Valve rod assembly, hydraulic control valve, hydraulic control system and operation equipment

Abstract

The utility model relates to the field of hydraulic control systems, and discloses a valve rod assembly, a hydraulic control valve, a hydraulic control system and operation equipment, and the valve rod assembly comprises a main valve core (21), a pressure compensation valve core (22) which can be installed in the main valve core in a sliding mode, and a reset spring (23) which elastically abuts against one end of the pressure compensation valve core. A first hydraulic control cavity (25) and a second hydraulic control cavity (26) are formed in the two ends of the pressure compensation valve element, and a valve element oil inlet (P21) and a valve element oil outlet (A21) which are communicated with the first hydraulic control cavity respectively are formed in the main valve element. The second hydraulic control cavity is used for being communicated with the discharge end of the valve element oil outlet, so that the pressure compensation valve element can slide in the inner cavity of the main valve element according to the change of the pressure difference between the front pressure and the rear pressure of the valve element oil outlet, and the opening degree of the valve element oil inlet communicated with the first hydraulic control cavity is adjusted. By means of the valve rod assembly, a pressure compensation valve can be integrated in a flow control valve, so that the size of a hydraulic control module is effectively reduced, and the system integration degree is improved.

Description

Technical Field

[0001] This utility model relates to a hydraulic control system, specifically to a valve stem assembly. Based on this, the utility model also relates to a hydraulic control valve including the valve stem assembly and a hydraulic control system including the hydraulic control valve. Furthermore, the utility model also relates to an operating device including the aforementioned hydraulic control system. Background Art

[0002] In various types of operating equipment (such as construction machinery and agricultural machinery) with multiple hydraulic actuators, such as concrete pump trucks, boom extension and retraction, lifting and lowering, and other movements are typically driven and controlled by a hydraulic control system. For example, in concrete pump trucks, the boom hydraulic control system typically utilizes a proportional multi-way valve mounted on the underbody to control the flow of hydraulic oil to each boom cylinder, providing hydraulic driving force and controlling boom movement speed. Furthermore, to prevent instability under high-inertia negative loads, a balancing valve can be installed in the hydraulic control circuit near the boom cylinder to control the boom lowering speed.

[0003] Chinese invention patent application CN105402180A provides a boom hydraulic control system for a concrete pump truck. The boom valve employed in this system is a proportional multi-way valve mounted on the undercarriage. This valve utilizes a single spool structure to control each boom cylinder. A pre-mounted pressure compensation valve limits the pressure differential across the oil inlet throttle to maintain a stable oil flow. Because the proportional multi-way valve is mounted on the undercarriage, the connecting pipes to the boom cylinders are long. This hydraulic control system suffers from problems such as delayed boom cylinder response and high pressure loss. Furthermore, when operating under high-inertia negative loads, this hydraulic control system is prone to mechanism stall, potentially leading to safety accidents. Even though a balancing valve positioned near the boom cylinders can provide back pressure and control the return oil flow within a certain range, there is still a risk of uncontrolled boom descent if the load pressure exceeds the balancing valve threshold.

[0004] To address the issues of delayed boom cylinder response and significant pressure loss in the boom hydraulic control system of concrete pump trucks caused by the use of proportional multi-way valves, existing technologies have proposed distributed boom valve structures to eliminate the adverse effects of long connecting pipelines between the control and execution ends, shortening system response time and reducing system energy consumption. Chinese invention patent application CN114909346A provides a distributed structure for an independent control valve group at the load port of the concrete pump truck boom. This involves installing a pair of rodless chamber control valve groups and a pair of rod chamber control valve groups near the hydraulic cylinders between each boom section. Each valve group includes two cartridge-type proportional flow valves for controlling the inlet and return oil flow rates. Simultaneously, pressure compensators are installed upstream of the inlet proportional flow valves to improve the linearity of the inlet flow control. However, under high inertia load conditions, the boom hydraulic control system using the aforementioned independent control valve groups needs to control the opening of the return oil flow control valve to ensure a smooth load descent, resulting in high control difficulty and complex algorithms.

[0005] In addition, in traditional technology, the pressure compensation valve and the corresponding flow control valve are set independently of each other, resulting in a larger hydraulic control module and the need for connections and pressure feedback oil circuits to be provided by pipelines or oil channels in the valve body, resulting in a low degree of integration. Utility Model Content

[0006] The purpose of this invention is to overcome the problem in the prior art where the pressure compensation valve and the corresponding flow control valve are set up independently, resulting in a large hydraulic control module with low integration. This invention provides a valve stem assembly and a hydraulic control valve having the valve stem assembly. The valve stem assembly integrates the valve core of the pressure compensation valve into the flow control valve, which can effectively reduce the size of the hydraulic control module and improve the system integration.

[0007] To achieve the above objectives, this utility model provides a valve stem assembly, including a hollow main valve core, a pressure compensation valve core slidably installed in the inner cavity of the main valve core, and a return spring elastically abutting one end of the pressure compensation valve core. The pressure compensation valve core has a first hydraulic control cavity and a second hydraulic control cavity at both ends. The portion of the main valve core corresponding to the first hydraulic control cavity has a valve core inlet and a valve core outlet, allowing hydraulic oil entering the first hydraulic control cavity through the valve core inlet to be discharged through the valve core outlet. The second hydraulic control cavity is connected to the discharge end of the valve core outlet, so that the pressure compensation valve core can adapt to the pressure difference change before and after the hydraulic oil flows through the valve core outlet, slide in the inner cavity of the main valve core, and adjust the opening degree of the valve core inlet connected to the first hydraulic control cavity.

