A multi-way valve for a loader, a hydraulic system of a loader, and a loader

Abstract

The application discloses a multi-way valve for a loader, a hydraulic system of the loader and the loader, and relates to the technical field of hydraulic systems of loaders. The multi-way valve comprises a valve body, an oil inlet P and an oil return port T arranged on the valve body, a first valve core arranged in the valve body and used for controlling the action of a bucket oil cylinder through working oil ports A1 and B1, pilot oil from a pilot valve driving the first valve core to reverse through pilot oil ports a1 and b1, a second valve core arranged in the valve body and used for controlling the action of a boom oil cylinder through working oil ports A2 and B2, pilot oil from the pilot valve driving the second valve core to reverse through pilot oil ports a2 and b2, and hydraulic oil flowing through each valve port set according to a set valve port matching rule during the reversing of the first valve core and the second valve core. The application can effectively improve the control characteristics of each action of the loader, reduce the impact of the whole machine, improve the operation feeling of the driver, and reduce the fatigue strength of the driver.

Description

Technical Field

[0001] This invention belongs to the field of loader technology, specifically relating to a multi-way valve for a loader, a hydraulic system for a loader, and a loader. Background Technology

[0002] In the field of construction machinery loaders, hydraulic systems are still mainly quantitative systems. In the existing technology, the valve port design of multi-way valves is not fully matched with the overall machine configuration, resulting in poor control characteristics of multi-way valves and large impact on the whole machine. As customers have higher and higher requirements for product operation performance, the valve port matching design of multi-way valves is of great significance for improving product performance. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a multi-way valve for loaders, a hydraulic system for loaders, and a loader, which can effectively improve the control characteristics of various actions of the loader, reduce the impact of the entire machine, enhance the driver's operating experience, and reduce the driver's fatigue.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, a multi-way valve for a loader is provided, comprising: a valve body; an oil inlet P and an oil return port T disposed on the valve body; a first valve core disposed within the valve body for controlling the action of the bucket cylinder via working oil ports A1 and B1, wherein pilot oil from a pilot valve drives the first valve core to switch direction via pilot oil ports a1 and b1; and a second valve core disposed within the valve body for controlling the action of the boom cylinder via working oil ports A2 and B2, wherein pilot oil from a pilot valve drives the second valve core to switch direction via pilot oil ports a2 and b2; during the switching process of the first valve core and the second valve core, hydraulic oil flows through each valve port set according to a set valve port matching rule.

[0006] Furthermore, the hydraulic oil flows through various valve ports set according to a predetermined valve port matching rule, including: when oil enters the pilot port a1 and pushes the first valve core to reverse, the valve port B1-T between the working port B1 and the return port T opens first, and the valve port P-A1 between the inlet port P and the working port A1 then opens. When P-A1 opens, the port area S of P-TA1... TA1 The following relationship must be satisfied:

[0007]

[0008] Where, k TA1 Q is the first coefficient; 怠 The flow rate is the unit's flow rate at idle; C d p is the fluid flow coefficient; TA1ρ is the minimum load pressure for the bucket cylinder to operate; ρ is the fluid density.

[0009] Furthermore, when P-A1 is open, the control pressure is equal to the opening pressure pka1 of the pilot valve's hopper position; when P-TA1 is closed, the control pressure is μ. P-A1 ·pza1, where μ P-A1 denoted as the pilot pressure coefficient at the bucket position, and pza1 is the control curve endpoint pressure at the bucket position of the pilot valve.

[0010] Furthermore, the hydraulic oil flows through various valve ports set according to a predetermined valve port matching rule, including: when oil enters the pilot port a2 and pushes the second valve core to reverse, valve port B2-T between the working port B2 and the return port T opens first, and valve port P-A2 between the inlet port P and the working port A2 opens subsequently. When P-A2 opens, the port area S of P-A2... TA2 The following relationship must be satisfied:

[0011]

[0012] Where, k TA2 Q is the second coefficient; 怠 The flow rate is the unit's flow rate at idle; C d p is the fluid flow coefficient; TA2 ρ is the minimum load pressure for the boom cylinder to operate; ρ is the fluid density.

[0013] Furthermore, when P-A2 is open, the control pressure is equal to the opening pressure pka2 of the pilot valve in the lifting position; when P-TA2 is closed, the control pressure is μ. P-A2 ·pza2, where μ P-A2 is the pilot pressure coefficient for the lifting position, and pza2 is the control curve endpoint pressure for the pilot valve in the lifting position.

