Hydraulic control device of forklift gantry and forklift

Abstract

A hydraulic control device of a forklift portal frame comprises a lifting oil cylinder set used for controlling lifting of the portal frame. The device further comprises a speed limiting valve, a switching valve and a control valve. The switching valve is provided with a first oil port, a second oil port and a third oil port, the first oil port is communicated with an oil inlet and an oil outlet of the lifting oil cylinder set, and the switching valve is communicated with the first oil port and the second oil port or the third oil port according to oil pressure switching of the oil inlet and the oil outlet; one end of the speed limiting valve is communicated with the second oil port so as to limit the speed of the flowing-in hydraulic oil; and the control valve is communicated with the third oil port and the other end of the speed limiting valve. According to the utility model, the descending speed of the gantry under the no-load working condition can be improved, and the working efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the field of forklifts, in particular to a hydraulic control device for a forklift mast and a forklift. Background Art

[0002] Forklifts carry heavy objects by lifting the fork. The types of goods that can be carried are relatively rich, and they are widely used in logistics, manufacturing, engineering and other fields. Therefore, it is particularly necessary to optimize the performance of forklifts. Given the advantages of a hydraulic system such as a wide speed regulation range and large output power, existing forklifts usually drive the mast to lift and lower through a hydraulic system, and then the mast drives the fork to perform corresponding actions.

[0003] At present, the lifting and lowering of a forklift mast is driven by multiple sets of lifting cylinders, and the lowering speed of the forklift mast is controlled by connecting a lowering speed limiting valve to the cylinder. However, this method cannot be controlled separately according to the no-load condition and the load-carrying condition. That is, when the forklift is in the no-load condition, the lowering speed of the mast is slow due to the low oil pressure of the lifting cylinder, which affects the work efficiency. This phenomenon is particularly obvious in the three-stage mast. Summary of the Utility Model

[0004] The main purpose of the utility model is to overcome the above defects of the existing hydraulic system, and propose a hydraulic control device for a forklift mast and a forklift, which can improve the lowering speed of the mast under no-load conditions and improve work efficiency.

[0005] The utility model adopts the following technical solutions:

[0006] A hydraulic control device for a forklift mast includes a set of lifting cylinders for controlling the lifting and lowering of the mast; it also includes a speed limiting valve, a switching valve and a control valve; the switching valve is provided with a first oil port, a second oil port and a third oil port. The first oil port is communicated with the oil inlet and outlet of the set of lifting cylinders, and the switching valve switches to connect the first oil port with the second oil port or the third oil port according to the oil pressure of the oil inlet and outlet; one end of the speed limiting valve is communicated with the second oil port to limit the speed of the flowing hydraulic oil; the control valve is communicated with the third oil port and the other end of the speed limiting valve.

[0007] Further, when the oil pressure of the flowing hydraulic oil is less than the set value, the switching valve is set to connect the first oil port with the third oil port, and when the oil pressure of the flowing hydraulic oil is greater than the set value, the switching valve is set to connect the first oil port with the second oil port.

[0008] Further, the control valve is provided with a first port, a second port and a third port. The first port is communicated with the other end of the speed limiting valve and the third oil port, and the control valve is used to control the connection between the first port and the second port or the third port.

[0009] Further, a fuel pump is connected to the second port of the control valve. The input end of the fuel pump communicates with the fuel tank, and the third port of the control valve communicates with the fuel tank. A filter is also connected to the input end of the fuel pump.

[0010] Further, a relief valve is included and is connected between the second port and the third port of the control valve.

[0011] Further, the switching valve is a cartridge valve with adjustable oil pressure.

[0012] Further, the lifting cylinder group includes a first cylinder group, a second cylinder group, and a third cylinder. The first oil inlet / outlet of the first cylinder group serves as the oil inlet / outlet of the lifting cylinder group to communicate with the first oil port of the switching valve. The second oil inlet / outlet of the first cylinder group communicates with the first oil inlet / outlet of the second cylinder group, and the second oil inlet / outlet of the second cylinder group communicates with the first oil inlet / outlet of the third cylinder.

[0013] Further, the first cylinder group includes two first cylinders. The first oil inlet / outlets of the two first cylinders communicate, and the second oil inlet / outlets of the two first cylinders are respectively connected to the first oil inlet / outlet of the second cylinder group.

