Hydraulic circuit system for construction machinery and pump device

Abstract

To provide a hydraulic circuit system and a pump device that use a tandem pump, in which two hydraulic pumps capable of independently controlling the flow rates of multiple discharge ports are disposed, and a plurality of switching valves, wherein operability is improved, and mounting characteristics are enhanced by miniaturizing the pump device and reducing the number of hydraulic hoses.SOLUTION: First and second hydraulic pumps 11, 12, which incorporate four pump elements capable of independently controlling the flow rates of pressurized oil discharged from discharge ports and are arranged in tandem along the axial direction of a shaft 14 so as to form a tandem pump 30, are such that the discharge ports are opened in a block surface of a port block 13, which is a shared component, and a manifold block 40, in which switching valves 41a-41d, 42a-42d are mounted and service ports 43, 44 are formed, is coupled to the block surface.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a hydraulic circuit system for a construction machine equipped with a pump device capable of independently controlling the flow rates of a plurality of discharge ports, and the pump device. [Background technology]

[0002] Patent Document 1 describes a pump device called a tandem pump, in which two pumps, a front pump and a rear pump, are arranged at an axial distance from each other (i.e., arranged in tandem), as a pump device used in the hydraulic circuit system of construction machinery, such as a hydraulic excavator. In this tandem pump, the front pump and the rear pump are each configured as a two-flow type piston pump that generates two discharge flow rates. In addition, by interposing a port block between the front pump and the rear pump and opening four discharge ports in pairs on different sides of the port block, four discharge flow rates can be extracted.

[0003] Patent Document 2 also describes a hydraulic circuit system equipped with a hydraulic pump that can independently control the flow rate of each of the four discharge ports. The four discharge ports are connected to four load port oil passages via 16 changeover valves, and by switching the changeover valves, the number of discharge ports according to the demands of the actuators can be connected to the load port oil passages, making it possible to supply the actuators with pressurized oil at a flow rate according to the demands. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5027878 [Patent Document 2] US 2019 / 0211849A1 Summary of the Invention [Problem to be solved by the invention]

[0005] The tandem pump described in Patent Document 1 has four discharge ports that are opened in pairs on different sides of the port block located between the front pump and the rear pump, allowing four discharge flow rates to be extracted, thereby making the port block smaller and miniaturizing the entire tandem pump. However, the front pump and the rear pump are called split flow pumps, each equipped with two discharge ports, and the two discharge flow rates cannot be controlled independently.

[0006] The hydraulic circuit system described in Patent Document 2 can extract four discharge flow rates from one pump and can control the four discharge flow rates independently. In addition, by switching the switching valve according to the requirements of the actuator and changing the number of discharge ports connected to the actuator, it is possible to supply the actuator with pressure oil at a flow rate according to the requirements.

[0007] However, in the hydraulic circuit system described in Patent Document 2, one pump has four discharge ports, and in order to extract four discharge flow rates from these four discharge ports, it is necessary to connect the four discharge ports to a switching valve block including 16 switching valves with four hydraulic hoses. This results in an increase in the size of the pump and a complex hose layout, which reduces the ease of installation on construction machinery.

[0008] This issue becomes particularly evident when increasing the number of pumps (discharge ports) to improve operability.

[0009] That is, in construction machinery that drives multiple actuators, such as hydraulic excavators, it is necessary to increase the number of pumps (discharge ports) connected to the actuators in order to improve operability when the actuators are driven, and in order to achieve this, it is preferable to use multiple hydraulic pumps that can independently control the flow rates of multiple discharge ports, as described in Patent Document 2. For example, when two hydraulic pumps are used as a tandem pump, the number of discharge ports that can independently control the flow rate increases to eight, so that the number of discharge ports required for the actuators can be changed in detail, and the speed fluctuation of the actuator accompanying switching also becomes smoother, leading to improved operability when the actuators are driven.

[0010] However, if, for example, two hydraulic pumps described in Patent Document 2 are used in a tandem arrangement, the number of discharge ports increases to eight and the number of hydraulic hoses connecting the eight discharge ports to the switching valve also increases to eight, resulting in a larger hydraulic source (pump device) and a more complex hose layout, significantly reducing the mountability of the pump device.

[0011] The object of the present invention is to provide a hydraulic circuit system and pump unit for construction machinery which improves operability when the actuator is driven and improves mountability on the construction machinery by making the pump unit smaller and reducing the hydraulic hoses when the pump unit of the hydraulic circuit system is constructed using a tandem pump in which two hydraulic pumps capable of independently controlling the flow rate of multiple discharge ports are arranged at an axial distance from each other and multiple switching valves. [Means for solving the problem]

[0012] In order to achieve the above object, the present invention provides a hydraulic circuit system for a construction machine comprising a prime mover, a pump device driven by the prime mover, a plurality of actuators driven by pressurized oil discharged from the pump device, and a plurality of directional control valves for controlling the flow of pressurized oil supplied from the pump device to the plurality of actuators, the pump device comprising a tandem pump having first and second hydraulic pumps arranged at intervals in the axial direction of a shaft driven and rotated by the prime mover, the system comprising a manifold block having a plurality of first switching valves and a plurality of second switching valves mounted thereon and forming a plurality of service ports, the first hydraulic pump containing two or more first pump elements capable of independently controlling the flow of pressurized oil discharged from two or more first discharge ports, the second hydraulic pump controlling the flow of pressurized oil discharged from two or more second discharge ports, a first hydraulic pump that includes two or more second pump elements capable of independently controlling the flow of the pressurized oil, the first and second hydraulic pumps being configured as shared parts of the first and second hydraulic pumps and having a port block having the two or more first discharge ports and the two or more second discharge ports opening to a side thereof, the manifold block being configured to switch the flow direction of the pressurized oil flowing in from the two or more first and second discharge ports of the port block by the multiple first and second switching valves and guide the pressurized oil to one of the multiple service ports, the manifold block being connected to the side of the port block where the two or more first and second discharge ports open, and the multiple service ports of the manifold block being connected via multiple piping to a control valve having the multiple directional control valves housed within a valve housing.

[0013] In order to achieve the above object, the present invention provides a pump device for a construction machine having a tandem pump with first and second hydraulic pumps arranged at a distance in the axial direction of a shaft driven and rotated by a prime mover, further comprising a manifold block having a plurality of first switching valves and a plurality of second switching valves mounted thereon and forming a plurality of service ports, the first hydraulic pump containing two or more first pump elements capable of independently controlling the flow of pressurized oil discharged from two or more first discharge ports, and the second hydraulic pump containing two or more second pump elements capable of independently controlling the flow of pressurized oil discharged from two or more second discharge ports. the first and second hydraulic pumps are configured as shared parts of the first and second hydraulic pumps and have a port block having the two or more first discharge ports and the two or more second discharge ports opening to a side portion thereof, the manifold block is configured to switch the flow direction of the pressurized oil flowing in from the two or more first and second discharge ports of the port block by the multiple first and second switching valves and guide the pressurized oil to one of the multiple service ports, and the manifold block is connected to the side portion of the port block where the two or more first and second discharge ports open.

