Valve device

Abstract

The purpose of the present invention is to improve the stability of the flow of hydraulic oil in a valve device for controlling the flow of hydraulic oil supplied to and discharged from a plurality of hydraulic actuators of a construction machine. A valve device for a construction machine according to an embodiment of the present invention is a valve device for a construction machine, which controls the flow of hydraulic oil supplied and discharged to a plurality of hydraulic actuators including a boom cylinder, and is provided with: a first valve body and a second valve body separated from each other in the axial direction; and a housing having: a plurality of spool holes including spool holes for a boom cylinder into which the first spool and the second spool are inserted; and a first pump passage, a second pump passage, a first tank passage, a second tank passage, a rod-side passage, and a head-side passage. An annular space around one small-diameter portion of the first valve body communicates with the first tank passage when the first valve body is at least located at the first neutral position; an annular space around one small-diameter portion of the second valve body communicates with the second tank passage when the second valve body is at least in the second neutral position.

Description

Technical Field

[0001] The present disclosure relates to a valve device that controls the flow of hydraulic oil supplied to and discharged from a plurality of hydraulic actuators included in a construction machine. Background Art

[0002] Patent document 1 discloses a valve device including a housing and a first valve core and a second valve core that are independent of each other. The housing has a pump passage, a first supply and discharge passage, a second supply and discharge passage, and a tank passage, and a first pilot chamber, a second pilot chamber, and a third pilot chamber are formed inside. In addition, the valve device is referred to as a "direction and flow control valve" in patent document 1. In this valve device, since the first valve core and the second valve core are independent of each other, the first valve core can be moved according to the pressure difference between the first pilot chamber and the third pilot chamber, and the second valve core can be moved according to the pressure difference between the second pilot chamber and the third pilot chamber. As a result, when the hydraulic actuator moves in either direction, independent metering control can be achieved on the inlet (Meter-In) side or the outlet (Meter-Out) side.

[0003] Prior art literature: Patent Literature: Patent document 1: International Publication No. 2022 / 080311. Summary of the invention

[0004] Problems to be solved by the invention: Construction machines such as hydraulic excavators and hydraulic cranes include a plurality of hydraulic actuators. When the valve device of Patent Document 1 is used for the valve device to move the plurality of hydraulic actuators of the construction machine, there is still room for improvement from the viewpoint of stabilizing the flow of the hydraulic oil.

[0005] Therefore, an object of the present disclosure is to improve the stability of the flow of hydraulic oil in a valve device that controls the flow of hydraulic oil supplied to and discharged from a plurality of hydraulic actuators of a construction machine.

[0006] Means of solving the problem: A valve device according to one form of the present disclosure is a valve device for construction machinery that controls the flow of working oil supplied to and discharged from a plurality of hydraulic actuators including a boom cylinder, and comprises: a first valve core and a second valve core, which are axially separated from each other; and a housing, which has: a plurality of valve core holes, including a boom cylinder valve core hole for inserting the first valve core and the second valve core; a first pump passage, a second pump passage, a first tank passage, and a second tank passage, which are connected to the boom cylinder valve core hole; a rod side passage, which is connected to the boom cylinder valve core hole and is connected to the rod side of the boom cylinder chamber; a head side passage connected to the boom cylinder valve core hole and connected to the head side chamber of the boom cylinder; and a first pilot chamber and a second pilot chamber, which are located on both sides of the boom cylinder valve core hole; a portion between the first valve core and the second valve core in the boom cylinder valve core hole constitutes a third pilot chamber; the first tank passage and the second tank passage intersect the plurality of valve core holes respectively; the first valve core, according to the pressure difference between the first pilot chamber and the third pilot chamber, switches the rod side passage from the first pump passage and the first tank passage to the first pump passage. The control valve is configured to move between a first neutral position in which the head side passage is cut off from both sides of the second pump passage and the second tank passage, and a first boom driving position in which the rod side passage is connected to either the first pump passage or the first tank passage; the second valve core moves between a second neutral position in which the head side passage is cut off from both sides of the second pump passage and the second tank passage, and a second boom driving position in which the head side passage is connected to either the second pump passage or the second tank passage, according to the pressure difference between the second pilot chamber and the third pilot chamber; each valve core of the first valve core and the second valve core includes: three or more shoulder portions arranged at intervals along the axial direction; and two or more small diameter portions connecting adjacent shoulder portions; an annular space around one of the two or more small diameter portions of the first valve core is connected to the first tank passage when the first valve core is at least in the first neutral position; an annular space around one of the two or more small diameter portions of the second valve core is connected to the second tank passage when the second valve core is at least in the second neutral position.

[0007] According to another form of the valve device disclosed herein, it is a valve device for construction machinery that controls the flow of working oil supplied to and discharged from multiple hydraulic actuators including a boom cylinder, and comprises: a first valve core and a second valve core, which are axially separated from each other; and a housing, which has: multiple valve core holes, including a boom cylinder valve core hole for inserting the first valve core and the second valve core; a first pump passage, a second pump passage, a first tank passage, and a second tank passage, which are connected to the boom cylinder valve core hole; a rod side passage, which is connected to the boom cylinder valve core hole and is connected to the The rod side chamber of the boom cylinder is connected; a head side passage is connected to the boom cylinder valve core hole and is connected to the head side chamber of the boom cylinder; and a first pilot chamber and a second pilot chamber are located on both sides of the boom cylinder valve core hole; a portion between the first valve core and the second valve core in the boom cylinder valve core hole constitutes a third pilot chamber; the first valve core includes: a first pump side shoulder portion opened and closed between the rod side passage and the first pump passage; a first tank side shoulder portion opened and closed between the rod side passage and the first tank passage; and a first small diameter portion connecting the first pump side shoulder portion and the first tank side shoulder portion; the second valve core includes: a second inner shoulder portion that cuts off the second pump passage from the third pilot chamber; a second intermediate shoulder portion that opens and closes between the head side passage and the second pump passage, and opens and closes between the head side passage and the second tank passage; a second outer shoulder portion that cuts off the second tank passage from the second pilot chamber; a second inner small diameter portion that connects the second inner shoulder portion and the second intermediate shoulder portion; and a second outer small diameter portion that connects the second outer shoulder portion and the second intermediate shoulder portion; the first pump side shoulder portion has a plurality of first notches, which are arranged at intervals in the circumferential direction on the end portion of the first small diameter portion side of the outer peripheral surface of the first pump side shoulder portion, for connecting the rod side passage with the first pump passage; at least one of the plurality of first notches has a taper portion whose depth decreases as it moves away from the end face of the first pump side shoulder portion connected to the first small diameter portion.

[0008] Effect of the invention: According to the present disclosure, it is possible to improve the stability of the flow of hydraulic oil in a valve device that controls the flow of hydraulic oil supplied to and discharged from a plurality of hydraulic actuators of a construction machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a side view of a hydraulic excavator equipped with a valve device according to an embodiment; Figure 2 is a diagram showing a portion of a hydraulic circuit including a valve device; Figure 3 is a top view of the valve device; Figure 4 is along Figure 3 A cross-sectional view of line IV-IV; Figure 5 A diagram illustrating a state in which a separate valve core of a valve device is located at a boom-dropped position; Figure 6 This is a diagram for explaining a state in which a separate valve core of a valve device is located at a boom-up position; Figure 7 It is a side sectional view of the split type valve core cut by a plane parallel to the axial direction; Figure 8 is a graph showing the relationship between the stroke amount of the valve core and the opening area of ​​the liquid inlet flow path when the boom is dropped; Explanation of symbols: 5A: Boom cylinder 5a: Rod side chamber 5b: Cephalad chamber 10: Valve device 11: Shell 12: Valve core 12A: Valve core for boom cylinder 23: Valve core hole 23A: Valve core hole for boom cylinder 25a: First pump passage 25b: Second pump passage 27a: First tank passage 27b: Second tank access 28: Rod side passage 29: Cephalad access 50: First valve core 51: First inner shoulder 51a: First notch 51b: First leakage groove 52: First inner small diameter portion 53: First intermediate shoulder 53a: Second notch 54: First outer small diameter portion 55: First outer shoulder 60: Second valve core 61: Second inner shoulder 61a: Second leakage groove 62: Second inner small diameter portion 63: Second intermediate shoulder 63a: Third notch 63b: Fourth slot 64: Second outer small diameter portion 65: Second outer shoulder 65a: Exhaust passage 81: First leakage path 81a: First inlet port 81b: First egress port 82: Second leakage path 82a: Second entry port 82b: Second egress port 91: First identification mark 92: Second identification mark P1: First pilot room P2: Second pilot room P3: The third pilot room. DETAILED DESCRIPTION

[0010] Hereinafter, a valve device according to an embodiment will be described with reference to the drawings.

[0011] Figure 1 1 is a side view of a hydraulic excavator 1 equipped with a valve device according to the present embodiment. The hydraulic excavator 1 is self-propelled and includes a traveling body 2. The hydraulic excavator 1 also includes a swinging body 3 supported on the traveling body 2 in a swingable manner and a boom that can pitch relative to the swinging body 3. A boom is swingably connected to the tip of the boom, and a bucket is swingably connected to the tip of the boom. A cabin 4 having a driver's seat is disposed on the swinging body 3. In addition, the hydraulic excavator 1 may not be self-propelled.

