Axle float control system and construction vehicle

Abstract

The application belongs to the field of engineering vehicles and relates to an axle float control system and an engineering vehicle. The axle float control system comprises a working oil source, a floating oil cylinder, a first reversing valve and a first pressure reducing valve arranged in series in a rodless cavity oil inlet oil path, and a second reversing valve and a second pressure reducing valve arranged in series in a rod cavity oil inlet oil path. The rodless cavity of the floating oil cylinder is connected with the working oil source through the rodless cavity oil inlet oil path, and the rod cavity is connected with the working oil source through the rod cavity oil inlet oil path. The pressure set value of the first pressure reducing valve is P1, the pressure set value of the second pressure reducing valve is P2, and P2>P1 is satisfied. The system realizes pressure balance of the large and small cavities of the floating oil cylinder without external force intervention through the pressure reducing valve, further increases the buffer valve to increase the buffer guarantee in the locking state, the vehicle rapidly passes through the concave-convex road surface in the locking state, and when the pressure change exceeds the load, the buffer oil return oil path can be temporarily opened to maintain the stability of the vehicle.

Description

Technical Field

[0001] This invention belongs to the field of engineering vehicles, specifically relating to a vehicle axle floating control system. Background Technology

[0002] To prevent road bumps and maintain a smooth ride, some mobile engineering vehicles are equipped with floating bridge structures. Correspondingly, a floating control oil circuit is also added to the axle to switch between the floating and locked working states of the floating bridge.

[0003] In existing technologies, floating control often employs a combination of a one-way throttle valve and a directional valve in the hydraulic circuit. However, this control circuit lacks pressure self-regulation. Specifically, when the vehicle is first started and the directional valve is energized, pressurized oil instantly enters the rod-side and rodless-side chambers of the floating cylinder. Due to the difference in the size of the two chambers' working surfaces, the floating cylinder experiences a brief extension motion, causing the vehicle frame to wobble. Furthermore, this control circuit lacks buffer protection in the locked state. If the vehicle is in the locked state, continuous high-intensity impacts may cause internal leakage in the floating cylinder, which could also lead to vehicle instability or even rollover. Summary of the Invention

[0004] The main objective of this invention is to propose a vehicle axle floating control system and an engineering vehicle to improve the stability of the engineering vehicle's movement.

[0005] To achieve the above objectives, the present invention provides a vehicle axle floating control system, the vehicle axle floating control system comprising:

[0006] Working oil source;

[0007] A floating hydraulic cylinder, wherein the rodless chamber of the floating hydraulic cylinder is connected to the working oil source through the rodless chamber oil inlet passage, and the rod chamber of the hydraulic cylinder is connected to the working oil source through the rod chamber oil inlet passage;

[0008] A first directional valve and a first pressure-reducing valve are connected in series in the oil inlet circuit of the rodless chamber; and

[0009] The second directional valve and the second pressure reducing valve are connected in series in the oil inlet circuit of the rod chamber.

[0010] Wherein, the pressure setting value of the first pressure reducing valve is P1, the pressure setting value of the second pressure reducing valve is P2, and P2>P1 is satisfied.

[0011] In some embodiments, the axle floating control system includes:

[0012] A rodless chamber return oil passage connects the rodless chamber of the cylinder to the return oil tank and is equipped with a first buffer valve; and

[0013] The rod chamber return oil passage is connected between the rod chamber of the oil cylinder and the return oil tank and is equipped with a second buffer valve.

[0014] The first buffer valve is set to pressure P3 and is configured to open the return oil circuit of the rodless chamber when the oil pressure in the rodless chamber of the cylinder is greater than P3; the second buffer valve is set to pressure P4 and is configured to open the return oil circuit of the rod chamber when the oil pressure in the rod chamber of the cylinder is greater than P4, and satisfies P4>P3.

[0015] In some embodiments, the maximum single-side load pressure of the axle borne by the floating cylinder is P0, satisfying P4>P3>P0>P2>P1.

