JPH09280161A - Variable displacement type piston pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compact a variable capacity type piston pump, constituting a power source for a construction machine of a shovel, etc., and also improve efficiency, and prevent the pollution of a pressurized oil and so on. SOLUTION: A variable capacity type piston pump is equipped with a cylinder block 2, for rotating integrally with a pump spindle 1; cylinder arrays 4a and 4b, formed in a cylinder block, and for housing reciprocatingly and slidably pistons 41 and 42; and a swash plate 50 for adjusting strokes of the reciprocating movement of the pistons. A group of ports 21, 22, and 23, communicated with cylinder chambers 24a, 24b, and 25 are formed on three or more concentric circumferential positions, having different diameters with each other, on the port side end surface 2a of the cylinder block. A suction side penetration hole, for communicating concurrently with about a half number of the port group, is formed in the suction side range of a valve plate 3 joined to the port side end surface; while, three or more delivery side penetration holes 32, 33, and 34, for communicating concurrently with the about half number of the port group formed on the concentric circumferential position, are formed on a delivery side. Then, a pressurized oil is independently discharged respectively, from the respective delivery side penetration holes, by the reciprocating movement of the pistons following the rotation of the cylinder block.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic piston pump for supplying a pressure liquid to various actuators to operate these actuators, and more particularly to a variable displacement piston pump used as a power source for construction machines such as shovels. Regarding

[0002]

2. Description of the Related Art Conventionally, in a construction machine such as a shovel, as shown in FIG. 7, three independent hydraulic systems are configured, and a first hydraulic system supplies pressure oil to a right side traveling system (100).
A pump (101), a second pump (111) for supplying pressure oil to the left traveling system (110), and a third pump (111) for supplying pressure oil to the swivel system (120).
Three hydraulic sources with pump (121) were needed. Here, the right-hand side traveling system (100) and the left-hand side traveling system (110) are independent of each other so that the straightness is maintained even when the loads applied to the left and right traveling systems (100, 110) are different from each other. This is because. In addition, the left and right running systems (100, 110) and turning system (1
20) is independent of the turning system even while driving
This is to keep the operation feeling of (120) good, and
This is to maintain straightness even during operation of (120).

Therefore, as a hydraulic power source for construction machines such as shovels, a multi-flow pump (200) having three flow paths as shown in FIG. 8 is generally adopted. This is a two-flow type piston pump (210) that independently supplies two equal amounts of discharge flow from one cylinder block (211).
In contrast, the input shaft (221) is the two-flow piston pump (2
Gear pump (22) rotated by pump shaft (212) of (10)
By adding 0), three flow paths are realized. For this type of two-flow piston pump,
For example, one described in JP-A-6-307330 is known. In this structure, a port group is formed at each of concentric circumferential positions having two different diameters centering on the pump shaft on the port-side end surface of the cylinder block. Then, for each of the even number of cylinder chambers formed in a row in the circumferential direction inside the cylinder block, each port constituting the above inner peripheral side port group and the above outer peripheral side port group are constituted. Connect each of the ports to be connected alternately one by one. Further, an arc-shaped inner groove that can communicate with the inner peripheral side port group and an arc-shaped outer groove that can communicate with the outer peripheral side port group are formed on the valve plate that is in sliding contact with the end surface. The pressure oil discharged from both of these grooves is independently supplied to each of the cylinder blocks, so that two equal-flow discharge flows are independently supplied. As a result, in the multi-flow pump, pressure oil is independently supplied from the double-flow piston pump to the left and right traveling systems, and pressure oil is independently supplied from the gear pump to the swivel system. You can do it.

[0004]

However, in the above-mentioned conventional multi-flow pump (200), the gear pump (220) is arranged on one end surface of the double-flow piston pump (210) in the pump axial direction. Therefore, the entire multi-flow pump (200) becomes large in the axial direction of the pump. Further, when driving these multi-flow pumps (200) by a prime mover, in general, since the output shaft of the prime mover and the pump shaft (212) are connected in series, this prime mover of the multi-flow pump (200) is connected. It must be arranged in the pump axial direction. Therefore, the multi-flow pump
Since the (200) lengthens in the axial direction of the pump, the power source as a whole must be increased in size. This is extremely inconvenient when designing a small excavator such as a so-called mini excavator having a weight of 6 tons or less.

Further, when the flow rate / pressure control of the conventional multi-flow pump (200) is performed by total horsepower control, the hydraulic system of the swivel system (120) supplied with pressure oil by the gear pump (220) is used. There is the actual situation that it has to be done except for it. This is because the amount of oil discharged from the gear pump (220) is determined by the input rotation speed from the prime mover, so the amount of oil discharged from the gear pump (220) is reduced in response to the increase in hydraulic pressure of the swivel system (120). Inevitably, the number of revolutions of the above-mentioned prime mover must be reduced, and as a result, the discharge oil amount of the two-flow piston pump (210) that is rotationally driven by the same prime mover becomes too low to effectively use the hydraulic pressure. Because. However, even in this case, the amount of discharge oil supplied to the hydraulic system of the swivel system (120) is determined irrespective of the hydraulic pressure, and as the hydraulic pressure increases, the load on the prime mover from the gear pump (220) increases. However, the prime mover is overloaded, and it is easy to cause inconveniences such as generation of black smoke and reduction in rotation speed. Moreover, when the hydraulic pressure of the hydraulic system of the swivel system (120) exceeds the maximum allowable value, there is no choice but to open the relief valve to release the hydraulic pressure, resulting in a large power loss.
Furthermore, a gear pump generally has a lower maximum discharge pressure and inferior sliding characteristics compared to a piston pump, so a multi-flow pump
(200) Overall operating efficiency is reduced by the addition of the gear pump (220). In addition, the gear pump has a disadvantage that abrasion powder is easily generated and the pressure oil is easily contaminated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-flow pump used for a construction machine such as an excavator, in which the outer dimensions of the multi-flow pump are particularly in the axial direction of the pump. It is to shorten the size and improve the mechanical efficiency, and at the same time, to prevent the overload of the prime mover while simultaneously improving the operating efficiency of the power source and the output.