[0012] The hydraulic excavator 1 is provided with a plurality of hydraulic actuators 5. Specifically, the hydraulic excavator 1 includes a boom cylinder 5A for pitching a boom, an arm cylinder 5B for swinging an arm, and a bucket cylinder 5C for swinging a bucket as the hydraulic actuators 5. Although not shown in the figure, the hydraulic excavator 1 may further include a left travel motor for driving a left crawler of a travel body 2, a right travel motor for driving a right crawler, and a swing motor for swinging a swing body 3 as bidirectional hydraulic actuators. The flow of the working oil supplied to and discharged from the plurality of hydraulic actuators 5 is controlled by the valve device of the present embodiment.

[0013] Figure 2 1 is a diagram showing a portion of a hydraulic circuit including the valve device 10 of the present embodiment. Specifically, Figure 2 Only the circuit related to the supply and discharge control of the boom cylinder 5A among the multiple hydraulic actuators 5 is shown, and the circuit related to the supply and discharge control of other hydraulic actuators 5 is omitted. The valve device 10 controls the flow of the working oil supplied from the hydraulic pump 6 to the multiple hydraulic actuators 5. The valve device 10 is interposed between the hydraulic pump 6 and the multiple hydraulic actuators 5 in the hydraulic circuit.

[0014] like Figure 2As shown, the boom cylinder 5A includes: a rod side chamber 5a, which is supplied with working oil when the boom is driven in the direction of the boom falling, that is, in the direction of gravity; and a head side chamber 5b, which is supplied with working oil when the boom is driven in the direction of the boom rising, that is, in the direction against gravity.

[0015] Figure 3 1 is a top view of the valve device 10 . Figure 4 is along Figure 3 The cross-sectional view of the IV-IV line. Figure 3 As shown, the valve device 10 includes a housing 11 and a plurality of valve cores 12 slidably held in the housing 11 .

[0016] The housing 11 includes a substantially rectangular parallelepiped housing body 11A and a block 11B extending along one side of the housing body 11A. The housing 11 includes the same number of first covers 11C and second covers 11D as the valve elements 12. However, the structure of the housing 11 is not limited to this and can be modified adaptively.

[0017] The housing body 11A includes a first surface 21 facing downward and a second surface 22 facing upward. The housing body 11A also includes a plurality of valve core holes 23. Figure 4 As shown, each valve core hole 23 extends in the up-down direction. Each valve core hole 23 penetrates the housing body 11A in the up-down direction and opens on the first surface 21 and the second surface 22. The plurality of valve core holes 23 are parallel to each other. That is, like the valve core holes 23, the plurality of valve cores 12 are also parallel to each other and extend in the up-down direction.

[0018] Again, if Figure 3 As shown, the plurality of valve body holes 23 are arranged in a row in a direction perpendicular to the up-down direction. Also, the plurality of valve bodies 12 are held in the housing body 11A in a state of being arranged in a row in a direction perpendicular to the up-down direction.

[0019] The plurality of valve core holes 23 correspond to the plurality of hydraulic actuators 5, respectively. That is, the number of the valve core holes 23 is the same as the number of the hydraulic actuators 5. The corresponding hydraulic actuator 5 is controlled by the valve core 12 sliding in each valve core hole 23. Figure 3 As shown, the number of valve core holes 23 is five. For example, the plurality of valve core holes 23 includes a valve core hole 23A for the boom cylinder 5A. Furthermore, the plurality of valve core holes 23 includes a valve core hole for the arm cylinder 5B and a valve core hole for the bucket cylinder 5C. In addition, the number of valve core holes 23 may be less than four or more than six. The number of valve core holes 23 may also be different from the number of hydraulic actuators 5.

[0020] Figure 4 The cross-sectional view is a view cut along the center line of the valve core hole 23A for the boom cylinder 5A among the plurality of valve core holes 23. Figure 4As shown, the boom cylinder valve core 12A inserted into the boom cylinder valve core hole 23A is a separated valve core. That is, the boom cylinder valve core 12A includes a first valve core 50 and a second valve core 60 that are axially separated from each other in the valve core hole 23A. The first valve core 50 is located below the second valve core 60. The details of the first valve core 50 and the second valve core 60 will be described later.

[0021] In this embodiment, Figure 3 and 4 Although not shown in the figure, a pump port 24a and a tank port 24b are arranged on one surface of the housing body 11A. Figure 2 As shown, the pump port 24 a is connected to the hydraulic pump 6 via a pipe, and the tank port 24 b is connected to the tank 7 via a pipe.

[0022] like Figure 2 As shown, the housing body 11A has a supply passage 25 from the pump port 24a to all the valve core holes 23. The supply passage 25 includes: a transverse passage 25c extending along the arrangement direction of the valve core 12 near the center of the valve core hole 23; and a first pump passage 25a and a second pump passage 25b for introducing working oil from the transverse passage 25c to the valve core hole 23A for the boom cylinder. A check valve 26 is arranged between the transverse passage 25c and the first pump passage 25a and the second pump passage 25b in the supply passage 25. The check valve 26 prevents the working oil from flowing back from the valve core hole 23A to the transverse passage 25c. As shown in FIG. Figure 4 As shown, the second pump passage 25b is connected to the valve body hole 23A at an upper position than the first pump passage 25a.

[0023] like Figure 2 As shown, the housing body 11A has a discharge passage 27 from all the valve core holes 23 to the tank port 24b. The discharge passage 27 includes: two first tank passages 27a and second tank passages 27b extending in the arrangement direction of the valve core 12 in the form of passing through both ends of each valve core hole 23; and an outlet passage 27c connecting the first tank passage 27a and the second tank passage 27b with the tank port 24b.

[0024] like Figure 3 As shown by the middle dotted line, the first tank passage 27a and the second tank passage 27b extend in a manner of traversing the plurality of valve core holes 23. In other words, the first tank passage 27a and the second tank passage 27b intersect the plurality of valve core holes 23, respectively.

[0025] like Figure 4As shown, the first tank passage 27a and the second tank passage 27b are connected to the valve core hole 23A at the outer side of the first pump passage 25a and the second pump passage 25b in the axial direction of the valve core hole 23A for the boom cylinder. More specifically, the first tank passage 27a is connected to the valve core hole 23A at a lower position than the first pump passage 25a, and the second tank passage 27b is connected to the valve core hole 23A at a higher position than the second pump passage 25b.

[0026] like Figure 4 As shown in FIG. 1 , a rod-side port 24c and a head-side port 24d corresponding to the boom cylinder valve core 12A are arranged on one surface of the housing body 11A. Figure 2 As shown, the rod-side port 24c is connected to the rod-side chamber 5a of the boom cylinder 5A through piping, and the head-side port 24d is connected to the head-side chamber 5b of the boom cylinder 5A through piping.

[0027] The housing body 11A includes a rod side passage 28. The rod side passage 28 connects between the rod side port 24c and the valve core hole 23A. That is, the rod side passage 28 is connected to the rod side chamber 5a of the boom cylinder 5A through the rod side port 24c. Figure 4 As shown, the rod side passage 28 is connected to the valve core hole 23A on the opposite side of the first pump passage 25a in the axial direction of the valve core hole 23A to the second pump passage 25b, that is, below the first pump passage 25a. The rod side passage 28 is connected to the valve core hole 23A between the first pump passage 25a and the first tank passage 27a in the axial direction of the valve core hole 23A.

[0028] The housing body 11A includes a head side passage 29. The head side passage 29 connects between the head side port 24d and the valve core hole 23A. That is, the head side passage 29 is connected to the head side chamber 5b of the boom cylinder 5A through the head side port 24d. Figure 4 As shown, the head side passage 29 is connected to the valve core hole 23A on the opposite side of the first pump passage 25a with respect to the second pump passage 25b in the axial direction of the valve core hole 23A, that is, above the second pump passage 25b. The head side passage 29 is connected to the valve core hole 23A between the second pump passage 25b and the second tank passage 27b in the axial direction of the valve core hole 23A.

[0029] The housing 11 has a first pilot chamber P1 and a second pilot chamber P2 located on both sides of the valve core hole 23A. Specifically, the first cover 11C has a container-like shape. The first cover 11C is mounted on the first surface 21 in a form in which the opening edge of the first cover 11C surrounds the opening of the lower end of the valve core hole 23A. In this way, the opening of the first cover 11C is closed by the first surface 21 of the housing body 11A to form the first pilot chamber P1. In addition, the second cover 11D has a container-like shape. The second cover 11D is mounted on the second surface 22 in a form in which the opening edge of the second cover 11D surrounds the opening of the upper end of the valve core hole 23A. In this way, the opening of the second cover 11D is closed by the second surface 22 of the housing body 11A to form the second pilot chamber P2.

[0030] A first spring 31 is disposed in the first pilot chamber P1 to apply a force to the first valve core 50 for maintaining the first valve core 50 in a neutral position. The first spring 31 directly applies a force to the first valve core 50 toward the second valve core 60 via a spring seat. On the other hand, a head attachment rod 32 is mounted on the end surface of the first valve core 50 on the opposite side to the second valve core 60, and the first spring 31 applies a force to the first valve core 50 in the opposite direction to the second valve core 60 via the spring seat and the head attachment rod 32.

