OIL PUMP

Abstract

Oil pump (30) which is attached at a predetermined position of a device which has an oil-supplied section which requires an oil supply, and which supplies oil to the oil-supplied section in such a way that a piston (31) which has a drive section (31a) engaged with a drive worm (10) arranged on the device moves back and forth in a pump housing (33) while rotating, wherein the oil pump (30) comprises: a mounting surface (33e) which is arranged on the pump housing (33) and attached at the specified position; and two positioning parts (46, 46) arranged on the mounting surface (33e), wherein the positioning parts (46, 46) position the oil pump (30) at the predetermined position when the oil pump (30) is attached, wherein the two positioning parts (46, 46) are spaced apart from each other in a direction of an axis (L) of the piston (31) and each of the positioning parts (46, 46) is placed on a center line (CL) of a cross-section of the piston (31), wherein, when the oil pump (30) is viewed from one side of the mounting surface (33e), the two positioning parts (46, 46) are spaced apart on the axis (L) of the piston (31) and wherein the two positioning parts (46, 46) are arranged such that they are placed transversely on both sides over a plane which is perpendicular to the axis (L) of the piston (31) and contains a center of rotation axis (N) of the drive worm (10).

Description

BACKGROUND OF THE INVENTION 1. AREA OF THE INVENTION

[0001] The invention relates to an oil pump for use with and attached to a device (for example, a chainsaw) which has an oil-supplied section that requires an oil supply. 2. DESCRIPTION OF THE RELEVANT TECHNOLOGY

[0002] In a chainsaw, a chain driven by a motor (engine, electric motor, etc.) rotates (runs) at high speed around a guide bar in contact with the guide bar. Therefore, the chainsaw is equipped with an oil pump that circulates lubricating oil to reduce friction and wear between the sliding parts of the saw chain and the guide bar.

[0003] DE 41 02 945 A1 discloses an oil pump for a chainsaw, comprising a drive unit with a drive shaft and a gear fixed to the drive shaft and meshing with a worm gear fixed to the output shaft of a motor. The oil pump assembly also includes a pump unit with a pump housing and a plunger piston rotatably and reciprocally movably arranged within the pump housing and driven by the drive shaft. The drive unit and the pump unit are manufactured as separate components and driven by a sliding connection that allows axial displacement of the plunger piston relative to the drive shaft.

[0004] GB 270 116 A discloses a pump primarily for lubricating an internal combustion engine, comprising a piston that is moved back and forth by a projecting finger on the piston skirt, the finger following a cam groove in a ring, while the piston is rotated by means of a wheel or worm gear that engages with teeth on the piston. The teeth are elongated to allow the reciprocating motion of the piston.

[0005] DE 25 41 495 A1 discloses a chainsaw characterized by a housing, a motor attached to the housing, a pump chamber formed by housing walls with an inlet slot and an outlet slot, a pump element which is rotatable in the pump chamber relative to the inlet and outlet slots and is designed in such a way that a pumping action takes place when it rotates, and a detachable, flexible drive connection which couples the pump element to the motor in such a way that the pump element is rotated by the motor.

[0006] DE 101 91 359 B4 discloses a lubricating oil pump for a motor chainsaw, comprising a pump housing with a pump cylinder, and a pump piston which is slidably mounted in the pump cylinder in the direction of a pump axis and which is removable to one side, and which, when rotated about the pump axis, performs axial pumping movements against the pressure of a first spring by means of an inclined control surface arranged on the pump piston running against a control head of an adjustable pump stroke adjustment device.

[0007] DE 33 41 834 A1 discloses a motor chainsaw in which a sprocket for a saw chain and a drive wheel for a lubricating oil pump are rotatably mounted on the crankshaft. The sprocket and the drive wheel are driven via a clutch drum. The drive wheel of the lubricating oil pump is connected to the clutch drum by a detachable plug connection via the drum's circumferential wall.

[0008] DE 19 40 815 U discloses a lubricating oil pump for conveying lubricating oil, in particular for saw chains of motor chainsaws, with a driven piston performing a rotary motion and, when conveying oil, a stroke motion, the cylinder chamber of which has an oil inlet and an oil outlet opening which are closed and open alternately, respectively, wherein the piston has a control surface inclined to its axis of rotation which rests against a cam adjustable transversely to the axis of rotation.

[0009] The publication “1000 design examples for practical use (p. 233 or 354), ISBN: 978-3-446-42034-2” reveals examples of screw and pin connections executed according to the usual design rules and negative examples.