[0014] Furthermore, the hydraulic oil flows through various valve ports set according to a predetermined valve port matching rule, including: when oil enters the pilot port b1 and pushes the first valve core to switch directions, valve port A1-T between the working port A1 and the return port T opens first, and valve port P-B1 between the inlet port P and the working port B1 opens subsequently. When valve port A1-T reaches its maximum area S... A1 When the following relationship is satisfied:

[0015]

[0016] Where, k A1 The third coefficient; d1 is the diameter of the bucket cylinder; C d p is the fluid flow coefficient; A1ρ is the average pressure in the large chamber of the bucket cylinder during the entire tipping motion under no-load conditions; l1 is the total tipping motion of the bucket cylinder; t1 is the total stroke time of the bucket.

[0017] Furthermore, when the A1-T valve port is open, the control pressure is greater than the opening pressure pkb1 of the pilot valve tipping position, and the control pressure when the A1-T valve port reaches its maximum area is μ. A1-T ·pzb1, where μ A1-T denoted as the pilot pressure coefficient for the tipping bucket position, and pzb1 is the endpoint pressure of the control curve for the tipping bucket position of the pilot valve.

[0018] Furthermore, the hydraulic oil flows through various valve ports set according to the established valve port matching rules, including: when the pilot port b2 receives oil and pushes the second valve core to switch directions, the valve port A2-T between the working port A2 and the return port T opens first, and the valve port P-B2 between the inlet port P and the working port B2 opens subsequently. When the A2-T valve port reaches its maximum area S... A2 When the following relationship is satisfied:

[0019]

[0020] Where, k A2 The fourth coefficient; d2 is the boom cylinder diameter; C d p is the fluid flow coefficient; A2 ρ is the average pressure in the large chamber of the boom cylinder during the entire lowering stroke under no-load conditions; l2 is the fluid density; t2 is the total lowering stroke time of the boom cylinder; and t2 is the total lowering stroke time.

[0021] Furthermore, when the A2-T valve port is open, the control pressure at this time is greater than the opening pressure pkb2 of the pilot valve when it descends to the lower position, and the control pressure when the A2-T valve port reaches its maximum area is μ. A2-T ·pzb2, where μ A2-T pzb2 is the pilot pressure coefficient for the descent position, and pzb2 is the control curve endpoint pressure for the descent position of the pilot valve.

[0022] In a second aspect, a loader hydraulic system is provided, wherein the loader hydraulic system is equipped with the multi-way valve for loaders described in the first aspect.

[0023] Thirdly, a loader is provided, the loader being equipped with the loader hydraulic system described in the second aspect.

[0024] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention uses a first valve core disposed within the valve body to control the action of the bucket cylinder through working oil ports A1 and B1. Pilot oil from the pilot valve drives the first valve core to switch direction through pilot oil ports a1 and b1. A second valve core disposed within the valve body to control the action of the boom cylinder through working oil ports A2 and B2. Pilot oil from the pilot valve drives the second valve core to switch direction through pilot oil ports a2 and b2. During the switching process of the first and second valve cores, hydraulic oil flows through each valve port set according to a predetermined valve port matching rule. Matching calculations are performed on the control ports for each action of the loader, improving the control performance of each action, reducing overall machine impact, enhancing the operator's experience, and reducing operator fatigue. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a loader hydraulic control multi-way valve quantitative hydraulic system using an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the valve ports of a multi-way valve in an embodiment of the present invention, wherein (A) is a schematic diagram of each valve port of the first valve core, and (B) is a schematic diagram of each valve port of the second valve core;

[0027] Figure 3 This is a schematic diagram of the pilot valve output pressure curve in an embodiment of the present invention.

[0028] Figure 1 The components are: 1. Multi-way valve; 2. Pilot valve; 3. Hydraulic pump; 4. Bucket cylinder; 5. Boom cylinder. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0030] Example 1:

[0031] like Figures 1-3 As shown, a multi-way valve for a loader includes: a valve body; an oil inlet P and an oil return port T disposed on the valve body; a first valve core disposed within the valve body for controlling the action of the bucket cylinder 4 via working oil ports A1 and B1, wherein pilot oil from a pilot valve 2 drives the first valve core to switch direction via pilot oil ports a1 and b1; and a second valve core disposed within the valve body for controlling the action of the boom cylinder 5 via working oil ports A2 and B2, wherein pilot oil from the pilot valve 2 drives the second valve core to switch direction via pilot oil ports a2 and b2; during the switching process of the first and second valve cores, hydraulic oil flows through each valve port set according to a set valve port matching rule.

