JP2016065482A - Tandem type hydraulic pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tandem type hydraulic pump capable of shrinking an axial size of an intermediate region of a casing formed with two-system discharging flow passages and then capable of shortening an entire axial length of the casing.SOLUTION: A tandem type hydraulic pump in accordance with a preferred embodiment includes a casing, two pump units, a suction flow passage and two-system discharging flow passages. The discharging flow passage of each of the systems has two flow inlets, one flow outlet and a merging part. Each of the flow inlets and the flow outlet is arranged at both ends in a flowing direction of hydraulic oil. The merging part merges hydraulic oils flowed in through the two flow inlets in the midway of the hydraulic oil flowing direction and guides it to one flow outlet. Then, the overlapped regions as seen from an axial direction of two-system discharging flow passages are spaced apart in such a way that the shortest size between the inner walls in the two-system discharging flow passages may become more than a prescribed size. In addition, the merging part is arranged at a side near the flow outlet rather than the overlapped regions.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to a tandem hydraulic pump.

  For example, a tandem hydraulic pump including two pump units is known as a hydraulic power source used in construction machines such as a hydraulic excavator. Among these tandem type hydraulic pumps, there is one in which two pump units are arranged side by side in the axial direction, and both pump units are operated by synchronously rotating a rotating shaft coupled coaxially.

  In this type of tandem hydraulic pump, a suction passage and a discharge passage are formed in a casing that houses two pump units. The suction passage is a flow path for supplying hydraulic oil to the suction ports of both pump units. The discharge flow path is a flow path for leading the pressure oil discharged from the discharge ports of both pump units to the outside. In general, two discharge channels are provided independently of each other so that the pressure oil discharged from the two pump units can be supplied to separate channels.

  These suction flow path and discharge flow path are usually arranged in an integrated manner in an intermediate casing (intermediate area of the casing) located at the intermediate part of two pump units provided apart in the axial direction. It is. The intermediate casing is connected to each pump unit via a valve plate. Here, the two discharge channels are arranged at positions close to each other while being separated from each other in the axial direction.

By the way, in the part where the two discharge channels are formed, it is necessary to secure a thickness between the discharge channels sufficiently to withstand the working pressure for safety strength. Moreover, it is desirable to design the pressure loss as small as possible from the discharge port of each pump unit to the outlet (outlet) of the discharge flow path of the intermediate casing.
Therefore, for example, there are cases where two ports are formed at locations corresponding to the discharge ports of the respective pump units in the valve plate. In such a case, the intermediate casing is formed with a flow path for joining the two ports on the valve plate side surface. As a result, one discharge passage (two discharge passages) is formed in the intermediate casing for each pump unit.

  In order to reduce the pressure loss in the intermediate casing, it is desirable to make the cross-sectional area of the discharge flow path of the intermediate casing as wide as possible. For this reason, the axial dimension of the intermediate casing is increased in view of securing the necessary dimension at the portion where the two discharge channels overlap when viewed from the axial direction (hereinafter, this portion is referred to as “wrap region portion”). As a result, the overall length of the tandem hydraulic pump in the axial direction (input shaft direction) becomes long, and there is a possibility that the request for shortening the overall length of the pump accompanying the recent downsizing of construction machinery cannot be fully met.

JP 2001-140749 A

  The problem to be solved by the present invention is that the axial dimension of the intermediate region of the casing in which the two discharge channels are formed can be shortened, and thereby the tandem type capable of shortening the total axial length It is to provide a hydraulic pump.

  The tandem hydraulic pump according to the embodiment has a casing, two pump units, a suction passage, and two discharge passages. The two pump units are provided in the casing so as to be separated from each other in the axial direction. The suction flow path is provided in the casing and guides hydraulic oil to the suction ports of the two pump units. The two discharge channels are provided in the casing and guide the pressure oil discharged from the discharge ports of the two pump units to the outside in a separate system for each pump unit. And two discharge flow paths are axially spaced apart from each other in the middle region of the casing located at the middle of the two pump units provided spaced apart in the axial direction. Moreover, the discharge flow path of each system has two inflow ports, one outflow port, and a junction. Pressure oil discharged from the discharge port of each pump unit flows into each of the two inlets, and faces the axial direction. One outflow port faces a direction orthogonal to the axial direction in which the pressure oil flows out to the outside. These inflow ports and discharge ports are respectively arranged at both ends in the flow direction of the pressure oil. The joining part joins the pressure oil flowing in from the two inflow ports in the middle of the flow direction of the pressure oil and guides it to one outflow port. The overlapping lap region portions that are overlapped when viewed from the axial direction of the two discharge channels are arranged at an interval such that the shortest dimension between the inner walls of the two discharge channels is a predetermined value or more. Moreover, the junction is arranged closer to the outlet than the wrap region portion. And the discharge flow path located in the side close | similar to an inflow port rather than a confluence | merging part is comprised as two flow paths each connected to two inflow ports.