[0010] For example, an oil pump disclosed in Japanese patent application JP S64 - 24 180 A is configured to supply lubricating oil to a guide rail in such a way that a pump piston, which has a gear meshing with a worm gear driven by a motor, moves in an axial direction while rotating a piston cylinder of a pump housing.

[0011] An oil pump with this configuration is often designed so that it is separate from the worm gear. This means the worm gear can be mounted on a rotating shaft driven by the engine, and the oil pump can be mounted separately from the worm gear on the chainsaw. Therefore, it is necessary that the oil pump is mounted on the chainsaw in such a way that the center-to-center distance between the rotating shaft (worm gear) and the pump piston (gear) is appropriate.

[0012] Regarding this point, the pump housing of an oil pump disclosed in Japanese patent application JP S64-24180A contains a cylindrical section above a pump piston, capable of accommodating a worm gear. From this, it can be concluded that, for example, if the cylindrical section is used to position the oil pump on the chainsaw, the oil pump can be mounted in a suitable position on the chainsaw.

[0013] The cylindrical section, however, makes the oil pump larger than necessary and also increases its weight. In recent years, there has been a demand for size and weight reduction in chainsaws, and it is equally necessary to reduce the size and weight of the oil pump used in and attached to the chainsaw. However, if the cylindrical section is removed to reduce size and weight, it becomes difficult to mount the oil pump in the appropriate position on the chainsaw.

[0014] It should be noted that such a problem is not limited to the oil pump used in the chainsaw, but that it applies, in a sense, generally to oil pumps used in various devices, each of which contains an oil-supplied section that requires an oil supply.

[0015] Therefore, it is an object of the invention to provide an oil pump for use with and attached to a device having an oil-supplied section which requires an oil supply, wherein the oil pump is capable of ensuring the accuracy of its attachment to the device and achieving a reduction in size and weight. This object is achieved by means of the oil pump according to claim 1. SUMMARY OF THE INVENTION

[0016] According to one aspect of the invention, an oil pump is provided that is configured to be mounted at a predetermined position of a device having an oil-supplied section that requires an oil supply. This oil pump is configured to supply oil to the oil-supplied section such that a pump piston with a gear section, which engages with a drive worm provided on the device, moves reciprocally within a pump housing as it rotates. The oil pump comprises: a mounting surface provided on the pump housing and mounted at the predetermined position; and two positioning elements provided on the mounting surface, the positioning elements positioning the oil pump at the predetermined position during an operation of mounting the oil pump.These two positioning parts are spaced apart in an axial direction of the pump piston, and each of them is arranged on a centerline of a cross-section of the pump piston. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a view showing an external appearance of a chainsaw in which an oil pump according to an embodiment of the present invention is used. Fig. Figure 2 is an enlarged cross-sectional view of the main parts of the chainsaw. Fig. 3A is a cross-sectional view of the oil pump. Fig. 3B is a cross-sectional view of AA of the Fig. 3A. Fig. 3C is a rear view of the oil pump. Fig. 3D is a top view of the oil pump. Fig. Figure 4 is an enlarged view of part B of the Fig. 3D. Fig. 5 is a cross-sectional view of CC. Fig. 3C. Fig. Figure 6 is a cross-sectional view of DD. Fig. 3C. Fig. Figure 7 is a perspective view of the oil pump. DESCRIPTION OF PREFERRED EXECUTION FORMS

[0017] The following is a description of embodiments of the present invention with reference to the accompanying drawings. Fig. 1 and Fig. Figure 2 shows a configuration of a chainsaw in which an oil pump according to an embodiment of the present invention is used. Fig. Figure 1 is a view that represents an external appearance of the chainsaw, and Fig. Figure 2 is an enlarged cross-sectional view (cross-sectional view along a backward-forward direction) of main components of the chainsaw.

[0018] As in Fig. As shown in Figure 1, a chainsaw 1 has a chainsaw housing 2 containing a drive unit (not shown), such as a motor or electric motor, and a sprocket (not shown) rotated by the drive unit. A front guard 3, a front handle 4, a rear handle 5, etc., are arranged inside the chainsaw housing. A guide bar 6 is also attached to the chainsaw housing 2. The guide bar 6 extends forward from the chainsaw housing 2, and a saw chain 7 is wound around the guide bar 6 and the sprocket. A rear side of the guide bar 6 (and the sprocket) is covered by a chain guard 8. A guide groove is formed on a circumferential edge of the guide bar 6, and the saw chain 7 runs along the guide groove of the guide bar 6 in the direction of the sprocket's rotation. In this way, the chainsaw 1 can cut an object, such as wood.