[0007]

In order to achieve the above object, an invention according to claim 1 comprises a pump shaft (1) and a cylinder block (2) which rotates integrally with the pump shaft (1).
And the piston in each cylinder block (2)
(41, 41, ..., 42, 42, ...) A plurality of cylinder chambers (24a, 24) accommodating slidably in the longitudinal direction of the pump shaft (1).
a, ..., 24b, 24b, ..., 25, 25, ...) are two or more cylinder rows (4a) arranged at two or more concentric circumferential positions of different diameters centering on the pump shaft (1). , 4b). In addition, each of the cylinder rows (4a, 4
b), one or more swash plates (50) for adjusting the stroke of the reciprocating motion of the pistons (41, 41, ..., 42, 42, ...) and the end surface of the cylinder block (2) on the port side. (2a) and a valve plate (3) joined so as to be slidable relative to each other. Then, of the two or more cylinder rows (4a, 4b), the two cylinder arrays (24a or 25a) forming one cylinder row (4a) are arranged in the inner and outer peripheral directions so as to communicate with each other. Row ports (21,22)
And another one or more rows of port groups (23) arranged in the circumferential direction so as to communicate with each of the plurality of cylinder chambers (25) forming one or more other cylinder rows (4b). Side end face (2
It is formed at concentric circumferential positions of different diameters of a). Further, the pump shaft (1) of the valve plate (3)
A wide suction-side through hole (31) is formed in the suction-side range occupying substantially half of the circumference centering on the center of the above-mentioned port so as to be able to simultaneously communicate with substantially half of each of the above three or more rows of port groups. And, in the discharge side area which occupies the other approximately half in the circumferential direction of the valve plate (3), the port group (21,
(22, 23) and three or more arc-shaped discharge side through-holes (32, 33, 32) formed at concentric circumferential positions of different diameters centering on the pump shaft (1) so as to communicate individually with approximately half each. 34) is installed. Then, the above three or more discharge side through holes (32, 33, 3
4) is configured to independently discharge the pressure liquid by the reciprocating motion of the pistons (41, 42) accompanying the rotation of the cylinder block (2).

In the case of the above configuration, it is possible to supply the pressurized liquid as three or more independent discharge streams from one cylinder block (2) of one variable displacement piston pump, and one variable pump is provided. The displacement type piston pump makes it possible to configure a hydraulic pressure source for construction machines such as shovels. As a result, the gear pump in the conventional multi-flow pump can be omitted, and the dimension in the axial direction of the pump can be shortened by that amount, so that the power source can be made compact and Since it is possible to arrange the individual suction ports and the plurality of discharge ports on the same surface of the same member, it becomes possible to easily perform piping of the hydraulic system. At the same time, the number of bearings is reduced to reduce mechanical loss, and the sealing surface for high-pressure liquid is reduced, so that power loss due to liquid leakage is reduced. Further, since the gear pump is replaced by the piston pump, the volumetric efficiency is improved, the discharge pressure can be increased, and the generation of abrasion powder is reduced to prevent the pressure liquid from being contaminated.

According to a second aspect of the invention, in the first aspect of the invention, two first and second cylinder rows (4a, 4a,
4b) and the first, second and third port groups (21,2
2,23) and. Then, the first and second two port groups (21, 22) communicate with the first cylinder row (4a), and the third port group (23)
Is connected to the second cylinder row (4b).

In the case of the above configuration, the cylinder row (4a, 4b) and the port group (21, 22, 2) according to the invention of claim 1
The configuration of 3) is specifically specified. That is, as the cylinder block (2) rotates, all pistons (41, 41, ..., 42, 4)
2, ...) revolves around the pump shaft (1), and the first cylinder row (4a) is reciprocated by the reciprocating movement of the pistons (41, 41, ...) housed in the first cylinder row (4a). The pressure liquid in each of the plurality of cylinder chambers (24a or 25a) constituting the above is discharged from each of the first and second port groups (21 or 22), and the first discharge side through hole (32) and the second It passes through the discharge side through hole (33) and is discharged as an independent discharge flow. Further, due to the reciprocating movement of the pistons (42, 42, ...) Stored in the second cylinder row (4b), the pressure in each of the plurality of cylinder chambers (25) forming the second cylinder row (4b) is reduced. Liquid is the third port group (23)
Is discharged from the nozzle, passes through the third discharge side through hole (34), and is discharged as an independent discharge flow. That is, it is possible to independently supply the pressure liquid of three discharge streams from one cylinder block (2).

According to a third aspect of the invention, in the second aspect of the invention, the first and second cylinder rows (4a, 4) are provided.
Each reciprocating stroke of each piston (41, 42) housed in b) is changed by one variable swash plate (5) whose inclination angle is increased or decreased.
Alternatively, it is configured to be changed and adjusted by 5 ').

In the case of the above construction, the construction of the swash plate (50) in the invention of claim 2 is specifically specified. That is, the reciprocating strokes of the pistons (41, 42) are increased / decreased by increasing / decreasing the inclination angle of the variable swash plate (5 or 5 '), so that both the first and second cylinder rows (4a) are adjusted. ，
4b), the amount of liquid discharged from each cylinder chamber (24a, 24b, 25) is increased / decreased and adjusted. As a result, the first, second, and third port groups (21, 22, 23) and the first, second, and third discharge-side through holes (32, 33, 34) respectively pass through. The amount of each discharge liquid of the pressure liquid supplied as three independent discharge flows is increased / decreased and adjusted. Therefore, even in the swirl type hydraulic system where the hydraulic pressure was conventionally released by opening the relief valve, the hydraulic pressure can be reduced by reducing the discharge liquid amount, and the frequency of opening the relief valve is reduced. Power loss is reduced.
Further, when the amount of liquid discharged from the first discharge side through hole (32) and the amount of liquid discharged from the second discharge side through hole (33) become maximum, the third liquid is discharged.
Since the amount of liquid discharged from the discharge-side through hole (34) is also maximized, it is possible to discharge the maximum amount of liquid discharged for the variable displacement piston pump as a whole.

According to a fourth aspect of the present invention, in the second aspect of the invention, the inclination angle of each reciprocating stroke of each piston (41) housed in the first cylinder row (4a) is increased or decreased. It is to be changed and adjusted by one variable swash plate (56). Further, each reciprocating stroke of each piston (42) housed in the second cylinder row (4b) is adjusted by one fixed swash plate (55) in a predetermined inclined state.