[0032] Hydraulic oil flows through various valve ports that are configured according to the set valve port matching rules, specifically including the following:

[0033] When pilot valve 2 has no output pressure, the valve core is in the neutral position, all oil ports A1 / A2 / B1 / B2 are closed, and PT is connected.

[0034] When oil enters the pilot port a1 of the multi-way valve 1 and pushes the first valve core to switch, the valve port B1-T between the working port B1 and the return port T opens first. At this time, the small chamber of the bucket cylinder is connected to the return port. As the pressure at port a1 gradually increases, the first valve core continues to switch until the valve port P-A1 between the inlet port P and the working port A1 opens. At this time, the large chamber of the bucket cylinder is connected to port P, and the opening area of ​​P-TA1 begins to gradually decrease to achieve pressure build-up at port P. However, the pressure at port P at this time is not enough to drive the bucket cylinder. As the pressure at port a1 of the multi-way valve continues to increase, P-TA1 continues to decrease until the pressure at port P rises to the load pressure of the large chamber of the bucket cylinder. At this time, the oil output by the hydraulic pump 3 enters the large chamber of the bucket cylinder 4 to drive the bucket to move until P-TA1 is completely closed. At this time, the operating speed of the bucket cylinder 4 reaches its maximum.

[0035] When P-A1 is open, the area S of the P-TA1 port is... TA1 The following relationship must be satisfied:

[0036]

[0037] Where, k TA1 The first coefficient, with a value ranging from 1 to 1.2; Q 怠 The flow rate is L / min at idle speed; C d p is the fluid flow coefficient; TA1 ρ is the minimum load pressure for bucket cylinder operation, in MPa; ρ is the fluid density, in kg / m³. 3 .

[0038] When P-A1 is open, the control pressure should be equal to the opening pressure pka1 of the pilot valve 2 at the hopper position. When P-TA1 is closed, the control pressure should be μ. P-A1 ·pza1, where μ P-A1 The pilot pressure coefficient for the bucket position is μ = 0.5-0.9, and pza1 is the control curve endpoint pressure of the bucket position of pilot valve 2.

[0039] When oil enters the pilot port b1 of the multi-way valve 1, pushing the first valve core to switch directions, the valve port A1-T between the working port A1 and the return port T opens first. At this time, the large chamber of the bucket cylinder 4 is connected to port T. Under the load pressure in the large chamber of the bucket cylinder 4, the bucket tipping action begins. As the pressure at port b1 gradually increases, the opening area of ​​A1-T gradually increases, and the tipping speed gradually increases until the valve port area of ​​A1-T reaches its maximum. When the valve port area of ​​A1-T reaches its maximum area S... A1 When the following relationship is satisfied:

[0040]

[0041] Where, k A1 The third coefficient, with a value ranging from 1.3 to 1.7; d1 is the diameter of the bucket cylinder, dm; C d p is the fluid flow coefficient; A1 The pressure in the large chamber of the bucket cylinder during the entire tipping motion under no-load conditions is MPa; ρ is the fluid density, kg / m³. 3 l1 represents the full stroke of the bucket cylinder tipping action, dm; t1 represents the full stroke time of the bucket, s.

[0042] When valve A1-T is open, the control pressure should be greater than the opening pressure pkb1 of pilot valve 2 at the tipping position. When valve A1-T reaches its maximum area, the control pressure should be μ. A1-T ·pzb1, where μ A1-T The pilot pressure coefficient for the tipping position is μ = 0.7~1, and pzb1 is the control curve endpoint pressure of the tipping position of pilot valve 2.