[0019] As in Fig. As shown in Figure 2, an oil pump 30 is also arranged in the chainsaw 1. In this embodiment, the oil pump 30 is designed as a piston pump and is attached to a predetermined position on the chainsaw 1 (more precisely, to a predetermined position on the chainsaw housing 2). The oil pump 30 supplies lubricating oil (chain oil) to the guide groove of the guide bar 6 such that a piston 31 of the oil pump 30 is driven by a drive element, which is attached to a rotating shaft (crankshaft, motor output shaft, etc.) 9 turned by the motor. In this embodiment, the drive element is a drive worm 10. In other words, in this embodiment, the oil pump 30 is configured to be driven by the motor via the drive worm 10, which is designed to be separate from the oil pump 30 and arranged (attached) to the chainsaw 1 (the chainsaw housing 2).Since the lubricating oil is supplied to the guide groove of the guide rail 6 by the oil pump 6, friction and wear between sliding parts of the guide groove of the guide rail 6 and the saw chain 7 can be reduced.

[0020] The Fig. 3A to 3D and the Fig. Figures 4 to 7 show a configuration of oil pump 30. Fig. 3A is a cross-sectional view (cross-sectional view viewed from the front) of oil pump 30, Fig. 3B is a cross-sectional view along line AA of the Fig. 3A, Fig. 3C is a rear view of oil pump 30 and Fig. 3D is a top view of oil pump 30. Furthermore, Fig. 4 an enlarged view of part B of the Fig. 3D, Fig. Figure 5 is a cross-sectional view along line CC of the Fig. 3C, Fig. Figure 6 is a cross-sectional view along line DD of the Fig. 3C and Fig. Figure 7 is a perspective view of oil pump 30.

[0021] The oil pump 30 has a pump housing 33 in which a cylinder 32 is formed, which accommodates the piston 31. The cylinder 32 is designed as a stepped cylinder with a section of larger diameter 32a and a section of smaller diameter 32b. The cylinder 32 is designed such that it moves the pump housing 33 in a longitudinal direction (left-right direction). Fig. 3, corresponding to the reverse-forward direction of the chainsaw 1), and both end sections of the cylinder 32 are individually closed by sealing plugs 34 and 35 (see Fig. 3A).

[0022] The piston 31 has a drive section 31a at a central point. A part of the piston 31 between the drive section 31a and a rear end (left in Fig. 3A) is included in the larger diameter section 32a of the cylinder 32, and a front end (right side in Fig. 3A) of the drive section 31a of the piston 31 is received in the smaller diameter section 32b of the cylinder 32. The drive section 31a of the piston is configured such that part of the drive section 31a may be exposed by an opening 33a formed on the pump body 33 (on an upper part thereof) (see Fig. 3D) and such that its exposed part can engage with the drive worm 10 arranged on the chainsaw housing 2. Furthermore, the piston 31 is held on both sides via the drive section 31a so that it is slidable and rotatable within the cylinder 32. In other words, the piston 31 is held by the pump housing 33 (an inner circumferential surface of the cylinder 32 thereof) at two points spaced apart from each other in a direction along an axis L of the piston 31.

[0023] As in Fig. As shown in Figure 3A, an oil seal 36 is attached at a predetermined location on the front end (right in the figure) of the drive section 31a of the piston 31. This seal seals a space between an outer circumferential surface of the piston 31 and an inner circumferential surface of the cylinder 32 (the smaller diameter section 32b thereof). Furthermore, a D-shaped section 31b is formed on a front end section (right end section in the figure) of the piston 31, and a rear end surface (left end surface in the figure) 31c of the piston 31 is formed into an inclined surface.A spring 37, which is arranged between such a side surface of the front end of the drive section 31a and the pump housing 33, more precisely a stepped surface of the cylinder 32, which represents a transition section from the section of larger diameter 32a to the section of smaller diameter 32b, then always pushes the piston 31 backwards (to the left in the figure).

[0024] At one end (the front end of the piston 31) in the longitudinal direction of the pump housing 33, an inlet opening 38 and an outlet opening 39 are formed, which communicate with an interior of the cylinder 32 (the smaller diameter section 32b thereof). The inlet opening 38 and the outlet opening 39 are designed to project from an outer circumferential surface of the pump housing 33, and the inlet opening 38 and the outlet opening 39 are arranged on opposite sides transversely across the axis (= central axis of the cylinder 32) L of the piston 31. In this embodiment, the inlet opening 38 is formed on a lower section of the pump housing 33, and the outlet opening 39 is formed on an upper section of the pump housing 33.When the piston 31 rotates and the D-shaped cut section 31b formed at the front end of the piston 31 comes to a position corresponding to the inlet opening 38, the inlet opening 38 is open to the interior of the cylinder 32, and when the piston 31 rotates and the D-shaped cut section 31b comes to a position corresponding to the outlet opening 39, the outlet opening is open to the interior of the cylinder 32 (see . Fig. 3A and Fig. 5).