[0016] In some embodiments, both the first buffer valve and the second buffer valve are normally closed hydraulic directional valves and include a shut-off position with a check valve and a conduction position that conducts the corresponding return oil path. The check valve is configured to allow hydraulic oil to be drawn from the return oil tank into the cylinder oil chamber and to shut off in the reverse direction.

[0017] In some embodiments, the rodless chamber return oil passage is connected to the rod chamber return oil passage.

[0018] In some embodiments, the cross-sectional area of ​​the rodless chamber of the hydraulic cylinder is A1, and the cross-sectional area of ​​the rod chamber of the hydraulic cylinder is A2, satisfying: P1*A1=P2*A2.

[0019] In some embodiments, the first pressure reducing valve is a hydraulically controlled directional valve and is configured to switch from the inlet position to the return position when the downstream oil pressure is greater than P1, and the second pressure reducing valve is a hydraulically controlled directional valve and is configured to switch from the inlet position to the return position when the downstream oil pressure is greater than P2.

[0020] In some embodiments, in the rodless chamber oil inlet circuit, the first directional valve is located downstream of the first pressure reducing valve along the oil inlet direction; in the rod chamber oil inlet circuit, the second directional valve is located downstream of the second pressure reducing valve along the oil inlet direction.

[0021] In some embodiments, the first and second directional valves are two-position two-way solenoid valves.

[0022] In addition, the present invention also provides an engineering vehicle, the engineering vehicle including the axle floating control system described above according to the present invention.

[0023] In some embodiments, the engineering vehicle is a telescopic boom forklift truck, the cylinder of the floating cylinder is hinged to the frame of the telescopic boom forklift truck, the piston rod of the floating cylinder is hinged to the axle of the telescopic boom forklift truck, and the two hinge points of the floating cylinder are located on the same side of the vehicle.

[0024] The axle floating control system of the present invention achieves pressure balance between the large and small chambers of the floating cylinder by synchronously supplying oil to the large and small chambers of the cylinder through a working oil source, combined with a series-connected reversing valve and a pressure reducing valve and their parameter settings. When the vehicle starts and switches to the floating state, the piston rod can be pressure balanced without external force intervention by setting the parameters of the pressure reducing valve, and the pressure shocks are canceled out, so the axle will not vibrate due to pressure shocks, thus improving the vehicle's driving stability.

[0025] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0026] The accompanying drawings are provided to illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0027] Figure 1 A hydraulic schematic diagram of a vehicle axle floating control system according to a specific embodiment of the present invention; and

[0028] Figure 2 This is a hydraulic schematic diagram of a vehicle axle floating control system according to another specific embodiment of the present invention.

[0029] Explanation of reference numerals in the attached figures

[0030]

[0031] Detailed Implementation

[0032] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0033] The following description, with reference to the accompanying drawings, describes an engineering vehicle and its axle floating control system according to the present invention.

[0034] This invention discloses a vehicle axle floating control system. For example... Figure 1 As shown, in one specific embodiment, the axle floating control system according to the present invention may include:

[0035] Working oil source P;

[0036] The floating cylinder 1 has a rodless chamber that is connected to the working oil source P through a rodless chamber oil inlet passage L1, and a rod chamber that is connected to the working oil source P through a rod chamber oil inlet passage L2.

[0037] The first directional valve 2 and the first pressure reducing valve 6 are connected in series in the rodless chamber oil inlet circuit L1; and

[0038] The second directional valve 3 and the second pressure reducing valve 7 are connected in series in the rod chamber oil inlet circuit L2;

[0039] The pressure setting value of the first pressure reducing valve 6 is P1, and the pressure setting value of the second pressure reducing valve 7 is P2, and P2>P1 is satisfied.