[0031] Similarly, a second spring 33 is disposed in the second pilot chamber P2 to apply a force to the second valve core 60 for maintaining the second valve core 60 in a neutral position. The second spring 33 directly applies a force to the second valve core 60 toward the first valve core 50 via a spring seat. On the other hand, a head attachment rod 34 is installed on the end surface of the second valve core 60 on the opposite side of the first valve core 50, and the second spring 33 applies a force to the second valve core 60 in the opposite direction of the first valve core 50 via the spring seat and the head attachment rod 34.

[0032] The first spring 31 and the second spring 33 have the same structure. That is, the force applied by the first spring 31 to the first valve core 50 and the force applied by the second spring 33 to the second valve core 60 are equal. In addition, the first spring 31 and the second spring 33 may also have different structures, and the force applied by the first spring 31 to the first valve core 50 and the force applied by the second spring 33 to the second valve core 60 may also be different.

[0033] The portion between the first valve core 50 and the second valve core 60 in the boom cylinder valve core hole 23A constitutes the third pilot chamber P3. The boom cylinder valve core 12A, which is a separate valve core, supplies or discharges the working oil relative to the boom cylinder 5A, or prohibits the supply or discharge of the working oil relative to the boom cylinder 5A, according to the pressure of each pilot chamber of the first pilot chamber P1, the second pilot chamber P2, and the third pilot chamber P3.

[0034] like Figure 2As shown, the valve device 10 includes: a first electromagnetic proportional valve 41 for adjusting the pressure of the first pilot chamber P1; a second electromagnetic proportional valve 42 for adjusting the pressure of the second pilot chamber P2; and a third electromagnetic proportional valve 43 for adjusting the pressure of the third pilot chamber P3. The first electromagnetic proportional valve 41 is connected to the first pilot chamber P1 through a pilot passage 44. The second electromagnetic proportional valve 42 is connected to the second pilot chamber P2 through a pilot passage 45. The third electromagnetic proportional valve 43 is connected to the third pilot chamber P3 through a pilot passage 46.

[0035] The valve device 10 includes a primary pressure passage 47 and a discharge passage 48. The primary pressure passage 47 is connected to the first electromagnetic proportional valve 41, the second electromagnetic proportional valve 42, and the third electromagnetic proportional valve 43. The primary pressure passage 47 has a primary pressure port 24e. The primary pressure port 24e is connected to the auxiliary pump 8 through a primary pressure pipe. The discharge passage 48 is connected to the first electromagnetic proportional valve 41, the second electromagnetic proportional valve 42, and the third electromagnetic proportional valve 43. The discharge passage 48 is connected to the tank 7, for example.

[0036] The first electromagnetic proportional valve 41 outputs secondary pressure to the first pilot chamber P1 of the boom cylinder valve core 12A, or communicates the first pilot chamber P1 with the drain passage 48. The second electromagnetic proportional valve 42 outputs secondary pressure to the second pilot chamber P2 of the boom cylinder valve core 12A, or communicates the second pilot chamber P2 with the drain passage 48. The third electromagnetic proportional valve 43 outputs secondary pressure to the third pilot chamber P3 of the boom cylinder valve core 12A, or communicates the third pilot chamber P3 with the drain passage 48.

[0037] The plurality of valve cores 12 may include a separate valve core in addition to the valve core 12A for the boom cylinder. In the valve device 10, regarding the separate valve core, a set of a first electromagnetic proportional valve 41, a second electromagnetic proportional valve 42 and a third electromagnetic proportional valve 43 is included. Moreover, the valve core other than the separate valve core in the plurality of valve cores 12 is an integrated valve core. The integrated valve core supplies or discharges working oil or prohibits the supply or discharge of working oil relative to the hydraulic actuator 5 corresponding to the integrated valve core according to the pressure of the first pilot chamber facing the lower end of the integrated valve core and the second pilot chamber facing the upper end of the integrated valve core. In the valve device 10, regarding the integrated valve core, a set of a first electromagnetic proportional valve 41 and a second electromagnetic proportional valve 42 is included.

[0038] In this embodiment, if Figure 3As shown, the second electromagnetic proportional valve 42 corresponding to each valve core 12 is installed on the block 11B. Similarly, the third electromagnetic proportional valve 43 corresponding to the separate valve core 12 is also installed on the block 11B. On the other hand, the first electromagnetic proportional valve 41 corresponding to each valve core 12 is installed on the first cover 11C. However, the installation method of the first electromagnetic proportional valve 41, the second electromagnetic proportional valve 42 and the third electromagnetic proportional valve 43 on the housing 11 is not limited to this. For example, the first electromagnetic proportional valve 41 can be installed on the block 11B together with the second electromagnetic proportional valve 42 and the third electromagnetic proportional valve 43, or it can be directly installed on the housing body 11A.

[0039] (Details of valve core for boom cylinder) Next, refer to Figures 4 to 7 The boom cylinder valve body 12A supplies or discharges hydraulic oil to or from the boom cylinder 5A according to the pressure of each pilot chamber of the first pilot chamber P1, the second pilot chamber P2, and the third pilot chamber P3, or prohibits the supply or discharge of hydraulic oil to or from the boom cylinder 5A.

[0040] The first valve body 50 switches whether the rod-side passage 28 communicates with the supply passage 25 or the discharge passage 27 , and the second valve body 60 switches whether the head-side passage 29 communicates with the supply passage 25 or the discharge passage 27 .

[0041] The first valve core 50 moves between the first neutral position, the first boom-down position, and the first boom-up position according to the pressure difference between the first pilot chamber P1 and the third pilot chamber P3. The second valve core 60 moves between the second neutral position, the second boom-down position, and the second boom-up position according to the pressure difference between the second pilot chamber P2 and the third pilot chamber P3. Figure 4 The state in which the first valve body 50 is located at the first neutral position and the second valve body 60 is located at the second neutral position is shown. Figure 5 The state where the first valve core 50 is located at the first boom-down position and the second valve core 60 is located at the second boom-down position is shown. Figure 6 The first valve core 50 is located at the first boom-up position, and the second valve core 60 is located at the second boom-up position. The first boom-down position and the first boom-up position correspond to the first boom-driving position, and the second boom-down position and the second boom-up position correspond to the second boom-driving position. Figure 5 and 6 In the embodiment, a part of the housing 11 is omitted.

[0042] like Figure 4As shown in the figure, when the first valve core 50 is located at the first neutral position and the second valve core 60 is located at the second neutral position, the supply and discharge of the hydraulic oil relative to the boom cylinder 5A is prohibited, and the boom is not driven. More specifically, when the first valve core 50 is located at the first neutral position, the first valve core 50 cuts off the rod side passage 28 from both the first pump passage 25a and the first tank passage 27a, and when the second valve core 60 is located at the second neutral position, the head side passage 29 is cut off from both the second pump passage 25b and the second tank passage 27b.

[0043] like Figure 5 As shown, when the first valve core 50 and the second valve core 60 move toward each other, the position of the first valve core 50 is the first boom-dropping position, and the position of the second valve core 60 is the second boom-dropping position. When the first valve core 50 is located at the first boom-dropping position, the first valve core 50 makes the rod-side passage 28 communicate with the first pump passage 25a, and when the second valve core 60 is located at the second boom-dropping position, the head-side passage 29 communicates with the second tank passage 27b. Thus, the working oil is supplied to the rod-side chamber 5a of the boom cylinder 5A, and the working oil is discharged from the head-side chamber 5b. As a result, the boom is driven in the downward direction.

[0044] like Figure 6 As shown, when the first valve core 50 and the second valve core 60 move away from each other, the position of the first valve core 50 is the first boom-up position, and the position of the second valve core 60 is the second boom-up position. When the first valve core 50 is at the first boom-up position, the first valve core 50 connects the rod-side passage 28 with the first tank passage 27a, and when the second valve core 60 is at the second boom-up position, the head-side passage 29 connects with the second pump passage 25b. Thus, the working oil is supplied to the head-side chamber 5b of the boom cylinder 5A, and the working oil is discharged from the rod-side chamber 5a. As a result, the boom is driven in the upward direction.

[0045] (Structure of the first valve core) The first valve core 50 includes a first inner shoulder portion 51, a first inner small diameter portion 52, a first intermediate shoulder portion 53, a first outer small diameter portion 54, and a first outer shoulder portion 55. The first inner shoulder portion 51, the first inner small diameter portion 52, the first intermediate shoulder portion 53, the first outer small diameter portion 54, and the first outer shoulder portion 55 are arranged in this order from the third pilot chamber P3 toward the first pilot chamber P1. That is, the first inner small diameter portion 52 connects the first inner shoulder portion 51 and the first intermediate shoulder portion 53, and the first outer small diameter portion 54 connects the first intermediate shoulder portion 53 and the first outer shoulder portion 55. In addition, the first inner shoulder portion 51 corresponds to the first pump side shoulder portion, the first intermediate shoulder portion 53 corresponds to the first tank side shoulder portion, and the first inner small diameter portion 52 corresponds to the first small diameter portion.

[0046] The first inner shoulder portion 51, the first intermediate shoulder portion 53, and the first outer shoulder portion 55 slide relative to the valve core hole 23A. The first inner small diameter portion 52 and the first outer small diameter portion 54 are smaller than the diameter of the valve core hole 23A, in other words, the diameters of the shoulders 51, 53, 55 of the first valve core 50. That is, the periphery of the first inner small diameter portion 52 in the valve core hole 23A and the periphery of the first outer small diameter portion 54 in the valve core hole 23A constitute annular spaces S1 and S2, respectively, into which the working oil flows in and out. The diameter of the first outer small diameter portion 54 is larger than the diameter of the first inner small diameter portion 52.