[0025] The inlet opening 38 is connected to an oil reservoir (not shown) via an oil suction line 11 (see Fig. 2) The outlet opening 39, on the other hand, is connected via an oil supply line 12 to the guide groove of the guide rail 6 or to its vicinity (see Fig. 2).

[0026] Furthermore, a through-bore 40 is formed at the other end (the rear end of the piston 31) of the pump housing 33, which passes through the pump housing 33 in a direction perpendicular to the axis (= the central axis of the cylinder 32) L of the piston 31. In this embodiment, the through-bore 40 passes through the pump housing 33 in an upward-downward direction, i.e., essentially parallel to the inlet opening 38 and the outlet opening 39, which project from the outer circumferential surface of the pump housing 33, and a control rod 41 is inserted through the through-bore 40, which is capable of controlling an amount of the reciprocating movement (stroke) of the piston 31 in the cylinder 32 (see Fig. 3A, Fig. 3C and Fig. 6).

[0027] An intermediate section of the control rod 41, extending along one axis M, is arranged in the through-bore 40, and both ends of the control rod 41 protrude from the through-bore 40 (are exposed to the outside). Part of the intermediate section is also located inside the cylinder 32 (the section with the larger diameter 32a thereof). The control rod 41 is held transversely on both sides (the upper and the lower sides) across the portion of the intermediate section located inside the cylinder 32, such that it is slidable and rotatable within the through-bore 40. In other words, part of the control rod 41 is arranged in the pump housing 33 (the through-bore 40), and the control rod 41 is held on the pump body 33 (the inner circumferential surface of the through-bore 40) at two points spaced apart in the direction of the axis M of the control rod 41 (i.e., the control rod 41 is held on both the upper and lower sides).

[0028] The control rod 41 includes a motion control section 41a, which regulates the amount of the reciprocating movement (stroke) of the piston 31 by bringing the rear end face (the inclined surface) 31c of the piston 31 into contact with the part of the intermediate section arranged in the cylinder 32. In this embodiment, the part of the intermediate section arranged in the cylinder 32 is configured such that it has an outer diameter that varies continuously in the direction of the axis M of the control rod 41, and that it has a section with a maximum diameter which functions as the motion control section 41a.

[0029] A pin element 42 is pressed into a section at one end (the upper end) of the control rod 41, which projects towards one side (the upper side) of the through-bore 40. This pin element 42 runs through the control rod 41 in a direction perpendicular to its axis M. Furthermore, several pairs of engagement sections 33b to 33d, differing in height, are formed in the upper section (or upper surface) of the pump housing 33 around an opening of the through-bore 40 (see figure). Fig. 3D and Fig. 4) Furthermore, both ends of the pin element 42, which pass through the control rod 41 and protrude from an outer circumferential surface of the control rod 41 (are exposed to the outside), are configured such that, depending on the rotational position of the control rod 41, they engage with a respective pair of the several pairs of engagement sections 33b to 33d. It should be noted that this describes a state in which both ends of the pin element 42 are engaged with the engagement sections 33c and 33d, which have a medium height. When the engagement sections that engage with both ends of the pin element 42 are changed, a position (a position in the direction of the axis M) of the control rod 41 in the through-bore 40 is changed, thereby changing the contact position of the motion control section 41a in contact with the rear end surface 31c of the piston 31, which is designed as an inclined surface.In this embodiment, the motion control section 41a is configured to be in contact, depending on the position of the control rod 41, with a position near an outer edge of the rear end surface (the inclined surface) 31c of the piston 31, a position near a center of the rear end surface 31c, or a position between these positions.

[0030] A stop ring (retaining ring) 43 is fitted to a predetermined position at the other end (the lower end) of the control rod 41, which protrudes on the other side (the lower side) of the through-bore 40, and a radially extending groove (a negative groove) 44 is formed on the other end face (the lower end face) of the control rod 41. The control rod 41 is furthermore always pressed in a direction by a spring 45 arranged between the pump housing 33 (the lower section of its lower surface) and the stop ring 43, in which the other end face (the lower surface) moves away from the pump body 33 (i.e. downwards).