[0014] Further, the second cylinder group includes two second cylinders. The first oil inlet / outlets of the two second cylinders communicate with the second oil inlet / outlet of the first cylinder group, and the second oil inlet / outlets of the two second cylinders communicate with the first oil inlet / outlet of the third cylinder.

[0015] A forklift includes a forklift body and also includes the hydraulic control device of the forklift mast described above.

[0016] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0017] In the device of the present invention, the switching valve and the speed limiting valve cooperate. When controlling the lowering of the mast, the switching valve can identify the loaded condition or the unloaded condition according to the oil pressure at the oil inlet / outlet of the lifting cylinder group, and control the hydraulic oil to directly flow into the control valve in the unloaded condition, reducing the oil pressure loss and increasing the lowering speed. While in the loaded condition, it controls the hydraulic oil to flow into the control valve after being speed-limited by the speed limiting valve, reasonably and effectively improving the working efficiency.

[0018] In the device of the present invention, the switching valve is a cartridge valve, and the oil pressure for controlling the movement of the control spool is adjustable, meeting different requirements, with low cost and being applicable to various forklifts, such as internal combustion counterbalanced forklifts. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1Hydraulic control device diagram of the present utility model (no-load condition);

[0020] Figure 2 Hydraulic control device diagram of the present utility model (loaded condition);

[0021] Figure 3 Relationship between the existing mast lowering speed and oil pressure (no-load condition);

[0022] Figure 4 Relationship between the mast lowering speed and oil pressure of the present utility model (no-load condition).

[0023] Wherein: 10, lifting cylinder group; 11, oil inlet and outlet; 12, first cylinder group; 13, second cylinder group; 14, third cylinder; 15, first oil inlet and outlet, 16, second oil inlet and outlet; 20, speed limiting valve; 30, switching valve; 31, first oil port; 32, second oil port; 33, third oil port; 40, control valve; 41, first port; 42, second port; 43, third port; 50, oil pump; 60, relief valve; 70, filter; 80, fuel tank. Specific embodiments

[0024] The present utility model will be further described below through specific embodiments.

[0025] See Figure 1 、 Figure 2 A hydraulic control device for a forklift mast includes a lifting cylinder group 10, a speed limiting valve 20, a switching valve 30, a control valve 40, etc. The lifting cylinder group 10 is used to control the lifting and lowering of the mast. The lifting cylinder group 10 has an oil inlet and outlet 11. When the forklift is in the no-load condition, the oil pressure at the oil inlet and outlet 11 of the lifting cylinder group 10 is relatively low. When the forklift is in the loaded condition, the oil pressure at the oil inlet and outlet 11 of the lifting cylinder group 10 is relatively high and higher than the oil pressure in the no-load condition. The switching valve 30 is provided with a first oil port 31, a second oil port 32, and a third oil port 33. The first oil port 31 is communicated with the oil inlet and outlet 11 of the lifting cylinder group 10. The switching valve 30 switches and connects the communication between the first oil port 31 and the second oil port 32 or the third oil port 33 according to the oil pressure at the oil inlet and outlet 11, that is, the switching valve 30 can be set to connect different oil ports according to the no-load condition or the loaded condition. In practical applications, the switching valve 30 is implemented by a cartridge valve with adjustable pressure.

[0026] One end of the speed limiting valve 20 is communicated with the second oil port 32 to limit the speed of the hydraulic oil flowing in from the second oil port 32, that is, the speed limiting valve 20 can be set to only limit the speed of the hydraulic oil flowing in during the loaded condition. The control valve 40 is communicated with the third oil port 33 and the other end of the speed limiting valve 20. That is, in the no-load condition, the hydraulic oil flowing out of the switching valve 30 directly flows into the control valve 40 without passing through the speed limiting valve 20, reducing the oil pressure loss and thus increasing the lowering speed of the mast.

[0027] Specifically, when the oil pressure of the hydraulic oil flowing into the switching valve 30 of the present utility model is less than the set value, the first oil port 31 is communicated with the third oil port 33; when the oil pressure of the flowing-in hydraulic oil is greater than the set value, the first oil port 31 is communicated with the second oil port 32. Wherein, the control end of the switching valve 30 is connected to the oil inlet and outlet 11 of the lifting cylinder group 10, and the spool of the switching valve 30 is controlled by the oil pressure of the oil inlet and outlet 11 to achieve switching. The set value of the switching valve 30 can be set and adjusted according to actual conditions and is not limited herein.