[0008] Preferably, one end of the main valve core is connected to a screw plug to define the second hydraulic control chamber between the screw plug and the pressure compensation valve core, and the return spring is arranged in the second hydraulic control chamber and abuts against the screw plug and the pressure compensation valve core at both ends.

[0009] Preferably, a first hydraulic control chamber communicating oil port is formed on a portion of the pressure compensating valve core corresponding to the first hydraulic control chamber, and the first hydraulic control chamber is connected to the valve core oil inlet and the valve core oil outlet respectively through the first hydraulic control chamber communicating oil port.

[0010] Preferably, the first hydraulic control chamber connecting oil port includes an oil inlet connecting oil port and an oil outlet connecting oil port distributed along the sliding direction of the pressure compensating valve core, wherein, when the pressure compensating valve core slides to different positions in the inner cavity of the main valve core, the flow cross-section between the valve core oil inlet and the oil inlet connecting oil port continuously changes between fully open and fully closed, and the flow cross-section between the valve core oil outlet and the oil outlet connecting oil port always remains constant.

[0011] Preferably, a pressure feedback connecting oil port is formed on the portion of the main valve core corresponding to the second hydraulic control chamber, and a second hydraulic control chamber connecting oil port is formed on the portion of the pressure compensation valve core corresponding to the second hydraulic control chamber. The second hydraulic control chamber is connected to the discharge end of the valve core oil outlet through the second hydraulic control chamber connecting oil port and the pressure feedback connecting oil port in sequence.

[0012] The second aspect of the present invention provides a hydraulic control valve, comprising a main valve body and the above-mentioned valve stem assembly, wherein the main valve body has a valve body oil inlet and a valve body oil outlet, and the valve stem assembly can be slidably installed in the main valve body so as to be controllable so that the valve body oil inlet and the valve core oil inlet, and the valve body oil outlet and the valve core oil outlet are connected to or cut off from each other.

[0013] A third aspect of the present invention provides a hydraulic control system including the hydraulic control valve.

[0014] Preferably, the hydraulic control system includes a variable displacement pump, a plurality of hydraulic actuators, and a plurality of hydraulic control valves respectively connected to the hydraulic actuators.

[0015] A fourth aspect of the present invention provides an operating device comprising the above-mentioned hydraulic control system.

[0016] Preferably, the operating equipment is a concrete pump truck, and the plurality of hydraulic control valves are respectively connected to boom cylinders of the concrete pump truck.

[0017] Through the above technical solution, the valve stem assembly of the utility model can have hydraulic oil pressure before and after the hydraulic oil flows through the valve core oil outlet by connecting the first hydraulic control chamber and the second hydraulic control chamber at both ends of the pressure compensation valve core to the inlet end and the discharge end of the valve core oil outlet respectively. Then, based on the hydraulic pressure of the first hydraulic control chamber and the second hydraulic control chamber and the spring force, the pressure compensation valve core slides within the main valve core and changes the opening of the valve core oil inlet to the first hydraulic control chamber, thereby achieving pressure compensation. Among them, the pressure compensation valve core is embedded in the main valve core of the flow valve, thereby integrating the pressure compensation valve into the flow control valve without the need to set up a separate pressure compensation valve or pressure compensation valve core, thereby effectively reducing the volume of the hydraulic control module and improving the system integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of a hydraulic control system according to a preferred embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of a hydraulic control valve according to a preferred embodiment of the present invention;

[0020] Figure 3 It is a partial cross-sectional view of a hydraulic control valve according to a preferred embodiment of the present utility model;

[0021] Figure 4 yes Figure 3 Cross-sectional view of the valve stem assembly of the hydraulic control valve.

[0022] Description of Reference Numerals

[0023] 1-Main valve body; 2-Valve stem assembly; 21-Main valve core; 22-Pressure compensation valve core; 23-Return spring; 24-Plug; 25-First hydraulic control chamber; 26-Second hydraulic control chamber

[0024] P1 - valve body oil inlet; A1 - valve body oil outlet; P21 - valve core oil inlet; A21 - valve core oil outlet; F21 - pressure feedback connecting port; P22 - first hydraulic control chamber connecting port; P221 - oil inlet connecting port; P222 - oil outlet connecting port; F22 - second hydraulic control chamber connecting port;

[0025] 100 - Hydraulic control valve group; 111 - First oil inlet pressure compensation valve; 112 - First oil return pressure compensation valve; 113 - Second oil inlet pressure compensation valve; 114 - Second oil return pressure compensation valve; 121 - First oil inlet flow control valve; 122 - First oil return flow control valve; 123 - Second oil inlet flow control valve; 124 - Second oil return flow control valve; 13 - Electric proportional pressure reducing valve; 141 - First overflow oil supply valve; 142 - Second overflow oil supply valve; 15 - Fixed value pressure reducing valve;

[0026] 200-hydraulic actuator; 300-load;

[0027] P- oil inlet; T- oil return port; A- first working oil port; B- second working oil port; Y- pilot oil return port;

[0028] L P -Main oil inlet line; L T - Main oil return line; L A -First working oil circuit; L B -Second working oil circuit. DETAILED DESCRIPTION

[0029] The following is a detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0030] In order to facilitate a clear understanding of the technical solution, working principle and advantages of the present invention, the following will mainly use the pump truck boom valve and the pump truck boom hydraulic control system as examples to illustrate the valve stem assembly, hydraulic control valve and hydraulic control system of the present invention. However, it can be understood that the valve stem assembly, hydraulic control valve and hydraulic control system can also be applied to other application scenarios that require pressure compensation or may perform motion control under positive or negative load conditions, such as various types of operating equipment with hydraulic control systems such as construction machinery, agricultural machinery, and operating robots.