[0014] In this way, in the present invention, a tandem pump is formed from two hydraulic pumps, a first hydraulic pump and a second hydraulic pump, and each of the first hydraulic pump and the second hydraulic pump is configured to contain two or more first pump elements capable of independently controlling the flow of pressurized oil discharged from two or more first discharge ports and two or more second pump elements capable of independently controlling the flow of pressurized oil discharged from two or more second discharge ports. This makes it possible to increase the number of discharge ports (pump elements) of the pump device, and increases or decreases the number of discharge ports (number of pump elements) connected to the actuator depending on the required flow rate, thereby enabling fine control of the discharge flow rate and improving operability when the actuator is driven.

[0015] Furthermore, in a pump unit equipped with such a tandem pump, the first and second discharge ports are opened on the side of a port block configured as a shared part of the first and second hydraulic pumps, and a manifold block equipped with first and second switching valves and having multiple service ports formed therein is connected to the side of the port block where the first and second discharge ports open. This makes it possible to eliminate all of the numerous hydraulic hoses connecting the discharge ports of the port block to the manifold block, and by reducing the size of the pump unit and the number of hydraulic hoses, it is possible to improve the ease of mounting on construction machinery. Effect of the Invention

[0016] According to the present invention, when a pump device of a hydraulic circuit system is constructed using a tandem pump in which two hydraulic pumps capable of independently controlling the flow rate of multiple discharge ports are arranged in tandem, and multiple switching valves, it is possible to improve operability when driving the actuator, and also improve mountability on construction machinery by making the pump device more compact and reducing the hydraulic hoses. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram showing a hydraulic excavator, which is a representative example of a construction machine equipped with a hydraulic circuit system according to a first embodiment of the present invention. [Diagram 2] 1 is a diagram showing a circuit configuration of a hydraulic circuit system according to a first embodiment of the present invention. FIG. [Diagram 3] FIG. 2 is a longitudinal cross-sectional view of the pump device taken along a shaft. [Figure 4] 4 is a vertical cross-sectional view of the pump device taken along line AA in FIG. 3. [Diagram 5] FIG. 2 is a partial cross-sectional top view of the pump device. [Figure 6] FIG. 4 is a top view of the pump device taken along line BB in FIG. 3. [Figure 7] FIG. 2 is a schematic diagram showing a part of an electronically controlled hydraulic pump equipped with a pump element, illustrating the operating principle of the first and second hydraulic pumps. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0019] <First embodiment> A first embodiment of the present invention will be described.

[0020] ~Construction machinery~ FIG. 1 is a diagram showing a hydraulic excavator, which is a representative example of a construction machine equipped with a hydraulic circuit system according to a first embodiment of the present invention.

[0021] The hydraulic excavator 100 shown in Figure 1 is configured such that an upper rotating body 102 equipped with a cab 102a for an operator is mounted via a rotating device 107 on a lower running body 101 equipped with left and right crawler-type running devices 108a, 108b.

[0022] A boom 104 of a front work machine 103 is connected to the front of the upper rotating body 102, and the boom 104 is driven by a boom cylinder 1, which is a single-rod hydraulic cylinder. An arm 105 is connected to the tip of the boom 104, and the arm 105 is driven by an arm cylinder 2. A bucket 106, which is a work tool, is connected to the tip of the arm 105, and the bucket 106 is driven by a bucket cylinder 3, which is a work tool cylinder. The swing device 107 is driven by a swing motor 4, and the traveling devices 108a, 108b are driven by left and right traveling motors 5a, 5b.

[0023] ~Hydraulic Circuit System~ FIG. 2 is a diagram showing a circuit configuration of a hydraulic circuit system according to a first embodiment of the present invention.

[0024] In Figure 2, the hydraulic circuit system comprises an engine 9 which is a prime mover, a pump device 10 driven by the engine 9, a plurality of actuators 1-5b (see Figure 1 for actuators 3-5b) driven by pressurized oil discharged from the pump device 10, a plurality of directional control valves 21-29 which control the flow of pressurized oil supplied from the pump device 10 to the plurality of actuators 1-5b, and a plurality of operating lever devices 56a, 56b, 56c, 56d which switch the plurality of directional control valves 21-29 and operate the plurality of actuators 1-5b.

[0025] The pump device 10 includes a tandem pump 30 having first and second hydraulic pumps 11, 12 spaced apart in the axial direction of a shaft 14 driven and rotated by an engine 9, and a manifold block 40 having four first switching valves 41a-41d as a plurality of first switching valves and four second switching valves 42a-42d as a plurality of second switching valves, and having first and second service ports 43, 44 as a plurality of service ports. The first and second hydraulic pumps 11, 12 are driven by the engine 9, suck hydraulic oil from a tank 55, and discharge pressurized oil. An electric motor may be used instead of the engine 9.

[0026] Further, the first and second hydraulic pumps 11, 12 each have four first discharge ports 45a-45d which are two or more first discharge ports and four second discharge ports 46a-46d which are two or more second discharge ports, the first hydraulic pump 11 includes four first pump elements 11a-11d which are two or more first pump elements capable of independently controlling the flow rate of the pressure oil discharged from the four first discharge ports 45a-45d, and the second hydraulic pump 12 includes four second pump elements 12a-12d which are two or more second pump elements capable of independently controlling the flow rate of the pressure oil discharged from the four second discharge ports 46a-46d. Details of the "pump elements" will be described later.

[0027] The manifold block 40 is configured to switch the flow direction of pressurized oil flowing in from the first and second discharge ports 45a-45d, 46a-46d using first and second switching valves 41a-41d, 42a-42d, and to guide the pressurized oil to either the first or second service port 43, 44.

[0028] The first and second switching valves 41a-41d, 42a-42d are electromagnetic switching valves that can be switched between a first position, which is an initial position, and a second position, which is a non-initial position. In the first position, the first switching valve 41a-41d connects the first discharge ports 45a-45d to the first service port 43, and in the second position, connects the first discharge ports 45a-45d to the second service port 44. In the first position, the second switching valve 42a-42d connects the second discharge ports 46a-46d to the second service port 44, and in the second position, connects the second discharge ports 46a-46d to the first service port 43.

[0029] The first and second service ports 43, 44 of the manifold block 40 are connected via first and second pipes 51, 52 to a control valve 20 which houses a plurality of directional control valves 21-29 in a valve housing.

[0030] The multiple actuators 1 to 5b are respectively the boom cylinder 1, arm cylinder 2, bucket cylinder 3, swing motor 4, left traveling motor 5a and right traveling motor 5b shown in Figure 1, and the multiple directional control valves 21 to 29 are respectively the right traveling directional control valve 21, the bucket directional control valve 22, the boom I directional control valve 23, the boom directional control valve 27, the swing directional control valve 25, the arm I directional control valve 26, the arm II directional control valve 24, the spare directional control valve 28 and the left traveling directional control valve 29.

[0031] The operating lever device 56a is for the boom 104 and bucket 106, the operating lever device 56b is for the arm 105 and swivel device 107, the operating lever device 56c is for the left traveling device 108a, and the operating lever device 56d is for the right traveling device 108b.

