JP2012233459A - Oil pump and cab tilt device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil pump without requiring to process a suction passage in a casing.SOLUTION: This oil pump 13 includes a cylinder 32 pressed in a cylinder storage chamber 30 formed in the casing 21, a piston 34 slidably fitted in a cylinder chamber 33 of the cylinder 32, a suction valve 40 for sucking oil in the cylinder chamber 33 in response to an advance-retreat of the piston 34, and a delivery valve 50 for delivering the oil from the cylinder chamber 33 in response to the advance-retreat of the piston 34. An end surface communicating groove 47 communicating with a suction port 42 is formed on an end surface of a valve cylinder 46 fitted in an end of the cylinder 32, and a side surface communicating groove 48 communicating with the end surface communicating groove 47 is formed in a press-in part with the casing 21 of a cylinder 32 side surface. A conical filter 49 in interposed outside the cylinder 32 in the cylinder storage chamber 30 and on the cam ring storage chamber 28 side.

Description

  The present invention relates to an oil pump and a carbitol device using the same.

Medium and large cabover trucks are equipped with a cabylt unit so that inspection and maintenance of the engine portion can be easily performed.
This type of conventional carbylating apparatus is configured as follows.
A tilt cylinder device driven by an oil pump is interposed between the cab and the frame, and the cab is lifted by supplying pressure oil to the oil passage on the raising side of the tilt cylinder device by the oil pump. The cab is lowered by supplying pressure oil to the lower side oil passage.

  In an oil pump used in such a carbylate device, a cylinder in which a piston reciprocates is press-fitted into a casing, and a suction valve is integrally assembled with the cylinder, and the suction path communicates with the tank. Is processed into a casing. For example, see Patent Document 1.

JP 2009-96283 A

  However, in an oil pump in which the suction path is processed into a casing, not only the processing of the casing is complicated, but also the casing becomes large and heavy, which causes a large and heavy weight of the cabylt device and thus the vehicle. there were.

  An object of the present invention is to provide an oil pump that does not require a suction passage to be processed into a casing, and a carbitol device using the oil pump.

Typical means for solving the above-described problems are as follows.
(1) A casing in which a cylinder storage chamber is formed, a cylinder that is press-fitted into the cylinder storage chamber, a piston that is slidably inserted into a cylinder chamber formed in the cylinder, and a forward and backward movement of the piston An oil pump comprising a suction valve for sucking oil into the cylinder chamber along with a discharge valve for discharging oil from the cylinder chamber as the piston moves forward and backward,
An end surface communication groove that communicates with the suction valve is formed on an end surface of the cylinder that faces the suction valve, and a side surface communication groove that communicates with the end surface communication groove is formed at a press-fitting portion with the casing on the side surface of the cylinder. An oil pump characterized by being formed.
(2) A tilt cylinder device that is interposed between the cab and the frame and tilts the cab, and an oil pump that supplies pressure oil to the upside and downside supply / discharge oil passages of the tilt cylinder device. And
The oil pump includes a casing in which a cylinder storage chamber is formed, a cylinder that is press-fitted into the cylinder storage chamber, a piston that is slidably inserted into a cylinder chamber formed in the cylinder, and a forward and backward movement of the piston. And a discharge valve that discharges oil from the cylinder chamber as the piston advances and retreats.
An end surface communication groove that communicates with the suction valve is formed on an end surface of the cylinder that faces the suction valve, and a side surface communication groove that communicates with the end surface communication groove is formed at a press-fitting portion with the casing on the side surface of the cylinder. A cabylt device characterized by being formed.

  According to this oil pump, since it is not necessary to process the suction passage into the casing, the processing of the casing can be simplified, and the casing can be reduced in size and weight.