[0031] A mounting surface 33e is formed on the rear side of the pump body 33, which is configured to be attached to the chainsaw housing 2 (see Fig. 3C and Fig. 3D). The oil pump 30 is configured such that the mounting surface 33e formed (provided) on the pump housing 33 can be attached to the chainsaw housing 2. The mounting surface 33e is designed as a surface corresponding to a predetermined position of the chainsaw housing 2. In this embodiment, the mounting surface 33e (and the predetermined position of the chainsaw housing 2) is a flat surface and is designed to have an extended section that faces away from the opening 33a (i.e., the side of the drive worm 10) (see Fig. 3C). An intermediate section in the longitudinal direction of the pump housing 33 contains the mounting surface 33e and is wider than other sections, and a front face (i.e. a side facing away from the mounting surface 33e of the pump housing 33) of the intermediate section is designed as a flat surface that is parallel to the mounting surface 33e (see Fig. 3C, Fig. 3D and Fig. 5).

[0032] Two guide pins 46 and 46 are mounted on the mounting surface 33e of the pump housing 33 on the chainsaw housing 2, and an additional mounting bore 47 is formed (see Fig. 3C and Fig. 3D). The guide pins 46 and 46 are used to set the mounting position of the oil pump 30 on the chainsaw housing 2 during the process of attaching the oil pump 30 to the chainsaw housing 2. Specifically, the guide pins 46 and 46 are individually inserted into corresponding guide bores (not shown) formed on the chainsaw housing 2, thereby setting the mounting position of the oil pump 30 on the chainsaw housing 2. In other words, when attaching the oil pump 30 to the chainsaw housing 2, the guide pins 46 and 46, together with the guide bores provided as positioning elements on the chainsaw 2, bring the oil pump 30 into the correct position. The guide pins 46 and 46 can be integrally formed with the pump body 33 or formed separately from the pump body 33 by pressing, etc.are attached to the mounting surface 33e of the pump body 33.

[0033] On the mounting surface 33e of the pump body 33, the guide pins 46 and 46 are arranged at a distance from each other in the direction of the axis (central axis of the cylinder 32) L of the piston 31, and each of the guide pins is arranged on a center line CL of a cross-section of the piston 31 (cylinder 32), i.e. on a line which passes through a center point (position of the axis L) on the cross-section (see Fig. 3B, Fig. 3C and Fig. 5) In other words, when the oil pump 30 (the pump housing 33) is viewed from the side of the mounting surface 33e (the rear), i.e., when the mounting surface 33e is viewed from the side of the chainsaw housing 2, the guide pins 46 and 46 are arranged at a predetermined distance from each other on the axis (central axis of the cylinder 32) L of the piston 31 (see Fig. 3C). More precisely, when the mounting surface 33e is viewed from the side of the chainsaw housing 2, the guide pins 46 and 46 are arranged on the axis L of the piston 31 such that they are arranged transversely on both sides over a plane that is perpendicular to the axis (central axis of the cylinder 32) L of the piston 31 and contains a center of rotation axis (= axis of the rotating shaft 9) N of the drive worm 10.

[0034] The mounting bore 47 is used to fasten the oil pump 30, which is positioned by the guide pins 46 and 46, to the chainsaw housing 2. In particular, a mounting bolt (not shown) is inserted through the mounting bore 47, and the mounting bolt thus inserted is additionally screwed into a bolt hole (not shown) formed in the chainsaw housing 2, thereby fastening the oil pump 30 to the chainsaw housing 2.

[0035] The mounting bore 47 is formed in the extended section of the mounting surface 33e in such a way that it is arranged on the side facing away from the drive worm 10 across a plane that is parallel to the axis of rotation (= axis of the rotating shaft 9) N of the drive worm 10 and contains the axis (central axis of the cylinder 32) L of the piston 31. In other words, the mounting bore is arranged such that, in a direction perpendicular to the axis (central axis of the cylinder 32) L of the piston 31 and in a direction perpendicular to the axis of rotation (axis of the rotating shaft 9) N of the drive worm 10, it is located further away (here further down than the guide pins 46 and 46) than the guide pins 46 and 46.In this embodiment, the mounting bore 47 is arranged such that it lies on the plane that is perpendicular to the axis (central axis of the cylinder 32) L of the piston 31 and contains the axis of rotation (axis of the rotating shaft 9) N of the drive worm 10. In this way, when the oil pump 30 (the pump housing 33) is viewed from the side of the mounting surface 33e, the guide pins 46 and 46 and the mounting bore 47 are arranged in such positions that a triangle (more precisely: an acute-angled triangle) is formed when the centers of these triangles are connected by a line.

[0036] The following is a description of the functions of oil pump 30, which has a configuration as described above.