[0047] The first inner shoulder 51 cuts off the first pump passage 25a from the third pilot chamber P3. The first inner shoulder 51 opens and closes the rod side passage 28 and the first pump passage 25a. The first intermediate shoulder 53 opens and closes the rod side passage 28 and the first tank passage 27a. The first outer shoulder 55 cuts off the first tank passage 27a from the first pilot chamber P1.

[0048] When the first valve element 50 is at least in the first neutral position, the first inner shoulder portion 51 cuts off the rod side passage 28 and the first pump passage 25a, and the first intermediate shoulder portion 53 cuts off the rod side passage 28 and the first tank passage 27a. Figure 4 As shown, when the first valve body 50 is located at the first neutral position, the end of the first pump passage 25 a is closed by the outer peripheral surface of the first inner shoulder portion 51 .

[0049] The annular space S2 around the first outer small diameter portion 54 communicates with the first tank passage 27a when the first valve element 50 is at least in the first neutral position. Figure 4 As shown, in this embodiment, the portion of the first tank passage 27a that intersects the valve core hole 23A and the first outer small diameter portion 54 have the same width in the axial direction of the valve core hole 23A. In addition, when the first valve core 50 is located at the first neutral position, when viewed perpendicularly to the axial direction of the valve core hole 23A, the first outer small diameter portion 54 completely overlaps with the portion of the first tank passage 27a that intersects the valve core hole 23A.

[0050] However, the width of the valve core hole 23A in the axial direction may be different between the portion of the first tank passage 27a intersecting the valve core hole 23A and the first outer small diameter portion 54. In addition, when the first valve core 50 is located at the first neutral position, when viewed perpendicularly to the axial direction of the valve core hole 23A, more than half of the first outer small diameter portion 54 preferably overlaps with the portion of the first tank passage 27a intersecting the valve core hole 23A.

[0051] (Structure of the second valve core) The second valve core 60 includes a second inner shoulder portion 61, a second inner small diameter portion 62, a second intermediate shoulder portion 63, a second outer small diameter portion 64, and a second outer shoulder portion 65. The second inner shoulder portion 61, the second inner small diameter portion 62, the second intermediate shoulder portion 63, the second outer small diameter portion 64, and the second outer shoulder portion 65 are arranged in this order from the third pilot chamber P3 toward the second pilot chamber P2. That is, the second inner small diameter portion 62 connects the second inner shoulder portion 61 and the second intermediate shoulder portion 63, and the second outer small diameter portion 64 connects the second intermediate shoulder portion 63 and the second outer shoulder portion 65.

[0052] The second inner shoulder portion 61, the second intermediate shoulder portion 63, and the second outer shoulder portion 65 slide relative to the valve core hole 23A. The second inner small diameter portion 62 and the second outer small diameter portion 64 are smaller than the diameter of the valve core hole 23A, in other words, the diameters of the respective shoulders 61, 63, 65 of the second valve core 60. That is, the periphery of the second inner small diameter portion 62 in the valve core hole 23A and the periphery of the second outer small diameter portion 64 in the valve core hole 23A respectively constitute annular spaces S3 and S4 into which the working oil flows in and out.

[0053] The second inner shoulder 61 cuts off the second pump passage 25b from the third pilot chamber P3. The second intermediate shoulder 63 opens and closes the head-side passage 29 and the second pump passage 25b, and opens and closes the head-side passage 29 and the second tank passage 27b. The second outer shoulder 65 cuts off the second tank passage 27b from the second pilot chamber P2.

[0054] The annular space S4 around the second outer small diameter portion 64 is connected to the second tank passage 27b when the second valve element 60 is at least in the second neutral position. Figure 4 As shown, in this embodiment, the second outer small diameter portion 64 has a larger width in the axial direction of the valve core hole 23A than the portion of the second tank passage 27b intersecting the valve core hole 23A. In addition, when the second valve core 60 is located at the second neutral position, when viewed perpendicularly to the axial direction of the valve core hole 23A, more than half of the second outer small diameter portion 64 overlaps with the portion of the second tank passage 27b intersecting the valve core hole 23A.

[0055] When the second valve core 60 is at least in the second neutral position, the second intermediate shoulder portion 63 cuts off the head side passage 29 and the second pump passage 25b, and cuts off the head side passage 29 and the second tank passage 27b. Figure 4 As shown, when the second valve body 60 is located at the second neutral position, the end of the head-side passage 29 is closed by the outer peripheral surface of the second intermediate shoulder portion 63 .

[0056] (notch) like Figure 4As shown in FIG. 1 , the first inner shoulder portion 51 has a plurality of first notches 51a for communicating the rod side passage 28 with the first pump passage 25a. The plurality of first notches 51a are arranged at intervals in the circumferential direction at the end portion on the first inner small diameter portion 52 side of the outer circumferential surface of the first inner shoulder portion 51. The plurality of first notches 51a extend from the end surface of the first inner shoulder portion 51 on the first inner small diameter portion 52 side in the axial direction of the valve core hole 23A.

[0057] The first intermediate shoulder portion 53 has a plurality of second notches 53a for communicating the rod side passage 28 with the first tank passage 27a. The plurality of second notches 53a are arranged at intervals in the circumferential direction at the end portion on the first inner small diameter portion 52 side of the outer peripheral surface of the first intermediate shoulder portion 53. The plurality of second notches 53a extend from the end surface of the first intermediate shoulder portion 53 on the first inner small diameter portion 52 side in the axial direction of the valve core hole 23A.

[0058] The second intermediate shoulder portion 63 has a plurality of third notches 63a for communicating the head side passage 29 with the second pump passage 25b. The plurality of third notches 63a are arranged at intervals in the circumferential direction at the end portion on the second inner small diameter portion 62 side of the outer peripheral surface of the second intermediate shoulder portion 63. The plurality of third notches 63a extend from the end surface of the second intermediate shoulder portion 63 on the second inner small diameter portion 62 side in the axial direction of the valve core hole 23A.

[0059] The second intermediate shoulder portion 63 has a plurality of fourth notches 63b for communicating the head side passage 29 with the second tank passage 27b. The plurality of fourth notches 63b are arranged at intervals in the circumferential direction at the end portion on the second outer small diameter portion 64 side of the outer peripheral surface of the second intermediate shoulder portion 63. The plurality of fourth notches 63b extend from the end surface of the second intermediate shoulder portion 63 on the second outer small diameter portion 64 side in the axial direction of the valve core hole 23A. The number of the plurality of fourth notches 63b is greater than the number of the plurality of third notches 63a.

[0060] Figure 7 This is a side sectional view of the separate valve core cut along a plane parallel to the axial direction. Figure 7 In the figure, the shapes of the first notch 51a, the second notch 53a, the third notch 63a, the fourth notch 63b, and the exhaust passage 65a and the leakage passages 81 and 82 described later are shown in section for easy understanding.

[0061] like Figure 7As shown, the shapes of the bottom surfaces of the first notch 51a and the second notch 53a and the third notch 63a and the fourth notch 63b are different from each other. The bottom surfaces of the first notch 51a and the second notch 53a are inclined outward in the radial direction as they move away from the end surface of each shoulder portion toward the axial center. In more detail, the first notch 51a has a slope portion whose depth decreases as it moves away from the end surface of the first inner shoulder portion 51 connected to the first inner small diameter portion 52. The second notch 53a has a slope portion whose depth decreases as it moves away from the end surface of the first intermediate shoulder portion 53 connected to the first inner small diameter portion 52. On the other hand, the bottom surfaces of the third notch 63a and the fourth notch 63b maintain a certain distance from the axial center of the valve core 12A from one end to the other end in the axial direction.

[0062] (Exhaust passage) The second outer shoulder portion 65 has an exhaust passage 65a. The exhaust passage 65a extends from the end surface of the second outer shoulder portion 65 facing the second pilot chamber P2 along the axial direction of the second valve core. Figure 4 As shown, the exhaust passage 65a is arranged on the outer peripheral surface of the second outer shoulder portion 65. That is, the exhaust passage 65a is a notch extending in the axial direction from the end surface of the second outer shoulder portion 65 facing the second pilot chamber P2 on the outer peripheral surface of the second outer shoulder portion 65. In addition, the exhaust passage 65a may also pass through the inside of the second outer shoulder portion 65.

[0063] The exhaust passage 65a cuts off the second tank passage 27b from the second pilot chamber P2 when the second valve core 60 is located at the second neutral position, and connects the second pilot chamber P2 and the second tank passage 27b when the second valve core 60 moves from the neutral position to a direction away from the second pilot chamber P2 by more than a specified distance.

[0064] The function of the exhaust passage 65a will be described. To explain in more detail, in the valve device 10 of the present embodiment, the second valve core 60 is located above the first valve core 50. For example, when the valve core 12A does not move when the construction machine is left for a certain period of time, the bubbles in the working oil in the first pilot chamber P1 and the valve core hole 23A gradually rise to the second pilot chamber P2 located above the first pilot chamber P1 and the valve core hole 23A including the third pilot chamber P3 through the gap between the inner peripheral surface of the valve core hole 23A and the outer peripheral surface of the valve core 12A. Therefore, the air in the second pilot chamber P2 gradually accumulates over time. In this way, even if the air accumulates in the second pilot chamber P2, when the hydraulic excavator 1 starts to be used, by moving the second valve core 60 in a direction close to the first valve core 50, for example, full stroke, the air accumulated in the second pilot chamber P2 can be released to the second tank passage 27b with a lower pressure than the second pilot chamber P2 through the exhaust passage 65a.