In the case of the above configuration, the configuration of the swash plate (50) in the invention of claim 2 different from that of the invention of claim 3 is specifically specified. That is, each reciprocating stroke of each piston (41) accommodated in the first cylinder row (4a) is changed and adjusted by increasing or decreasing the inclination angle of the variable swash plate (56),
As a result, the first cylinder row (4a) is discharged from the cylinder chambers (24a or 25a) forming the first and second cylinder rows (4a).
Each port group (21, 22) and first and second discharge side through holes
It is possible to increase / decrease each discharge amount of the pressure liquid supplied as two independent discharge flows through (32, 33). Further, each piston (42) housed in the second cylinder row (4b) reciprocates in the stroke adjusted by the predetermined tilted state of the fixed swash plate (55), whereby the second cylinder The pressure liquid discharged from each cylinder chamber (25) forming the row (4b) is supplied to the third port group (23) and the third discharge side through hole (3).
4) It becomes possible to supply it as an independent discharge stream by passing through and.

According to a fifth aspect of the invention, the inclination angle of the variable swash plate (5 or 5 ') according to the third aspect of the invention is independently discharged from each discharge side through hole (32, 33, 34). The configuration is provided with a change adjusting mechanism (8) that adjusts the product of the sum total of the discharge liquid amounts and the sum total of the discharge liquid pressures to a substantially constant value by increasing / decreasing based on the liquid pressure of the pressurized liquid.

In the case of the above construction, in addition to the operation of the invention described in claim 3, in the flow rate / pressure control of the variable displacement piston pump, the product of the sum of the discharge liquid amounts and the sum of the discharge liquid pressures is substantially reduced. It is done by total horsepower control that keeps it constant. As a result, in the total hydraulic system, the amount of discharged liquid is reduced as the hydraulic pressure increases, so that the load on the prime mover is kept below a predetermined set value, and the overload operation is eliminated.

According to a sixth aspect of the present invention, the first force receiving portion (53) is formed on one end side of the variable swash plate (5) according to the fifth aspect of the invention in a direction orthogonal to the tilt axis (52). On the other hand, the second force receiving portion (54) is formed on the other end side. Then, the urging means (8) for urging the change adjusting mechanism (8) to urge the first force receiving portion (53) in a direction in which the tilt angle of the variable swash plate increases and in a size substantially inversely proportional to the tilt angle ( 6) and the sum of the hydraulic pressures of the discharge flows as a pilot pressure, and the second force receiving portion is received.
(54) is constituted by an adjusting piston (7) that presses the variable swash plate (5) in a direction in which the inclination angle of the variable swash plate (5) decreases.

In the case of the above configuration, the configuration of the change adjusting mechanism (8) in the invention according to claim 5 is specifically specified. That is, the angle of the variable swash plate (5) is maintained in a state where the urging force of the urging means (6) and the pressing force of the adjusting piston (7) are balanced. Here, the biasing force is set so as to be substantially inversely proportional to the inclination angle of the variable swash plate (5), and the sum of the discharge liquid amounts of the variable displacement piston pump is substantially proportional to the inclination angle. Therefore, the urging force is approximately inversely proportional to the total discharge amount of the variable displacement piston pump. The pressing force of the adjusting piston (7) is approximately proportional to the total discharge pressure of the variable displacement piston pump. Therefore, when the urging force and the pressing force are in equilibrium, the sum total of the discharge liquid amount is substantially inversely proportional to the sum total of the discharge pressure, and the sum total of the discharge liquid amount and the discharge pressure of the variable displacement piston pump. The product of the sum and the sum will be kept almost constant.

According to a seventh aspect of the invention, the first force receiving portion (53 ') is provided at one end side of the variable swash plate (5') of the fifth aspect of the invention in a direction orthogonal to the tilt axis (52 ') thereof. To form. Then, the change adjusting mechanism (8) urges the first force receiving portion (53 ') in a direction in which the tilt angle of the variable swash plate (5') increases and in a size substantially inversely proportional to the tilt angle. The urging means (6) is provided. Also, the tilting shaft (52 ') is moved by the hydraulic pressure on the discharge side acting on the variable swash plate (5') via the pistons (41, 41, ..., 42, 42, ...). )
The moment generated around increases with the increase of the inclination angle of the variable swash plate (5 ') on the side of the variable swash plate (5') that is tilted toward the cylinder block (2), and vice versa. The pistons (41, 41, ..., 42, 42, ...) and the variable swash plate (5 ') are reduced so as to decrease on the side.
It is arranged such that it is displaced from the sliding contact surface with the pump shaft (1) in the longitudinal direction of the pump shaft (1).