[0037] First, the oil pump 30 is attached to the chainsaw housing 2 and secured to it by the mounting bolt, which is inserted through the mounting bore 47 formed in the mounting surface 33e of the pump housing 33. During this process, the guide pins 46 and 46, located on the mounting surface 33e of the pump housing 33, are inserted into the guide bores on the chainsaw housing 2 described above, thereby aligning the mounting position of the oil pump 30 on the chainsaw housing 2 correctly. This ensures a suitable axial distance (i.e., a suitable engagement state) between the drive worm 10 located on the chainsaw housing 2 and the drive section 31a of the piston 31 located on the oil pump 30.

[0038] When the drive worm 10 is rotated by the drive shaft 9 of the chainsaw motor 1, the piston 31 is driven by the drive section 31a of the drive worm 10. The piston 31 then rotates in the cylinder of the pump housing 30 and moves back and forth in the cylinder 32 by a function between the rear end face (the inclined surface) 31c of the piston 31 and the motion control section 41a of the control rod 41. In this way, the oil pump 30 draws the lubricating oil supplied in the oil reservoir through the oil suction line 11 from the inlet opening 38, compresses the lubricating oil, and discharges the lubricating oil from the outlet opening 39, repeating these steps. The lubricating oil discharged from the outlet opening 39 is then supplied to the guide groove of the guide bar 6 via the oil supply line 12.

[0039] Furthermore, in the oil pump 30, the engagement sections 33b to 33d, with which both ends of the pin element 42 arranged at one end of the control rod 41 are engaged, are changed, thereby altering the delivery quantity of the lubricating oil, i.e., the supply quantity of the lubricating oil to the guide groove of the guide rail 6. The change of the engagement sections 33b to 33d, with which both ends of the pin element 42 are engaged, is carried out, for example, by inserting the tip of a slotted screwdriver, etc., into a groove 44 formed on the other end face of the control rod 41 and rotating the control rod 41 while the control rod 41 is pressed against the compressive force of the spring 45.When the engagement sections 33b to 33d, with which both ends of the pin element 42 are to be brought into engagement, are changed, the positions in the radial direction of the rear end surface (the inclined surface) 31c of the piston 31, which engages with the motion control section 41a, are also changed. In this way, the amount of the reciprocating movement (the stroke amount) of the piston 31 is changed, and the delivery quantity (amount of lubricating oil supplied) of the oil pump 30 is changed.

[0040] It should be noted that in this embodiment the guide groove of the guide rail 6 corresponds to an “oil-supplied section requiring an oil supply” of the present invention, the chainsaw 1 (the chainsaw housing 2) corresponds to a “device containing the oil-supplied section requiring an oil supply” of the present invention, the chainsaw housing 2 corresponds to a “predetermined position” of the present invention, the guide pins 46 and 46 correspond to “two positioning parts” of the present invention, and the fastening bore 47 corresponds to a “fastening section” of the present invention.

[0041] The two guide pins 46 and 46 for adjusting the mounting position of the oil pump 30 are located on the chainsaw housing 2. Specifically, these two guide pins, used to position the oil pump 30 when attaching it to the chainsaw housing 2, are arranged on the mounting surface 33e of the pump housing 33 on the chainsaw housing 2. The mounting surface 33e is designed as a surface (in this case, a flat surface) corresponding to the predetermined position of the chainsaw 1. Furthermore, the two guide pins 46 and 46 are spaced apart along the axis L (central axis of the cylinder 32) of the piston, and each guide pin is located on the centerline CL of the cross-section of the piston 31 (of the cylinder 32).In other words, when the oil pump 30 is viewed from the rear (the mounting surface 32e), the two guide pins 46 and 46 are spaced apart on the axis (the central axis of the cylinder 32) L of the piston 31.

[0042] Therefore, the accumulation of tolerances, for example when attaching the oil pump 30 to the chainsaw housing 2, can be reduced, thereby suppressing variations in the axial distance between the drive worm 10 and the drive section 31a of the piston 31. Furthermore, it is possible to position the guide pins 46 and 46 within the area where the piston 31 is located, thus reducing the size of the pump housing and allowing the overall size of the oil pump 30 to be reduced compared to previous designs. In this way, the size and weight of the oil pump 30 can be reduced while ensuring the accuracy of its attachment to the chainsaw housing 2.Furthermore, the mounting surface 33e and the guide pins 46 and 46 can be useful as processing standards of the pump housing 33, and consequently the processing accuracy of the pump housing 33 and ultimately the manufacturing accuracy of the oil pump 30 can also be improved.