1 is a longitudinal sectional view showing a tandem hydraulic pump according to a first embodiment. It is a block diagram which shows the intermediate casing of the tandem hydraulic pump of 1st Embodiment, (A) is a side view, (B) is an end view of an axial direction. It is a block diagram which shows the intermediate casing of the tandem hydraulic pump of 2nd Embodiment, (A) is a side view, (B) is an end view of an axial direction.

  Hereinafter, a tandem hydraulic pump according to an embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a longitudinal sectional view showing a tandem hydraulic pump according to the first embodiment.
The tandem hydraulic pump 1 (hereinafter sometimes simply referred to as “hydraulic pump 1”) is, for example, a tandem swash plate type axial piston pump mounted as a hydraulic source on a construction machine such as a hydraulic excavator.

  The hydraulic pump 1 includes a casing 10 that forms the entire outer shell, and an input shaft (rotating shaft) 20 that is rotatably disposed at the center of the casing 10. The input shaft 20 is rotationally driven by a rotational drive source such as an engine provided outside the pump. In the casing 10, two pump units 30 </ b> A and 30 </ b> B are accommodated in the axial direction of the input shaft 20 (left and right direction in FIG. 1). In the following, the right end side in FIG. 1 is referred to as the front end side, the left end side is referred to as the rear end side, the pump unit 30A on the front end side is referred to as the first pump unit, and the pump unit 30B on the rear end side is referred to as the second pump unit. I will explain.

  The casing 10 includes a first casing body 11A on the front end side, a second casing body 11B on the rear end side, a front cover 12A that closes a front end opening of the first casing body 11A, and a second casing body 11B. The rear cover 12B closes the rear end opening and the intermediate casing 13 sandwiched between the first and second casing bodies 11A and 11B. These are arranged in the order of the front cover 12A, the first casing body 11A, the intermediate casing 13, the second casing body 11B, and the rear cover 12B from the front end side to the rear end side in the axial direction. The intermediate casing 13 forms an intermediate region in the axial direction of the casing 10. The first pump unit 30A is accommodated in a cylindrical first casing main body 11A arranged on the front end side, and the second pump unit 30B is a cylindrical second arranged on the rear end side. Is accommodated in the casing main body 11B.

  Here, the casing 10 is composed of a first casing body 11A having a front end side with a reference sign “A” and a rear end side having a second casing body 11B having a reference sign “B” with the intermediate casing 13 as a boundary. It is configured. For this reason, among the members that form a pair on the front end side and the rear end side of the casing 10 and the pump units 30A, 30B, the members provided on the front end side are denoted by the symbol “A”, and the members provided on the rear end side. The symbol “B” is attached to the symbol “B”.

  Both pump units 30A, 30B are configured as variable displacement swash plate type axial piston pumps each capable of adjusting the discharge capacity. Each pump unit 30A, 30B configured as a swash plate type axial piston pump includes an annular plate-like swash plate 35A, 35B, a plurality of pistons 33A, 33B, cylinder blocks 31A, 31B, and a valve plate (valve). Plate) 34A, 34B and rotating shafts 21, 22 and the like. These members are arranged symmetrically in the axial direction with respect to the intermediate casing 13. That is, the valve plates 34 </ b> A and 34 </ b> B are disposed at positions in contact with both end surfaces 13 </ b> A and 13 </ b> B in the axial direction of the intermediate casing 13.

  The swash plates 35A and 35B are disposed inside the cylinder blocks 31A and 31B, and are provided on the inner surfaces of the front cover 12A and the rear cover 12B via the swash plate support members 36A and 36B so that the tilt angle can be adjusted. In the vicinity of the swash plate support members 36A and 36B, there is provided tilt angle adjusting means (not shown) such as a tilt piston for adjusting the tilt angle of the swash plates 35A and 35B via the swash plate support members 36A and 36B. It has been.