[0028] The control valve 40 is provided with a first port 41, a second port 42 and a third port 43. The first port 41 is communicated with the other end of the speed limiting valve 20 and the third oil port 33. The control valve 40 is used to control the connection between the first port 41 and the second port 42 or the third port 43. Wherein, a oil pump 50 is connected to the second port 42 of the control valve 40. The input end of the oil pump 50 is communicated with the fuel tank 80, that is, the oil pump 50 pumps the hydraulic oil from the fuel tank 80 and then enters the second port 42 of the control valve 40. A filter 70 is further connected to the input end of the oil pump 50 for filtering impurities in the hydraulic oil. The third port 43 of the control valve 40 is communicated with the fuel tank 80, that is, the hydraulic oil flowing out from the other end of the speed limiting valve 20 or the third oil port 33 of the switching valve 30 flows back to the fuel tank 80 through the third port 43 of the control valve 40.

[0029] The present utility model further includes a relief valve 60. The relief valve 60 is connected between the second port 42 and the third port 43 of the control valve 40 and is used to convey the overflowed hydraulic oil between the second port 42 of the control valve 40 and the output end of the oil pump 50 to the fuel tank 80.

[0030] In the present utility model, the lifting cylinder group 10 includes a first cylinder group 12, a second cylinder group 13 and a third cylinder 14. The first cylinder group 12 can be used to lift the outer gantry. The first oil inlet and outlet 15 of the first cylinder group 12 serves as the oil inlet and outlet 11 of the lifting cylinder group 10 to be communicated with the first oil port 31 of the switching valve 30. The second oil inlet and outlet 16 of the first cylinder group 12 is communicated with the first oil inlet and outlet 15 of the second cylinder group 13. The second oil inlet and outlet 16 of the second cylinder group 13 is communicated with the first oil inlet and outlet 15 of the third cylinder 14. The second cylinder group 13 can be used to lift the middle gantry. The third cylinder 14 can be used to lift the inner gantry. The third cylinder 14 is only provided with the first oil inlet and outlet 15.

[0031] Specifically, the first oil cylinder group 12 includes two first oil cylinders. The first oil inlet / outlet ports 15 of the two first oil cylinders are communicated, and the second oil inlet / outlet ports 16 of the two first oil cylinders are respectively connected to the first oil inlet / outlet ports 15 of the second oil cylinder group 13. The second oil cylinder group 13 includes two second oil cylinders. The first oil inlet / outlet ports 15 of the two second oil cylinders are communicated with the second oil inlet / outlet ports 16 of the first oil cylinder group 12, and the second oil inlet / outlet ports 16 of the two second oil cylinders are communicated to the first oil inlet / outlet port 15 of the third oil cylinder 14. In practical applications, the number of oil cylinders in the lifting oil cylinder group 10 is not limited to this, and it can also be adjusted according to the specific settings of the forklift mast.

[0032] Based on this, the present utility model further provides a forklift, which includes a forklift body and the above hydraulic control device for a forklift mast.

[0033] The hydraulic control device and the forklift of the present utility model control the working pressure of the mast to descend as follows:

[0034] When the control valve 40 receives a command to control the mast to descend, it connects the communication between the third port 43 and the first port 41. Then, the hydraulic oil at the oil inlet / outlet port 11 of the lifting oil cylinder group 10 enters the switching valve 30. When the forklift is in a loaded condition, the oil pressure of the hydraulic oil at the oil inlet / outlet port 11 is greater than the set value. Then, the switching valve 30 connects the first oil port 31 and the second oil port 32, and the hydraulic oil enters the speed limit valve 20 for speed limiting, and the descending speed of the mast slows down. Then, it flows back to the fuel tank 80 through the control valve 40. However, when the forklift is in an unloaded condition, the oil pressure of the hydraulic oil at the oil inlet / outlet port 11 is less than the set value. Then, the switching valve 30 connects the first oil port 31 and the third oil port 33, and the hydraulic oil directly flows back to the fuel tank 80 through the control valve 40, reducing the oil pressure loss and increasing the descending speed of the mast.