[0040] As can be seen, in this hydraulic system, the working oil source P supplies oil to both the large and small chambers of the floating cylinder 1. Both the first pressure reducing valve 6 and the second pressure reducing valve 7 are constant pressure reducing valves. Specifically, a portion of the pressurized oil supplied by the working oil source P1 flows to the rodless chamber of the cylinder after being reduced in pressure by the first pressure reducing valve 6. When the pressure setting value of the first pressure reducing valve 6 (i.e., the pressure value at the outlet of the pressure reducing valve) is P1, the oil pressure in the rodless chamber of the cylinder is also P1, ignoring low-level back pressure (such as the back pressure of the check valve in the first directional valve 2 shown in the figure). Similarly, another portion of the pressurized oil supplied by the working oil source P1 flows to the rod chamber of the cylinder after being reduced in pressure by the second pressure reducing valve 7. When the pressure setting value of the second pressure reducing valve 7 is P2, the oil pressure in the rod chamber of the cylinder is also P2. Due to the different cross-sectional force-bearing areas of the large and small chambers, the values ​​of P1 and P2 can be precisely adjusted to achieve left-right force balance of the piston. In other words, by setting pressure reducing valves, pressure balance between the large and small chambers of the floating cylinder is achieved without external force intervention. In this way, when the floating cylinder 1 is installed on the engineering vehicle and this axle floating control system is used, the vehicle body will not vibrate due to pressure shock during the switching between the floating state and the locked state.

[0041] See Figure 1 In this embodiment, assuming a standard cylinder design and ignoring friction, if the cross-sectional area of ​​the rodless chamber of the floating cylinder 1 is A1, and the cross-sectional area of ​​the rod chamber is A2 (equivalent to A1 minus the cross-sectional area of ​​the piston rod), then in this embodiment, the following condition is met: P1*A1 = P2*A2. This achieves a basic pressure balance on both sides of the piston within the cylinder. Of course, this is only a theoretical design; in practice, the values ​​of P1 and P2 can be adjusted based on other influencing factors. Therefore, in this embodiment, both the first pressure-reducing valve 6 and the second pressure-reducing valve 7 are configured with adjustable outlet pressure for ease of operation.

[0042] It should be noted that the working oil source P here can be pumped oil with a hydraulic pump, or it can be an external vehicle pumping oil circuit, which simultaneously supplies oil to the large and small chambers of the oil cylinder.

[0043] In this embodiment, both the first pressure-reducing valve 6 and the second pressure-reducing valve 7 are commercially available three-way pressure-reducing valves. See [link / reference] Figure 1The first pressure reducing valve 6 is a hydraulically controlled directional valve, configured to switch from the inlet position to the return position when the downstream oil pressure is greater than P1. Specifically, the oil at the outlet of the first pressure reducing valve 6 is used as pilot oil to guide one hydraulically controlled end of the pressure reducing valve, and the other hydraulically controlled end can be equipped with an adjustable spring. Under normal conditions, the hydraulically controlled directional valve is in the left position shown in the figure, i.e., the inlet position. At this time, the working oil from the working oil source P1 enters the first pressure reducing valve 6 through the inlet and flows out from the outlet of the pressure reducing valve, and then flows through the first directional valve 2 to the rodless chamber of the cylinder.

[0044] Once the oil pressure in the rodless chamber of the cylinder increases, causing the oil pressure at the outlet of the first pressure reducing valve 6 (i.e., the downstream oil pressure of the first pressure reducing valve 6) to exceed P1, the pressure at the hydraulic control end will push the valve core to the right, thereby switching to the return oil position. At this time, some of the oil from the rodless chamber of the cylinder flows to the return oil tank T through the outlet of the pressure reducing valve and the return oil port of the first pressure reducing valve 6. In this way, the excessive oil pressure in the rodless chamber of the cylinder can be relieved.