  The tilt angle adjusting means such as the tilt piston is mainly arranged in the longitudinal section orthogonal to FIG. 1 and is not shown in FIG. 1, but is operated by the pressure of the pilot pump 80, The tilt angle of the swash plates 35A and 35B is controlled. The swash plates 35 </ b> A and 35 </ b> B are adjustable in tilt angle within a vertical cross section perpendicular to FIG. 1 including the central axis L of the input shaft 20. As will be described later, when the tilt angles of the swash plates 35A and 35B change, the stroke amounts of the pistons 33A and 33B change, and the flow rate of the pressure oil discharged from the pump units 30A and 30B is controlled. .

  The swash plates 35A and 35B have a smooth surface opposite to the swash plate support members 36A and 36B, and the shoes 39A and 39B are in contact with the smooth surfaces so as to be slidable in the circumferential direction. The pistons 33A and 33B engage with the shoes 39A and 39B in a swingable manner via the spherical head at the tip. The shoes 39A and 39B are supported by the retainer members 38A and 38B mounted on the outer periphery of the input shaft 20 via the retainer plate 37B so as to be tiltable together with the swash plates 35A and 35B.

  The cylinder blocks 31A and 31B are formed in a columnar shape and are rotatably accommodated in the casing bodies 11A and 11B. In the cylinder blocks 31A and 31B, a plurality of cylinder chambers (also referred to as cylinder bores) 32A and 32B that hold the pistons 33A and 33B slidably are formed. The plurality of cylinder chambers 32A and 32B are formed at equal intervals in the circumferential direction around the rotation axis of the cylinder blocks 31A and 31B (coincident with the central axis L of the input shaft 20).

  The first rotary shaft 21 passes through the center hole of the cylinder block 31A of the first pump unit 30A in a spline-fitted state. Further, the second rotary shaft 22 passes through the center hole of the cylinder block 31B of the second pump unit 30B in a spline-fitted state. The first rotating shaft 21 is rotatably supported by a front tapered roller bearing 26A attached to the front cover 12A and a rear needle bearing 27A attached to the intermediate casing 13. The second rotary shaft 22 is rotatably supported by a rear tapered roller bearing 26B attached to the rear cover 12B and a front needle bearing 27B attached to the intermediate casing 13.

  The first rotating shaft 21 and the second rotating shaft 22 are arranged coaxially on the front side and the rear side, and are spline fitted to the rear end of the first rotating shaft 21 and the front end of the second rotating shaft 22. The couplings 25 are connected to each other so as to rotate synchronously. The first rotating shaft 21 and the second rotating shaft 22 connected by the coupling 25 constitute one input shaft 20 that penetrates the casing 10.

  The front end of the first rotating shaft 21 protrudes outside from the front cover 12A, and a rotational drive source such as an engine is connected to the protruding end. Further, the rear end of the second rotating shaft 22 protrudes from the rear cover 12B to the outside, and the drive shaft of the pilot pump 80 is connected to the protruding end. The pilot pump 80 is operated by the rotation of the input shaft 20 and supplies hydraulic oil to the tilt angle adjusting means of the swash plates 35A and 35B as described above.

  Outside the tapered roller bearings 26A and 26B, annular bearing support members 14A and 14B are provided that fix the tapered roller bearings 26A and 26B in the thrust direction while projecting the end of the input shaft 20 to the outside. The bearing support members 14A and 14B are bolted in a state of being fitted to the inner periphery of the front cover 12A and the rear cover 12B.

  The cylinder blocks 31A and 31B rotate integrally with the first rotating shaft 21 and the second rotating shaft 22 in a state in which the end face facing the intermediate casing 13 is slidably adhered to the valve plates 34A and 34B. To do. The cylinder chambers 32A and 32B of the cylinder blocks 31A and 31B are intermittently connected to the suction ports 51A and 51B and the discharge ports 61A and 61B of the valve plates 34A and 34B through the end face opening of the cylinder blocks 31A and 31B on the intermediate casing 13 side. Communicate with each other.

  Here, each of the valve plates 34A and 34B is opened with one bowl-shaped suction port 51A and 51B, respectively. Each valve plate 34A, 34B is opened with two bowl-shaped discharge ports 61A, 61B. The reason why each of the valve plates 34A and 34B is provided with two discharge ports 61A and 61B is to reduce pressure pulsation and pressure loss. The pressure oil discharged from these two discharge ports 61A and 61B is led to the outside after merging downstream.