In the case of the above configuration, the configuration of the change adjusting mechanism (8) in the invention of claim 5 different from that of the invention of claim 5 is specifically specified. That is, the piston (4
1, 41, ..., 42, 42, ...) via the variable swash plate (5 ') acting on the variable swash plate (5') by the hydraulic pressure on the discharge side of the variable displacement piston pump. The moment around (52 ') is balanced when the inclination angle of the variable swash plate (5') is 0 degree, but as the inclination angle increases, the displacement of the tilt axis (52 ') causes the moment Variable swash plate (5
′) Increases on the side tilting toward the cylinder block (2) and decreases on the opposite side. Therefore, a self-returning moment (M) is generated in the variable swash plate (5 ') in the direction of decreasing the inclination angle thereof. Also,
The variable swash plate (5 ') is urged by the urging means (6) in such a direction that its inclination angle increases, and the angle is maintained in a state where the urging force and the self-returning moment (M) are balanced. To be done. Here, the biasing force is applied to the variable swash plate (5).
Is set so as to be substantially inversely proportional to the inclination angle of the variable displacement piston pump, and the total discharge liquid amount of the variable displacement piston pump is substantially proportional to the inclination angle. It is approximately inversely proportional to the total amount of discharge. Further, the sum of the discharge pressures of the variable displacement piston pump and the self-returning moment (M) are substantially proportional. Therefore, when the urging force and the self-returning moment (M) are in balance, the sum of the discharge liquid amounts is substantially inversely proportional to the sum of the discharge pressures, and the discharge liquid amount of the variable displacement piston pump is The product of the total sum and the total discharge pressure will be kept substantially constant. In addition, as compared with the invention described in claim 5, since the adjusting piston (7) and the like are unnecessary, the structure is relatively simple, and the variable displacement piston pump can be reduced in cost and further downsized. Become.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 shows a variable displacement piston pump (hereinafter simply referred to as a pump) according to a first embodiment of the present invention, and 1 is supported by a bearing (1a) and is not shown. A pump shaft rotated by a rotational force input from a prime mover, 2 is a cylinder block that rotates integrally with the pump shaft (1), and 3 is a cylinder block (2)
Is a valve plate that is slidably joined to the port-side end surface (2a) in an oil-tight manner and distributes the pressure oil discharged from the cylinder block (2). 4a and 4b are cylinder rows formed in the cylinder block (2), of which 4a is a first cylinder row arranged on the outer peripheral side of the cylinder block (2), and 4b is an inner periphery thereof. It is the 2nd cylinder row arranged at the side. Further, 5 is a variable swash plate for increasing / decreasing and adjusting the stroke of each reciprocating motion of each piston (41, 42) housed in each cylinder chamber constituting the above cylinder row (4a, 4b), and 6 is this variable swash plate. The coil spring (60) is used in the present embodiment as a biasing means for biasing (5) in the direction in which its inclination angle increases. Also, 7
Is an adjusting piston that receives the pilot pressure from the discharge side passages (91, 92, 93) of the pump and presses the variable swash plate (5) in a direction in which the inclination angle thereof decreases.
A change adjusting mechanism (8) is configured by the (60) and the adjusting piston (7). Further, while 9 is joined to the valve plate (3), a pump case (10) described later is provided.
End caps 10 that together with the exterior of the pump
Is a pump case which is formed in a bottomed cylindrical shape and accommodates the cylinder block (2) and the like therein.

The cylinder block (2) is formed in a substantially cylindrical shape, and is connected to the pump shaft (1) penetrating the center portion thereof in the column axis direction (left and right direction) through a spline to form the pump. It is adapted to rotate integrally with the shaft (1). Further, ten cylinder chambers (24a, 2a) are formed on the outer peripheral side thereof in a row in the circumferential direction, and accommodate the pistons (41) so as to be reciprocally slidable in the longitudinal direction of the pump shaft (1).
4b, ...) Form the first cylinder row (4a). And, 10 cylinder chambers (25, 25, ...) In which the pistons (42) are housed so as to be able to reciprocate in the longitudinal direction of the pump shaft (1) on the inner peripheral side thereof, are arranged in rows in the circumferential direction. Further, the second cylinder row (4a) is formed by being alternately formed for each cylinder chamber (24a or 25a) of the first row.

On the port side end surface (2a) of the cylinder block (2) (see FIG. 2), port groups (21, 22, 23) are provided at three concentric circumferential positions around the pump shaft (1). Five ports (21a) forming the first port group (21) are formed at equal intervals at a first circumferential position that is closest to the outer circumference. Each of these ports (21a) is connected to each of the first group of five cylinder chambers (24a, 24a, ...) Arranged in the first cylinder row (4a) every other one. They are communicated one after another. In addition, inside the second circumferential position, each port (22a) that constitutes the second port group (22)
5 are formed at equal intervals and alternately for each port (21a) of the first group. And the second of them
Each port (22a) of the group is connected to the first cylinder row (4
5 of the second group other than the above first group in a)
The cylinder chambers (24b, 24b, ...) Are in communication with each one. Furthermore, a third circle is located at the third circumferential position that is closest to the inner circumference.
Of the 10 ports (23a, 23a,
…) Are formed at even intervals and their respective ports (23
a) communicates with each cylinder chamber (25) of the third group, which constitutes the second cylinder row (4b), one by one.

On the swash plate side (see FIG. 1) of the cylinder block (2), an outer peripheral side end surface where each cylinder chamber (24a or 25a) constituting the first cylinder row is opened, and an outer peripheral side end surface An inner peripheral side end surface is formed which projects from the inner side in the pump shaft (1) direction and is open to each of the cylinder chambers (25) forming the second cylinder row. The pistons (41, 42) have their base ends at the cylinder chambers (2
4a, 24b, 25) while projecting the tip end of the piston shoe (43, 44) from the opening toward the variable swash plate (5). It slidably abuts on the variable swash plate (5). As a result, the pistons (41, 42) revolve around the pump shaft (1) by the rotation of the cylinder block (2) and the variable swash plate (5) moves in the pump shaft (1) direction. It is configured to reciprocate according to the inclination angle.

The valve plate (3) (see FIG. 3)
Is attached to the inner surface of the end cap (9) and is a pin.
The position is fixed by (11), while the end face on the port side (2
It is slidably joined to a). Then, a wide arc-shaped suction-side through hole (31) is formed in the suction-side range occupying substantially half of the pump shaft (1) in the circumferential direction, and each port group (21, The ports (21a, 21a, ..., 22a, 22a, ..., 23a, 23a ,. The suction side passage (not shown) formed on the inner surface of the end cap (9) and the ports (21a, 21a, ..., 22a, 22a, ..., 23a, 23)
a, ...) and oil supplied from an oil tank to be described later is connected to the cylinder chamber (24a, 24a, ..., 24b, 24b, ..., 25, 25,
...).

Further, in the discharge side range which occupies substantially half of the valve plate (3) in the circumferential direction about the pump shaft (1), a concentric circumferential position about the pump shaft (1) is provided. Three substantially arc-shaped discharge-side through holes (32, 33, 34) are formed, and the first discharge-side through hole (32) closest to the outer periphery is formed.
Are ports (21a, 21a, 21a, 21a, 21a,
...) are arranged so that they can communicate with almost half of them simultaneously. Further, the second discharge side through hole (33) formed on the inner peripheral side of the first discharge side through hole (32) has the second port group (22).
Of the ports (22a, 22a, ...) Of the third port group (23). Of the ports (23a, 23a, ...) Constituting at the same time are arranged so that they can communicate with each other. Then, the piston (41,41, ..., 42,4
2, ...) reciprocating motion causes cylinder chambers of each group above
(24a, 24a,…, 24b, 24b,…, 25, 25…) The pressure fluid inside is discharged from the ports (21, 21,…, 22,22,…, 23,23,…) of each group above. , A first discharge-side passage (91) (see FIG. 1) and a second discharge-side passage (see FIG. 1) formed in the end cap (9) through the respective discharge-side through holes (32, 33, 34). 92) and the third discharge side passageway (93).