1 is a perspective view showing a cab-over type automobile equipped with a cabylt device according to an embodiment of the present invention. It is a hydraulic circuit diagram of the cabylt device. It is a side view which shows the oil pump which is one Embodiment of this invention. It is side surface sectional drawing which shows the principal part. (A) is a cross-sectional view taken along line VV in FIG. 4, (b) is a cross-sectional view taken along line bb in (a), (c) is a cross-sectional view taken along line cc in (a), It is. (A) is side sectional drawing which shows the principal part of the oil pump which is 2nd embodiment of this invention, (b) is sectional drawing which follows the bb line of (a), (c) is (a). It is sectional drawing which follows the cc line | wire. (A) is a side view which shows the oil pump which is 3rd embodiment of this invention, (b) is sectional drawing which follows the bb line of (a), (c) is cc of (a). It is sectional drawing which follows a line.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the cabylt device according to the present embodiment includes a tilt cylinder device 3 that is interposed between the cab 1 and the frame 2 and performs a tilt operation of the cab 1 by hydraulic expansion and contraction. ing. That is, the cab 1 is supported by the frame 2 so as to be rotatable in the front-rear direction by a fulcrum 1a, and the upper end of the piston rod 4 of the tilt cylinder device 3 is pivotally attached to the cab 1 via a link. The lower end of the cylinder 5 is pivotally attached to the frame 2.

As shown in FIG. 2, the hydraulic drive circuit 10 of the tilt cylinder device 3 includes a raising-side supply / discharge oil passage (hereinafter, referred to as “up-side oil passage”) 11 and a lower-side supply / discharge oil passage (hereinafter, referred to as “lowering”). (Referred to as a side oil passage) 12, an oil pump 13, a tank 14, and a manual switching valve (hereinafter referred to as a switching valve) 15.
The raising side oil passage 11 is fluidly connected to a frame side hydraulic chamber (hereinafter referred to as raising side hydraulic chamber) 5 a of the cylinder 5, and the lowering side oil passage 12 is connected to the cab side hydraulic chamber (hereinafter referred to as lower side) of the cylinder 5. Fluidly connected to the hydraulic chamber 5b).

The switching valve 15 is configured as a 4-port, 2-position, manually operated switching valve. The switching valve 15 is configured so that the load port a of the raising side oil passage 11 is the tank port T and the load port b of the lowering side oil passage 12 is the pump port during normal times (during traveling with the cab lowered). P is connected to each other, and when switching is performed by operating the lever 15a (when tilting up), the load port a of the raising side oil passage 11 is connected to the pump port P, and the load port b of the lowering side oil passage 12 is connected to the tank port. It is configured to be connected to each T. The tank port T is connected to the tank 14 via a return oil passage 62.
The switching valve 15 is installed in the oil pump 13 (see FIG. 3).

  A first pilot operated check valve (hereinafter referred to as a first pilot check valve) 16 is provided in the raised oil passage 11, and a second pilot operated check valve ( (Hereinafter referred to as a second pilot check valve) 17 is interposed. The first pilot check valve 16 and the second pilot check valve 17 prevent the flow from the cylinder 5 side to the switching valve 15 side when the hydraulic pressure is less than a preset pilot pressure value, and the set pilot pressure When the value is exceeded, the flow is allowed.

3 to 5 show the oil pump 13 according to the present embodiment.
The oil pump 13 includes a casing 21 formed in a substantially rectangular parallelepiped shape, and a casing 22 constituting the tank 14 is covered on one end surface of the casing 21. The housing 22 is provided with a safety valve 19. The safety valve 19 allows the inside and outside of the tank 14 to communicate with each other when the pressure inside the tank 14 exceeds a set pressure.
A rotating shaft 24 is inserted into the casing 21 from the opposite side to the housing 22 and is rotatably supported. An end of the rotating shaft 24 on the opposite side to the housing 22 protrudes outside the casing 21. A DC motor 25 is connected to the projecting side end of the rotating shaft 24, and the rotating shaft 24 is rotated by the DC motor 25.
The oil pump 13 is installed on the frame 2 so that the casing 22 side is on the upper side (top) in the direction of gravity and the DC motor 25 side is on the lower side (ground).