  The intermediate casing 13 is provided with two suction passages 53A and 53B for guiding hydraulic oil to the suction ports 51A and 51B of the valve plates 34A and 34B, respectively. The two suction flow passages 53A and 53B are branched from one suction port 52 opened on the outer surface of the intermediate casing 13 toward the valve plates 34A and 34B. Then, the end portions of the two suction flow paths 53A and 53B are opened in a bowl shape so as to communicate with the suction ports 51A and 51B of the valve plates 34A and 34B on both end faces 13A and 13B of the intermediate casing 13, respectively. Yes.

  Further, in the intermediate casing 13, two systems of discharge flows that guide the pressure oil discharged from the discharge ports 61 </ b> A and 61 </ b> B of the valve plates 34 </ b> A and 34 </ b> B to the outside independently from each other for each pump unit 30 </ b> A and 30 </ b> B. Roads 60A and 60B are provided.

2A and 2B are configuration diagrams showing the intermediate casing 13, wherein FIG. 2A is a side view and FIG. 2B is an end view in the axial direction.
In the intermediate casing 13, two discharge flow paths 60 </ b> A and 60 </ b> B corresponding to the two pump units 30 </ b> A and 30 </ b> B are arranged apart from each other in the axial direction. That is, the discharge flow path 60A is disposed on the front side close to the pump unit 30A, and the discharge flow path 60B is disposed on the rear side close to the pump unit 30B.

  As described above, the two discharge ports 61A and 61B are provided in the valve plates 34A and 34B of the pump units 30A and 30B, respectively. Accordingly, the discharge flow paths 60A and 60B of each system of the intermediate casing 13 have two inlets 62A and 62B and one outlet 63A and 63B at both ends in the flow direction of the pressure oil, respectively, It is comprised as a flow path which has merge part 66A, 66B in the middle of the flow direction of oil.

  The two inlets 62A and 62B are inlets into which the pressure oil discharged from the two discharge ports 61A and 61B of the pump units 30A and 30B flows, respectively, and are circular holes opened in the axial direction. It is configured. Each of the outlets 63A and 63B is an outlet through which the pressure oil flows out, and is configured by circular holes facing in a direction orthogonal to the axial direction. Accordingly, the two inflow ports 62A and 62B of the two discharge channels 60A and 60B are open to both end surfaces 13A and 13B in the axial direction of the intermediate casing 13, respectively.

  Further, the outlets 63A and 63B of the two discharge channels 60A and 60B are open to the outer surface 13C facing the direction orthogonal to the axial direction of the intermediate casing 13. The joining portions 66A and 66B are portions that join the pressure oil flowing in from the two inflow ports 62A and 62B and guide the pressure oil to the one outflow port 63A and 63B. The outlets 63A and 63B of the two discharge flow paths 60A and 60B are output ports of the tandem hydraulic pump 1 connected to the flow paths of a hydraulic circuit (not shown).

  The two systems of discharge flow paths 60A and 60B that are formed in the intermediate casing 13 so as to be spaced apart from each other in the axial direction have lap region portions that overlap each other when viewed from the axial direction. FIG. 2B shows the wrap region portions R1 and R2 by hatching.

  As described above with reference to FIG. 1, the suction flow paths 52 </ b> A and 52 </ b> B and the discharge flow paths 60 </ b> A and 60 </ b> B are collectively arranged in the intermediate casing 13 (intermediate area of the casing 10). Two of the discharge channels 60A and 60B are arranged at positions close to each other while being separated from each other in the axial direction. Therefore, there are wrap region portions R1 and R2 that overlap each other when viewed in the axial direction.

  In the portion where the two discharge channels 60A and 60B are formed while being close to each other in this way, a thickness (necessary thickness) that can sufficiently withstand the working pressure is secured between the discharge channels 60A and 60B for safety strength. It is necessary to secure it. Further, the flow path cross-sectional area from the discharge ports 61A and 61B of the valve plates 34A and 34B of the pump units 30A and 30B to the outlets of the discharge flow paths 60A and 60B (outflow ports 63A and 63B) is reduced in pressure loss. It is desirable to keep it as wide as possible.