[0032] The multiple directional control valves 21-29 are divided into a first valve group 33 including a boom I directional control valve 23 and a boom II directional control valve 27, which are directional control valves for a specific first actuator that is operated relatively frequently, and a second valve group 34 including an arm I directional control valve 26 and an arm II directional control valve 24, which are directional control valves for a specific second actuator that is operated relatively frequently. The control valve 20 has first and second pump ports 31, 32 connected to the first and second valve groups 33, 34, and the first and second pump ports 31, 32 are connected to first and second service ports 43, 44 via first and second piping 51, 52. The number of the first and second service ports 43, 44 and the first and second pump ports is two, which is the same as the number of the first and second hydraulic pumps 11, 12 of the tandem pump 30.

[0033] Pressurized oil from the first service port 43 flows through the first piping 51 and from the pump port 31 into the control valve 20, and is supplied to the right traveling directional control valve 21, the bucket directional control valve 22, the boom I directional control valve 23, and the boom II directional control valve 27 of the first valve group 33. Pressurized oil from the second service port 44 flows through the second piping 52 and from the pump port 32 into the control valve 20, and is supplied to the swing directional control valve 25, the arm I directional control valve 26, the arm II directional control valve 24, the spare directional control valve 28, and the left traveling directional control valve 29 of the second valve group 34.

[0034] The first valve group 33 has directional control valves 21, 22, 23, 27 arranged in a center bypass line 33a and is configured as an open center circuit in which the directional control valves 21, 22, 23, 27 are connected in parallel to one another, and the second valve group 34 has directional control valves 24, 25, 26, 28, 29 arranged in a center bypass line 34a and is configured as an open center circuit in which the directional control valves 24, 25, 26, 28, 29 are connected in parallel to one another.

[0035] The directional control valves 21-29 are in a neutral state when the levers of the operating lever devices 56a, 56b, 56c, and 56d are not operated and there is no command from the controller 57, and the pressure oil flowing in from the pump port 32 flows back to the tank 55 through the center bypass lines 33a and 34a. When the levers of the operating lever devices 56a, 56b, 56c, and 56d are operated and a command is generated from the controller 57, the directional control valves 21-29 switch from the neutral state, adjust the flow rate distribution of the pressure oil flowing in from the pump ports 31 and 32, and supply the pressure oil to the respective actuators 1-5b. In addition, when the boom I directional control valve 23 and the boom II directional control valve 27 switch from the neutral state, the pressure oil from these directional control valves 23 and 27 join together and are supplied to the boom cylinder 1. When the arm I directional control valve 26 and the arm II directional control valve 24 also switch from the neutral state, the pressure oil from these directional control valves 24 , 26 joins together and is supplied to the arm cylinder 2 .

[0036] The controller 57 inputs operation signals from the operating lever devices 56a-56d and sensor signals such as the RPM of the engine 9 and the pressure of each part, such as the discharge pressure of the first and second hydraulic pumps 11, 12, and based on these signals, issues commands to the pump controllers 58, 59, the switching valves 41a-41d, 42a-42d, and the control valve 20. In response to commands from the controller 57, the pump controllers 58, 59 independently control the discharge flow rates of the first and second pump elements 11a-11d, 12a-12d.

[0037] The rotation speed of the engine 9 can be detected, for example, by arranging a rotation sensor such as an encoder on the shaft 14 in the first hydraulic pump 11 or the second hydraulic pump 12. The discharge pressure of the first and second hydraulic pumps 11, 12 can be detected, for example, by connecting a pressure sensor to the pipes 51, 52. The sensor signal of the rotation sensor is used to control the flow rate of the pressurized oil of the first and second pump elements 11a-11d, 12a-12d, and the sensor signal of the pressure sensor is used to control the horsepower of the pressurized oil of the first and second pump elements 11a-11d, 12a-12d.

[0038] ~Operation~ Next, an example of operation of the boom 104 and the arm 105 in the above configuration will be described.

[0039] 2, when the levers of the operating lever devices 56a-56d are not operated and there is no command from the controller 57, the switching valves 41a-41d, 42a-42d are in the positions shown in the figure, the four pump elements 11a-11d in the first hydraulic pump 11 are connected to the first valve group 33, and the four pump elements 12a-12d in the second hydraulic pump 12 are connected to the second valve group 34. In addition, the pump elements 11a-11d, 12a-12d have a discharge flow rate of zero or discharge a very small amount of flow. Since the directional control valves 21-29 are in a neutral state, the pressure oil flows to the tank 55 through the center bypass lines 33a, 34a.

[0040] When the lever of the operating lever device 56a is operated in the boom drive direction, the boom I directional control valve 23 and the boom II directional control valve 27 are displaced according to the lever operation amount (required flow rate) in response to a command from the controller 57, and the boom cylinder 1 is driven by pressure oil from the first hydraulic pump 11. In addition, the flow rate of the first hydraulic pump 11 also increases according to the lever operation amount in response to a command from the pump controller 58, and first the discharge flow rate of the pump element 11a begins to increase, and when the pump element 11a reaches its maximum flow rate, next the discharge flow rate of the pump element 11b increases. When the pump element 11b reaches its maximum flow rate, the discharge flow rate of the pump element 11c increases, and when the pump element 11c reaches its maximum flow rate, the discharge flow rate of the pump element 11d increases. If the amount of lever operation further increases and the required flow rate of the boom cylinder 1 cannot be met by the first hydraulic pump 11 alone, the changeover valve 42a can be switched to add the flow rate of the pump element 12a, and the changeover valves 42a, 42b, 42c, and 42d can be switched to add the total flow rate of the second hydraulic pump 12. In other words, since all eight pump elements 11a to 11d and 12a to 12d can be connected to the boom cylinder 1, high-speed operation of the boom cylinder 1 is possible.

[0041] When the lever of the operating lever device 56b is operated in the arm drive direction, the arm I direction control valve 26 and the arm II direction control valve 24 are displaced according to the lever operation amount by a command from the controller 57, and the arm cylinder 2 is driven by the pressure oil from the second hydraulic pump 12. Also, the flow rate of the second hydraulic pump 12 increases according to the lever operation amount by a command from the pump controller 59, and the discharge flow rate of the pump element 12d starts to increase first, and when the pump element 12d reaches the maximum flow rate, the discharge flow rate of the pump element 12c increases. When the pump element 12c reaches the maximum flow rate, the discharge flow rate of the pump element 12b increases, and when the pump element 12b reaches the maximum flow rate, the discharge flow rate of the pump element 12c increases. If the lever operation amount further increases and the required flow rate of the arm cylinder 2 cannot be met by the second hydraulic pump 12 alone, the switching valve 41d can be switched to add the flow rate of the pump element 11d, and the total flow rate of the first hydraulic pump 11 can be added by switching the switching valves 41d, 41c, 41b, and 41a. That is, since all eight pump elements 11a to 11d, 12a to 12d can be connected to the arm cylinder 2, high speed operation of the arm cylinder 2 is possible.