[0065] (Leakage passage) like Figure 7 As shown, the first valve core 50 has a first leakage passage 81, which extends from a portion on the outer peripheral surface of the first inner shoulder portion 51, which is located closer to the third pilot chamber P3 side than the connection portion between the boom cylinder valve core hole 23A and the first pump passage 25a, to the first outer small diameter portion 54. The first leakage passage 81 includes a first inlet port 81a and a first outlet port 81b. The first inlet port 81a is arranged on a portion of the first inner shoulder portion 51 that cuts off the first pump passage 25a and the third pilot chamber P3. The first outlet port 81b is arranged on the first outer small diameter portion 54. The portion between the first inlet port 81a and the first outlet port 81b in the first leakage passage 81 passes through the interior of the first valve core 50.

[0066] More specifically, the first inner shoulder portion 51 has a first leakage groove 51b on its outer circumferential surface. The first leakage groove 51b is positioned on the outer circumferential surface of the first inner shoulder portion 51 so as to always be located between the connection portion of the third pilot chamber P3 and the first pump passage 25a in the boom cylinder valve core hole 23A even when the first valve core 50 and the second valve core 60 move away from each other. The first inlet port 81a is disposed on the first leakage groove 51b.

[0067] The second valve core 60 has a second leakage passage 82 extending from a portion on the outer peripheral surface of the second inner shoulder portion 61, which is located closer to the third pilot chamber P3 than the connection portion between the boom cylinder valve core hole 23A and the second pump passage 25b, to the second outer small diameter portion 64. The second leakage passage 82 includes a second inlet port 82a and a second outlet port 82b. The second inlet port 82a is arranged at a portion that cuts off the second pump passage 25b and the third pilot chamber P3 in the second inner shoulder portion 61. The second outlet port 82b is arranged at the second outer small diameter portion 64. The portion between the second inlet port 82a and the second outlet port 82b in the second leakage passage 82 passes through the interior of the second valve core 60.

[0068] More specifically, the second inner shoulder portion 61 has a second leakage groove 61a on its outer circumferential surface. The second leakage groove 61a is positioned on the outer circumferential surface of the second inner shoulder portion 61 so as to always be located between the connection portion between the third pilot chamber P3 and the second pump passage 25b in the boom cylinder valve core hole 23A even when the first valve core 50 and the second valve core 60 move away from each other. The second leakage groove 61a is provided with a second inlet port 82a.

[0069] (Identification mark) like Figure 4As shown, the first valve core 50 has a first identification mark 91 for identifying the first valve core 50. The first identification mark 91 is arranged on the outer peripheral surface of the first inner small diameter portion 52. The first identification mark 91 is, for example, engraved. The first identification mark 91 can be directly engraved on the small diameter portion of the first valve core 50. Alternatively, the first identification mark 91 can also be engraved on other components such as a nameplate installed relative to the small diameter portion of the first valve core 50. The engraving can be, for example, laser engraving, or it can be engraving using a puncher or an air pen. The model of the first valve core 50 can be grasped by the first identification mark 91.

[0070] The first identification mark 91 includes not only information for identifying the first valve core 50, but also information for identifying the first spring 31 that applies force to the first valve core 50. Specifically, in this embodiment, the first cover 11C, the first spring 31, the head attachment rod 32, and the first valve core 50 constitute a unit that is integrally mounted relative to the housing body 11A, and the first identification mark 91 can realize the identification of the unit. That is, the type of the first spring 31 can be grasped through the first identification mark 91.

[0071] In the present embodiment, the first inner small diameter portion 52 is longer in the axial direction than the first outer small diameter portion 54. Therefore, there is more space for arranging marks on the outer peripheral surface of the first inner small diameter portion 52, so the first identification mark 91 is arranged on the outer peripheral surface of the first inner small diameter portion 52, but the first identification mark 91 may also be arranged on the first outer small diameter portion 54.

[0072] The second valve core 60 has a second identification mark 92 for identifying the second valve core 60. The second identification mark 92 is arranged on the outer peripheral surface of the second outer small diameter portion 64. The second identification mark 92 is, for example, engraved. For example, the second identification mark 92 can be directly engraved on the small diameter portion of the second valve core 60. Alternatively, the second identification mark 92 can also be engraved on other components such as a nameplate installed relative to the small diameter portion of the second valve core 60. The engraving can be, for example, laser engraving, or it can be engraving using a puncher or an air pen. The model of the second valve core 60 can be grasped by the second identification mark 92.

[0073] The second identification mark 92 includes not only information for identifying the second valve core 60, but also information for identifying the second spring 33 that applies force to the second valve core 60. Specifically, in this embodiment, the second cover 11D, the second spring 33, the head attachment rod 34, and the second valve core 60 constitute a unit integrally mounted relative to the housing body 11A, and the second identification mark 92 can realize the identification of the unit. That is, the type of the second spring 33 can be grasped through the second identification mark 92.

[0074] In this embodiment, the second inner small diameter portion 62 and the second outer small diameter portion 64 have substantially the same length in the axial direction. The oil pressure of the annular space S3 around the second inner small diameter portion 62 is lower than the oil pressure of the annular space S4 around the second outer small diameter portion 64, so in this embodiment, the second identification mark 92 is arranged on the outer peripheral surface of the second outer small diameter portion 64 to avoid high pressure as much as possible, but the second identification mark 92 can also be arranged on the second inner small diameter portion 62.

[0075] (Effect) As described above, in the valve device 10 of the present embodiment, when the first valve core 50 is located at the first neutral position, the annular space S2 around the first outer small diameter portion 54 communicates with the first tank passage 27a, and when the second valve core 60 is located at the second neutral position, the annular space S4 around the second outer small diameter portion 64 communicates with the second tank passage 27b. Therefore, the flow path cross-sectional area at the intersection of the first tank passage 27a and the second tank passage 27b with the boom cylinder valve core hole 23A can be ensured, and the pressure loss of the working oil flowing in the first tank passage 27a and the second tank passage 27b can be reduced. As a result, the stability of the flow of the working oil can be improved.

[0076] Furthermore, in order to lower the boom, the second valve core 60 is moved, and when the working oil flows from the head side passage 29 to the second tank passage 27b, the flow rate of the working oil from the head side passage 29 to the second tank passage 27b is large. In this embodiment, when the second valve core 60 is located at the second neutral position, the end of the head side passage 29 is closed by the outer peripheral surface of the second intermediate shoulder portion 63. Therefore, when the working oil flows from the head side passage 29 to the second tank passage 27b, the pressure of the head side passage 29 is borne by the outer peripheral surface of the second intermediate shoulder portion 63, and the pressure of the annular space S4 around the second outer small diameter portion 64 is kept low. Therefore, when the boom falls, the second valve core 60 is less likely to be subjected to the axial fluid force from the working oil.

[0077] In the present embodiment, the number of the plurality of fourth notches 63b is greater than the number of the plurality of third notches 63a, so that the flow rate of the hydraulic oil sent from the head side chamber 5b to the tank 7 through the plurality of fourth notches 63b when the boom is lowered can be increased.

[0078] In the present embodiment, the plurality of first notches 51a have a slope portion whose depth decreases as they move away from the end surface of the first inner shoulder portion 51 connected to the first inner small diameter portion 52. Therefore, it is possible to prevent the opening area from changing greatly with respect to the stroke of the first valve element 50 when the boom is lowered. Figure 8 A graph showing the relationship between the stroke amount of the first valve element 50 when the boom is lowered and the opening area of ​​the inlet flow path, in other words, the opening area of ​​the flow path from the first pump passage 25a to the rod side passage 28. Figure 8As shown, by making the first notch 51a have the aforementioned slope, the rate of increase of the flow path cross-sectional area of ​​the inner peripheral surface surrounding the first notch 51a and the valve core hole 23A relative to the stroke amount of the first valve core 50 is kept constant or substantially constant. This can prevent a large amount of working oil from flowing into the rod side chamber 5a when the boom falls.

[0079] Furthermore, in the present embodiment, the working oil leaking from the first pump passage 25a to between the outer peripheral surface of the first inner shoulder portion 51 and the inner peripheral surface of the valve core hole 23A for the boom cylinder can be allowed to escape to the first tank passage 27a through the first leakage passage 81, and the working oil leaking from the second pump passage 25b to between the outer peripheral surface of the second inner shoulder portion 61 and the inner peripheral surface of the valve core hole 23A for the boom cylinder can be allowed to escape to the second tank passage 27b through the second leakage passage 82.

[0080] In the present embodiment, the first valve core 50 has the first identification mark 91, and the second valve core 60 has the second identification mark 92, so that the first valve core 50 and the second valve core 60 can be identified. In addition, the first identification mark 91 and the second identification mark 92 are arranged at a position that does not contact the housing 11, so that the degradation of each identification mark can be suppressed.