[0045] Similarly, in this embodiment, the second pressure-reducing valve 7 has the same structure as the first pressure-reducing valve 6, both being hydraulically controlled directional valves. The second pressure-reducing valve 7 is configured to switch from the inlet position to the return position when the downstream oil pressure is greater than P2. Likewise, once the oil pressure in the rod chamber of the cylinder increases, causing the downstream oil pressure of the second pressure-reducing valve 7 to exceed P2, the valve core moves to the right. Excess oil in the rod chamber of the cylinder can flow to the return oil tank T through the pressure-reducing valve outlet and return port of the second pressure-reducing valve 7, thereby achieving pressure relief in the rod chamber.

[0046] Of course, those skilled in the art will understand that the return port of the first pressure-reducing valve 6 and the second pressure-reducing valve 7 are not limited to the three-way pressure-reducing valve shown in the figure. Pressure-reducing valves of various structural forms capable of achieving pressure reduction and overpressure reflux should all be within the scope of protection of this invention. Similarly, the first reversing valve 2 and the second reversing valve 3 in this embodiment are two-position two-way solenoid valves as shown in the figure, but this invention is not limited to this. Two-position two-way solenoid valves are convenient for electronic switching or remote control, but obviously they could also be other ordinary reversing valves or zero-leakage valves, etc.

[0047] Specifically, in this embodiment, in the rodless chamber oil inlet passage L1, the first directional valve 2 is located downstream of the first pressure reducing valve 6 along the oil inlet direction; in the rod chamber oil inlet passage L2, the second directional valve 3 is located downstream of the second pressure reducing valve 7 along the oil inlet direction. This arrangement prevents repeated impacts on the second pressure reducing valve 7 and the first pressure reducing valve 6 due to oil pressure changes when locking the floating cylinder 1.

[0048] like Figure 2 As shown, in another specific embodiment, in Figure 1 In addition, a buffer valve was added to the existing system.

[0049] Specifically, the axle floating control system includes:

[0050] The rodless chamber return oil passage L3 connects the rodless chamber of the cylinder to the return oil tank T and is equipped with a first buffer valve 4; and

[0051] The rod chamber return oil passage L4 is connected between the rod chamber of the oil cylinder and the return oil tank T and is equipped with a second buffer valve 5;

[0052] The pressure setting value of the first buffer valve 4 is P3, and it is set to open the return oil circuit L3 of the rodless chamber when the oil pressure in the rodless chamber of the cylinder is greater than P3; the pressure setting value of the second buffer valve 5 is P4, and it is set to open the return oil circuit L4 of the rod chamber when the oil pressure in the rod chamber of the cylinder is greater than P4, and P4>P3 is satisfied.

[0053] By adding a buffer valve, when the floating cylinder 1 is locked, that is, when the first directional valve 2 and the second directional valve 3 are switched to the left position, the oil pressure fluctuation in the rodless chamber or the rod chamber of the cylinder can be buffered by the buffer valve, and the impact oil can be returned through the buffer valve, avoiding repeated impacts on the directional valve, thus playing a buffer protection role in the locked state. This will be explained in detail below.

[0054] Based on the above description, since P2 > P1, correspondingly P4 > P3, and it should also satisfy P4 > P3 > P2 > P1. It needs to be clarified that when the floating cylinder 1 is installed on the vehicle, if the maximum single-sided load pressure of the axle borne by the floating cylinder 1 is P0, then P4 > P3 > P0 > P2 > P1 should be satisfied.

[0055] See Figure 2 In this embodiment, both the first buffer valve 4 and the second buffer valve 5 are normally closed hydraulic directional valves and include a shut-off position with a check valve and a conducting position that connects the corresponding return oil path. For example, the first buffer valve 4 shown in the figure includes a left shut-off position and a right conducting position with a first check valve 41. P3 is the reversing pressure; when the hydraulic pressure at the control end is greater than P3, the valve core can be pushed to change position. Similarly, the second buffer valve 5 also includes a left shut-off position and a right conducting position with a second check valve 51. In the shut-off position, both the first check valve 41 and the second check valve 51 are configured to allow hydraulic oil to be drawn from the return oil tank T into the oil chamber of the cylinder and to shut off in the reverse direction.