[0031] Reference Figure 1 As shown, one aspect of the present invention provides a hydraulic control system, which includes a main oil inlet circuit L P , Main oil return line L T , respectively connected to the first working oil passages L of the different working chambers of the hydraulic actuator 200 A and the second working oil passage L B And can be controlled so that the main oil inlet oil path L P And the main oil return line L T Selectively connected to the first working oil passage L A Or the second working oil circuit L B The hydraulic control valve group 100. Among them, the main oil inlet oil circuit L P A hydraulic pump may be provided on the main oil return line L to pressurize the hydraulic oil in the hydraulic oil tank and pump it to the hydraulic actuator 200. TIt can be connected to the hydraulic oil tank to collect the hydraulic oil discharged by the hydraulic actuator 200 and the like. Here, the hydraulic actuator 200 is shown as an oil cylinder, which can be connected to a load 300 such as a pump truck boom, so that it can be driven by the pump truck boom cylinder to realize the arm extension and arm retraction movements. The hydraulic control valve group 100 can be controlled so that the oil inlet and return oil circuits in the hydraulic control system form different on-off states to change the telescopic movement direction of the boom cylinder. In the preferred embodiment shown in the figure, the first working oil circuit L A Connected to the rodless chamber of the hydraulic actuator 200 (i.e., the boom cylinder), the second working oil circuit L B Connected to the rod chamber of the boom cylinder, thus, when the hydraulic control valve group 100 is controlled to make the main oil inlet oil path L P Connect to the first working oil circuit L A , Main oil return line L T Connected to the second working oil passage L B When the main oil inlet line L P The pumped hydraulic oil will cause the piston rod of the boom cylinder to extend; when the hydraulic control valve group 100 is controlled to make the main oil inlet line L P Connect to the second working oil circuit L B , Main oil return line L T Connected to the first working oil passage L A At that time, the main oil inlet line L P The pumped hydraulic oil will cause the piston rod of the boom cylinder to retract. It is understandable that the hydraulic actuator 200 can also be a hydraulic motor or a double-rod piston rod cylinder, etc., and is not limited to the single-rod piston cylinder shown in the figure.

[0032] In order to facilitate driving the load 300 in different movement directions and different load conditions of the hydraulic actuator 200 so that the load 300 can move smoothly, the hydraulic control valve group 100 also includes a pressure compensation valve for reducing flow fluctuations in the inlet and return oil flow paths, so as to reduce or avoid the impact of load changes on the inlet oil flow supplied to the hydraulic actuator 200 and the return oil flow returned from the hydraulic actuator 200 to the hydraulic oil tank. Specifically, the hydraulic control valve group 100 includes a first inlet oil pressure compensation valve 111, a first return oil pressure compensation valve 112, a second inlet oil pressure compensation valve 113 and a second return oil pressure compensation valve 114, wherein the first inlet oil pressure compensation valve 111 is arranged on the main inlet oil path L P and the first working oil circuit L A The oil passage between the first working oil passage L A When oil is fed into the hydraulic actuator 200, the valve opening is adjusted by receiving pressure feedback to maintain the oil flow rate; the first return oil pressure compensation valve 112 is set in the first working oil circuit L A And the main oil return line L TThe oil circuit portion between the hydraulic actuator 200 and the first working oil circuit L A When returning oil, the valve opening is adjusted by receiving pressure feedback to maintain the return oil flow rate; the second oil inlet pressure compensation valve 113 is set in the main oil inlet oil circuit L P and the second working oil passage L B The oil passage between the two parts can be B When oil is fed into the hydraulic actuator 200, the valve opening is adjusted by receiving pressure feedback to maintain the oil flow rate; the second return oil pressure compensation valve 114 is set in the second working oil circuit L B And the main oil return line L T The oil circuit portion between the hydraulic actuator 200 and the second working oil circuit L B When returning oil, the valve opening is adjusted by receiving pressure feedback to maintain the return oil flow.

[0033] Therefore, the hydraulic control system can compensate for the pressure of the inlet and return oil in different working chambers of the hydraulic actuator 200 under different load conditions. This allows the movement speed of the hydraulic actuator under positive load conditions to be mainly determined by the inlet oil flow rate under pressure compensation by the first inlet oil pressure compensation valve 111 or the second inlet oil pressure compensation valve 113, while the movement speed under negative load conditions is mainly determined by the return oil flow rate under pressure compensation by the first return oil pressure compensation valve 112 or the second return oil pressure compensation valve 114. This achieves adaptive control for positive and negative loads. In particular, it can ensure smooth operation under large inertia negative load conditions without the need for complex control algorithms, effectively reducing the control difficulty.

[0034] For example, under positive load conditions, when the piston rod of the hydraulic actuator 200 extends, the main oil inlet circuit L P Connected to the first working oil passage L A Main return oil circuit L T Connect to the second working oil circuit L B First working oil circuit L A The driving force generated is greater than or equal to the load force, and the boom cylinder overcomes the load force and moves. P Flowing to the first working oil circuit L ADuring this process, the first inlet pressure compensation valve 111 receives pressure feedback from the valve (e.g., the illustrated first inlet flow control valve 121) used to control the on / off state of the hydraulic control valve assembly 100. It then adjusts the valve opening accordingly to maintain a substantially constant pressure differential across the valve as the load changes. The hydraulic oil flow rate (i.e., the inlet flow rate) passing through it is determined solely by the valve opening. During this process, the control pressure differential of the second return pressure compensation valve 114 is less than the set pressure differential (the feedback pressure is lower), and its valve opening is fully open, effectively reducing pressure loss.