[0081] Furthermore, in the present embodiment, the diameter of the first outer small diameter portion 54 is larger than the diameter of the first inner small diameter portion 52. By increasing the diameter of the first outer small diameter portion 54 in this way, when the hydraulic oil flows from the rod side passage 28 to the first tank passage 27a, the oil pressure received in the axial direction by the end surface of the first intermediate shoulder portion 53 on the opposite side of the first outer small diameter portion 54 can be supported.

[0082] (Other embodiments) The present disclosure is not limited to the aforementioned embodiments, and the structures thereof can be changed, added, or deleted.

[0083] In the above embodiment, the valve device is mounted on a hydraulic excavator, but the construction machine on which the valve device is mounted is not limited thereto. For example, the construction machine may be another construction machine including a boom cylinder such as a hydraulic crane.

[0084] In the above embodiment, the plurality of valve cores 12 extend in the up-down direction, but the orientation of the valve core 12 is not limited thereto. For example, the posture of the valve device can be freely determined according to the construction machine in which the valve device is assembled. For example, the plurality of valve cores and the plurality of valve core holes in the valve device can be inclined relative to the up-down direction, or extend in the horizontal direction.

[0085] In the above embodiment, the plurality of valve elements 12 are all arranged in one row, but the arrangement of the plurality of valve elements 12 is not limited thereto. The plurality of valve elements 12 may be arranged in two or more rows.

[0086] The shapes of the first valve core 50 and the second valve core 60 are not limited to those described in the above embodiment. For example, the axial width and diameter of the plurality of shoulder portions and the plurality of small diameter portions included in the first valve core 50 and the second valve core 60 can be adaptively changed. For example, the diameter of the first outer small diameter portion 54 can be the same as the diameter of the first inner small diameter portion 52, or can be smaller than the diameter of the first inner small diameter portion 52.

[0087] In the above embodiment, the first valve core 50 is a structure having three shoulder portions 51, 53, and 55, but the first valve core 50 may be provided with four or more shoulder portions. For example, the first inner shoulder portion 51 may be a structure including a first sub-shoulder portion and a second sub-shoulder portion connected to each other in the axial direction through a small diameter portion. In this case, the first sub-shoulder portion may open and close the rod side passage 28 and the first pump passage 25a, and the second sub-shoulder portion may cut off the first pump passage 25a from the third pilot chamber P3. In addition, the annular space around the small diameter portion connecting the first sub-shoulder portion and the second sub-shoulder portion may be connected to the first pump passage 25a when the first valve core 50 is at least in the first neutral position. In addition, the first leakage groove 51b may be arranged on the outer peripheral surface of the second sub-shoulder portion. In this way, the first inner shoulder portion may include a plurality of sub-shoulder portions as long as it has the functions described in the above embodiment, that is, the function of opening and closing the rod side passage and the first pump passage and cutting off the first pump passage and the third pilot chamber. Similarly, each of the first intermediate shoulder portion and the first outer shoulder portion may include a plurality of sub-shoulder portions as long as they have the functions of each shoulder portion described in the above embodiment.

[0088] In the above embodiment, the second valve core 60 is a structure having three shoulder portions 61, 63, and 65, but the second valve core 60 may be provided with four or more shoulder portions. For example, the second intermediate shoulder portion 63 may be a structure including a third sub-shoulder portion and a fourth sub-shoulder portion connected to each other in the axial direction through a small diameter portion. In this case, the third sub-shoulder portion may open and close the head side passage 29 and the second pump passage 25b, and the fourth sub-shoulder portion may open and close the head side passage 29 and the second tank passage 27b. The annular space around the small diameter portion connecting the third sub-shoulder portion and the fourth sub-shoulder portion may be connected to the head side passage 29 when the second valve core 60 is at least in the second neutral position. In this way, the second intermediate shoulder portion may include a plurality of sub-shoulder portions as long as it has the functions described in the above embodiment, that is, the functions of opening and closing the head side passage and the second pump passage and opening and closing the head side passage and the second tank passage. Similarly, each of the second inner shoulder portion and the second outer shoulder portion may include a plurality of sub-shoulder portions as long as they have the functions of each shoulder portion described in the above embodiment.

[0089] The first valve core 50 may have only two shoulder portions. For example, the first valve core may include a first pump side shoulder portion that opens and closes the rod side passage and the first pump passage, a first tank side shoulder portion that opens and closes the rod side passage and the first tank passage, and a first small diameter portion that connects the first pump side shoulder portion and the first tank side shoulder portion. In this case, when the first valve core is located at the first neutral position that cuts off the rod side passage from both the first pump passage and the first tank passage, the end of the first tank passage may be closed by the outer peripheral surface of the first tank side shoulder portion.

[0090] As long as the first valve core and the second valve core have the functions of each valve core, the outer peripheral surface of the shoulder portion of each valve core of the first valve core and the second valve core may have a groove. For example, the groove on the outer peripheral surface of the shoulder portion may extend in the circumferential direction or in the axial direction. For example, in the above-mentioned embodiment, the outer peripheral surface of the first inner shoulder portion 51 has the first leakage groove 51b, but the outer peripheral surface of the first inner shoulder portion 51 may also have grooves other than the first leakage groove 51b. Again, for example, in the above-mentioned embodiment, the outer peripheral surface of the second inner shoulder portion 61 has the second leakage groove 61a, but the outer peripheral surface of the second inner shoulder portion 61 may also have grooves other than the second leakage groove 61a.

[0091] The second outer shoulder portion 65 has the exhaust passage 65 a , but the first outer shoulder portion 55 may have an exhaust passage instead of or in addition to the second outer shoulder portion 65 having the exhaust passage 65 a .

[0092] In the above embodiment, the second intermediate shoulder portion 63 may not have the plurality of fourth notches 63b for connecting the head side passage 29 and the second tank passage 27b. Furthermore, the shape and number of each notch of the first notch 51a, the second notch 53a, the third notch 63a, and the fourth notch 63b are not limited to the above description and the contents of the drawings. For example, all the first notches 51a may have the aforementioned slope, and a portion of the first notches may not have the slope. It is sufficient that at least one of the first notches has the slope.

[0093] Only one of the first valve body 50 and the second valve body 60 may have an identification mark, or both of the first valve body 50 and the second valve body 60 may not have an identification mark. The first identification mark 91 and the second identification mark 92 may not include information for identifying the spring.

[0094] Contrary to the above-mentioned embodiment, when the first valve core 50 and the second valve core 60 move closer to each other, the rod side passage 28 and the head side passage 29 are respectively connected to the supply passage 25 and the discharge passage 27; when the first valve core 50 and the second valve core 60 move away from each other, the head side passage 29 and the rod side passage 28 are respectively connected to the supply passage 25 and the discharge passage 27.

[0095] In the above embodiment, the first pump passage 25a, the rod side passage 28, and the first tank passage 27a are connected in this order in the direction from the third pilot chamber P3 to the first pilot chamber P1 with respect to the valve core hole 23A, but the connection point between the first pump passage 25a and the valve core hole 23A and the connection point between the first tank passage 27a and the valve core hole 23A may be opposite. In addition, in the above embodiment, the second pump passage 25b, the head side passage 29, and the second tank passage 27b are connected in this order in the direction from the third pilot chamber P3 to the second pilot chamber P2 with respect to the valve core hole 23A, but the connection point between the second pump passage 25b and the valve core hole 23A and the connection point between the second tank passage 27b and the valve core hole 23A may be opposite.

[0096] [Public form] The following aspects are disclosures of preferred embodiments.

[0097] [Form 1] A valve device for a construction machine that controls the flow of hydraulic oil supplied to and discharged from a plurality of hydraulic actuators including a boom cylinder, comprising: A first valve core and a second valve core are separated from each other in the axial direction; and A housing having: a plurality of valve core holes, including a valve core hole for a boom cylinder into which the first valve core and the second valve core are inserted; a first pump passage, a second pump passage, a first tank passage, and a second tank passage, which are connected to the valve core hole for the boom cylinder; a rod side passage, which is connected to the valve core hole for the boom cylinder and to the rod side chamber of the boom cylinder; a head side passage, which is connected to the valve core hole for the boom cylinder and to the head side chamber of the boom cylinder; and a first pilot chamber and a second pilot chamber, which are located on both sides of the valve core hole for the boom cylinder; The portion between the first valve core and the second valve core in the valve core hole of the boom cylinder constitutes a third pilot chamber; The first tank passage and the second tank passage intersect the plurality of valve core holes respectively; The first valve element moves between a first neutral position for cutting off the rod side passage from both the first pump passage and the first tank passage and a first boom driving position for connecting the rod side passage to either the first pump passage or the first tank passage, according to a pressure difference between the first pilot chamber and the third pilot chamber; The second valve element moves between a second neutral position for cutting off the head side passage from both the second pump passage and the second tank passage and a second boom driving position for connecting the head side passage to either the second pump passage or the second tank passage, according to a pressure difference between the second pilot chamber and the third pilot chamber; Each valve core of the first valve core and the second valve core includes: three or more shoulder portions arranged at intervals along the axial direction; and two or more small-diameter portions connecting adjacent shoulder portions; The annular space around one of the two or more small-diameter portions of the first valve element is communicated with the first tank passage when the first valve element is at least located at the first neutral position; The annular space around one of the two or more small-diameter portions of the second valve element communicates with the second tank passage when the second valve element is located at least in the second neutral position.