[0043] Furthermore, the two guide pins 46 and 46 are arranged such that they are positioned transversely on both sides across the plane that is perpendicular to the axis (= central axis of the cylinder 32) L of the piston 31 and contains the axis of rotation (axis of the rotating shaft 9) N of the drive worm 10. In other words, when the oil pump 30 is viewed from the side of the mounting surface 33e, the two guide pins 46 and 46 are arranged transversely on both sides across a line that is perpendicular to both the axis (central axis of the cylinder 32) L of the piston 31 and the axis of rotation (axis of the rotating shaft 9) N of the drive worm 10 (see Fig. 3C). Therefore, fluctuations in the mounting position (inclination) of the oil pump 30 can be reduced, and in addition, fluctuations in the axial distance between the drive worm 10 and the drive section 31a of the piston 31 can be reduced more effectively.

[0044] Furthermore, the mounting bore 47 for attaching the oil pump 30 to the chainsaw housing 2 is located on the mounting surface 33e of the pump housing 33 on the chainsaw housing 2. The mounting bore 47 is thus located on the side facing away from the side of the drive worm 10 across the plane that is parallel to the axis of rotation (= axis of the drive shaft 9) N of the drive worm 10 and contains the axis (central axis of the cylinder 32) L of the piston 31. In particular, the mounting bore 47 is arranged such that it lies on the plane that is perpendicular to the axis (central axis of the cylinder 32) L of the piston 31 and contains the axis of rotation (axis of the drive shaft 9) N of the drive worm 10.In other words, when the oil pump 30 is viewed from the side of the mounting surface 33e, the mounting bore 47 is formed in a position that lies on a straight line perpendicular to both the axis (central axis of the cylinder 32) L of the piston 31 and the axis of rotation (axis of the rotating shaft 9) N of the drive worm 10, and is further away from the drive worm 10 than the two guide pins 46 and 46 (see . Fig. 3C). In this way, the oil pump 30, positioned by the two guide pins 46 and 46, can be stably attached to the chainsaw body, while the enlargement of the oil pump 30 (of the pump housing 33) can be reduced by the mounting bore 47.

[0045] Furthermore, the intermediate section in the longitudinal direction of the pump housing 33 contains the mounting surface 33e and is wider than other sections. Additionally, the side of the pump housing 33 facing away from the mounting surface 33e is designed as a flat surface parallel to the flat mounting surface 33e. In this way, the installation space for the oil pump 30 in the chainsaw 1 can be reduced, and the installation of other components adjacent to the oil pump 30 can also be carried out conveniently.

[0046] Furthermore, the piston 31 and the control rod 41 are held on the pump housing 33 at two points spaced apart in their respective axial directions (axis L, axis M). In this way, tilting of the piston 31 and the control rod 41 during operation can be reduced, and stable operation of the pump can be achieved.

[0047] One embodiment of the present invention has been described above; however, the present invention is not limited to the embodiment described above, and of course various modifications and changes based on the technical concept of the present invention are possible. Some of the modifications and changes are mentioned below by way of example.

[0048] For example, in the preceding embodiment, the two guide pins 46 and 46 are arranged such that they are positioned transversely on both sides across the plane that is perpendicular to the axis (= central axis of the cylinder 32) L of the piston 31 and contains the axis of rotation (axis of the rotating shaft 9) N of the drive worm 10. However, the present invention is not limited thereto, and one of the guide pins 46 and 46 can be arranged on the plane that is perpendicular to the axis (= central axis of the cylinder 32) L of the piston 31 and contains the axis of rotation (axis of the rotating shaft 9) N of the drive worm 10. When the oil pump 30 is viewed from the side of the mounting surface 33e, in this case one of the two guide pins 46 and 46 is arranged on the straight line perpendicular to the axis (central axis of the cylinder 32) L of the piston 31 and the axis of rotation (axis of the rotating shaft 9) N of the drive worm 10, similar to the mounting bore 47.In the aforementioned embodiment, however, the distance between the two guide pins 46 and 46 in the direction of the axis (central axis of the cylinder 32) L of the piston 31 can be increased more, and consequently, it can be said that the aforementioned embodiment is better with regard to stabilizing the mounting setting of the oil pump 30.

[0049] Furthermore, in the aforementioned embodiment, the two guide pins 46 and 46 are provided on the mounting surface 33e of the pump housing 33 on the chainsaw housing 2; however, instead of the two guide pins 46 and 46, two guide bores can be formed on the mounting surface 33e. In this case, only two guide pins (positioning elements), which, together with the two guide bores, set the mounting position of the oil pump 30, need to be arranged on the chainsaw housing 2. That is, the oil pump 30 can be configured such that, instead of the guide pins 46 and 46, which are to be inserted into the corresponding guide bores formed on the chainsaw housing 2, it has two guide bores into which corresponding guide pins formed on the chainsaw housing 2 are to be inserted.