[0035] Under negative load conditions, when the piston rod of the hydraulic actuator 200 extends, the second working oil circuit L... B The generated resistance is less than or equal to the load force, and the load 300 drives the boom cylinder to move. At this time, the hydraulic oil discharged from the boom cylinder is transported through the second working oil circuit L. B Flows to the main oil return line L T During the process, the second return oil pressure compensation valve 114 can receive pressure feedback before and after the valve (such as the second return oil flow control valve 124 shown in the figure) in the aforementioned hydraulic control valve group 100 for controlling the on-off state, and adjust the valve opening accordingly to keep the pressure difference before and after the valve basically constant when the load changes, and the hydraulic oil flow (i.e., return oil flow) passing through it is only determined by the opening of the valve itself.

[0036] Therefore, the hydraulic control system of the present invention can perform pressure compensation for the inlet and return oil of different working chambers of the hydraulic actuator under different load conditions, and can automatically adapt to positive and negative load conditions, with small pressure loss and good load impact resistance. It can ensure smooth operation under large inertia negative load conditions without the need for complex control algorithms.

[0037] Reference Figures 2 to 4As shown, the hydraulic control valve assembly 100 has an oil inlet port P, an oil return port T, and a first working oil port A and a second working oil port B, respectively, for connecting to different working chambers of the hydraulic actuator 200. To facilitate smooth operation of the load 300 under different motion directions and load conditions of the hydraulic actuator 200, the hydraulic control valve assembly 100 of the present invention includes a pressure compensation valve for reducing flow fluctuations in the inlet and return oil flow paths. This reduces or eliminates the impact of load changes on the oil flow supplied to the hydraulic actuator 200 and the return oil flow from the hydraulic actuator 200 to the hydraulic oil tank. Specifically, the hydraulic control valve group 100 includes a first oil inlet pressure compensation valve 111, a first oil return pressure compensation valve 112, a second oil inlet pressure compensation valve 113 and a second oil return pressure compensation valve 114, wherein the first oil inlet pressure compensation valve 111 is arranged in the oil circuit portion between the oil inlet port P and the first working oil port A, and is capable of adjusting the valve port opening by receiving pressure feedback when supplying oil to the hydraulic actuator 200 through the first working oil port A to maintain the oil inlet flow rate; the first return oil pressure compensation valve 112 is arranged in the oil circuit portion between the first working oil port A and the oil return port T, and is capable of adjusting the valve port opening by receiving pressure feedback when supplying oil to the hydraulic actuator 200 through the first working oil port A to maintain the oil inlet flow rate; 0 When oil is returned through the first working oil port A, the valve port opening is adjusted by receiving pressure feedback to maintain the return oil flow rate; the second oil inlet pressure compensation valve 113 is arranged in the oil circuit portion between the oil inlet port P and the second working oil port B, and is capable of adjusting the valve port opening by receiving pressure feedback when oil is supplied to the hydraulic actuator 200 through the second working oil port B to maintain the oil inlet flow rate; the second oil return pressure compensation valve 114 is arranged in the oil circuit portion between the second working oil port B and the oil return port T, and is capable of adjusting the valve port opening by receiving pressure feedback when the hydraulic actuator 200 returns oil through the second working oil port B to maintain the return oil flow rate.

[0038] Therefore, similar to the above-mentioned hydraulic control system, the hydraulic control valve group 100 can perform pressure compensation on the inlet and return oil of different working chambers of the hydraulic actuator 200 under different load conditions, so that the movement speed of the hydraulic actuator under positive load conditions is mainly determined by the inlet oil flow under pressure compensation by the first inlet oil pressure compensation valve 111 or the second inlet oil pressure compensation valve 113, while the movement speed under negative load conditions is mainly determined by the return oil flow under pressure compensation by the first return oil pressure compensation valve 112 or the second return oil pressure compensation valve 114, thereby realizing adaptive control of positive and negative loads, especially ensuring smooth movement under large inertia negative load conditions without the need for complex control algorithms, effectively reducing the control difficulty.

[0039] Because they share the same principle, the hydraulic control valve assembly 100 of the various embodiments described above and below is applicable to the hydraulic control system provided by this utility model. Therefore, the various preferred and alternative embodiments of the hydraulic control valve assembly 100 described below can be considered as descriptions of corresponding embodiments of the hydraulic control system.

[0040] exist Figure 1 and Figure 2 In the preferred embodiment shown, the hydraulic control valve group 100 includes a first oil inlet flow control valve 121, a first oil return flow control valve 122, a second oil inlet flow control valve 123 and a second oil return flow control valve 124, wherein the first oil inlet flow control valve 121 is arranged in series with the first oil inlet pressure compensation valve 111 in the oil circuit portion between the oil inlet port P and the first working oil port A. When oil is supplied to the hydraulic actuator 200 through the first working oil port A, the first oil inlet pressure compensation valve 111 adjusts the valve port opening according to the pressure difference before and after the hydraulic oil flows through the first oil inlet flow control valve 121 to keep the pressure difference before and after the first oil inlet flow control valve 121 constant; the first oil return flow control valve 122 is arranged in series with the first oil return pressure compensation valve 112 in the oil circuit portion between the first working oil port A and the oil return port T. When the hydraulic actuator 200 returns oil through the first working oil port A, the first oil return pressure compensation valve 112 adjusts the valve port opening according to the pressure difference before and after the hydraulic oil flows through the first oil return flow control valve 12 2 before and after the pressure difference changes and adjusts the valve port opening to keep the pressure difference before and after the first return oil pressure compensation valve 112 constant; the second oil inlet flow control valve 123 is arranged in series with the second oil inlet pressure compensation valve 113 in the oil circuit between the oil inlet port P and the second working oil port B. When oil is supplied to the hydraulic actuator 200 through the second working oil port B, the second oil inlet pressure compensation valve 113 adjusts the valve port opening according to the pressure difference before and after the hydraulic oil flows through the second oil inlet flow control valve 123 to keep the pressure difference constant. The pressure difference before and after the second oil inlet pressure compensation valve 113 is constant; the second return oil flow control valve 124 is arranged in series with the second return oil pressure compensation valve 114 in the oil circuit part between the second working oil port B and the return oil port T. When the hydraulic actuator 200 returns oil through the second working oil port B, the second return oil pressure compensation valve 114 adjusts the valve port opening according to the change in the pressure difference before and after the hydraulic oil flows through the second return oil flow control valve 124 to keep the pressure difference before and after the second return oil pressure compensation valve 114 constant.