[0056] Similar to the pressure reducing valve in the diagram, the hydraulic control oil for the first buffer valve 4 and the second buffer valve 5 originates from the rodless chamber and rod chamber of the hydraulic cylinder, respectively, and is introduced into their respective hydraulic control terminals on one side and an adjustable spring terminal on the other side. The adjustable spring terminal allows the pressure setting of the buffer valve to be adjusted according to the actual application environment. When the oil pressure in the rodless chamber or rod chamber of the hydraulic cylinder exceeds the oil pressure setting of the buffer valve, a portion of the pilot oil will push the valve core to move through the hydraulic control terminal, opening the conduction position. This allows excess oil in the hydraulic cylinder chamber to return through the hydraulic return oil circuit from the conduction position.

[0057] like Figure 1 As shown, the oil return circuit L3 of the rodless chamber is connected to the oil return circuit L4 of the rod chamber. Thus, in the locked state of the cylinder, if the pressure in either the rodless or rod chamber increases, causing the piston to move, a negative pressure is generated in the other chamber. The oil pressure on one side increases can be released through the corresponding buffer valve, while the negative pressure on the other side can be drawn in through the one-way valve in the cut-off position, thereby ensuring that the oil volume in both chambers of the cylinder remains constant.

[0058] It should be noted that, Figure 1 , Figure 2 The control valves shown can exist independently or be integrated with any components to form a valve assembly.

[0059] Based on the aforementioned axle floating control system, this invention also discloses an engineering vehicle that includes the axle floating control system described above. Through the axle floating control system of this invention, the engineering vehicle achieves higher vehicle stability, smoother travel, and maintains pressure balance in the floating cylinder, ensuring vehicle stability even when switching between the locked and floating states of the cylinder.

[0060] The engineering vehicle can be a wheeled vehicle or other types. In the above embodiment, as an example, the engineering vehicle is a telescopic boom forklift with high requirements for vehicle stability, which needs to be equipped with the above-mentioned axle floating control system to eliminate the risks of forklift operation caused by instability. In specific installation, the cylinder of the floating cylinder 1 can be hinged to the frame of the telescopic boom forklift, the piston rod of the floating cylinder 1 can be hinged to the axle of the telescopic boom forklift, and the two hinge points of the floating cylinder 1 are located on the same side of the vehicle.

[0061] The following will be combined with the appendix Figure 2 The floating control system of the axle and its application in telescopic boom forklifts are described, specifically how to achieve the locking state of the floating cylinder, the stable switching between the floating state and the floating state, and how to maintain the stability of the vehicle body.

[0062] When the machine is started for the first time, the first reversing valve 2 and the second reversing valve 3 are simultaneously energized and switched to the left position, at which point the axle is in a floating state. At this time, the telescopic boom forklift is moved back and forth on uneven road surfaces, causing the single wheel of the floating axle to move up and down continuously, thereby driving the floating cylinder to extend and retract back and forth, and thus filling the entire control oil circuit with hydraulic oil.

[0063] Switching to floating state: When the first reversing valve 2 and the second reversing valve 3 are simultaneously energized, the pressure oil at the working oil source P enters the left position of the first reversing valve 2 and the second reversing valve 3 through the first pressure reducing valve 6 and the second pressure reducing valve 7, respectively, and then enters the rodless chamber and the small chamber of the floating cylinder. At this time, the pressure in the rodless chamber of the floating cylinder 1 is the pressure setting value P1 of the first pressure reducing valve 6, and the pressure in the small chamber is the pressure setting value P2 of the second pressure reducing valve 7. Since P1*A1=P2*A2, the floating cylinder 1 is in a state of force balance without external force intervention, and will not cause vehicle body vibration due to pressure shock during the switching process.