[0043] When oil enters the pilot port a2 of the multi-way valve 1, pushing the second valve core to switch directions, the valve port B2-T between the working port B2 and the return port T opens first. At this time, the small chamber of the boom cylinder 5 is connected to the return port. As the pressure at port a2 gradually increases, the valve core continues to switch directions until P-A2 opens. At this time, the large chamber of the boom cylinder 5 is connected to port P, and the opening area of ​​P-TA2 begins to gradually decrease to build up pressure at port P. However, the pressure at port P is not yet sufficient to drive the boom cylinder 5. As the pressure at port a2 of the multi-way valve continues to increase, P-TA2 continues to decrease until the pressure at port P rises to the load pressure of the large chamber of the boom cylinder. At this time, the hydraulic pump 3 enters the large chamber of the boom cylinder 5 to drive the bucket to move until P-TA1 is completely closed. At this time, the operating speed of the boom cylinder 5 reaches its maximum. When P-A2 opens, the area S of port P-TA2... TA2 The following relationship must be satisfied:

[0044]

[0045] Where, k TA2 The second coefficient, with a value ranging from 1 to 1.2; Q 怠The flow rate is L / min at idle speed; C d p is the fluid flow coefficient; TA2 ρ is the minimum load pressure for boom cylinder operation, in MPa; ρ is the fluid density, in kg / m³. 3 .

[0046] When P-A2 is open, the control pressure should be equal to the opening pressure pka2 of the pilot valve 2 in the lifting position. When P-TA2 is closed, the control pressure should be μ. P-A2 ·pza2, where μ P-A2 The pilot pressure coefficient for the lifting position is μ = 0.5 to 0.9, and pza2 is the control curve endpoint pressure of the pilot valve 2 in the lifting position.

[0047] When oil enters the pilot port b2 of the multi-way valve 1, pushing the second valve core to switch directions, the valve port A2-T between the working port A2 and the return port T opens first. At this time, the large chamber of the boom cylinder 5 is connected to port T. Under the load pressure in the large chamber of the boom cylinder 5, the boom begins to descend. As the pressure at port b2 gradually increases, the opening area of ​​A2-T gradually increases, and the boom descent speed gradually accelerates until the valve port area of ​​A2-T reaches its maximum. When the valve port area of ​​A2-T reaches its maximum S... A2 When the following relationship is satisfied:

[0048]

[0049] Where, k A2 The fourth coefficient, with a value ranging from 1.3 to 1.7; d2 is the boom cylinder diameter, dm; C d p is the fluid flow coefficient; A2 The pressure in the large chamber of the boom cylinder during the entire lowering stroke under no-load conditions is the average pressure in MPa; ρ is the fluid density, kg / m³. 3 l2 represents the full stroke of the boom cylinder during descent, in meters (dm); t2 represents the time of the full descent stroke, in seconds (s).

[0050] When valve A2-T is open, the control pressure is greater than the opening pressure pkb2 of pilot valve 2 when it descends to the lower position. The control pressure when valve A2-T reaches its maximum area should be μ. A2-T ·pzb2, where μ A2-T The pilot pressure coefficient for the descent position is μ = 0.7-1, and pzb2 is the control curve endpoint pressure of the pilot valve 2 in the descent position.

[0051] This invention uses the above method to match and calculate the control ports of the loader for each action, thereby improving the control performance of each action, reducing the impact on the whole machine, improving the driver's operating experience, and reducing driver fatigue.

[0052] Example 2:

[0053] Based on the multi-way valve for loaders described in Embodiment 1, this embodiment provides a loader hydraulic system, which is equipped with the multi-way valve for loaders described in Embodiment 1; specifically, it includes: a hydraulic pump 3 inputting hydraulic oil into the multi-way valve 1, the multi-way valve 1 switching under the control of the pilot valve 2, and controlling the bucket cylinder 4 and the boom cylinder 5 respectively to complete the set actions.

[0054] Example 3:

[0055] Based on the loader hydraulic system described in Embodiment 2, this embodiment provides a loader equipped with the loader hydraulic system described in Embodiment 2.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multi-way valve for a loader, characterized in that, include: Valve body; An oil inlet P and an oil return port T are provided on the valve body; The first valve core is installed in the valve body for controlling the action of the bucket cylinder (4) through the working oil port A1 and the working oil port B1. The pilot oil from the pilot valve (2) drives the first valve core to switch direction through the pilot oil port a1 and the pilot oil port b1. The valve body contains a second valve core for controlling the action of the boom cylinder (5) via working oil port A2 and working oil port B2. Pilot oil from the pilot valve (2) drives the second valve core to switch directions via pilot oil port a2 and pilot oil port b2. During the switching process of the first valve core and the second valve core, the hydraulic oil flows through each valve port set according to the set valve port matching rules, including: When oil enters through the pilot port b1 and pushes the first valve core to reverse, valve port A1-T between the working port A1 and the return port T opens first, followed by valve port P-B1 between the inlet port P and the working port B1. When valve port A1-T reaches its maximum area... When the following relationship is satisfied: in, It is the third coefficient; The diameter of the bucket cylinder; The fluid flow coefficient; The average pressure in the large chamber of the bucket cylinder during the entire stroke of the tipping action under no-load conditions; For fluid density; This refers to the entire stroke of the bucket cylinder's tipping action; This refers to the total travel time of the bucket. When oil enters through the pilot port b2 and pushes the second valve core to reverse, valve port A2-T between the working port A2 and the return port T opens first, followed by valve port P-B2 between the inlet port P and the working port B2. When valve port A2-T reaches its maximum area... When the following relationship is satisfied: in, It is the fourth coefficient; Where the boom cylinder diameter is; The fluid flow coefficient; The average pressure in the large chamber of the boom cylinder during the entire lowering stroke under no-load conditions; For fluid density; This refers to the entire stroke of the boom cylinder during descent. To reduce the overall travel time.

2. The multi-way valve for loaders according to claim 1, characterized in that, Hydraulic oil flows through various valve ports configured according to a set valve port matching rule, including: When oil enters through the pilot port a1 and pushes the first valve core to reverse, the valve port B1-T between the working port B1 and the return port T opens first, and the valve port P-A1 between the inlet port P and the working port A1 opens subsequently. When P-A1 opens, the area of ​​port P-TA1... The following relationship must be satisfied: in, The first coefficient; This refers to the flow rate of the entire machine at idle speed. The fluid flow coefficient; This is the minimum load pressure required for the bucket cylinder to operate; The fluid density is given.

3. The multi-way valve for loaders according to claim 2, characterized in that, When P-A1 is open, the control pressure is equal to the opening pressure pka1 of the pilot valve (2) at the hopper position. When P-TA1 is closed, the control pressure is μ. P-A1 ·pza1, where μ P-A1 is the pilot pressure coefficient at the bucket position, and pza1 is the control curve endpoint pressure of the pilot valve (2) at the bucket position.

4. The multi-way valve for a loader according to claim 1, characterized in that, Hydraulic oil flows through various valve ports configured according to a set valve port matching rule, including: When oil enters through the pilot port a2 and pushes the second valve core to reverse, valve port B2-T between the working port B2 and the return port T opens first, and valve port P-A2 between the inlet port P and the working port A2 opens subsequently. When P-A2 opens, the area of ​​port P-TA2 increases. The following relationship must be satisfied: in, The second coefficient; This refers to the flow rate of the entire machine at idle speed. The fluid flow coefficient; This is the minimum load pressure required for the boom cylinder to operate; The fluid density is given.

5. The multi-way valve for a loader according to claim 4, characterized in that, When P-A2 is open, the control pressure is equal to the opening pressure pka2 of the pilot valve (2) at the lifting position. When P-TA2 is closed, the control pressure is μ. P-A2 ·pza2, where μ P-A2 pza2 is the pilot pressure coefficient for the lifting position, and pza2 is the control curve endpoint pressure of the pilot valve (2) for the lifting position.

6. The multi-way valve for a loader according to claim 1, characterized in that, When the A1-T valve port is open, the control pressure at this time is greater than the opening pressure pkb1 of the pilot valve (2) at the tipping position. When the A1-T valve port reaches its maximum area, the control pressure is μ. A1-T ·pzb1, where μ A1-T is the pilot pressure coefficient of the tipping bucket position, and pzb1 is the control curve endpoint pressure of the tipping bucket position of the pilot valve (2).

7. The multi-way valve for a loader according to claim 1, characterized in that, When the A2-T valve port is open, the control pressure at this time is greater than the opening pressure pkb2 of the pilot valve (2) when it is in the descending position. When the A2-T valve port reaches its maximum area, the control pressure is μ. A2-T ·pzb2, where μ A2-T pzb2 is the pilot pressure coefficient for the descent position, and pzb2 is the control curve endpoint pressure of the pilot valve (2) at the descent position.

8. A hydraulic system for a loader, characterized in that, The loader hydraulic system is equipped with a multi-way valve for loaders as described in any one of claims 1 to 7.

9. A loader, characterized in that, The loader is equipped with the loader hydraulic system as described in claim 8.

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