[0041] Furthermore, the first inlet flow control valve 121, the first return flow control valve 122, the second inlet flow control valve 123, and the second return flow control valve 124 can be solenoid valves or hydraulically controlled valves, so as to control their respective valve cores by electromagnetic force or hydraulic pressure. In the preferred embodiment shown in the figure, each of the above-mentioned flow control valves is respectively set as a hydraulically controlled flow valve. This is to facilitate the flow from the main inlet oil circuit L... PAlternatively, if a suitable hydraulic control pressure is obtained at the oil inlet P, the hydraulic control valve assembly 100 of this invention may also include a connection to the main oil inlet circuit L. P Alternatively, a pilot control oil circuit equipped with a pressure-reducing valve may be established between the oil inlet P and the hydraulic control chamber of each of the aforementioned flow control valves. Specifically, such as... Figure 1 and Figure 2 As shown, the pilot control oil circuit may be equipped with a fixed-value pressure reducing valve 15 and electro-proportional pressure reducing valves 13 corresponding to each flow control valve. The fixed-value pressure reducing valve 15 can convert the high-pressure oil at the inlet P into low-pressure oil with constant pressure, and then apply pressure to the hydraulic control chamber of the flow control valve through the electro-proportional pressure reducing valve 13. Excess oil can be discharged through the pilot return port Y. The electro-proportional pressure reducing valve 13 includes a first electro-proportional pressure reducing valve 131 located in the oil circuit between the inlet P and the hydraulic control chamber of the first inlet flow control valve 121, a second electro-proportional pressure reducing valve 132 located in the oil circuit between the inlet P and the hydraulic control chamber of the first return flow control valve 122, a third electro-proportional pressure reducing valve 133 located in the oil circuit between the inlet P and the hydraulic control chamber of the second inlet flow control valve 123, and a fourth electro-proportional pressure reducing valve 134 located in the oil circuit between the inlet P and the hydraulic control chamber of the second return flow control valve 124. These electric proportional pressure reducing valves 13 convert the pressure output by the fixed value pressure reducing valve 15 (if any) into different levels of pressure based on the current control signal, and then act on the first oil inlet flow control valve 121, the first oil return flow control valve 122, the second oil inlet flow control valve 123 and the second oil return flow control valve 124 respectively, so as to realize the control of the main oil inlet oil circuit L. P And the main oil return line L T (Oil inlet P and oil return port T) and the first working oil circuit L A and the second working oil passage L B The on / off state and inlet / outlet flow rates between the first working port A and the second working port B are controlled. Therefore, based on the hydraulic pressure output by each electro-proportional pressure reducing valve 13, the on / off state and opening degree of the first inlet flow control valve 121, the first return flow control valve 122, the second inlet flow control valve 123, and the second return flow control valve 124 can be adjusted. In conjunction with the corresponding first inlet pressure compensation valve 111, the first return pressure compensation valve 112, the second inlet pressure compensation valve 113, and the second return pressure compensation valve 114, the inlet and return flow rates of the first working port A and the second working port B can be controlled, enabling the hydraulic actuator 200 and the load 300 to move smoothly under different operating conditions.

[0042] It can be understood that when the system working pressure is relatively low, the first oil inlet flow control valve 121, the first oil return flow control valve 122, the second oil inlet flow control valve 123 and the second oil return flow control valve 124 can be set as solenoid valves, thereby omitting the above-mentioned electric proportional pressure reducing valves 13.

[0043] Furthermore, the hydraulic control valve assembly 100 may also include a first relief replenishing valve 141 and a second relief replenishing valve 142. The first relief replenishing valve 141 is connected in parallel with the first return pressure compensation valve 112 in the oil passage between the first working port A and the return port T, allowing return oil from the first working port A to overflow through the return port T or replenishing oil to the first working port A. The second relief replenishing valve 142 is connected in parallel with the second return pressure compensation valve 114 in the oil passage between the second working port B and the return port T, allowing return oil from the second working port B to overflow through the return port T or replenishing oil to the second working port B. Thus, the first relief replenishing valve 141 and the second relief replenishing valve 142 can respectively limit the maximum working pressure of the first working port A and the second working port B, and replenish hydraulic oil when their working pressure is too low, providing a safety protection function. For example, when the boom cylinder, serving as the hydraulic actuator 200, is extended and under negative load, the first overflow valve 141 can be opened to replenish hydraulic oil to the rodless chamber. It should be understood that although generally referred to as a "overflow valve," it can be two relatively independent valves (a check valve and a relief valve).

