VALVE ASSEMBLY

TECHNICAL FIELD

The present utility model generally relates to a valve assembly, more particularly to a valve assembly used for a hydraulic system of a machine. The present utility model further relates to a hydraulic system comprising the valve assembly, and a machine comprising the hydraulic system.

BACKGROUND OF THE UTILITY MODEL

A machine such as a wheel loader, an excavator, a bulldozer, a grader or other types of heavy equipments generally accomplishes various tasks by using a plurality of actuators (for example hydraulic cylinder) supplied with hydraulic fluid from one or more pumps on the machine. The working device of such machine, especially the wheel loader, mainly comprises a boom and a bucket. A hydraulic system of the machine supplies hydraulic fluid to a lifting hydraulic cylinder and a bucket hydraulic cylinder which are associated with the boom and the bucket respectively, so as to realize different actions, such as lifting or descending of the boom, excavating, dumping and unloading of the bucket, and the like.

In order to realize the above mentioned various actions, the hydraulic system of the machine usually comprises a directional valve for controlling a lifting action direction of the boom, a directional valve for controlling a moving direction of the bucket, a main relief valve for setting a highest pressure of the hydraulic system, an anti-backflush load check valve for preventing pressure from a working load from damaging the working pump, a lifting float control valve for controlling fluid communication between a rod end chamber and a head end chamber of the lifting hydraulic cylinder, a relief valve for limiting a highest pressure of a head end chamber of the bucket hydraulic cylinder, and a make-up and relief valve for limiting a highest pressure of a rod end chamber of the bucket hydraulic cylinder and replenishing the hydraulic fluid of the rod end chamber during rapid bucket dumping. In the existing machine, these valve elements are generally assembled in a single valve block. Since these valve elements are disposed in at least three layers in the valve block, the passage design in the valve block is relatively complex, there are more features to be machined, and the valve block occupies a relative large space.

The present utility model aims to solve the above problems and/or other problems in the prior art.

SUMMARY OF THE UTILITY MODEL

In one aspect, the present utility model relates to a valve assembly for a hydraulic system of a machine, and the valve assembly comprises:

- a pump port P for being in fluid connection with a working pump;

- a tank port T for being in fluid connection with a hydraulic oil tank;

- a first working port for being in fluid connection with a head end chamber of a bucket hydraulic cylinder of the hydraulic system, a second working port for being in fluid connection with a rod end chamber of the bucket hydraulic cylinder, a third working port for being in fluid connection with a head end chamber of a lifting hydraulic cylinder of the hydraulic system, and a fourth working port for being in fluid connection with a rod end chamber of the lifting hydraulic cylinder;

- a first directional valve, wherein the first directional valve is configured to be in fluid connection with the working pump so as to receive hydraulic fluid pumped by the working pump, and selectively guide the received hydraulic fluid to the head end chamber of the bucket hydraulic cylinder via the first working port or to the rod end chamber of the bucket hydraulic cylinder via the second working port;

- a second directional valve, wherein the second directional valve is configured to be in fluid connection with the first directional valve so as to receive the hydraulic fluid from the first directional valve, and selectively guide the received hydraulic fluid to the lifting hydraulic cylinder;

- a main relief valve, an input port of which is in fluid connection with the pump port, and an output port of which is in fluid connection with the tank port;

- a first load check valve, an input port of which is in fluid connection with the pump port, and an output port of which is in fluid connection with the first directional valve;

- a second load check valve, an input port of which is in fluid connection with the first directional valve, and an output port of which is in fluid connection with the second directional valve;

- a first relief valve, an input port of which is in fluid connection with the first working port, and an output port of which is in fluid connection with the tank port;

- a make-up and relief valve, an input port of which is in fluid connection with the second working port, and an output port of which is in fluid connection with the tank port; and

- a float control valve disposed between the second directional valve and the tank port, characterized in that the first directional valve, the second directional valve, the main relief valve, the first and second load check valves, the first relief valve, the make-up and relief valve and the float control valve are integrated in a valve block, wherein the float control valve, the first relief valve and the make-up and relief valve are disposed in parallel along a horizontal direction in a first horizontal layer of the valve block, and the first directional valve, the second directional valve and the first load check valve are disposed in parallel along the horizontal direction in a second horizontal layer of the valve block.