[0098] According to the above structure, when the first valve core is located at the first neutral position, the annular space around the small diameter portion of the first valve core is connected to the first tank passage, and when the second valve core is located at the second neutral position, the annular space around the small diameter portion of the second valve core is connected to the second tank passage. Therefore, the flow path cross-sectional area at the intersection of the first tank passage and the second tank passage with the boom cylinder valve core hole can be ensured, and the pressure loss of the working oil flowing in the first tank passage and the second tank passage can be reduced. As a result, the stability of the flow of the working oil can be improved.

[0099] [Form 2] According to the valve device described in form 1, The three or more shoulder portions of the first valve core include: a first inner shoulder portion for opening and closing the rod-side passage and the first pump passage; a first intermediate shoulder portion for opening and closing the rod-side passage and the first tank passage; and a first outer shoulder portion that cuts off the first tank passage from the first pilot chamber; The two or more small-diameter portions of the first valve core include: a first inner small diameter portion connecting the first inner shoulder portion and the first intermediate shoulder portion; and a first outer small diameter portion connecting the first outer shoulder portion and the first intermediate shoulder portion; The three or more shoulder portions of the second valve core include: a second inner shoulder portion that cuts off the second pump passage from the third pilot chamber; a second intermediate shoulder portion that opens and closes the head-side passage and the second pump passage, and opens and closes the head-side passage and the second tank passage; and a second outer shoulder portion that cuts off the second tank passage from the second pilot chamber; The two or more small-diameter portions of the second valve core include: a second inner small diameter portion connecting the second inner shoulder portion and the second intermediate shoulder portion; and A second outer small diameter portion connects the second outer shoulder portion and the second intermediate shoulder portion.

[0100] In order to lower the boom, the second valve core is moved, and when the working oil flows from the head side passage to the second tank passage, the flow rate of the working oil from the head side passage to the second tank passage is large. According to the structure, when the second valve core is located at the second neutral position, the head side passage is closed by the second intermediate shoulder. Therefore, when the working oil flows from the head side passage to the second tank passage, the pressure of the head side passage is borne by the outer peripheral surface of the second intermediate shoulder, and the pressure of the annular space around the second outer small diameter portion is ensured to be low. Therefore, when the boom falls, the second valve core is less likely to be affected by the fluid force from the working oil.

[0101] [Form 3] According to the valve device described in the second embodiment, when the first valve element is at least in the first neutral position, the first inner shoulder portion cuts off the rod side passage and the first pump passage, and the first intermediate shoulder portion cuts off the rod side passage and the first tank passage; When the second valve element is located at least in the second neutral position, the second intermediate shoulder portion blocks the head-side passage from the second pump passage and blocks the head-side passage from the second tank passage.

[0102] According to the above configuration, when the first valve element is located at the first neutral position and the second valve element is located at the second neutral position, the hydraulic oil is not supplied or discharged to or from the boom cylinder, so the boom can be stopped in advance.

[0103] [Form 4] The valve device according to the second or third aspect, wherein the first inner shoulder portion has a plurality of first notches, the plurality of first notches being arranged at intervals in the circumferential direction at an end portion on the first inner small diameter portion side of the outer circumferential surface of the first inner shoulder portion, for connecting the rod side passage and the first pump passage; The first intermediate shoulder portion has a plurality of second notches arranged at intervals in the circumferential direction at an end portion of the outer circumferential surface of the first intermediate shoulder portion on the side of the first inner small diameter portion, for connecting the rod side passage and the first tank passage; The second intermediate shoulder portion has a plurality of third notches arranged at intervals in the circumferential direction at an end portion of the outer peripheral surface of the second intermediate shoulder portion on the second inner small diameter portion side for connecting the head side passage and the second pump passage.

[0104] According to the above structure, the controllability of the flow rate of the working oil from the first pump passage to the rod side passage, the flow of working oil from the rod side passage to the first tank passage, and the flow of working oil from the second pump passage to the head side passage can be improved.

[0105] [Form 5] According to the valve device described in the fourth embodiment, the second intermediate shoulder portion has a plurality of fourth notches, the plurality of fourth notches are arranged at intervals in the circumferential direction at an end portion on the second outer small diameter portion side of the outer peripheral surface of the second intermediate shoulder portion, and are used to connect the head side passage and the second tank passage; The number of the plurality of fourth notches is greater than the number of the plurality of third notches.

[0106] According to the above configuration, the flow rate of the hydraulic oil sent from the head side chamber to the tank through the plurality of fourth notches when the boom is lowered can be increased.

[0107] [Form 6] According to the valve device described in aspect 4 or 5, at least one of the plurality of first notches has a slope portion whose depth decreases as it moves away from an end surface of the first inner shoulder portion connected to the first inner small-diameter portion.

[0108] According to the above configuration, the opening area can be prevented from changing more with respect to the stroke of the first valve element when the boom is lowered. Therefore, a large amount of hydraulic oil can be suppressed from flowing into the rod side chamber when the boom is lowered.

[0109] [Form 7] A valve device according to any one of aspects 2 to 6, The second outer shoulder portion has an exhaust passage, which cuts off the second tank passage from the second pilot chamber when the second valve core is located at the second neutral position, and connects the second pilot chamber and the second tank passage when the second valve core moves more than a specified distance from the second neutral position in a direction away from the second pilot chamber.

[0110] According to the above structure, for example, when time passes in a state where the valve device is arranged in a form in which the second valve core is located above the first valve core, air gradually accumulates in the second pilot chamber located above the valve core hole for the boom cylinder as time passes. In this case, the air accumulated in the second pilot chamber can escape to the external second tank passage through the exhaust passage by the movement of the second valve core.

[0111] [Form 8] A valve device according to any one of aspects 2 to 7, The first valve core has a first leakage passage extending from a portion of the outer peripheral surface of the first inner shoulder portion located closer to the third pilot chamber than a connection portion between the boom cylinder valve core hole and the first pump passage to the first outer small diameter portion; The second valve body has a second leakage passage extending from a portion of the outer peripheral surface of the second inner shoulder portion located closer to the third pilot chamber than a connection portion between the boom cylinder valve body hole and the second pump passage to the second outer small diameter portion.

[0112] According to the structure, the working oil leaking from the first pump passage side to the space between the outer peripheral surface of the first inner shoulder portion and the inner peripheral surface of the valve core hole for the boom cylinder can escape to the first tank passage through the first leakage passage, and the working oil leaking from the second pump passage side to the space between the outer peripheral surface of the second inner shoulder portion and the inner peripheral surface of the valve core hole for the boom cylinder can escape to the second tank passage through the second leakage passage.

[0113] [Form 9] According to the valve device described in form 8, The outer peripheral surface of the first inner shoulder portion has a first leakage groove; The first leakage passage includes a first inlet port disposed in the first leakage groove and a first outlet port disposed in the first outer small diameter portion; The outer peripheral surface of the second inner shoulder portion has a second leakage groove; The second leakage passage includes a second inlet port disposed in the second leakage groove and a second outlet port disposed in the second outer small-diameter portion.

[0114] [Form 10] A valve device according to any one of aspects 2 to 9, At least one of the first valve element and the second valve element has an identification mark for identifying the at least one valve element on an outer peripheral surface of the small-diameter portion of the at least one valve element.

[0115] According to the above structure, at least one of the first valve body and the second valve body can be identified by the identification mark. In addition, since the identification mark is arranged in the small diameter portion that does not contact the housing, degradation of the identification mark can be suppressed.

[0116] [Form 11] A valve device according to any one of aspects 2 to 10, The first outer small-diameter portion has a diameter larger than that of the first inner small-diameter portion.

[0117] According to the above configuration, by increasing the diameter of the first outer small diameter portion, the oil pressure in the axial direction received by the end surface of the first intermediate shoulder portion on the opposite side of the first outer small diameter portion can be supported when the hydraulic oil flows from the rod side passage to the first tank passage.

[0118] [Form 12] A valve device for a construction machine that controls the flow of hydraulic oil supplied to and discharged from a plurality of hydraulic actuators including a boom cylinder, comprising: A first valve core and a second valve core are separated from each other in the axial direction; and A housing having: a plurality of valve core holes, including a valve core hole for a boom cylinder into which the first valve core and the second valve core are inserted; a first pump passage, a second pump passage, a first tank passage, and a second tank passage, which are connected to the valve core hole for the boom cylinder; a rod side passage, which is connected to the valve core hole for the boom cylinder and to the rod side chamber of the boom cylinder; a head side passage, which is connected to the valve core hole for the boom cylinder and to the head side chamber of the boom cylinder; and a first pilot chamber and a second pilot chamber, which are located on both sides of the valve core hole for the boom cylinder; The portion between the first valve core and the second valve core in the valve core hole of the boom cylinder constitutes a third pilot chamber; The first valve core comprises: a first pump side shoulder portion for opening and closing the rod side passage and the first pump passage; a first tank-side shoulder portion for opening and closing the rod-side passage and the first tank passage; and a first small diameter portion connecting the first pump side shoulder portion and the first tank side shoulder portion; The second valve core comprises: a second inner shoulder portion that cuts off the second pump passage from the third pilot chamber; a second intermediate shoulder portion that opens and closes between the head-side passage and the second pump passage, and opens and closes between the head-side passage and the second tank passage; a second outer shoulder portion that cuts off the second tank passage from the second pilot chamber; a second inner small diameter portion connecting the second inner shoulder portion and the second intermediate shoulder portion; and a second outer small diameter portion connecting the second outer shoulder portion and the second intermediate shoulder portion; The first pump side shoulder portion has a plurality of first notches arranged at intervals in the circumferential direction at an end portion on the first small diameter portion side of the outer peripheral surface of the first pump side shoulder portion for connecting the rod side passage and the first pump passage; At least one of the plurality of first notches has a slope portion whose depth decreases as it moves away from the end surface of the first pump-side shoulder portion to which the first small-diameter portion is connected.