  Therefore, it is necessary to satisfy a predetermined dimensional condition for the wrap region portions R1 and R2 where the two discharge channels 60A and 60B overlap when viewed from the axial direction. Therefore, in this tandem hydraulic pump 1, first, the shortest dimension between the inner walls of the two discharge passages 60A, 60B (that is, one lap region portion R1, R2 of the two discharge passages 60A, 60B) The distance between the inner walls of the approaching portions (SA) is set at an interval such that SA is equal to or greater than a predetermined value (required wall thickness).

  In addition, the merging portions 66A and 66B of the discharge flow paths 60A and 60B are arranged closer to the outlets 63A and 63B than the wrap region portions R1 and R2. In other words, the two flow paths 60A, 60B located closer to the inlets 62A, 62B than the junctions 66A, 66B communicate with the two discharge ports 61A, 61B of the valve plates 34A, 34B, respectively. It is configured as 64A, 65A, 64B, 65B. Thereby, the wrap region portions R1 and R2 are configured by one of the two channels 64A, 65A, 64B, and 65B.

  That is, in one wrap region portion R1, only one flow path 65A, 65B is set to overlap in the axial direction. Moreover, in the other wrap area | region part R2, only the other one flow path 64A, 64B is set so that it may overlap in an axial direction.

  As described above, in the range including the wrap region portions R1 and R2 (upstream of the discharge flow paths 60A and 60B), the discharge flow paths 60A and 60B are configured by the two flow paths 64A, 65A, 64B, and 65B. Therefore, the cross-sectional area of each one flow path can be halved. Therefore, the cross-sectional areas of the flow paths of the respective wrap region portions R1 and R2 can be halved. Thereby, the longest dimension SB between the flow path inner walls of the wrap region portions R1 and R2 can be reduced. As a result, the overall length of the tandem hydraulic pump 1 can be reduced.

For example, assuming that the required channel cross-sectional area S when the discharge channels 60A and 60B of each system are each composed of one channel is 100, the same channel cross-sectional area S (= 100) is divided into two. When the area s is covered by the channel, since “S = 2s”, the channel cross-sectional area s of each one of the two channels is 50, which is half.
If the cross section of the flow path is circular, the cross section area in the case of one is equal to the cross section area in the case of adding two, so the radius of the flow path in the case of one is R. If the radius of each flow path in the case of two is r, then r = R / √2≈R × 0.7. That is, the radius or diameter of the flow path when two lines are used is about 30% smaller than that when one line is used.

  Accordingly, the wrap region portions R1 and R2 in which the two discharge channels 60A and 60B overlap when viewed from the axial direction are used as one of the two channels 64A, 65A, 64B, and 65B. It can be made smaller than the channel diameter of the wrap region when the same cross-sectional area as the two channels is covered by one channel. For this reason, it is possible to reduce the longest dimension SB between the flow path inner walls while securing the shortest dimension SA between the flow path inner walls to a required thickness or more. As a result, the axial dimension SC of the intermediate casing 13 can be shortened.

  The tandem hydraulic pump according to the present embodiment has the above-described configuration, and the operation thereof will be described below.

  First, when the input shaft 20 is rotationally driven by operating a rotational drive source such as an engine, the cylinder blocks 31A and 31B of both pump units 30A and 30B rotate in synchronization. When the cylinder blocks 31A and 31B rotate, the pistons 33A and 33B engaged with the shoes 39A and 39B slidably contacting the swash plates 35A and 35B reciprocate in the cylinder chambers 32A and 32B. As a result, the hydraulic oil is sucked from the suction port 52 of the intermediate casing 13 and passes through the suction passages 53A and 53B and the suction ports 51A and 51B of the valve plates 34A and 34B, and the cylinder chambers 32A and 31B of the cylinder blocks 31A and 31B. 32B is inhaled.

  The hydraulic oil sucked into the cylinder chambers 32A and 32B is now pressurized by the pistons 33A and 33B and becomes pressurized oil, and passes through the discharge ports 61A and 61B and the discharge flow paths 60A and 60B of the intermediate casing 13 to the outside. It is discharged and supplied to hydraulic equipment connected to the discharge flow paths 60A and 60B, respectively.

  When the tilt angles of the swash plates 35A and 35B change, the stroke amounts of the pistons 33A and 33B are appropriately adjusted. Thereby, the flow volume of the pressure oil discharged from each pump unit 30A, 30B is variably controlled.