[0042] When the boom 104 and the arm 105 are operated simultaneously, when the lever of the operating lever device 56a is operated in the boom drive direction and the lever of the operating lever device 56b is operated in the arm drive direction, the boom I directional control valve 23 and the boom II directional control valve 27 are displaced according to the lever operation amount (required flow rate) by a command from the controller 57, and the arm I directional control valve 26 and the arm II directional control valve 24 are displaced. Also, at this time, for example, when the lever of the operating lever device 56a is input at 20% of the full operation amount and the lever of the operating lever device 56b is input at 20% of the full operation amount, the pump elements 11a, 11b and the pump elements 12d, 12c discharge pressure oil, and the boom cylinder 1 is driven by the pressure oil from the pump elements 11a, 11b, and the arm cylinder 2 is driven by the pressure oil from the pump elements 12d, 12c. If a demand is input that exceeds the combined maximum flow rate of all eight pump elements 11a to 11d, 12a to 12d, for example if the lever of operating lever device 56a is set at 100% and the lever of operating lever device 56b is set at 60%, pump elements 11a to 11d, 12a to 12d are allocated according to the ratio of the two (100:60 → 5:3), and the boom cylinder 1 is driven by the five pump elements 11a, 11b, 11c, 11d, 12a, and the arm cylinder 2 is driven by the three pump elements 12d, 12c, 12b.

[0043] In this way, the boom cylinder 1 and the arm cylinder 2 are driven independently without the pressure oil supplied from each pump element being divided, so each pump element only needs to supply the flow rate of the minimum pressure required for the boom cylinder 1 and the arm cylinder 2. This eliminates the need to reduce the pressure by throttling the pressure oil with a directional control valve, and it is possible to reduce division loss.

[0044] ~Operation principle of the first and second hydraulic pumps~ The first pump elements 11a-11d and the second pump elements 12a-12d of the first and second hydraulic pumps 11, 12 are each composed of a plurality of cylinder working chambers and solenoid valves that vary the net volume (capacity) thereof, and the discharge flow rates of the first pump elements 11a-11d and the second pump elements 12a-12d are controlled by switching the solenoid valves and changing the net volume of the cylinder working chambers based on commands output from a controller 57 and pump controllers 58, 59. A hydraulic pump incorporating such pump elements is sometimes called a digital pump.

[0045] The details of the operating principle of the first hydraulic pump 11 and the second hydraulic pump 12 will be explained using Fig. 7. Fig. 7 is a schematic diagram showing a part of an electronically controlled hydraulic pump 200 that contains multiple pump elements, and the first and second hydraulic pumps 11, 12 each have the same configuration as the hydraulic pump 200.

[0046] The hydraulic pump 200 has a pump shaft 204 and at least three cylinder working chambers (hereinafter simply referred to as working chambers) 202 whose volumes change periodically as the pump shaft 204 rotates.

[0047] The hydraulic pump 200 also has a low pressure valve 209 that controls the flow of pressurized oil between a low pressure manifold 201 connected to a tank port 216 and the working chamber 202, and a high pressure valve 212 that controls the flow of pressurized oil between a high pressure manifold 213 connected to a discharge port 214 and the working chamber 202.

[0048] The hydraulic pump 200 forms a plurality of pump elements by means of working chambers 202, and each pump element has one or more working chambers 202 (typically multiple working chambers 202) and is connected to the aforementioned high-pressure manifold 213 which is common to the multiple working chambers 202 of each pump element.

[0049] The controller 207 corresponds to the pump controllers 58 and 59 shown in Figure 2, and actively controls at least the low-pressure valve in phase correlation with the volume cycle of the working chamber 202, thereby determining whether each working chamber 202 will perform an active cycle in which a net volume of the working chamber 202 is formed between the low-pressure manifold 210 and the high-pressure manifold 213, or an inactive cycle in which a net volume of the working chamber 202 is not formed between the low-pressure manifold 210 and the high-pressure manifold 213, and thereby controlling the net volume of the working chamber 202 of each pump element leading to each discharge port 214 via each high-pressure manifold 213 according to the required flow rate.

[0050] The hydraulic pump 200 includes a plurality of cylinders 201 that form a plurality of working chambers 202 by their inner circumferential surfaces, and a plurality of pistons 203 that are driven by an eccentric cam 205 provided on a pump shaft 204 and reciprocate within the cylinders 201 to periodically change the volume of the working chambers 202 of the cylinders 201. The hydraulic pump 200 also includes a sensor 206 that detects the angular position and / or rotational speed of the shaft 204 at that time, and sends the detection information of the sensor 206 to a controller 207 via a signal line 208, and the controller 207 determines the phase of the volume cycle of each working chamber 202 at that time based on the detection information.

[0051] The working chambers 202 are each associated with a low pressure valve (LPV) 209 configured as an electronically actuated face-sealing poppet valve that is operable to selectively close the flow path from the working chambers 202 to a low pressure manifold 210. The low pressure manifold 210 may thereby connect one or more, or all, of the working chambers 202 associated with each pump element to a tank port 216.

[0052] The LPV 209 is a normally open solenoid valve that is passively open during the intake stroke when the pressure in the working chamber 202 is equal to or less than the pressure in the low pressure manifold 210, placing the working chamber 202 in fluid communication with the low pressure manifold 210, while the LPV 209 is connected to the controller 207 via an LPV control line 211 and can be selectively closed under active control by the controller 207, placing the working chamber 202 out of fluid communication with the low pressure manifold 210. The LPV 209 may alternatively be a normally closed solenoid valve.

[0053] Each of the working chambers 202 is further associated with a high pressure valve (HPV) 212 configured as a pressure actuated discharge valve. The HPV 212 opens outwardly from the respective working chamber 202 and is operable to seal a flow passage extending from the working chamber 202 to the high pressure manifold 213. When the HPV 212 is open, the high pressure manifold 213 connects the working chamber 202 to the discharge port 214, allowing pressurized oil to flow from the working chamber 202 to the discharge port 214. The HPV 212 functions as a normally closed pressure relief check valve that opens passively in balance with the biasing force of a biasing member within the HPV 212 due to a pressure differential across the HPV 212. In some embodiments, the HPV 212 also functions as a normally closed electromagnetic check valve that, once opened by the pressure within the working chamber 202, is selectively held open by the controller 207 via the HPV control line 215. Typically, the HPV 212 cannot be opened by the controller 207 against pressure in the high pressure manifold 213. The HPV 212 may also be open or partially open under the control of the controller 207 when there is pressure in the high pressure manifold 213 and no pressure in the working chamber 202.

[0054] In the discharge mode, the controller 207 selects a net volumetric flow rate from the working chamber 202 to the high pressure manifold 213 by the hydraulic pump 200 by actively closing one or more LPVs 209 near a maximum volumetric point in the volumetric cycle of the associated working chamber 202 to close the flow path to the low pressure manifold 210, thereby allowing hydraulic fluid to flow through the associated HPV 212 (but without actively opening the HPV 212) on the subsequent contraction stroke, resulting in a useful cycle with a net volumetric flow rate of the working chamber 202. Alternatively, the LPV 209 may be left open throughout the entire cycle of the working chamber 202 (or the working chamber 202 may be closed throughout the entire cycle), resulting in a non-useful cycle with no net volumetric flow rate. The controller 207 selects the number and sequence of useful and non-useful cycles to generate flow or generate shaft torque or power to meet the selected net volumetric flow rate of the working chamber 202 of the pump element connected to the same high pressure manifold 213 and discharge port 214, and to meet the flow rate demand of the pump element.