[0035] See Figure 3 and Figure 4 From the relationship diagram of, it can be seen that by adopting the device of the present application, in the unloaded condition, due to the smaller pressure loss from point A to point B, the descending speed of the mast is higher than that of the existing solution.

[0036] The terms "first", "second", etc. that appear in the present utility model are only for convenient description to distinguish different components with the same name, and do not indicate the sequence or primary-secondary relationship.

[0037] In the description of the present utility model, the orientation or positional relationship indicated by "upper", "lower", "left", "right", "front", and "rear" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model, rather than indicating or implying that the device referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present utility model.

[0038] In addition, in the description of this application, unless otherwise specified, "a plurality of" means two or more. "And / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, both A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0039] The above are only the specific implementation manners of the present utility model, but the design concept of the present utility model is not limited thereto. Any non-substantive modification made to the present utility model using this concept shall fall within the scope of infringement of the protection scope of the present utility model.

Claims

1. A hydraulic control device for a forklift mast, comprising a lifting cylinder group, wherein the lifting cylinder group is used to control the lifting and lowering of the mast; characterized in that: It also includes a speed limiting valve, a switching valve and a control valve; the switching valve is provided with a first oil port, a second oil port and a third oil port, the first oil port is connected with the oil inlet and outlet ports of the lifting cylinder group, and the switching valve switches the connection between the first oil port and the second oil port or the third oil port according to the oil pressure of the inlet and outlet ports; one end of the speed limiting valve is connected with the second oil port to limit the speed of the inflowing hydraulic oil; the control valve is connected with the third oil port and the other end of the speed limiting valve.

2. A hydraulic control device for a forklift mast as claimed in claim 1, characterized in that: The switching valve is configured such that when the oil pressure of the inflowing hydraulic oil is less than a set value, the first oil port is communicated with the third oil port, and when the oil pressure of the inflowing hydraulic oil is greater than the set value, the first oil port is communicated with the second oil port.

3. A hydraulic control device for a forklift mast as claimed in claim 1, characterized in that: The control valve is provided with a first port, a second port and a third port. The first port is connected to the other end of the speed limiting valve and the third oil port. The control valve is used to control the connection between the first port and the second port or the third port.

4. A hydraulic control device for a forklift mast as claimed in claim 3, characterized in that: The second port of the control valve is connected to an oil pump, the input end of the oil pump is connected to an oil tank, and the third port of the control valve is connected to the oil tank; the input end of the oil pump is also connected to a filter.

5. A hydraulic control device for a forklift mast as claimed in claim 4, characterized in that: A relief valve is also included, and the relief valve is connected between the second port and the third port of the control valve.

6. A hydraulic control device for a forklift mast as claimed in claim 1, characterized in that: The switching valve adopts an oil pressure adjustable cartridge valve.

7. A hydraulic control device for a forklift mast as claimed in claim 1, characterized in that: The lifting cylinder group includes a first cylinder group, a second cylinder group and a third cylinder; the first inlet and outlet of the first cylinder group serves as the inlet and outlet of the lifting cylinder group to communicate with the first oil port of the switching valve, the second inlet and outlet of the first cylinder group is communicated with the first inlet and outlet of the second cylinder group, and the second inlet and outlet of the second cylinder group is communicated with the first inlet and outlet of the third cylinder.

8. A hydraulic control device for a forklift mast as claimed in claim 7, characterized in that: The first oil cylinder group includes two first oil cylinders, the first oil inlets and outlets of the two first oil cylinders are connected, and the second oil inlets and outlets of the two first oil cylinders are respectively connected to the first oil inlet and outlets of the second oil cylinder group.

9. A hydraulic control device for a forklift mast as claimed in claim 7, characterized in that: The second cylinder group includes two second cylinders, the first oil inlet and outlet of the two second cylinders are connected to the second oil inlet and outlet of the first cylinder group, and the second oil inlet and outlet of the two second cylinders are connected to the first oil inlet and outlet of the third cylinder.

10. A forklift, comprising a forklift body, characterized in that: It also includes a hydraulic control device for a forklift mast according to any one of claims 1 to 9.

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