  In the first embodiment described above, the wrap region portions R1 and R2 in which the two discharge channels 60A and 60B overlap when viewed from the axial direction are included in the two channels 64A, 65A, 64B, and 65B. The case of using one flow path has been described. However, the present invention is not limited to this, and the wrap region portions R1 and R2 are constituted by two flow paths 64A, 65A, 64B, and 65B, and the flow path diameter in the wrap region portions R1 and R2 is set to one flow path. What is necessary is just to be able to make smaller than the flow path diameter in the case of comprising. That is, the locations where the two flow paths 64A, 65A, 64B, 65B are formed may overlap each other when viewed from the axial direction.

(Second Embodiment)
3A and 3B are configuration diagrams showing an intermediate casing of the tandem hydraulic pump according to the second embodiment, wherein FIG. 3A is a side view and FIG. 3B is an end view in the axial direction. In addition, the same code | symbol is attached | subjected to the component similar to 1st Embodiment shown in FIG. 2, and description is abbreviate | omitted.

  The tandem hydraulic pump according to the second embodiment is different only in the configuration of the intermediate casing in the first embodiment. Accordingly, the valve plate of each pump unit is provided with two discharge ports 61A and 61B, respectively, as in the first embodiment.

The intermediate casing 113 is provided with two systems of discharge flow paths 160A and 160B that are separated in the axial direction. The discharge flow paths 160A and 160B of each system are configured by one flow path 166A and 166B having inflow ports 162A and 162B and outflow ports 163A and 163B at both ends in the pressure oil flow direction, respectively.
The inlets 162A and 162B are inlets into which the pressure oil discharged from the two discharge ports 61A and 61B of the pump units 30A and 30B flows together. The inflow ports 162A and 162B open in a bowl shape on the axial end surfaces 13A and 13B of the intermediate casing 113.

  Further, the outlets 163A and 163B are outlets for leading the pressure oil flowing in from the inlets 162A and 162B to the outside. The outlets 163A and 163B are opened as circular holes on the outer surface facing the direction orthogonal to the axial direction of the intermediate casing 113. The flow paths 166A and 166B extending from the inlets 162A and 162B to the outlets 163A and 163B are configured as channels that are bent at a right angle.

  At this time, the overlapping region R1 (hatched portion in FIG. 3B) overlapping when viewed from the axial direction of the two discharge channels 160A and 160B is between the inner walls of the two discharge channels 160A and 160B. The shortest dimension SA is arranged at an interval such that the minimum dimension SA is greater than or equal to a predetermined value (more than the required thickness). Further, the flow path in the range including the wrap region portion R1 is a flow path having an oval cross section (including an elliptical cross section) whose cross sectional dimension T1 in the direction orthogonal to the axial direction is larger than the cross sectional dimension T2 in the axial direction. It is configured. Therefore, the axial cross-sectional dimension of the flow path can be made smaller than when the flow path is configured with a circular cross section.

  As a result, in the wrap region portion R1, the longest dimension SB between the flow path inner walls can be reduced while securing the shortest dimension SA between the flow path inner walls to a required thickness or more. Therefore, the axial dimension SC of the intermediate casing 113 can be shortened, and the overall length of the tandem hydraulic pump 1 can be shortened.

  According to at least one embodiment described above, the positions of the joining portions 66A and 66B of the two systems of the discharge flow paths 60A and 60B formed in the intermediate casing 13 are located downstream of the wrap region portions R1 and R2 (flow By setting it on the side close to the outlets 63A, 63B, the discharge flow paths 60A, 60B are configured by two flow paths 64A, 65A, 64B, 65B in a range including the wrap region portions R1, R2. Therefore, when each of the discharge channels 60A and 60B is configured with two channels, the cross-sectional area of each channel can be halved. Further, in each of the wrap region portions R1 and R2, a channel that overlaps when viewed from the axial direction can be one of the two channels 64A, 65A, 64B, and 65B.