The variable swash plate (5) is a donut-shaped main body having a sliding surface (51a) on its upper surface (left side surface in FIG. 1).
(51) and a tilting shaft (52) having a central axis positioned inside the sliding surface (51a) and projecting outward from the outer peripheral edge portion on the diameter of the main body portion (51). The first projection is formed by projecting outward from both end sides in the direction orthogonal to the tilt axis (52).
A force receiving portion (53) and a second force receiving portion (54) are formed. The variable swash plate (5) has a first stopper (1) in which the first force receiving portion (53) is arranged inside the pump case (10).
In a normal state in which it abuts against 2a) and further tilting is prevented, the tilting angle is maximum (for example, 17 degrees) and is set to the maximum tilting state (L). In addition, the variable swash plate (5) is a second body in which the bottom surface (51b) of the body portion (51) (right side surface in FIG. 1) is disposed inside the pump case (10).
When the stopper (12b) is in contact with the stopper (12b) to prevent further tilting, the tilt angle is set to a neutral state (N) of zero degree. The pistons (41, 41, ..., 42, 42, ...) that are in sliding contact with the sliding surface (51a) via piston shoes (43, 43, ..., 44, 44, ...) reciprocate. The movement stroke is adjusted to be increased or decreased by tilting the variable swash plate (5).

The coil spring (60) includes the first force receiving portion (5
The variable force swash plate (5) is disposed between the end cap and the end cap by pressing the first force receiving portion (53) (to the right in FIG. 1) by the pressing biasing force. It is configured to urge in a direction in which the inclination angle increases (counterclockwise in FIG. 1). When the pump is stopped (S) and the pump shaft (1) is not rotated, the variable swash plate (5) is kept in the maximum tilted state (L).

The adjusting piston (7) is inserted at its base end into an adjusting cylinder (71) arranged between the second force receiving portion (54) and the end cap (9). The front end portion is positioned so as to contact the second force receiving portion (54). The adjusting piston (7) receives the pilot pressure from each of the discharge side passages (91, 92, 93) via the three sensor pins (72a, 72b, 72c) that abut on the base end. (To the right in FIG. 1), the second force receiving portion (54) is pressed (to the right in FIG. 1) and thereby,
The variable swash plate (5) is configured to be urged in the direction in which the inclination angle is reduced (clockwise in FIG. 1).

The end cap (9) has three first, second, and third discharge ports (91a, 92a, 93a) and a suction port (not shown) formed therein. Discharge side passage (91,
92, 93) and the suction-side passages through the discharge-side through holes
(32, 33, 34) communicates with the suction side through hole (31). Further, the first discharge port (91a) is a left running system of the shovel (not shown), the second discharge port (92a) is a right running system of the shovel, and the third discharge port (93a) is of the shovel. The turning system is independently connected to each other by hydraulic piping, and the suction port is connected to an oil tank (not shown) arranged on the shovel by hydraulic piping.

In the present embodiment, the biasing force of the coil spring (60) provided between the first force receiving portion (53) and the end cap (9) is used as the biasing means. ,
Not limited to this, for example, the coil spring (60) may be connected to the first force receiving portion (5
It may be arranged between the pump case (10) and the pump case (10) to use a tensile biasing force, and the coil spring (60) may be used as the second force receiving portion.
It is possible to use various configurations such as disposing between (54) and the pump case (10).

Next, the operation, action and effect of the pump according to the first embodiment will be described.

First, the pump shaft (1) is rotated by the operation of a prime mover (not shown). At this time, since the variable swash plate (5) is in the maximum inclination state (L), each piston (41,
42) sucks the maximum amount of oil by reciprocating the maximum reciprocating stroke and delivers the maximum amount of pressure oil to each cylinder chamber (24a, 24b, 25).
Discharge from. Then, the cylinder chamber (24
a, 24a, ...) Passes through the first port group (21) and the first discharge side through hole (32) and is independently supplied to the first discharge side passageway (91) as the first discharge flow. Sent to the second group of cylinder chambers (2
4b, 24b, ...) Passes through the second port group (22) and the second discharge side through hole (33) to the second pressure oil inside the second discharge side passageway (92).
Cylinder chamber of the 3rd group, sent independently as discharge flow
The pressure oil in (25, 25, ...) passes through the third port group (23) and the discharge side through hole (34), and independently as a third discharge flow in the third discharge side passageway (93). Sent. Then, the respective discharge flows are independently supplied from the respective discharge ports (91a, 92a, 93a) to the respective hydraulic systems of the shovel through the hydraulic pipes. Here, the first discharge flow and the second discharge flow are respectively the first cylinder row (4
Since the equal amounts of discharge flows are discharged from the cylinder chambers (24a, 25a) of equal volume constituting a), the left and right traveling systems of the excavator supplied with these discharge flows are rotated at a constant speed. . Thereby, the straightness of the shovel can be kept good. Further, in the swivel system of the shovel to which the third discharge flow is independently supplied, the operability can be kept good without being affected by the operations of the left and right traveling systems.

Further, the hydraulic pressure in each of the discharge side passages (91, 92, 93) rises as the pressure oil is discharged from the pump, and the adjusting piston (which receives these hydraulic pressures through the sensor pins (72a, 72b, 72c) ( 7) presses the variable swash plate (5) in the direction in which its inclination angle decreases against the pressing biasing force of the coil spring (60). Therefore, the variable swash plate (5) has a pressing force that is substantially proportional to the sum of the discharge pressure of the pump by the adjusting piston (7) and the pressing biasing force that is substantially inversely proportional to the tilt angle of the variable swash plate (5). The angle is maintained in a balanced state with and. Here, since the sum total of the discharge oil amount of the pump is substantially proportional to the inclination angle of the variable swash plate (5), the sum total of the discharge oil amount of the pump and the sum total of the discharge pressure are substantially inversely proportional to each other. Become. In other words, the pump will be controlled by comprehensive total horsepower control in which the product of the sum of the amount of discharged oil and the sum of the discharge pressure is kept substantially constant, thereby effectively utilizing the output of the prime mover. As a result, the maximum operating speed of the hydraulic cylinders and hydraulic motors in the swing system and the traveling system can be increased. That is, the maximum speed of the shovel can be increased.