[0055] The controller 207 is operable not only to decide for each cycle whether to close or leave the LPV 209 open, selecting between active and inactive cycles, but also to precisely vary the phase at which the LPV 209 and / or HPV 212 are closed in relation to the changing volume of the working chamber 202, thereby selecting the net volumetric amount from the high pressure manifold 213 to the low pressure manifold 210 or vice versa.

[0056] The arrows on the manifolds 210, 213 indicate the flow of hydraulic fluid in pump mode, with the flow being reversed in motor mode.

[0057] While the illustrated example shows all working chambers 202 connected to the same high pressure manifold 213 and discharge port 214, typically the hydraulic pump 200 further comprises working chambers 202 forming one or more separate pump elements with their respective high pressure manifolds 213, discharge ports 214, and demand signals.

[0058] More specifically, in the first hydraulic pump 11, four high-pressure manifolds 213 and four discharge ports 214 corresponding to the first discharge ports 45a, 45b, 45c, and 45d are provided, and each high-pressure manifold 213 is connected to the working chamber 202 via a high-pressure valve 209. The same is true for the second hydraulic pump 12.

[0059] The demand signal may be expressed in any suitable units. As an example, the demand signal is expressed as a "volume change rate Fd," which is the maximum possible volume change per revolution of the pump shaft 204. The target flow rate is expressed as the product of the volume change rate Fd and the rotational speed of the pump shaft 204.

[0060] ~Pump device structure~ Next, the structure of the pump device 10 according to this embodiment will be described.

[0061] Figures 3 to 6 show the structure of pump device 10 in the hydraulic circuit system shown in Figure 1, with Figure 3 being a longitudinal cross-sectional view along shaft 14 of pump device 10, Figure 4 being a longitudinal cross-sectional view of pump device 10 along line AA in Figure 3, Figure 5 being a partially cross-sectional top view of pump device 10, and Figure 6 being a top view of pump device 10 along line BB in Figure 3.

[0062] The structure of the pump device 10 in the hydraulic circuit system of this embodiment will be described with reference to FIGS.

[0063] In Figure 3, as described above, the pump device 10 comprises a tandem pump 30 having first and second hydraulic pumps 11, 12 arranged at a distance in the axial direction of the shaft 14, and a manifold block 40 which is equipped with first switching valves 41a-41d and second switching valves 42a-42d (see Figure 5) and which forms first and second service ports 43, 44 (see Figure 5).

[0064] In addition, the first and second hydraulic pumps 11, 12 have a port block 13 configured as a common part of the first and second hydraulic pumps 11, 12, and the port block 13 has four first discharge ports 45a to 45d and four second discharge ports 46a to 46d opening in a side portion 13S as shown in Fig. 6. The manifold block 40 is coupled to the side portion 13S (see Figs. 3, 5, and 6) of the port block 13 where the first and second discharge ports 45a to 45d, 46a to 46d open.

[0065] In the illustrated embodiment, the side 13S of the port block 13 has a single block surface, and the first and second discharge ports 45a-45d, 46a-46d open onto that block surface; however, the side 13S of the port block 13 may be formed with multiple stepped surfaces, for example a first surface and a second surface parallel to the first surface, with the first discharge ports 45a-45d formed on the first surface and the second discharge ports 46a-46d formed on the second surface.

[0066] The first hydraulic pump 11 has a casing 48 and two first radial piston pumps 36a, 36b arranged at an interval in the axial direction of the shaft 14a inside the casing 48. The first radial piston pump 36a forms two first pump elements 11a, 11d of the above-mentioned four first pump elements 11a to 11d, and the first radial piston pump 36b forms the remaining two first pump elements 11b, 11c.

[0067] The second hydraulic pump 12 similarly has a casing 49 and two second radial piston pumps 37a, 37b arranged at a distance from each other on the shaft 14b within the casing 49. The second radial piston pump 37a forms two second pump elements 12a, 12d out of the four second pump elements 12a to 12d, and the second radial piston pump 37b forms the remaining two second pump elements 12b, 12c.

[0068] The hydraulic oil from the tank 55 is guided via the suction port 47 formed in the port block 13 to the space in the casings 48, 49 in which the first radial piston pumps 36a, 36b are located and to the space in which the second radial piston pumps 37a, 37b are located.

[0069] The first radial piston pump 36a is mainly composed of a shaft 14a constituting a part of the shaft 14, an eccentric cam 15 rotating integrally with the shaft 14a, a piston 16 in sliding contact with the outer peripheral surface of the eccentric cam 15, a cylinder 19 in which the piston 16 reciprocates, and an intake check valve 17a and a discharge check valve 18a communicating with a cylinder chamber 50 formed by the piston 16 and the cylinder 19. Similarly, the first radial piston pump 36b is mainly composed of the shaft 14a, the eccentric cam 15, the piston 16, the cylinder 19, the intake check valve 17b, and the discharge check valve 18b.

[0070] The second radial piston pump 37a is similarly constructed with a shaft 14b, an eccentric cam 15, a piston 16, a cylinder 19, an suction check valve 17c, and a discharge check valve 18c as its main components, and the second radial piston pump 37b is similarly constructed with a shaft 14b, an eccentric cam 15, a piston 16, a cylinder 19, an suction check valve 17d, and a discharge check valve 18d as its main components.

[0071] The shaft 14a is rotatably supported by the casing 48 and the port block 13 via bearings, and the shaft 14b is rotatably supported by the casing 49 and the port block 13 via bearings. The shafts 14a and 14b are connected by a coupling 14c to constitute the shaft 14.

[0072] 4, the first radial piston pump 36a has six piston pumps 60 each composed of a piston 16 and a cylinder 19 and arranged radially at an equal angle with respect to the shaft 14a, and when the eccentric cam 15 integral with the shaft 14a rotates, each piston 16 of the piston pumps 60 reciprocates in the cylinder 19, sucking the hydraulic oil filled in the space in the casing 48 from the intake check valve 17a (see FIG. 3) into the cylinder chamber 50 and discharging it from the discharge check valve 18a. The discharged hydraulic oil passes through the internal passages 38a, 38d of the casing 48, flows into the port block 13 from the openings 39a, 39d formed on the end face of the casing 48 on the port block 13 side, and is guided to any one of the first discharge ports 45a to 45d shown in FIG. 6, the first discharge ports 45a, 45d in the illustrated embodiment, and is discharged from these discharge ports 45a, 45d.

[0073] Although not shown, the first radial piston pump 36b and the second radial piston pumps 37a, 37b are configured in the same manner. However, in the case of the first radial piston pump 37b, the pressure oil discharged from the discharge check valve 18b is guided to the first discharge ports 45b, 45c shown in Fig. 6 and discharged from these discharge ports 45b, 45c. In the case of the first radial piston pump 37a, the pressure oil discharged from the discharge check valve 18c is guided to the second discharge ports 46a, 46d shown in Fig. 6 and discharged from these discharge ports 46a, 46d, and in the case of the second radial piston pump 37b, the pressure oil discharged from the discharge check valve 18d is guided to the second discharge ports 46b, 46c shown in Fig. 6 and discharged from these discharge ports 46b, 46c.