  Accordingly, the cross-sectional area of each wrap region portion R1, R2 can be halved, and as a result, in the wrap region portion R1, the shortest dimension SA between the flow channel inner walls is ensured more than the required thickness. The longest dimension SB between the flow path inner walls can be reduced. Therefore, the axial dimension SC of the intermediate casing 113 can be shortened, and the overall length of the tandem hydraulic pump 1 can be shortened.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Tandem hydraulic pump, 10 ... Casing, 11A, 11B ... Casing main body, 13 ... Intermediate casing (intermediate part area | region of casing), 13A, 13B ... End surface of an axial direction, 13C ... Outer surface, 30A, 30B ... Pump unit 35A, 35B ... valve plate, 51A, 51B ... suction port, 53A, 53 ... suction passage, 60A, 60B ... discharge passage, 61A, 61B ... discharge port, 62A, 62B ... inlet, 63A, 63B ... flow Outlet, 66A, 66B ... Merging portion, SA ... Shortest dimension between inner walls, 64A, 65A ... Two channels, 64B, 65B ... Two channels, 113 ... Intermediate casing (intermediate region of casing), 160A, 160B ... discharge channel, 162A, 162B ... inflow port, 163A, 163B ... outflow port, 166A, 166B ... flow channel, R1, R2 ... wrap Band portion, the direction of the cross-sectional dimension perpendicular to the T1 ... axial, T2 ... axial cross-sectional dimension

Claims (4)

A casing,
Two pump units provided in the casing so as to be separated from each other in the axial direction;
A suction passage provided in the casing, for guiding hydraulic oil to each suction port of the two pump units;
Two discharge flow paths that are provided in the casing and guide the pressure oil discharged from the discharge ports of the two pump units to the outside in a separate system for each pump unit;
Have
A tandem hydraulic pump in which the two systems of discharge flow paths are axially separated from each other in an intermediate region of the casing located in an intermediate portion of two pump units provided apart in the axial direction Because
The discharge channel of each system is
Two inlets facing in the axial direction into which pressure oil discharged from the discharge port of each pump unit flows,
With one outflow port facing in the direction orthogonal to the axial direction for causing the pressure oil to flow outside, at both ends in the flow direction of the pressure oil,
In the middle of the flow direction of the pressure oil, it is configured as a flow path including a merge portion that joins the pressure oil flowing in from the two inflow ports and leads to the one outflow port,
The overlapping lap region portions as seen from the axial direction of the two discharge channels are arranged at an interval such that the shortest dimension between the inner walls of the two discharge channels is equal to or greater than a predetermined value.
The junction is disposed closer to the outlet than the wrap region portion, and the discharge passages positioned closer to the inlet than the junction communicate with the two inlets, respectively. A tandem hydraulic pump configured as two flow paths.   The tandem hydraulic pump according to claim 1, wherein the wrap region portion is one of the two flow paths. A casing,
Two pump units provided in the casing so as to be separated from each other in the axial direction;
A suction passage provided in the casing, for guiding hydraulic oil to each suction port of the two pump units;
Two discharge flow paths that are provided in the casing and guide the pressure oil discharged from the discharge ports of the two pump units to the outside in a separate system for each pump unit;
Have
A tandem hydraulic pump in which the two systems of discharge flow paths are axially separated from each other in an intermediate region of the casing located in an intermediate portion of two pump units provided apart in the axial direction Because
The discharge channel of each system is
An axially directed inlet into which pressure oil discharged from the discharge port of each pump unit flows,
It is configured as a flow path provided with both outlets in the flow direction of the pressure oil with one outflow port facing the direction orthogonal to the axial direction for flowing the pressure oil to the outside,
The overlapping lap region portion as seen from the axial direction of the two discharge channels,
The shortest dimension between the inner walls of the two discharge channels is arranged at a predetermined distance or more, and the sectional dimension in the direction orthogonal to the axial direction is larger than the sectional dimension in the axial direction. A tandem hydraulic pump configured as a channel with a set oval cross section. The two pump units are constituted by swash plate type axial piston pumps each having a variable discharge capacity, which are operated by synchronous rotation of rotating shafts arranged in the axial direction and connected coaxially.
The casing is composed of two casing bodies each housing the two pump units, and an intermediate casing as an intermediate region of the casing sandwiched between axially intermediate portions of the two casing bodies. ,
A valve plate having two discharge ports of each pump unit constituted by the swash plate type axial piston pump is disposed at a position in contact with both axial end surfaces of the intermediate casing;
Each inlet of the discharge passages of the two systems opens to both end surfaces in the axial direction of the intermediate casing,
The tandem hydraulic pump according to any one of claims 1 to 3, wherein each of the outlets of the two discharge channels has an opening on an outer surface facing a direction orthogonal to the axial direction of the intermediate casing. .

Images