As shown in FIG. 4, a cam 26 is formed eccentrically with a predetermined eccentric amount with respect to the center of rotation at the tip of the rotary shaft 24, and a cam ring comprising a rolling bearing is provided on the outer periphery of the cam 26. 27 is attached.
A cam ring housing chamber 28 is opened at a portion corresponding to the cam ring 27 of the casing 21, and a pair of cylinder housing chambers 30, 30 are opened outside the cam ring housing chamber 28 of the casing 21. The pair of cylinder housing chambers 30, 30 are respectively extended in the eccentric direction of the cam 26 and opened so that one end (hereinafter referred to as an inner end) opens in the cam ring housing chamber 28.
A plug portion 31 that closes the outer opening is formed at the outer end of one cylinder housing chamber 30, and the other cylinder housing chamber 30 is closed by a plug 31A.

A pair of cylinders 32, 32 are press-fitted into the pair of cylinder housing chambers 30, 30 so as to extend in the eccentric direction of the cam 26. A pair of pistons 34, 34 are fitted in the cylinder chambers 33, 33 of the pair of cylinders 32, 32 slidably in the eccentric direction of the cam 26.
Since the configuration and function of the pair of cylinders 32 and 32 and the pair of pistons 34 and 34 are the same, the configuration on the plug portion 31 side will be described below with reference to FIG.
A connecting member 64 that is formed in a C-ring shape using an elastic material is disposed at the end of the cam ring housing chamber 28 opposite to the rotating shaft 24, and the pair of pistons 34 and 34 are connected to the connecting member 64. Are connected to each other via a pair of pins 63 and 63 so as to move integrally with each other. A pair of tool engagement holes 65 are formed at both ends of the groove in the C ring shape of the connecting member 64. In a state where the tool is engaged with the pair of tool engagement holes 65 and 65 and the connecting member 64 is opened against the elastic force, the pair of pistons 34 and 34 is interposed via the pair of pins 63 and 63. By being engaged, the connecting member 64 always pushes the inner end surfaces of the pair of pistons 34, 34 to the outer peripheral surface of the cam 26 with an elastic force that opposes the inertial force and frictional resistance of the pistons 34, 34 when the pump is driven. Make contact.

  As shown in FIG. 4, the pair of cylinders 32, 32 are provided with a pair of intake valves 40, 40 at the outer ends, respectively. Since the configuration and function of the pair of suction valves 40 are the same, the suction valve 40 on the plug portion 31 side will be described below with reference to FIG.

As shown in FIG. 5, the suction valve 40 includes a valve cylinder 46 in which a valve chamber 41 is formed. The valve cylinder 46 is formed in a cylindrical shape having an outer diameter smaller than that of the cylinder housing chamber 30 and an inner diameter smaller than or equal to that of the cylinder chamber 33, and an outer end is press-fitted into the cylinder chamber 33 and fixed to the cylinder 32. Has been. A cylindrical hollow portion of the valve cylinder 46 forms a valve chamber 41, and the valve chamber 41 communicates with the cylinder chamber 33.
A valve port 42 is formed at the outer end of the valve chamber 41 so as to communicate with the inside of the cylinder housing chamber 30, and a valve seat 43 is formed in a circular ring shape at the connection portion of the valve port 42 with the valve chamber 41. Has been. A valve body 44 made of a ball is housed in the valve chamber 41 so as to open and close the valve port 42 by being seated on and off the valve seat 43.
The valve body 44 is prevented from jumping out to the cylinder chamber 33 by the seat 66.

The valve cylinder 46 is formed in a circular ring shape whose outer diameter is smaller than that of the cylinder housing chamber 30 and whose inner diameter is larger than that of the valve port 42, and is arranged coaxially with the valve port 42. An end face communication groove 47 is formed in a cross groove shape on the end face (outer end face) opposite to the valve opening 42 of the valve cylinder 46. The end surface communication groove 47 forms a communication path that allows the valve port 42 and the cylinder housing chamber 30 to communicate with each other.
A plurality of side surface communication grooves 48 (three in the illustrated example) and vertically (in a direction parallel to the axis of the cylinder 32) are disposed in the press-fitting portion with the cylinder housing chamber 30 on the side surface of the cylinder 32. The side surface communication groove 48 forms a communication path that allows the cylinder housing chamber 30 and the tank 14 to communicate with each other. That is, the end surface communication groove 47 and the side surface communication groove 48 constitute a suction path that allows the suction valve 40 and the tank 14 to communicate with each other.
A conical filter 49 is interposed outside the cylinder 32 in the cylinder housing chamber 30 and on the cam ring housing chamber 28 side. The filter 49 filters oil flowing from the cam ring housing chamber 28 to the communication groove 48 of the cylinder 32.