In another aspect, the present utility model relates to a hydraulic system comprising the valve assembly.

In still another aspect, the present utility model relates to a machine comprising the hydraulic system. BRIEF DESCRIPTION OF THE DRAWINGS

The present utility model is described in greater detail by referring to schematic drawings. The drawings and corresponding embodiments are merely intended to explain rather than limit the present utility model. In the drawings:

- Figure 1 is a schematic view of a housing of a valve assembly according to the present utility model;

- Figure 2 schematically shows an assembled valve assembly;

- Figure 3 shows arrangement of fluid passages of a valve assembly in an incarnating manner;

- Figure 4 shows a hydraulic circuit corresponding to the valve assembly;

- Figure 5 is a top view of fluid passages in a second horizontal layer of a valve block; and

- Figure 6 is a bottom view of fluid passages in a first horizontal layer of a valve block.

DETAILED DESCRIPTION OF THE EMBODFMENTS

A valve assembly 10 of the present utility model is described in detail with reference to the drawings. In preferable embodiments as shown in the drawings, the valve assembly can be used for a machine in which a boom and a bucket are used as main working devices, such as a wheel loader. But it should be understood that the present utility model is not limited to the specific embodiments, and covers other equivalent solutions with its design concept.

As shown in Figure 1, the valve 10 comprises a housing 100, a plurality of fluid passages are formed in the housing 100 (with reference to Figure 3), the respective valve elements contained in the valve assembly can be inserted from proper ports on the surface of the housing 100 and are assembled together, thus obtaining the valve assembly. Figure 2 schematically shows the assembled valve assembly 10.

As shown in Figure 1, and with reference to Figure 2 and Figure 4, a top of the housing 100 is provided with a port 110 used for inserting a second load check valve 122, a port 120 used for inserting a main relief valve 1, first and second working ports 150 and 160 used for being in fluid connection with a head end chamber and a rod end chamber of a bucket hydraulic cylinder, and third and fourth working ports 130 and 140 used for being in fluid connection with a head end chamber and a rod end chamber of a lifting hydraulic cylinder. A front side surface (that is, the side surface close to the reader in Figure 1) of the housing 100 is provided with a pump port (oil inlet, P) used for being in fluid connection with a working pump of the hydraulic system and a tank port (oil returning port, T) used for being in fluid connection with a hydraulic oil tank. A right side surface of the housing 100 is provided with a port 200 used for inserting a float control valve 3, a port 210 used for inserting a first relief valve 4, a port 220 used for inserting a make-up and relief valve 5, a port 230 used for inserting a valve core of a first directional valve 7, and a port 240 used for inserting a valve core of a second directional valve 6. In addition, a part of the housing adjacent to the pump port P and the tank port T is provided with a convex part, and a port 190 used for inserting a first load check valve 121 is formed at a right side surface of the convex part. It should be noted that the direction terms such as "top", "front side surface", "right side surface" and "horizontal direction" are defined relative to the placement of the valve assembly (or the housing thereof) in Figure 1, and are merely intended for the purpose of clear description.

It can be understood that the positions of the pump port P, the tank port T, the port 210 for the first relief valve 4, the port 220 for the make-up and relief valve 5, and the port 120 for the main relief valve 1 on the housing 100 can be appropriately changed as required, and are not limited to the positions as shown in Figure 1.

In the present embodiment, the first directional valve 7 is associated with the bucket hydraulic cylinder for controlling action of a bucket, and the first directional valve is configured to be in fluid connection with the working pump so as to receive hydraulic fluid pumped by the working pump, and selectively guide the received hydraulic fluid to the bucket hydraulic cylinder, for example, guide to the head end chamber of the bucket hydraulic cylinder via the first working port 150 or guide to the rod end chamber of the bucket hydraulic cylinder via the second working port 160. The second directional valve 6 is associated with the lifting hydraulic cylinder for controlling the lifting and descending of a boom, and the second directional valve is configured to be in fluid connection with the first directional valve 7 so as to receive hydraulic fluid from the first directional valve 7, and selectively guide the received hydraulic fluid to the lifting hydraulic cylinder, for example, guide to the head end chamber of the lifting hydraulic cylinder via the third working port 130 or guide to the rod end chamber of the lifting hydraulic cylinder via the fourth working port 140.

