamping enabling system and control method provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A forklift clamping enabling system for driving the action of the attachment cylinder (6), characterized in that, include: Main oil circuit, wherein a main oil circuit shut-off valve (2) is connected in series inside the main oil circuit; The attachment oil supply circuit is connected in parallel with the main oil circuit shut-off valve (2). An attachment reversing valve (1) is connected in series inside the attachment oil supply circuit. The oil change port of the attachment reversing valve (1) is connected to the oil change port of the attachment cylinder (6). When the main oil circuit shut-off valve (2) is turned on, the high-pressure end and the low-pressure end of the attachment oil supply circuit are connected. The main oil circuit shut-off valve (2) is a normally open two-position two-way solenoid valve. The two oil change ports of the main oil circuit shut-off valve (2) are connected to the high-pressure end and the low-pressure end of the main oil circuit, respectively. Also includes: An enable switch (3) is arranged in the control mechanism of the attachment reversing valve (1); The micro switch (5) is used to detect the working position of the attachment reversing valve (1). When the attachment reversing valve (1) is in a non-intermediate position, the micro switch (5) is triggered. When the triggering states of the enable switch (3) and the micro switch (5) are consistent, the main oil circuit shut-off valve (2) is energized and in the shut-off state.

2. The forklift clamping enabling system according to claim 1, characterized in that, The micro switch (5) and the enable switch (3) are respectively connected in series with a single-pole double-control relay, and the two sets of relays are electrically connected to the main oil circuit shut-off valve (2) in the form of a double-control circuit.

3. The forklift clamping enabling system according to claim 1, characterized in that, The attachment directional valve (1) is a three-position six-way directional valve or a three-position four-way directional valve. When the valve stem of the attachment directional valve (1) is in one end position, the micro switch (5) is in the triggered state; when the attachment directional valve (1) is in the middle end position or the other end position, the micro switch (5) is in the non-triggered state.

4. The forklift clamping enabling system according to any one of claims 1-3, characterized in that, The enable switch (3) is located at the attachment control handle (7) used to control the valve stem movement of the attachment reversing valve (1).

5. The forklift clamping enabling system according to claim 1, characterized in that, The main oil circuit shut-off valve (2) includes: A pilot-operated two-position two-way valve (201) is connected in series in the main oil line; The pilot oil circuit of the pilot two-position two-way valve (201) is connected to the low-pressure end of the main oil circuit through the main oil circuit solenoid valve (202); when the main oil circuit solenoid valve (202) is in the conducting state, the main oil circuit shut-off valve (2) is in the conducting state.

6. The forklift clamping enabling system according to claim 5, characterized in that, The main oil circuit solenoid valve (202) is a normally open two-position two-way solenoid valve.

7. The forklift clamping enabling system according to claim 1, characterized in that, The oil inlet of the attachment cylinder (6) during its retraction stroke is connected to the low-pressure end of the main oil circuit via a pilot-operated overflow valve (4).

8. A forklift control method based on the forklift clamping enabling system according to any one of claims 1-7, characterized in that, Includes the following actions: Obtain the execution signal; When the execution signal is to cut off the main oil circuit shut-off valve (2) and control the attachment reversing valve (1) to be in the conducting position, the attachment cylinder (6) is controlled to move. When the execution signal is to shut off the main oil circuit shut-off valve (2) and control the attachment reversing valve (1) to be in the shut-off position, the attachment cylinder (6) is controlled not to operate. When the execution signal is to turn on the main oil circuit shut-off valve (2) and control the attachment reversing valve (1) to be in the open or closed position, the attachment cylinder (6) is controlled not to move.

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