Furthermore, when the hydraulic pressure increases due to the operating load of the hydraulic cylinders and hydraulic motors in each hydraulic system of the shovel, the tilting angle of the variable swash plate (5) is increased by the adjusting piston (7) that receives the hydraulic pressure. Is reduced, the discharge oil amount of the pump is reduced and the hydraulic pressure is reduced. Therefore, the overload operation of the prime mover is eliminated, and the power loss due to the opening of the relief valve in each of the hydraulic systems is reliably reduced.
Energy saving can be achieved.

As described above, the variable displacement piston pump according to the first embodiment of the present invention can independently supply the pressure oil to the three hydraulic systems, so that the hydraulic pump of a construction machine such as a shovel can be used alone. The power source can be configured and the power source such as a shovel can be made compact because it is shortened in the pump axial direction. Also, one suction port and three discharge ports (91a, 92a, 93a) are end caps (9).
Since they are arranged in the same plane, hydraulic piping becomes easy. In addition, the gear pump is connected to the second row of pistons (42, 42,
...), the volumetric efficiency is improved and the discharge pressure can be increased compared to the conventional multi-flow type pump. In addition, the generation of abrasion powder is reduced and contamination of the pressure fluid is prevented. To be done. In addition, the output of the prime mover can be effectively used by comprehensive total horsepower control, which can increase the maximum speed of the shovel and the like.

<Second Embodiment> FIG. 4 shows a variable displacement piston pump (hereinafter, simply referred to as a pump) according to a second embodiment of the present invention. In the figure, 5'is a piston (41,
41, ..., 42, 42, ...) is a variable swash plate for increasing / decreasing and adjusting the stroke of reciprocating motion, and its tilting shaft (52 ') is arranged offset in the pump shaft (1) direction. Further, the change adjusting mechanism (8) is composed of a coil spring (60) as a biasing means (6) for biasing the variable swash plate (5 ') in a direction in which its tilt angle increases. Since the other configurations of the pump are the same as those of the first embodiment,
The same members are designated by the same reference numerals and the description thereof will be omitted.

The variable swash plate (5 ') has an upper surface (see FIG. 4).
Donut-shaped main body (51 ') having a sliding surface (51a') on the left side), and a tilting shaft (52) protruding outward from the outer peripheral edge of the main body (51 ') on the diameter. ') And a first force receiving portion (53') protruding outward from one end side in the direction orthogonal to the tilt axis (52) is formed. And
The variable swash plate (5 ') has a first stopper (12) in which the force receiving portion (53') is disposed inside the pump case (10).
It is configured to reach the maximum inclination state (L) in which the inclination angle is maximum (for example, 17 degrees) in the state where it abuts against a) and further inclination is prevented. Further, in the variable swash plate (5 '), the bottom surface (51b') of the main body portion (51 ') (right side surface in Fig. 4) is the second stopper (12b) disposed inside the pump case (10). ) And is prevented from further tilting, the tilt angle is set to a neutral state (N) of zero degree. And, of the pistons (41, 41, ..., 42, 42, ...) slidingly contacting the sliding surface (51a ') via the piston shoes (43, 43, ..., 44, 44, ...). The stroke of the reciprocating motion is adjusted to be increased or decreased by tilting the variable swash plate (5 ').

The coil spring (60) constituting the change adjusting mechanism (8) has the first force receiving portion as in the first embodiment.
By pressing (53 ') (to the right in FIG. 4), the variable swash plate (5') is biased in the direction in which the inclination angle increases (counterclockwise in FIG. 4). There is. When the pump is stopped (S) and the pump shaft (1) is not rotated, the variable swash plate (5) is kept in the maximum tilted state (L).

The tilting shaft (52 ') is connected to the variable swash plate (5).
′) Is provided at a position offset from the sliding surface (51a ′) of the pump shaft (1) to the side opposite to the cylinder block (2), whereby the variable swash plate (5 ′) is provided. As the tilt angle increases, the self-returning moment (M) in the direction of decreasing the tilt angle acts on the.

The self-returning moment (M) will be described below with reference to FIG. In the figure, in order to simplify the description, the piston (41) located closest to the cylinder block (2) (upper piston in FIG. 5) and the piston (41) located farthest from the cylinder block. (The lower piston in FIG. 5) will be described.

In FIG. 5, F is a pressing force that presses the variable swash plate (5 ') by each piston (41) which discharges pressure oil as a reaction force, and r1 is the variable swash plate (5).
′) The pressing force (F) and the tilting shaft on the side tilted toward the cylinder block (2) (upper side in FIG. 5).
(52 '), r2 is the pressing force (F) on the opposite side of the variable swash plate (5') (the lower side in FIG. 5) and the tilting axis.
It is the distance from (52 '). Further, θ is the variable swash plate (5
′) Is the tilt angle, and d is the offset amount of the tilt axis (52 ′). From the figure, the moment acting on the variable swash plate (5 ') is the moment on the side of the variable swash plate (5') tilted toward the cylinder block (2) (upper side of Fig. 5). In the direction of decreasing the inclination angle (θ), M1 = F · r1 and in the direction of increasing the inclination angle (θ) on the opposite side (lower side of FIG. 5) of the variable swash plate (5 ′), M2 = F · r2
It is.

Therefore, the self-restoration moment (M) is M = M1−M2 = F · (r1−r2) = 2 · F · d · s
in θ. That is, the self-returning moment (M) is substantially proportional to the hydraulic pressure on the discharge side of the pump and also to the inclination angle (θ) of the variable swash plate (5 ′).

Next, the operation, action and effect of the pump according to the second embodiment will be described in detail mainly about the operation different from that of the first embodiment.

First, the pump shaft (1) is rotated by an unillustrated prime mover to reciprocate the pistons (41, 41, ..., 42, 42, ...). Three discharge flows, that is, the second and third discharge flows, are independently supplied to each hydraulic system of the shovel through the hydraulic pipes. Therefore, the straightness of the shovel can be kept good, and at the same time, the operability of the turning system of the shovel can be kept good.