[0074] In FIG. 3, the suction check valve 17a is an electromagnetic on-off valve (hereinafter referred to as a solenoid valve), and when the solenoid valve is OFF, the valve is always open by a spring as shown in the suction check valve 17a. Therefore, the hydraulic oil sucked into the cylinder chamber 50 when the piston 16 descends returns from the suction check valve 17a to the inside of the casing 48 when the piston 16 ascends, and is not discharged. By turning the solenoid valve ON when the piston 16 ascends, the valve is closed as shown in the suction check valve 17b, the cylinder chamber 50 is pressurized, the discharge check valve 18b opens, and the oil is discharged. In addition, by controlling the timing of turning ON and OFF, the timing of closing the suction check valve is controlled, and the discharge flow rate in one stroke of the piston 16 can be controlled. In this way, by controlling the ON and OFF of the solenoid valve and the timing of turning ON and OFF, the flow rate of the piston pump 60 can be controlled independently for each pump.

[0075] In this manner, in this embodiment, a plurality of piston pumps 60 capable of independent flow control are used, and the pressurized oil from the plurality of piston pumps 60 is joined together and discharged, and this is called a "pump element."

[0076] In this embodiment, three piston pumps 60 are used for one pump element to reduce pump pulsation, and in the first hydraulic pump 11, four pump elements 11a-11d are formed from the twelve piston pumps 60 of the first radial piston pumps 36a, 36b, and pressure oil from the pump elements 11a-11d is discharged from four discharge ports 45a-45d. Similarly, in the second hydraulic pump 12, four pump elements 12a-12d are formed from the twelve piston pumps 60 of the second radial piston pumps 37a, 37b, and pressure oil from the pump elements 12a-12d is discharged from four discharge ports 46a-46d.

[0077] This will be further explained with reference to FIG.

[0078] In Fig. 4, the six piston pumps 60 of the first radial piston pump 36a are indicated by symbols 60a, 60b, 60c, 60d, 60e, and 60f in a clockwise direction. The discharge oils of the piston pumps 60a, 60c, and 60e are merged to form the pump element 11a, and the discharge oils of the piston pumps 60b, 60d, and 60f are merged to form the pump element 11d. The respective merged discharge flow rates flow into the port block 13 from the openings 39a and 39d, and are guided to the discharge ports 4a and 45d shown in Fig. 6. The same is true for the first radial piston pump 36b of the first hydraulic pump 11, and the first radial piston pump 36b forms two pump elements 11b and 11c, and the respective merged discharge flow rates are guided to the discharge ports 45b and 45c shown in Fig. 6.

[0079] The second radial piston pumps 37a, 37b of the second hydraulic pump 12 are similar, and the second radial piston pump 37a forms two pump elements 12a, 12d, and the combined discharge flow rates of the two pump elements are led to discharge ports 46a, 46d shown in Figure 6, while the second radial piston pump 37b forms two pump elements 12b, 12c, and the combined discharge flow rates of the two pump elements are led to discharge ports 46b, 46c shown in Figure 6.

[0080] In this way, the six piston pumps 60 of each of the two first radial piston pumps 36a, 36b are each divided into two groups, and the pressurized oil discharged from each piston pump 60 for each group is joined together to form one of the four pump elements 11a to 11d of the first hydraulic pump 11. Similarly, the six piston pumps 60 of each of the two second radial piston pumps 37a, 37b are each divided into two groups, and the pressurized oil discharged from each piston pump 60 for each group is joined together to form one of the four pump elements 12a to 12d of the second hydraulic pump 12.

[0081] The manifold block 40 has a block body 40a coupled to a side portion 13S where the eight discharge ports 45a-45d, 46a-46d of the port block 13 open, and as shown in Fig. 3 and Fig. 5, the first switching valves 41a-41d are attached to the side surface of the block body 40a on the first hydraulic pump 11 side, and the second switching valves 42a-42d are attached to the side surface of the block body 40a on the second hydraulic pump 12 side. In addition, two passages 43a, 44a are formed on the outlet sides (above the first and second switching valves 41a-41d, 42a-42d in Fig. 3) of the first and second switching valves 41a-41d, 42a-42d in the block body 40a, which extend in parallel as shown in Fig. 5 and open at the end faces opposite to each other of the block body 40a, and the first service port 43 is formed at the opening of the passage 43a, and the second service port 44 is formed at the opening of the passage 44a. The first service port 43 and the second service port 44 may be formed by opening the passages 43a, 44a to the upper surface of the block body 40a.

[0082] In addition, within the block body 40a of the manifold block 40, there are formed internal passages that guide the pressure oil from the eight discharge ports 45a to 45d, 46a to 46d to the electromagnetic switching valves 41a to 41d, 42a to 42d, respectively, and internal flow paths that guide the pressure oil to either the passages 43a or 43b depending on the presence or absence of a command to the switching valves 41a to 41d, 42a to 42d from the controller 57. These internal passages are configured to form the hydraulic circuit of the manifold block 40 as shown in FIG.

[0083] ~Effects~ According to this embodiment, the following effects can be obtained.

[0084] 1. In this embodiment, as described above, when the boom 104 is operated alone, the eight pump elements 11a-11d, 12a-12d are sequentially connected to the boom cylinder 1 according to the lever operation amount (required flow rate), so that the number of pump elements (discharge flow rate) can be finely controlled according to the lever operation amount, and the speed fluctuation of the boom cylinder 1 caused by switching of the discharge port by the switching valves 41a-41d, 42a-42d becomes smooth, improving operability. Also, since all eight pump elements 11a-11d, 12a-12d can be connected to the boom cylinder 1, high-speed operation of the boom cylinder 1 is possible, and the amount of work can be secured.

[0085] When the arm 105 is operated alone, the number of pump elements (discharge flow rate) can be finely controlled according to the amount of lever operation, improving operability, as in the case of boom operation. Also, high-speed operation of the arm cylinder 2 becomes possible, ensuring the amount of work.

[0086] In addition, if the switching valves 41a-41d, 42a-42d are installed away from the pump, eight hydraulic hoses are required to connect the discharge ports 45a-45d, 46a-46d to the switching valves 41a-41d, 42a-42d, and in order to connect the eight hydraulic hoses to the discharge ports 45a-45d, 46a-46d, the space required to pass the hoses reduces the mountability, and many problems arise, such as an increase in the labor required to connect the hoses and a risk of leakage and reliability due to the increase in hydraulic connections. In addition, since it is necessary to increase the distance between the discharge ports 45a-45d, 46a-46d in order to connect the eight hydraulic hoses, the port block 13 becomes larger, and the pump device 10 itself becomes larger, which also reduces the mountability.

[0087] In this embodiment, the manifold block 40 is connected to the side 13S where the eight discharge ports 45a to 45d, 46a to 46d of the port block 13 open, so that all hydraulic hoses connecting the discharge ports 45a to 45d, 46a to 46d to the switching valves 41a to 41d, 42a to 42d can be eliminated, and the pump unit 10 can be made smaller and the hydraulic hoses reduced, thereby improving the ease of installation on construction machinery.