[0044] exist Figures 1 to 4 In the preferred embodiment shown, the first oil inlet flow control valve 121, the first oil return flow control valve 122, the second oil inlet flow control valve 123 and the second oil return flow control valve 124 are respectively shown as two parts located before and after the corresponding pressure compensation valve in the hydraulic principle diagram. This is because it adopts Figure 3 and Figure 4The embedded structure of the combined valve core (i.e., valve stem assembly 2) shown, its corresponding relationship and specific operating principle will be described in detail later. In this preferred embodiment, each of the flow control valves described above, corresponding to the same hydraulic actuator 200, has an independent valve stem assembly 2 and an integrated pressure compensation valve. Thus, the hydraulic control valve assembly 100 can include a main valve body 1, on which the oil inlet P, oil return port T, and first and second working oil ports A and B can be located. The first inlet pressure compensating valve 111 and the first inlet flow control valve 121, the first return pressure compensating valve 112 and the first return flow control valve 122, the second inlet pressure compensating valve 113 and the second inlet flow control valve 123, and the second return pressure compensating valve 114 and the second return flow control valve 124 can each have an integrated valve stem assembly 2. The valve stem assembly 2 is slidably mounted within the main valve body 1 and can be controlled to adjust the flow rate of the valve core assembly 2, that is, to achieve different inlet and return flow rates between the oil inlet port P and / or the return port T and the first working oil port A and / or the second working oil port B. Thus, by integrating the valve core of the pressure compensating valve into the flow control valve through the integrated design of the valve stem assembly 2, the volume of the hydraulic control module can be effectively reduced, thereby improving the system integration level.

[0045] The following combination Figures 2 to 4 The embedded valve stem assembly 2 of the preferred embodiment of this utility model will be described below:

[0046] The valve stem assembly 2 includes a hollow main valve core 21, a pressure-compensating valve core 22 slidably mounted within the inner cavity of the main valve core 21, and a return spring 23 elastically abutting one end of the pressure-compensating valve core 22. The main valve core 21 is mounted to slide with the main valve body 1. A first hydraulic control chamber 25 and a second hydraulic control chamber 26 are defined at both ends of the pressure-compensating valve core 22. The return spring 23 and the oil pressure within the second hydraulic control chamber 26 exert forces on the pressure-compensating valve core 22 in the same direction.

[0047] like Figure 3 and Figure 4 As shown, the portion of the main valve core 21 corresponding to the first hydraulic control chamber 25 is formed with a valve core oil inlet P21 and a valve core oil outlet A21. These allow the hydraulic oil introduced into the first hydraulic control chamber 25 via the valve core oil inlet P21 to be discharged through the valve core oil outlet A21. The second hydraulic control chamber 26 is connected to the discharge end of the valve core oil outlet A21, allowing the pressure compensation valve core 22 to slide within the inner cavity of the main valve core 21 in response to the pressure differential before and after the hydraulic oil flows through the valve core oil outlet A21, thereby adjusting the opening of the valve core oil inlet P21 to the first hydraulic control chamber 25.

[0048] For ease of understanding, Figure 2The schematic diagram schematically illustrates the positions of the valve core oil inlet P21, valve core oil outlet A21, first hydraulic control chamber 25, and second hydraulic control chamber 26 in the oil path between the oil inlet P and the first working oil port A. Based on the above arrangement, the valve stem assembly 2 can be driven electrically or hydraulically to slide relative to the main valve body 1, enabling the valve body oil inlet P1 on the main valve body 1 to communicate with or be disconnected from the valve core oil inlet P21, or to have different flow cross-sectional areas. Simultaneously, the valve body oil outlet A1 on the main valve body 1 can be connected to or be disconnected from the valve core oil outlet A21, or to have different flow cross-sectional areas. When the valve stem assembly 2 is used in the oil path between the oil inlet P and the first working oil port A, the valve body oil inlet P1 serves as, or is connected to, the oil inlet P of the hydraulic control valve assembly 100, and the valve body oil outlet A1 serves as, or is connected to, the first working oil port A of the hydraulic control valve assembly 100. When the valve stem assembly 2 is used in the oil circuit portion between the first working oil port A and the return oil port T, the valve body oil inlet P1 is the first working oil port A of the hydraulic control valve group 100 or is connected to the first working oil port A, and the valve body oil outlet A1 is the return oil port T of the hydraulic control valve group 100 or is connected to the return oil port T.

[0049] Since the pressure compensation valve core 22 can slide in the inner cavity of the main valve core 21 according to the pressure difference before and after the hydraulic oil flows through the valve core oil outlet A21, and adjust the opening of the valve core oil inlet P21 to the first hydraulic control chamber 25, under different load conditions, the oil inlet circuit or oil return circuit provided with the valve stem assembly 2 can perform pressure compensation for the inlet and return oil of the hydraulic actuator, reducing or avoiding the influence of load changes on the inlet and return oil flow rates.

[0050] When the valve stem assembly 2 is not flowing with oil, that is, the corresponding oil inlet or return oil circuit is cut off, the valve core oil inlet port P21 is connected to the first hydraulic control chamber 25 under the action of the return spring 23. At the same time, the valve core oil outlet port A21 is connected to the first hydraulic control chamber 25, and the discharge end of the valve core oil outlet port A21 is connected to the second hydraulic control chamber 26. At this time, the hydraulic forces acting on the first hydraulic control chamber 25 and the second hydraulic control chamber 26 of the pressure compensation valve core 22 are P and P, respectively. p A and P a A, and has the following relationship:

[0051] (P p -P a )A≤kx0

[0052] Among them, P p and P a are the oil pressures in the first hydraulic control chamber 25 and the second hydraulic control chamber 26 respectively, A is the effective area at both ends of the pressure compensation valve core 22, k is the stiffness of the return spring, and x0 is the pre-compression amount of the return spring.