The pressing force (F) received by the variable swash plate (5 ') from each piston (41, 42) for discharging pressure oil increases in proportion to the oil pressure on the discharge side of the pump. ,
A self-returning moment (M) having a magnitude substantially proportional to the sum of the hydraulic pressure acts on the variable swash plate (5 ') in the direction of decreasing its inclination angle. Therefore, the variable swash plate (5
The angle ′) is maintained in a state where the pressing biasing force of the coil spring (60) in the direction of increasing its inclination angle and the self-returning moment (M) are balanced. Here, the pressing biasing force is substantially inversely proportional to the tilt angle of the variable swash plate (5 '), and the total amount of oil discharged from the pump is substantially proportional to the tilt angle of the variable swash plate (5). To do. Therefore, the sum total of the discharge oil amount of the pump and the sum total of the hydraulic pressure on the discharge side of the pump (that is, the discharge pressure of the pump) are substantially inversely proportional to each other, and the pump has the sum of the discharge oil amount and the discharge pressure. It is controlled by comprehensive total horsepower control in which the product of the sum and the sum is kept substantially constant. As a result, similarly to the first embodiment, the output of the prime mover can be effectively used,
As a result, the maximum speed of the shovel can be increased. Further, it is possible to eliminate the overload operation of the prime mover and reduce the power loss due to opening of the relief valve or the like, and thereby reduce the fuel consumption.

As described above, the variable displacement piston pump according to the second embodiment of the present invention is similar to the first embodiment.
Three discharge streams can be independently supplied from a compact main body that is shortened in the longitudinal direction, and a power source such as a shovel can be made compact, and its variable swash plate (5 '). Since the change adjusting mechanism (8) for increasing / decreasing the inclination angle of the pump according to the discharge pressure of the pump is simplified, the pump can be made more compact and the cost can be reduced. Further, it is possible to obtain the same effects as those of the first embodiment, such as simplification of hydraulic piping, improvement in volumetric efficiency, and prevention of pressure oil contamination.

<Other Embodiments> The present invention relates to the first embodiment.
The present invention is not limited to the second embodiment, and includes various other embodiments. That is, in the first and second embodiments, the stroke of the reciprocating motion of each piston (42) housed in the second cylinder row (4b) is adjusted to be increased or decreased by the variable swash plate (5 or 5 '). However, not limited to this, as shown in FIG. 6, it is also possible to adjust the reciprocating stroke of each piston (42) by the fixed swash plate (55) in a predetermined inclined state.

In the second embodiment, the variable swash plate (5 ') is used.
The tilting shaft (52 ') is arranged on the side opposite to the cylinder block (2) in an offset manner, but not limited to this, various offset arrangements are possible.

In the first and second embodiments, the cylinder rows (4a, 4b) are arranged in two rows on the outer peripheral side and the inner peripheral side of the cylinder block (2), and the first outer peripheral side is arranged. Two independent pressure oils are discharged from each cylinder row (4a), and one independent pressure oil is discharged from the second cylinder row (4b) on the inner peripheral side to discharge three independent discharge streams. However, the present invention is not limited to this, and it is also possible to discharge four or more discharge streams by, for example, three cylinder rows.

[0052]

As described above, according to the variable displacement piston pump of the first aspect of the invention, three or more pressure liquids are supplied from one variable displacement piston pump that is shortened in the pump axial direction. Since it can be supplied as an independent discharge flow of, the power source of construction machines such as shovels can be made compact. In addition, the discharge port (91a, 92a, 9
Since 3a) and the suction port are arranged close to each other on the same surface of the pump, hydraulic piping becomes easy. Furthermore, by replacing the gear pump with a piston pump, volumetric efficiency can be improved and high pressure can be achieved.
The efficiency of the variable displacement piston pump as a whole is improved. At the same time, since the generation of abrasion powder is reduced, it is possible to prevent the pressure liquid from being contaminated.

According to the second aspect of the invention, the configuration of the cylinder block (2) in the first aspect of the invention is specifically specified, whereby the effect of the first aspect of the invention can be relatively achieved. It can be reliably obtained with a simple configuration.

According to the third aspect of the invention, in addition to the effect of the second aspect of the invention, it is possible to increase / decrease the discharge liquid amount in all the hydraulic systems, whereby the relief valve and the like can be changed. It is possible to surely reduce the power loss due to the release of the hydraulic pressure through the energy saving. At the same time, the maximum displacement of the variable displacement piston pump can be discharged, and the maximum speed of the shovel or the like can be improved.

According to the invention described in claim 4, due to the structure different from that of the invention described in claim 3, it is possible to surely obtain the effect by the invention described in claim 2.

According to the invention of claim 5, in addition to the effect of the invention of claim 3, the variable swash plate (5 or 5)
The tilt angle of ′) is increased / decreased by the change adjustment mechanism (8), so that the product of the sum total of the discharge liquid amount and the sum total of the discharge liquid pressure of the variable displacement piston pump is kept substantially constant. Since the total horsepower control is performed, the output of the prime mover can be effectively used. According to the invention of claim 6, the biasing means (6) is used as the change adjusting means (8) in the invention of claim 5 above. ) And the adjusting piston (7), the product of the sum of the discharge liquid amount and the sum of the discharge pressure of the variable displacement piston pump can be surely kept substantially constant. It is possible to reliably obtain the effects of the invention described in item 5.

According to the invention described in claim 7, by using the configuration different from the invention described in claim 6 as the change adjusting means (8) in the invention described in claim 5,
The effect of the invention according to claim 5 can be reliably obtained by the configuration that is smaller, lighter and less expensive than the invention according to claim 6.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a variable displacement piston pump according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a port-side end surface of a cylinder block constituting the variable displacement piston pump of FIG.

3 is a plan view showing a valve plate constituting the variable displacement piston pump of FIG. 1. FIG.

FIG. 4 is a vertical sectional view showing a variable displacement piston pump according to a second embodiment of the present invention.

5 is a conceptual diagram showing how a self-returning moment (M) acts on a variable swash plate that constitutes the variable displacement piston pump of FIG.

FIG. 6 is a variable displacement piston according to another embodiment of the present invention configured to adjust the stroke of reciprocal movement of each piston housed in the second cylinder row by a fixed swash plate in a predetermined inclined state. It is a longitudinal cross-sectional view showing a pump.