[0088] In addition, there is no need to connect hoses, the pump device is easy to install, and the number of leak points is reduced, improving reliability against leaks.

[0089] In this embodiment, the number of pump elements and discharge ports of the first hydraulic pump 11 and the second hydraulic pump 12 are four, i.e., pump elements 11a-11d, pump elements 12a-12d, discharge ports 45a-45d, and discharge ports 46a-46d, respectively, but is not limited to this. The number of pump elements and discharge ports of the first hydraulic pump 11 and the second hydraulic pump 12 may be two or more, such as two, three, or five, and the effects of the present invention can be obtained in terms of operability, energy saving, mountability, etc.

[0090] 2. The control valve 20 is configured such that the boom I directional control valve 23 and the boom II directional control valve 27 are concentrated in the first valve group 33, and the arm I directional control valve 26 and the arm II directional control valve 24 are concentrated in the second valve group 34. Therefore, during combined operation of the boom 104 and the arm 105, the boom cylinder 1 and the arm cylinder 2 are driven independently without dividing the pressurized oil supplied from the connected pump elements, so each pump element only needs to supply the flow rate of the minimum pressure required for the boom cylinder 1 and the arm cylinder 2. Therefore, there is no need to throttle the pressurized oil with the directional control valve to reduce the pressure, which reduces division loss and improves energy efficiency.

[0091] 3. Since the number of service ports 43, 44 of the manifold block 40 and the pump ports 31, 32 of the control valve 20, which are connected by piping 51, 52, is the same as the number of the first and second hydraulic pumps 11, 12 of the tandem pump 30 (2), the manifold block 40 and the control valve 20 can be connected with a minimum number of hoses, which also reduces the number of hoses and improves the ease of installation on construction machinery.

[0092] 4. Within the manifold block 40, the hydraulic circuit is configured such that the first switching valves 41a to 41d, in the first position (initial position), connect the first discharge ports 45a to 45d to the first service port 43, and in the second position, connect the first discharge ports 45a to 45d to the second service port 44, and the second switching valves 42a to 42d, in the first position (initial position), connect the second discharge ports 46a to 46d to the second service port 44, and in the second position, connect the second discharge ports 46a to 46d to the first service port 43. Therefore, when pump elements 11a-11d are connected in sequence to boom cylinder 1 in accordance with the lever operation amount (required flow rate) to supply the discharge flow rate of pump elements 11a-11d to boom cylinder 1, the discharge flow rate can be supplied without switching over switchover valves 41a-41d, so no pressure fluctuations due to switching over switchover valves 41a-41d occur, and the boom cylinder 1 can be smoothly started or accelerated. The same is true when pump elements 42a-42d are connected in sequence to arm cylinder 2 in accordance with the lever operation amount (required flow rate) to supply the discharge flow rate of pump elements 12a-12d to arm cylinder 2, so no pressure fluctuations due to switching over switchover valves 42a-42d occur, and the arm cylinder 2 can be smoothly started or accelerated.

[0093] Furthermore, when the eight pump elements 11a-11d, 12a-12d are sequentially connected to the boom cylinder 1 in accordance with the lever operation amount to drive the boom cylinder 1, none of the switching valves 41a-41d, 42a-42d are switched from the first position until the required flow rate of the boom cylinder 1 can be supplied by only the first hydraulic pump 11, and when the required flow rate of the boom cylinder 1 cannot be supplied by only the first hydraulic pump 11, the switching valves 42a-42d can be switched to the second position. The same is true when the eight pump elements 11a-11d, 12a-12d are sequentially connected to the arm cylinder 2 in accordance with the lever operation amount to drive the arm cylinder 2, and when the required flow rate of the arm cylinder 2 cannot be supplied by only the second hydraulic pump 12, the switching valves 41a-41d can be switched to the second position. Therefore, the number of times the switching valves 41a to 41d, 42a to 42d are switched when driving the boom cylinder 1 or the arm cylinder 2 can be reduced, and the durability of the switching valves 41a to 41d, 42a to 42d can be improved. [Explanation of symbols]

[0094] 1...Boom cylinder (specific first actuator) 2...Arm cylinder (specific second actuator) 3...Bucket cylinder 4...Slewing motor 1~5b…Multiple actuators 9…Engine 10. Pump unit 11…First hydraulic pump 11a to 11d: First pump element 12…Second hydraulic pump 12a to 12d: Second pump element 13…Port block 14…Shaft 15...Eccentric cam 16…Piston 17a~17d…Suction check valve 18a~18d…Discharge check valve 19…Cylinder 20…Control valve 21…Directional control valve for right travel 22... Bucket directional control valve 23...Directional control valve for boom I 24…Directional control valve for arm II 25...Rotation directional control valve 26…Directional control valve for arm I 27…Boom 1 directional control valve 28…Back-up directional control valve 29…Directional control valve for left travel 30…Tandem piston 31…First pump port 32…Second pump port 33…First valve group 34…Second valve group 36a, 36b...First radial piston pump 37a, 37b...Second radial piston pump 40…Manifold block 41a to 41d: First switching valve 42a to 42d: Second switching valve 43…First service port 44…Second service port 45a~45d…First discharge port 46a~46d…Second discharge port 47…Suction port 48,49…Casing 50…Cylinder chamber 51…First pipe 52…Second piping 55…Tank 56a, 56b, 56c, 56d...Operating lever device 57…Controller 58,59…Pump controller 60a~60f...Piston pump 100...Hydraulic excavator 101...Lower running body 102...Upper rotating body 108a, 108b...Travel gear

Claims

1. Prime engine and, A pump device driven by the aforementioned prime mover, Multiple actuators driven by pressurized oil discharged from the pump device, The system includes a plurality of directional control valves that control the flow of pressurized oil supplied from the pump device to the plurality of actuators, The pump device is A hydraulic circuit system for a construction machine comprising a tandem pump having first and second hydraulic pumps arranged at intervals in the axial direction of a shaft driven and rotated by the prime mover, The pump device further comprises a manifold block equipped with a plurality of first switching valves and a plurality of second switching valves, and having a plurality of service ports. The first hydraulic pump includes a plurality of first pump elements capable of independently controlling the flow of pressurized oil discharged from a plurality of first discharge ports. The second hydraulic pump includes a plurality of second pump elements capable of independently controlling the flow of pressurized oil discharged from a plurality of second discharge ports. The first and second hydraulic pumps are configured as shared components of the first and second hydraulic pumps, and have a port block in which the plurality of first discharge ports and the plurality of second discharge ports are opened on the same side. The manifold block is configured to switch the flow direction of pressurized oil flowing in from the plurality of first and second discharge ports of the port block using the plurality of first and second switching valves, and to guide the pressurized oil to one of the plurality of service ports. The manifold block is coupled to the side portion of the port block through which the plurality of first and second discharge ports are opened. A hydraulic circuit system for construction machinery, characterized in that the multiple service ports of the manifold block are connected via multiple pipes to a control valve in which the multiple directional control valves are housed within a valve housing.