[0053] When oil is flowing through the valve stem assembly 2 (i.e., the corresponding oil inlet or return lines are connected), hydraulic oil enters the first hydraulic control chamber 25 through the valve core oil inlet port P21. Under the action of the oil pressure, the pressure-compensating valve core 22 overcomes the action of the return spring 23 and moves toward the second hydraulic control chamber 26. The hydraulic oil is then discharged through the valve core oil outlet port A21. Since the discharge end of the valve core oil outlet port A21 is connected to the second hydraulic control chamber 26, the oil pressure at this discharge end acts on the second hydraulic control chamber 26. At this point, the hydraulic forces acting on the first and second hydraulic control chambers 25, 26 of the pressure-compensating valve core 22 have the following relationship:

[0054] (P p -P a )A=k(x0+x)

[0055] Where x is the displacement of the pressure compensation valve core.

[0056] Therefore, to ensure good pressure compensation, the displacement of the pressure compensation valve core 22 within the inner cavity of the main valve core 21 can be set to be much smaller than the pre-compression of the return spring 23 in its initial installation state, i.e., x << x0. Thus, according to the above formula, during the oil inlet and outlet processes, P... p -P a The pressure difference between the inlet and outlet of the valve core outlet A21 is approximately constant, so that the flow rate through the valve core outlet A21 is only related to the sliding position of the valve stem assembly 2 in the main valve body 1, and is not affected by load changes.

[0057] Continue to refer to Figures 2 to 4 As shown, a screw plug 24 can be connected to one end of the main valve core 21 to define a second hydraulic control chamber 26 between the screw plug 24 and the pressure compensation valve core 22. A return spring 23 can be installed in the second hydraulic control chamber 26 and abuts against the screw plug 24 and the pressure compensation valve core 22 at both ends, respectively.

[0058] Furthermore, to facilitate adjusting the opening of the valve inlet P21 connecting to the first hydraulic control chamber 25 as the pressure-compensating valve spool 22 slides within the inner cavity of the main valve spool 21, a concave structure can be formed on the end of the pressure-compensating valve spool 22 facing the first hydraulic control chamber 25. Accordingly, a first hydraulic control chamber communication port P22 can be formed in the portion of the pressure-compensating valve spool 22 corresponding to the first hydraulic control chamber 25. Through this first hydraulic control chamber communication port P22, the first hydraulic control chamber 25 is connected to the valve inlet P21 and the valve outlet A21, respectively. As the pressure-compensating valve spool 22 slides to different positions within the inner cavity of the main valve spool 21, the flow cross-sectional area between the valve inlet P21 and the first hydraulic control chamber communication port P22 changes, thereby adjusting the opening of the valve inlet P21 connecting to the first hydraulic control chamber 25. This allows pressure compensation based on the pressure differential between the hydraulic oil flowing through the valve outlet A21 and before and after the hydraulic oil passes through it.

[0059] The first hydraulic control chamber connecting port P22 may include an inlet connecting port P221 and an outlet connecting port P222 distributed along the sliding direction of the pressure compensation valve core 22. When the pressure compensation valve core 22 slides to different positions within the inner cavity of the main valve core 21, the flow cross-section between the valve core inlet port P21 and the inlet connecting port P221 continuously changes between fully open and fully closed, while the flow cross-section between the valve core outlet port A21 and the outlet connecting port P222 remains constant. Therefore, as illustrated, the outlet connecting port P222 can be configured such that its length in the sliding direction of the pressure compensation valve core 22 is greater than the length of the inlet connecting port P221. This facilitates changing the flow cross-sectional area between the valve core inlet port P21 and the inlet connecting port P221 during the sliding process of the pressure compensation valve core 22, and ensures that the valve core outlet port A21 and the outlet connecting port P222 remain fully connected.

[0060] To facilitate the return spring 23 applying a stable force to the pressure compensation valve core 22, the end of the pressure compensation valve core 22 facing the second hydraulic control cavity 26 can also have a concave structure. Correspondingly, the portion of the main valve core 21 corresponding to the second hydraulic control cavity 26 can have a pressure feedback connection port F21, and the portion of the pressure compensation valve core 22 corresponding to the second hydraulic control cavity 26 has a second hydraulic control cavity connection port F22. The second hydraulic control cavity 26 is connected to the discharge end of the valve core outlet A21 via the second hydraulic control cavity connection port F22 and the pressure feedback connection port F21. Thus, the oil pressure at the discharge end of the valve core outlet A21 can act on the pressure compensation valve core 22 within the second hydraulic control cavity 26. This configuration also fully utilizes the length space of the valve stem assembly 2, further improving compactness and facilitating a reduction in the size of the hydraulic control module.

[0061] Based on this, the present invention provides a hydraulic control valve, which includes a main valve body 1 and the aforementioned valve stem assembly 2. The main valve body 1 has a valve body inlet P1 and a valve body outlet A1. The valve stem assembly 2 is slidably installed within the main valve body 1 so as to be controllable to allow the valve body inlet P1 to communicate with or be closed to its valve core inlet P21, and the valve body outlet A1 to communicate with or be closed to its valve core outlet A21. For example, this hydraulic control valve can be configured as the aforementioned hydraulic control valve assembly 100.