[0064] Floating State: At this time, the first reversing valve 2 and the second reversing valve 3 remain energized. When the tire on the side where the floating cylinder 1 is installed climbs onto a raised surface or the tire on the side where the floating cylinder is not installed falls into a depression, the pressure in the rodless chamber of the floating cylinder 1 will exceed the pressure setting value P1 of the first pressure reducing valve 6. The hydraulic oil in the rodless chamber pushes the valve core of the first pressure reducing valve 6 into the right position. At this time, the rodless chamber of the floating cylinder 1 is connected to the return oil tank T through the first reversing valve 2 and the first pressure reducing valve 6. The pressure oil in the rodless chamber is released, the piston of the floating cylinder 1 retracts, and the floating cylinder side of the axle lifts. To maintain vehicle stability; when the tire on the side where the floating cylinder 1 is installed falls into a depression or the tire on the side where the floating cylinder is not installed climbs onto a raised surface, the pressure in the small chamber of the floating cylinder 1 will be greater than the pressure setting value P2 of the second pressure reducing valve 7. The hydraulic oil in the small chamber pushes the valve core of the second pressure reducing valve 7 into the right position. At this time, the small chamber of the floating cylinder 1 is connected to the return oil tank T through the second reversing valve 3 and the second pressure reducing valve 7. The pressure oil in the small chamber is released, the floating cylinder 1 is pulled out, and the floating cylinder side of the axle falls down, maintaining vehicle stability.

[0065] Locked State: At this time, the first directional valve 2 and the second directional valve 3 remain de-energized. Both the large and small chambers of the floating cylinder 1 are disconnected from the P and T ports shown in the diagram. Because the internal hydraulic oil cannot flow, the floating cylinder 1 cannot move, and the axle and tires are locked by the floating cylinder 1, preventing them from moving up and down.

[0066] Lock-up Buffer: When the hydraulic circuit is locked, the floating cylinder 1 cannot move. When the tires on the floating bridge travel over uneven surfaces, the pressure in the large and small chambers of the floating cylinder 1 changes accordingly. When the vehicle travels too fast and passes over uneven surfaces, the pressure in the large and small chambers of the floating cylinder 1 may exceed the set pressure values ​​P3 and P4 of the first buffer valve 4 and the second buffer valve 5, respectively. When the pressure in the rodless chamber of the cylinder is greater than P3, the first buffer valve 4 switches to its right position under hydraulic pressure. At the same time, due to the pressure on the cylinder piston, it moves to the left, causing a negative pressure to be generated in the small chamber of the cylinder. Under the action of the negative pressure, the valve port of the second one-way valve 51 on the left side of the second buffer valve 5 opens, allowing oil to be drawn into the small chamber of the cylinder. In this way, the rodless chamber of the cylinder is connected to the rod chamber of the cylinder in one direction, and is also connected to the return oil tank T. The floating cylinder 1 can retract briefly to eliminate the impact and maintain the vehicle balance. Similarly, when the pressure in the rod chamber of the hydraulic cylinder is greater than P4, the second buffer valve 5 is in the right position under pressure. The rod chamber of the hydraulic cylinder is connected to the rodless chamber of the hydraulic cylinder in one direction, and is also connected to the return oil tank T. The floating hydraulic cylinder 1 can extend briefly to eliminate the impact and maintain the balance of the vehicle.

[0067] In summary, the axle floating control system of this invention achieves pressure balance between the large and small chambers of the floating cylinder under conditions of no external force intervention through a three-way pressure reducing valve, and further adds a buffer valve to provide buffer protection in the locked state. When the vehicle is started and the floating valve is energized to switch to the floating state, the piston rod is pressure balanced under conditions of no external force intervention because the pressure set by the three-way pressure reducing valve and the working surface area of ​​the large and small chambers of the cylinder have the aforementioned equation P1*A1=P2*A2. This cancels out the pressure impact, thus preventing the axle from shaking due to pressure impact. When the vehicle is in the locked state and quickly passes over uneven road surfaces, if the pressure change exceeds the load, the oil circuit is briefly opened when the impact force on the floating cylinder exceeds the set value of the buffer valve, eliminating the impact on the floating cylinder and maintaining vehicle stability.