After all valve elements (i.e., the main relief valve 1, the first and second load check valves 121 and 122, the float control valve 3, the first relief valve 4, the make-up and relief valve 5 and valve cores of the first and second directional valves) are inserted into the housing 100 through corresponding ports and are assembled together, the valve assembly 10 according to the present utility model can be obtained, as shown in Figure 2.

A hydraulic circuit corresponding to the valve assembly 10 is shown in Figure 4. By the hydraulic circuit, the hydraulic fluid pumped by the working pump can be selectively guided to the lifting hydraulic cylinder and/or the bucket hydraulic cylinder, so as to realize different actions, such as lifting or descending of the boom, excavating, dumping and unloading of the bucket, and the like.

As shown in Figure 4, the first directional valve 7 is a three-position six-way valve, comprising a first port 21 in fluid connection with the hydraulic oil tank, a second port 22 in fluid connection with an output end (i.e. pump port P) of the working pump directly, a third port 23 in fluid connection with the output end of the working pump via the second load check valve 122, a fourth port 24 in fluid connection with the rod end chamber of the bucket hydraulic cylinder, a sixth port 26 in fluid connection with the head end chamber of the bucket hydraulic cylinder, and a fifth port 25 in fluid connection with the second directional valve 6. The second load check valve 122 only allows the fluid to flow to the third port 23 from the working pump, and does not allow flowing in the opposite direction, and has a function of preventing a pressure of a working load from impacting and damaging the working pump.

The first directional valve 7 has a first working position, a second working position and a third working position, wherein, when the first directional valve is in the first working position (the middle position as shown in Figure 4), the first port 21, the third port 23, the fourth port 24 and the sixth port 26 are cut off, and the second port 22 and the fifth port 25 are in fluid communication. When the first directional valve is in the second working position (the left position as shown in Figure 4), the first port 21 and the sixth port 26 are in fluid communication, the third port 23 and the fourth port 24 are in fluid communication, and the second port 22 and the fifth port 25 are cut off. When the first directional valve is in the third working position (the right position as shown in Figure 4), the first port 21 and the fourth port 24 are in fluid communication, the third port 23 and the sixth port 26 are in fluid communication, and the second port 22 and the fifth port 25 are cut off.

Therefore, when the first directional valve is in the first working position, the hydraulic fluid from the working pump is guided to the second directional valve via the first directional valve; and when the first directional valve is in the second or third working position, the hydraulic fluid from the working pump is guided to one of the first and second working ports via the first directional valve, and the hydraulic fluid at the other one of the first and second working ports is returned back to the hydraulic oil tank via the first directional valve.

The second directional valve 6 is also a three-position six-way valve, comprising a first port 31 in fluid connection with the hydraulic oil tank, a second port 32 in fluid connection with the fifth port 25 of the first directional valve 7, a third port 33 in fluid connection with the fifth port 25 of the first directional valve 7 via the first load check valve 121, a fourth port

34 in fluid connection with the head end chamber of the lifting hydraulic cylinder, a fifth port

35 in fluid connection with the hydraulic oil tank, and a sixth port 36 in fluid connection with the rod end chamber of the lifting hydraulic cylinder. The first load check valve 121 only allows the fluid to flow to the third port 33 of the second directional valve 6 from the fifth port 25 of the first directional valve 7, and does not allow flowing in the opposite direction, thereby can prevent a pressure of a working load from impacting and damaging the working pump.

The second directional valve 6 has a first working position, a second working position and a third working position, wherein, when the second directional valve is in the first working position (the middle position as shown in Figure 4), the first port 31, the third port 33, the fourth port 34 and the sixth port 36 are cut off, and the second port 32 and the fifth port 35 are in fluid communication. When the second directional valve is in the second working position (the left position as shown in Figure 4), the first port 31 and the sixth port 36 are in fluid communication, the third port 33 and the fourth port 34 are in fluid communication, and the second port 32 and the fifth port 35 are cut off. When the second directional valve is in the third working position (the right position as shown in Figure 4), the first port 31 and the fourth port 34 are in fluid communication, the third port 33 and the sixth port 36 are in fluid communication, and the second port 32 and the fifth port 35 are cut off.