FIG. 7 is a schematic diagram showing a hydraulic system of a construction machine such as a shovel.

FIG. 8 is a partially cutaway view showing a multi-flow pump conventionally used as a hydraulic power source for a construction machine such as a shovel.

[Explanation of symbols]

1 Pump Shaft 2 Cylinder Block 2a Port Side End Surface 3 Valve Plate 4a First Cylinder Row 4b Second Cylinder Row 5, 5'Variable Swash Plate (Swash Plate) 6 Energizing Means (Change Adjusting Mechanism) 7 Adjusting Piston (Change Adjusting mechanism) 8 Change adjusting mechanism 21 First port group 22 Second port group 23 Third port group 24a, 24b Cylinder chamber forming first cylinder row 25 Cylinder chamber forming second cylinder row 31 Suction side through hole 32 First discharge side through hole 33 Second discharge side through hole 34 Third discharge side through hole 41 Piston housed in the first cylinder row 42 Piston housed in the second cylinder row 50 Swash plate 52,52 'Tilt shaft 53,53' First force receiving portion 54 Second force receiving portion 55 Fixed swash plate (swash plate) 56 Variable swash plate (swash plate)

Claims (7)

[Claims] 1. A pump shaft (1), a cylinder block (2) which rotates integrally with the pump shaft (1), and a piston (41, 41) inside the cylinder block (2).
41, ..., 42, 42, ...) are housed in a plurality of cylinder chambers (24a, 24a,
, 24b, 24b, ..., 25, 25, ...) are two or more cylinder rows (4a, 4b) arranged at two or more concentric circumferential positions of different diameters centering on the pump shaft (1). ) And a piston housed in each of the cylinder rows (4a, 4b)
(41,41, ..., 42,42, ...) Relative to one or more swash plates (50) for adjusting the stroke of reciprocating motion, and the port side end face (2a) of the cylinder block (2). Slidingly joined valve plate (3)
And a plurality of cylinder chambers (24a or 24b) forming one cylinder row (4a) among the two or more cylinder rows (4a, 4b) on the port-side end surface (2a). Two rows of ports (21, 2
2) and another port group (23) of one or more rows arranged in the circumferential direction so as to communicate with each of the plurality of cylinder chambers (25) forming one or more other cylinder rows (4b). The valve plates (3) are formed in concentric circumferential positions having different diameters, and the valve plates (3) are arranged in a suction side range that occupies approximately half of a circumference of the pump shaft (1) in the circumferential direction, and the three rows are arranged. A wide suction side through hole (31) formed so that it can communicate with approximately half of each of the above port groups (21, 22, 23) at the same time.
And the pump shaft (1) so as to be arranged in a discharge side range occupying substantially the other half of the circumferential direction and individually communicate with approximately half each of the three or more rows of port groups (21, 22, 23). ) And three or more arc-shaped discharge side through holes (32, 33, 34) formed at concentric circumferential positions having different diameters from each other, and the above three or more discharge side through holes (32, 33, 34) is a variable displacement type characterized in that it is configured to discharge the pressure liquid independently by the reciprocating motion of the pistons (41, 42) accompanying the rotation of the cylinder block (2). Piston pump. 2. The first and second cylinder rows (4a, 4b) according to claim 1, and the first, second and third three port groups (21, 22, 23). The first and second two port groups (21, 22) are the same as the first
A variable displacement piston pump, which is in communication with a cylinder row (4a) and in which the third port group (23) is in communication with the second cylinder row (4b). 3. The reciprocating stroke of each piston (41, 42) housed in each of the first and second cylinder rows (4a, 4b) is increased or decreased in inclination angle according to claim 2. A variable displacement piston pump, characterized in that it is configured to be changed and adjusted by one variable swash plate (5 or 5 '). 4. The piston (41) according to claim 2, wherein each piston (41) is housed in the first cylinder row (4a).
Each reciprocating stroke of the piston is configured to be changed and adjusted by one variable swash plate (56) whose inclination angle is increased / decreased, and each piston ((b) accommodated in the second cylinder row (4b) 42)
Each reciprocating stroke of a single fixed swash plate (5
A variable displacement piston pump characterized in that it is configured to be adjusted by 5). 5. The product of the sum total of the discharge liquid amount and the sum total of the discharge liquid pressure according to claim 3, wherein the tilt angle of the variable swash plate (5 or 5 ′) is increased or decreased based on the liquid pressure on the discharge side. A variable displacement piston pump, comprising a change adjusting mechanism (8) for adjusting to a substantially constant value. 6. The variable swash plate (5) according to claim 5, wherein the first force receiving portion (53) is provided at one end side in a direction orthogonal to the tilt axis (52).
Has a second force receiving portion (54) on the other end side, and the change adjusting mechanism (8) changes the first force receiving portion (53) in a direction in which the tilt angle of the variable swash plate increases. In addition, the urging means (6) for urging with a magnitude substantially inversely proportional to the tilt angle, and the second force receiving portion (54) for receiving the total of the hydraulic pressures on the discharge side as the pilot pressure and the variable swash plate (54). A variable displacement piston pump, comprising: an adjusting piston (7) that presses in a direction in which the inclination angle of (5) decreases. 7. The variable swash plate (5 ′) according to claim 5, wherein the variable force swash plate (5 ′) has a first force receiving portion (53 ′) on one end side in a direction orthogonal to the tilt axis (52 ′), The adjusting mechanism (8) urges the first force receiving portion (53 ') in a direction in which the tilt angle of the variable swash plate (5') increases and in a size substantially inversely proportional to the tilt angle. Means (6)
The tilting shaft (52 ') is composed of pistons (41, 41, ..., 42, 42, ...).
The moment generated around the tilting shaft (52) by the hydraulic pressure on the discharge side acting on the variable swash plate (5 ') via the variable swash plate (5') increases with the increase of the tilt angle of the variable swash plate (5 '). The pistons (41, 41, ..., 42, 42, ...) and the pistons (41, 41, ..., 42, 42, ...) A variable displacement piston pump, wherein the variable displacement piston pump is arranged so as to be offset from a sliding contact surface with a variable swash plate (5 ') in a longitudinal direction of a pump shaft (1).