[0050] Furthermore, in the aforementioned embodiment, the two guide pins 46 and 46 and the mounting bore 47 are provided on the mounting surface 33e of the pump housing 33 on the chainsaw housing 2. However, the two guide pins 46 and 46 and the mounting bore 47 only need to be arranged on the same plane and do not necessarily have to be arranged on a continuous surface. In addition, the mounting bore 47 can be arranged in a different position than in the aforementioned embodiment.

[0051] Furthermore, in the aforementioned embodiment, the oil pump 30 for use with and attached to the chainsaw 1 was described; however, the present invention is not limited thereto and is also applicable to an oil pump for use with and attached to various devices, each containing the oil-supplied section which requires an oil supply.

[0052] According to the oil pump of the present invention, the accumulation of tolerances, e.g. when attaching the oil pump to the device, can be reduced, and its attachment accuracy can be ensured, while at the same time the size and weight of the oil pump can be reduced.

Claims

[1] Oil pump (30) which is attached at a predetermined position of a device which has an oil-supplied section which requires an oil supply, and which supplies oil to the oil-supplied section in such a way that a piston (31) which has a drive section (31a) engaging with a drive worm (10) arranged on the device moves back and forth in a pump housing (33) while rotating, wherein the oil pump (30) comprises: a mounting surface (33e) which is arranged on the pump housing (33) and attached at the specified position; and two positioning parts (46, 46) arranged on the mounting surface (33e), wherein the positioning parts (46, 46) position the oil pump (30) at the predetermined position when the oil pump (30) is attached, wherein the two positioning parts (46, 46) are spaced apart from each other in a direction of an axis (L) of the piston (31) and each of the positioning parts (46, 46) is placed on a center line (CL) of a cross-section of the piston (31), wherein, when the oil pump (30) is viewed from one side of the mounting surface (33e), the two positioning parts (46, 46) are spaced apart on the axis (L) of the piston (31) and wherein the two positioning parts (46, 46) are arranged such that they are placed transversely on both sides over a plane which is perpendicular to the axis (L) of the piston (31) and contains a center of rotation axis (N) of the drive worm (10). [2] Oil pump (30) according to claim 1, further comprising: a fastening section (47) which is arranged on the pump housing (33), wherein the fastening section (47) fastens the oil pump (30) at the predetermined position (2), wherein the fastening section (47) is arranged such that it is placed on a side facing away from the drive worm (10) transversely over a plane which is parallel to the axis of rotation (N) of the drive worm (10) and contains the axis (L) of the piston (31). [3] Oil pump (30) according to claim 2, wherein the fastening section (47) is arranged such that it is placed on a plane that is perpendicular to the axis (L) of the piston (31) and contains the axis of rotation (N) of the drive worm (10). [4] Oil pump (30) according to claim 2 or 3, wherein the fastening section (47) is formed on the fastening surface (33e) on which the two positioning parts (46, 46) are arranged. [5] Oil pump (30) according to one of claims 1 to 4, wherein a surface of the pump housing (33) facing away from the mounting surface (33e) is designed as a flat surface parallel to the mounting surface (33e). [6] Oil pump (30) according to one of claims 1 to 5, wherein the piston (31) is held at two points spaced apart in the axial direction (L) of the piston (31) on the pump housing (33). [7] Oil pump (30) according to one of claims 1 to 6, wherein at one end of the pump housing (33), in the direction of the axis (L) of the piston (31), an inlet opening (38) through which the oil is drawn in and an outlet opening (39) through which the oil is discharged are formed, and at the other end of the pump housing (33) a control rod (41) is received which is able to change an amount of the reciprocating movement of the piston (31). [8] Oil pump (30) according to claim 7, wherein the control rod (41) is held by the pump housing (33) at two points spaced apart in the direction of an axis (M) of the control rod (41). [9] Oil pump (30) according to claim 7 or 8, wherein the control rod (41) passes through the pump housing (33) in a direction perpendicular to the axis (L) of the piston (31) and protrudes from the pump housing (33) at both ends. [10] Oil pump (30) according to one of claims 1 to 9, wherein the two positioning parts (46, 46) are guide pins to be inserted into guide bores which are formed in the predetermined position, or are guide bores into which guide pins which are arranged in the predetermined position are to be inserted.

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