[0119] According to the above structure, the change amount of the opening area relative to the stroke of the first valve core when the boom is lowered can be prevented from increasing. Therefore, a large amount of working oil flowing into the rod side chamber when the boom is lowered can be suppressed. Therefore, the stability of the flow of working oil can be improved.

Claims

1. A valve device, characterized in that: A valve device for construction machinery that controls the flow of hydraulic oil supplied to and discharged from a plurality of hydraulic actuators including a boom cylinder, comprising: A first valve core and a second valve core are separated from each other in the axial direction; and A housing having: a plurality of valve core holes, including a valve core hole for a boom cylinder into which the first valve core and the second valve core are inserted; a first pump passage, a second pump passage, a first tank passage, and a second tank passage, which are connected to the valve core hole for the boom cylinder; a rod side passage, which is connected to the valve core hole for the boom cylinder and to the rod side chamber of the boom cylinder; a head side passage, which is connected to the valve core hole for the boom cylinder and to the head side chamber of the boom cylinder; and a first pilot chamber and a second pilot chamber, which are located on both sides of the valve core hole for the boom cylinder; The portion between the first valve core and the second valve core in the valve core hole of the boom cylinder constitutes a third pilot chamber; The first tank passage and the second tank passage intersect the plurality of valve core holes respectively; The first valve element moves between a first neutral position for cutting off the rod side passage from both the first pump passage and the first tank passage and a first boom driving position for connecting the rod side passage to either the first pump passage or the first tank passage, according to a pressure difference between the first pilot chamber and the third pilot chamber; The second valve element moves between a second neutral position for cutting off the head side passage from both the second pump passage and the second tank passage and a second boom driving position for connecting the head side passage to either the second pump passage or the second tank passage, according to a pressure difference between the second pilot chamber and the third pilot chamber; Each valve core of the first valve core and the second valve core includes: three or more shoulder portions arranged at intervals along the axial direction; and two or more small-diameter portions connecting adjacent shoulder portions; The annular space around one of the two or more small-diameter portions of the first valve element is communicated with the first tank passage when the first valve element is at least located at the first neutral position; The annular space around one of the two or more small-diameter portions of the second valve element communicates with the second tank passage when the second valve element is located at least in the second neutral position.

2. The valve device according to claim 1, characterized in that The three or more shoulder portions of the first valve core include: a first inner shoulder portion for opening and closing the rod-side passage and the first pump passage; a first intermediate shoulder portion for opening and closing the rod-side passage and the first tank passage; and a first outer shoulder portion that cuts off the first tank passage from the first pilot chamber; The two or more small-diameter portions of the first valve core include: a first inner small diameter portion connecting the first inner shoulder portion and the first intermediate shoulder portion; and a first outer small diameter portion connecting the first outer shoulder portion and the first intermediate shoulder portion; The three or more shoulder portions of the second valve core include: a second inner shoulder portion that cuts off the second pump passage from the third pilot chamber; a second intermediate shoulder portion that opens and closes the head-side passage and the second pump passage, and opens and closes the head-side passage and the second tank passage; and a second outer shoulder portion that cuts off the second tank passage from the second pilot chamber; The two or more small-diameter portions of the second valve core include: a second inner small diameter portion connecting the second inner shoulder portion and the second intermediate shoulder portion; and A second outer small diameter portion connects the second outer shoulder portion and the second intermediate shoulder portion.

3. The valve device according to claim 2, characterized in that When the first valve element is at least in the first neutral position, the first inner shoulder portion blocks the rod side passage and the first pump passage, and the first intermediate shoulder portion blocks the rod side passage and the first tank passage; When the second valve element is located at least in the second neutral position, the second intermediate shoulder portion blocks the head-side passage from the second pump passage and blocks the head-side passage from the second tank passage.

4. The valve device according to claim 2 or 3, characterized in that: The first inner shoulder portion has a plurality of first notches arranged at intervals in the circumferential direction at an end portion of the outer circumferential surface of the first inner shoulder portion on the side of the first inner small-diameter portion, for connecting the rod-side passage and the first pump passage; The first intermediate shoulder portion has a plurality of second notches arranged at intervals in the circumferential direction at an end portion of the outer circumferential surface of the first intermediate shoulder portion on the side of the first inner small diameter portion, for connecting the rod side passage and the first tank passage; The second intermediate shoulder portion has a plurality of third notches arranged at intervals in the circumferential direction at an end portion of the outer peripheral surface of the second intermediate shoulder portion on the second inner small diameter portion side for connecting the head side passage and the second pump passage.

5. The valve device according to claim 4, characterized in that The second intermediate shoulder portion has a plurality of fourth notches arranged at intervals in the circumferential direction at an end portion of the outer peripheral surface of the second intermediate shoulder portion on the side of the second outer small diameter portion, for connecting the head side passage and the second tank passage; The number of the plurality of fourth notches is greater than the number of the plurality of third notches.

6. The valve device according to claim 4, characterized in that At least one of the plurality of first notches includes a slope portion whose depth decreases as it moves away from the end surface of the first inner shoulder portion to which the first inner small-diameter portion is connected.

7. The valve device according to claim 2 or 3, characterized in that: The second outer shoulder portion has an exhaust passage, which cuts off the second tank passage from the second pilot chamber when the second valve core is located at the second neutral position, and connects the second pilot chamber and the second tank passage when the second valve core moves more than a specified distance from the second neutral position in a direction away from the second pilot chamber.

8. The valve device according to claim 2 or 3, characterized in that: The first valve core has a first leakage passage extending from a portion of the outer peripheral surface of the first inner shoulder portion located closer to the third pilot chamber than a connection portion between the boom cylinder valve core hole and the first pump passage to the first outer small diameter portion; The second valve core has a second leakage passage extending from a portion of the outer peripheral surface of the second inner shoulder portion, which is located closer to the third pilot chamber than a connection portion between the boom cylinder valve core hole and the second pump passage, to the second outer small diameter portion.

9. The valve device according to claim 8, characterized in that The outer peripheral surface of the first inner shoulder portion has a first leakage groove; The first leakage passage includes a first inlet port disposed in the first leakage groove and a first outlet port disposed in the first outer small diameter portion; The outer peripheral surface of the second inner shoulder portion has a second leakage groove; The second leakage passage includes a second inlet port disposed in the second leakage groove and a second outlet port disposed in the second outer small-diameter portion.

10. The valve device according to claim 2 or 3, characterized in that: At least one of the first valve element and the second valve element has an identification mark for identifying the at least one valve element on an outer peripheral surface of the small diameter portion of the at least one valve element.

11. The valve device according to claim 2 or 3, characterized in that The first outer small-diameter portion has a diameter larger than that of the first inner small-diameter portion.

12. A valve device, characterized in that: A valve device for construction machinery that controls the flow of hydraulic oil supplied to and discharged from a plurality of hydraulic actuators including a boom cylinder, comprising: A first valve core and a second valve core are separated from each other in the axial direction; and A housing having: a plurality of valve core holes, including a valve core hole for a boom cylinder into which the first valve core and the second valve core are inserted; a first pump passage, a second pump passage, a first tank passage, and a second tank passage, which are connected to the valve core hole for the boom cylinder; a rod side passage, which is connected to the valve core hole for the boom cylinder and to the rod side chamber of the boom cylinder; a head side passage, which is connected to the valve core hole for the boom cylinder and to the head side chamber of the boom cylinder; and a first pilot chamber and a second pilot chamber, which are located on both sides of the valve core hole for the boom cylinder; The portion between the first valve core and the second valve core in the valve core hole of the boom cylinder constitutes a third pilot chamber; The first valve core comprises: a first pump side shoulder portion for opening and closing the rod side passage and the first pump passage; a first tank-side shoulder portion for opening and closing the rod-side passage and the first tank passage; and a first small diameter portion connecting the first pump side shoulder portion and the first tank side shoulder portion; The second valve core comprises: a second inner shoulder portion that cuts off the second pump passage from the third pilot chamber; a second intermediate shoulder portion that opens and closes between the head-side passage and the second pump passage, and opens and closes between the head-side passage and the second tank passage; a second outer shoulder portion that cuts off the second tank passage from the second pilot chamber; a second inner small diameter portion connecting the second inner shoulder portion and the second intermediate shoulder portion; and a second outer small diameter portion connecting the second outer shoulder portion and the second intermediate shoulder portion; The first pump side shoulder portion has a plurality of first notches arranged at intervals in the circumferential direction at an end portion on the first small diameter portion side of the outer peripheral surface of the first pump side shoulder portion for connecting the rod side passage and the first pump passage; At least one of the plurality of first notches has a slope portion whose depth decreases as it moves away from the end surface of the first pump-side shoulder portion to which the first small-diameter portion is connected.

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