[0062] In order to clearly illustrate the technical solution and working principle of the present invention, the above description only relates to the hydraulic control system and the hydraulic control valve corresponding to the same hydraulic actuator in conjunction with the accompanying drawings. In a preferred embodiment of the hydraulic control system of the present invention, it may include a main oil inlet circuit L PThe system includes a variable displacement pump and multiple hydraulic control valves connected to the hydraulic actuator 200. Each hydraulic control valve can be configured in a working order and mounted on the hydraulic actuator 200, such as a boom cylinder, forming a hydraulic supply system similar to a bus-powered system. Thus, the hydraulic control valves are connected in parallel, and their inlet ports P can be connected to the main inlet oil circuit L as needed. P The required hydraulic oil is obtained through the main return oil circuit L, via the return port T and the pilot return port Y. T The return oil design can greatly reduce the number of pipelines in the hydraulic control system, reduce system leakage points and lower piping costs, and effectively improve the response time of the actuator.

[0063] The aforementioned hydraulic control system and hydraulic control valves are suitable for applications requiring smooth control of hydraulic actuators under different load conditions, such as boom extension and retraction control of concrete pump trucks and lifting control of hoisting platforms. Based on the above, this utility model also provides an operating device including the aforementioned hydraulic control valves or hydraulic control system. This operating device can be used in various types of operating equipment with hydraulic actuators, such as construction machinery, agricultural machinery, and work robots. Typically, this operating device can be a concrete pump truck, which includes multiple aforementioned hydraulic control valves respectively connected (e.g., via plate connections) to the boom cylinders.

[0064] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A valve stem assembly, characterized in that: The invention comprises a hollow main valve core (21), a pressure compensation valve core (22) slidably mounted in an inner cavity of the main valve core (21), and a return spring (23) elastically abutting against one end of the pressure compensation valve core (22), wherein the two ends of the pressure compensation valve core (22) are provided with a first hydraulic control cavity (25) and a second hydraulic control cavity (26), and a portion of the main valve core (21) corresponding to the first hydraulic control cavity (25) is formed with a valve core oil inlet (P21) and a valve core oil outlet (A21) to allow the valve core to control the oil pressure of the main valve core. The hydraulic oil introduced into the first hydraulic control chamber (25) through the oil inlet (P21) is discharged through the valve core oil outlet (A21); the second hydraulic control chamber (26) is used to be connected to the discharge end of the valve core oil outlet (A21), so that the pressure compensation valve core (22) can adapt to the pressure difference change before and after the hydraulic oil flows through the valve core oil outlet (A21) and slide in the inner cavity of the main valve core (21) and adjust the opening of the valve core oil inlet (P21) connected to the first hydraulic control chamber (25).

2. The valve stem assembly according to claim 1, characterized in that: One end of the main valve core (21) is connected to a screw plug (24) to define the second hydraulic control chamber (26) between the screw plug (24) and the pressure compensation valve core (22); the return spring (23) is arranged in the second hydraulic control chamber (26) and abuts against the screw plug (24) and the pressure compensation valve core (22) at two ends thereof.

3. The valve stem assembly according to claim 1, characterized in that: A first hydraulic chamber connecting oil port (P22) is formed at a portion of the pressure compensating valve core (22) corresponding to the first hydraulic chamber (25); the first hydraulic chamber (25) is connected to the valve core oil inlet (P21) and the valve core oil outlet (A21) respectively through the first hydraulic chamber connecting oil port (P22).

4. The valve stem assembly according to claim 3, characterized in that: The first hydraulic control chamber connecting oil port (P22) includes an oil inlet connecting oil port (P221) and an oil outlet connecting oil port (P222) distributed along the sliding direction of the pressure compensation valve core (22), wherein when the pressure compensation valve core (22) slides to different positions in the inner cavity of the main valve core (21), the flow cross section between the valve core oil inlet port (P21) and the oil inlet connecting oil port (P221) continuously changes between fully open and fully closed, and the flow cross section between the valve core oil outlet port (A21) and the oil outlet connecting oil port (P222) always remains constant.

5. The valve stem assembly according to claim 1, characterized in that: The portion of the main valve core (21) corresponding to the second hydraulic control chamber (26) is formed with a pressure feedback connecting oil port (F21), and the portion of the pressure compensation valve core (22) corresponding to the second hydraulic control chamber (26) is formed with a second hydraulic control chamber connecting oil port (F22), and the second hydraulic control chamber (26) is connected to the discharge end of the valve core oil outlet (A21) through the second hydraulic control chamber connecting oil port (F22) and the pressure feedback connecting oil port (F21) in sequence.

6. A hydraulic control valve, characterized in that: It comprises a main valve body (1) and a valve stem assembly according to any one of claims 1 to 5, wherein the main valve body (1) has a valve body oil inlet (P1) and a valve body oil outlet (A1), and the valve stem assembly can be slidably installed in the main valve body (1) so as to be controllable so that the valve body oil inlet (P1) and the valve core oil inlet (P21), and the valve body oil outlet (A1) and the valve core oil outlet (A21) are connected to or blocked from each other.

7. A hydraulic control system, characterized in that: Comprising a hydraulic control valve according to claim 6.

8. The hydraulic control system according to claim 7, characterized in that: The hydraulic control system comprises a variable displacement pump, a plurality of hydraulic actuators (200), and a plurality of hydraulic control valves respectively connected to the hydraulic actuators (200).

9. An operating device, characterized in that: The working equipment comprises the hydraulic control system according to claim 7 or 8.

10. The working equipment according to claim 9, characterized in that: The operating equipment is a concrete pump truck, and the plurality of hydraulic control valves are respectively connected to boom cylinders of the concrete pump truck.

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