Therefore, when the second directional valve is in the first working position, the hydraulic fluid from the first directional valve is directly returned back to the hydraulic oil tank via the second directional valve; and when the second directional valve is in the second or third working position, the hydraulic fluid from the first directional valve is guided to one of the third and fourth working ports via the second directional valve, and the hydraulic fluid at the other one of the third and fourth working ports is returned back to the hydraulic oil tank via the second directional valve.

In addition, as shown in Figure 4, an input port of the main relief valve 1 for setting a highest pressure of the hydraulic circuit is in fluid connection with the pump port P, and an output port thereof is in fluid connection with the tank port T. The first relief valve 4 is used for limiting a highest pressure of the head end chamber of the bucket hydraulic cylinder, an input port thereof is in fluid connection with the first working port (leading to the head end chamber of the bucket hydraulic cylinder), and an output port thereof is in fluid connection with the tank port T. The make-up and relief valve 5 is used for limiting a highest pressure of the rod end chamber of the bucket hydraulic cylinder and replenishing hydraulic fluid to the rod end chamber when the bucket is quickly tipped, an input port thereof is in fluid connection with the second working port (leading to the rod end chamber of the bucket hydraulic cylinder), and an output port thereof is in fluid connection with the tank port T. The float control valve 3 is disposed between the second directional valve and the tank port and is used for controlling the communication between the head end chamber and the rod end chamber of the lifting hydraulic cylinder during floating operation of the machine.

By means of the Figures 3, 5 and 6, the arrangement of the respective valve elements in the housing 100 can be well known. For the purpose of clarity and convenient understanding, Figures 3, 5 and 6 actually show in a manner that the fluid passages formed within the housing 100 are incarnated. As shown in the Figures, the respective valve elements are integrated in a valve block in two layers, wherein the float control valve 3, the first relief valve 4 and the make-up and relief valve 5 are disposed in parallel along a horizontal direction in a first horizontal layer (the upper layer as shown in Figure 3) of the valve block, and the first directional valve 7, the second directional valve 6 and the first load check valve 121 are disposed in parallel along the same horizontal direction in a second horizontal layer (the lower layer as shown in Figure 3) of the valve block.

In addition, the main relief valve 1 and the second load check valve 122 are disposed along a direction perpendicular to the first and second horizontal layers, and are at least partially located in the first horizontal layer. Referring to Figures 1 and 3, the first working port 150, the second working port 160, the third working port 130 and the fourth working port 140 are arranged at the top of the valve block in a vertical orientation perpendicular to the first and second horizontal layers. The tank port T is disposed in a side surface of the valve block in a horizontal orientation parallel to the first and second horizontal layers, and is located in the first horizontal layer. The pump port P is disposed in a side surface of the valve block in a horizontal orientation parallel to the first and second horizontal layers, and is located in the second horizontal layer.

Figures 5 and 6 show the first and second horizontal layers in a sectional view respectively. As shown in the Figures, a fluid passage 450 leads to the first working port 150, a fluid passage 460 leads to the second working port 160, a fluid passage 470 leads to the third working port 130, and a fluid passage 440 leads to the fourth working port 140. A fluid passage 490 is communicated with the hydraulic oil tank. A fluid passage 480 is used for receiving the second load check valve 122. A fluid passage 410 is used for receiving the main relief valve 1.

In the valve assembly according to the present utility mode, the respective valve elements are arranged in two horizontal layers, compared with the valve block (wherein the respective valve elements are disposed in at least three layers) in the prior art, such arrangement is advantageous in that the valve block structure is more compact, the integration among the valve elements is optimized, the features to be machined in the housing of the valve block are reduced, manufacturing cost of the valve block is significantly reduced, and occupying space of the valve block is decreased.

A hydraulic system incorporated with the valve assembly of the present utility model is particularly suitable for a loader. It is understood that the valve assembly can be used for other machines in appropriate circumstances.

The valve assembly of the present utility model is described by means of the specific embodiments. It is obvious for those skilled in the art that various changes and variants can be made to the valve assembly of the present utility model without departing from the spirit of the present utility model. The description and examples are only exemplary, and the true scope is defined by the annexed claims and their equivalent solutions.