2. In the hydraulic circuit system for construction machinery described in claim 1, The multiple service ports of the manifold block are connected to the multiple pump ports provided on the control valve via the multiple pipes. A hydraulic circuit system for construction machinery, characterized in that the number of service ports and pump ports is the same as the number of first and second hydraulic pumps of the tandem pump.

3. In the hydraulic circuit system for construction machinery described in claim 1, The plurality of actuators include a specific first actuator and a specific second actuator that are operated relatively frequently. The plurality of directional control valves are divided within the control valve into a first valve group including two directional control valves for a specific first actuator, and a second valve group including two directional control valves for a specific second actuator. The plurality of service ports include first and second service ports, and the plurality of piping includes first and second piping, A hydraulic circuit system for construction machinery, characterized in that the control valve has first and second pump ports connected to the first and second valve groups, respectively, and the first and second pump ports are connected to the first and second service ports via the first and second piping.

4. In the hydraulic circuit system for construction machinery described in claim 1, The plurality of service ports include the first and second service ports, The plurality of first and second switching valves are switchable between a first position, which is the initial position, and a second position, which is a non-initial position. The plurality of first switching valves, in the first position, connect the plurality of first discharge ports to the first service port, and in the second position, connect the plurality of first discharge ports to the second service port. A hydraulic circuit system for construction machinery, characterized in that the plurality of second switching valves communicate the plurality of second discharge ports to the second service port in the first position, and the plurality of second discharge ports to the first service port in the second position.

5. In the hydraulic circuit system for construction machinery described in claim 1, The plurality of first and second pump elements of the first and second hydraulic pumps are each four first and second pump elements, and the plurality of first and second discharge ports are each four first and second discharge ports. A hydraulic circuit system for construction machinery, characterized in that the plurality of first and second switching valves in the manifold block are each four first and second switching valves.

6. In the hydraulic circuit system for construction machinery described in claim 1, The first hydraulic pump has a plurality of first radial piston pumps arranged at intervals in the axial direction of the shaft, Each of the plurality of first radial piston pumps has a plurality of piston pumps arranged radially with respect to the shaft, and the plurality of piston pumps are divided into a plurality of groups, and the pressurized oil discharged from each piston pump within each group is combined to form one of the plurality of pump elements of the first hydraulic pump. The second hydraulic pump has a plurality of second radial piston pumps arranged at intervals in the axial direction of the shaft, A hydraulic circuit system for construction machinery, characterized in that each of the plurality of second radial piston pumps has a plurality of piston pumps arranged radially with respect to the shaft, the plurality of piston pumps are divided into a plurality of groups, and the pressurized oil discharged from each piston pump within each group is combined to form one of the plurality of pump elements of the second hydraulic pump.

7. In the hydraulic circuit system for construction machinery described in claim 1, A hydraulic circuit system for construction machinery, characterized in that the plurality of first discharge ports are formed on the first surface of the side portion of the port block, and the plurality of second discharge ports are formed on the first surface of the side portion of the port block or on a second surface parallel to the first surface.

8. A pumping device for a construction machine, comprising a tandem pump with first and second hydraulic pumps arranged at intervals in the axial direction of a shaft driven and rotated by a prime mover, The system further includes a manifold block equipped with multiple first switching valves and multiple second switching valves, and forming multiple service ports. The first hydraulic pump includes a plurality of first pump elements capable of independently controlling the flow of pressurized oil discharged from a plurality of first discharge ports. The second hydraulic pump includes a plurality of second pump elements capable of independently controlling the flow of pressurized oil discharged from a plurality of second discharge ports. The first and second hydraulic pumps are configured as shared components of the first and second hydraulic pumps, and have a port block in which the plurality of first discharge ports and the plurality of second discharge ports are opened on the same side. The manifold block is configured to switch the flow direction of pressurized oil flowing in from the plurality of first and second discharge ports of the port block using the plurality of first and second switching valves, and to guide the pressurized oil to one of the plurality of service ports. The pumping device for construction machinery is characterized in that the manifold block is coupled to the side portion of the port block through which the plurality of first and second discharge ports are opened.

9. In the pump device for construction machinery according to claim 8, The plurality of service ports include the first and second service ports, The plurality of first and second switching valves are switchable between a first position, which is the initial position, and a second position, which is a non-initial position. The plurality of first switching valves, in the first position, connect the plurality of first discharge ports to the first service port, and in the second position, connect the plurality of first discharge ports to the second service port. A pumping device for construction machinery, characterized in that the plurality of second switching valves, in the first position, connect the plurality of second discharge ports to the second service port, and in the second position, connect the plurality of second discharge ports to the first service port.

10. In the pump device for construction machinery according to claim 8, The plurality of first and second pump elements of the first and second hydraulic pumps are each four first and second pump elements, and the plurality of first and second discharge ports are each four first and second discharge ports. A pumping device for construction machinery, characterized in that the plurality of first and second switching valves in the manifold block are each four first and second switching valves.

11. In the pump device for construction machinery according to claim 8, The first hydraulic pump has a plurality of first radial piston pumps arranged at intervals in the axial direction of the shaft, Each of the plurality of first radial piston pumps has a plurality of piston pumps arranged radially with respect to the shaft, and the plurality of piston pumps are divided into a plurality of groups, and the pressurized oil discharged from each piston pump within each group is combined to form one of the plurality of pump elements of the first hydraulic pump. The second hydraulic pump has a plurality of second radial piston pumps arranged at intervals in the axial direction of the shaft, The pumping device for construction machinery is characterized in that each of the plurality of second radial piston pumps has a plurality of piston pumps arranged radially with respect to the shaft, the plurality of piston pumps are divided into a plurality of groups, and the pressurized oil discharged from each piston pump within each group is combined to form one of the plurality of pump elements of the second hydraulic pump.

12. In the pump device for construction machinery according to claim 8, A pump device for construction machinery, characterized in that the plurality of first discharge ports are formed on the first surface of the side portion of the port block, and the plurality of second discharge ports are formed on the first surface of the side portion of the port block or on a second surface parallel to the first surface.

13. In the hydraulic circuit system for construction machinery described in claim 1, The first and second hydraulic pumps each have a pump shaft, and The pump has at least three working chambers whose volume changes periodically in accordance with the rotation of the pump shaft, Each of the working chambers of the first and second hydraulic pumps is A low-pressure valve controls the flow of pressurized oil between the working chamber and the low-pressure manifold, The system includes a high-pressure valve that controls the flow of pressurized oil between the working chamber and the high-pressure manifold, The working chambers of the first and second hydraulic pumps form a plurality of pump elements, each pump element has one or more working chambers, and is connected to the high-pressure manifold which is provided in common to one or more working chambers of each pump element. A hydraulic circuit system for construction machinery, further comprising a controller, the controller actively controls at least the low-pressure valve in phase correlation with the volume cycle of the working chamber, thereby determining for each volume cycle of the working chamber whether each working chamber performs an effective cycle that forms a net displacement volume of pressurized oil between the low-pressure manifold and the high-pressure manifold, or an ineffective cycle that does not form a net displacement volume of pressurized oil between the low-pressure manifold and the high-pressure manifold, and controlling the net displacement volume of the working chambers of each pump element leading to each of the discharge ports via each of the high-pressure manifolds according to the respective required flow rates of pressurized oil.

Images