[0068] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0069] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0070] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0071] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A vehicle axle floating control system, characterized in that, The axle floating control system includes: Working oil source (P); A floating cylinder (1) has its rodless chamber connected to the working oil source (P) via a rodless chamber oil inlet passage (L1), and its rod chamber connected to the working oil source (P) via a rod chamber oil inlet passage (L2). The first directional valve (2) and the first pressure reducing valve (6) are connected in series in the rodless chamber oil inlet circuit (L1); and The second directional valve (3) and the second pressure reducing valve (7) are connected in series in the oil inlet circuit (L2) of the rod chamber; A rodless chamber return oil passage (L3) is connected between the rodless chamber of the cylinder and the return oil tank (T) and is equipped with a first buffer valve (4); and The rod chamber return oil passage (L4) is connected between the rod chamber of the oil cylinder and the return oil tank (T) and is equipped with a second buffer valve (5). Wherein, the pressure setting value of the first pressure reducing valve (6) is P1, the pressure setting value of the second pressure reducing valve (7) is P2, and P2 > P1 is satisfied; the pressure setting value of the first buffer valve (4) is P3, and it is set to open the oil return passage (L3) of the rodless chamber of the oil cylinder when the oil pressure is greater than P3; the pressure setting value of the second buffer valve (5) is P4, and it is set to open the oil return passage (L4) of the rod chamber of the oil cylinder when the oil pressure is greater than P4, and P4 > P3 is satisfied.

2. The axle floating control system according to claim 1, characterized in that, The maximum load pressure on one side of the axle borne by the floating cylinder (1) is P0, which satisfies P4 > P3 > P0 > P2 > P1.

3. The axle floating control system according to claim 1, characterized in that, The first buffer valve (4) and the second buffer valve (5) are both normally closed hydraulic control directional valves and include a stop position with a check valve and a conduction position that conducts the corresponding return oil circuit. The check valve is configured to allow hydraulic oil to be drawn into the oil cylinder chamber from the return oil tank and to be cut off in the reverse direction.

4. The axle floating control system according to claim 1, characterized in that, The rodless chamber return oil passage (L3) is connected to the rod chamber return oil passage (L4).

5. The axle floating control system according to any one of claims 1 to 4, characterized in that, The cross-sectional area of ​​the rodless chamber of the hydraulic cylinder is A1, and the cross-sectional area of ​​the rod chamber of the hydraulic cylinder is A2, satisfying: P1*A1=P2*A2.

6. The axle floating control system according to claim 5, characterized in that, The first pressure reducing valve (6) is a hydraulic control directional valve and is configured to switch from the inlet position to the return position when the oil pressure after the valve is greater than P1. The second pressure reducing valve (7) is a hydraulic control directional valve and is configured to switch from the inlet position to the return position when the oil pressure after the valve is greater than P2.

7. The axle floating control system according to claim 1, characterized in that, In the rodless chamber oil inlet circuit (L1), along the oil inlet direction, the first directional valve (2) is located downstream of the first pressure reducing valve (6); in the rod chamber oil inlet circuit (L2), along the oil inlet direction, the second directional valve (3) is located downstream of the second pressure reducing valve (7).

8. The axle floating control system according to claim 1, characterized in that, The first reversing valve (2) and the second reversing valve (3) are two-position two-way solenoid valves.

9. An engineering vehicle, characterized in that, The engineering vehicle includes the axle floating control system according to any one of claims 1 to 8.

10. The engineering vehicle according to claim 9, characterized in that, The engineering vehicle is a telescopic boom forklift truck. The cylinder of the floating cylinder (1) is hinged to the frame of the telescopic boom forklift truck, and the piston rod of the floating cylinder (1) is hinged to the axle of the telescopic boom forklift truck. The two hinge points of the floating cylinder (1) are located on the same side of the vehicle.

Images