As shown in FIG. 4, a pair of discharge valves 50 and 50 are provided on the side walls of the pair of cylinders 32 and 32, respectively.
As shown in FIG. 5B, the discharge valve 50 includes a valve chamber 51, and the valve chamber 51 is opened on the side wall of the cylinder 32. A valve port 52 is opened at the inner end of the valve chamber 51 so as to communicate with the inside of the cylinder chamber 33, and a valve seat 53 is formed in a circular ring shape at a connection portion between the valve port 52 and the valve chamber 51. Yes. A valve body 54 made of a ball is accommodated in the valve chamber 51 so as to open and close the valve port 52 by being seated on and off the valve seat 53.
One end of the discharge path 58 is opened at a position facing the valve chamber 51 of the casing 21, and the other end of the discharge path 58 is the pump port P of the switching valve 15 installed in the casing 21 (see FIG. 2). It is connected to the. The axial lines of the valve chamber 51 and the discharge path 58 are shifted from each other in the axial direction of the piston 34 so that the valve element 54 does not jump out of the discharge path 58 (see FIG. 4).

  As shown in FIG. 2, a relief passage 60 is connected to the discharge passage 58, and a relief valve 61 is interposed in the relief passage 60. The relief valve 61 prevents the hydraulic pressure in the hydraulic circuit from becoming abnormally high due to some failure.

  Next, the operation of the carbitol device according to the above configuration will be described.

  When the cab 1 is tilted up at an automobile maintenance shop or the like, the cab lock of the cab lock device 148 is released by the manual lever 149. Thereafter, the switching lever 15a of the switching valve 15 is set to the tilt-up side. 2, the pump port P of the switching valve 15 is connected to the load port a, and the tank port T is connected to the load port b.

Subsequently, the DC motor 25 is operated, and the rotating shaft 24 of the oil pump 13 is rotated by the rotational force of the DC motor 25. Thereby, the cam 26 rotates and the pair of pistons 34 and 34 reciprocate.
When the piston 34 moves forward, the discharge valve 50 is closed and the suction valve 40 is opened, and the oil in the tank 14 is sucked into the cylinder chamber 33 through the filter 49, the side surface communication groove 48, the end surface communication groove 47, and the suction valve 40. . When the piston 34 moves backward, the suction valve 40 is closed and the discharge valve 50 is opened by the pressure in the cylinder chamber 33, and oil is sent out to the discharge path 58.
As shown in FIG. 2, the oil sent to the discharge passage 58 is sent to the switching valve 15 and sent to the raising side oil passage 11.
The pressure oil pressure-fed to the raising side oil passage 11 flows into the raising side hydraulic chamber 5a of the cylinder 5 of the tilt cylinder device 3 through the first pilot check valve 16, and the piston rod 4 is extended to operate the cab 1. Is lifted from frame 2 and tilted up.

Here, in order to extend the piston rod 4, it is necessary to discharge the pressure oil in the lower hydraulic chamber 5 b of the cylinder 5.
In FIG. 2, the second pilot check valve 17 opens when the pressure in the raising side oil passage 11 becomes equal to or higher than the pilot pressure value set in the second pilot check valve 17. When the second pilot check valve 17 is opened, the pressure oil in the lower side hydraulic chamber 5 b of the cylinder 5 passes through the second pilot check valve 17, the switching valve 15, and the return passage 62 of the lower side oil passage 12. To be discharged.
Therefore, the piston rod 4 of the tilt cylinder device 3 can be extended to tilt the cab 1 up.

When the cab 1 is tilted up to a preset position, the operator stops the operation of the oil pump 13 by the DC motor 25. At this time, the lowered cab 1 is automatically prevented from being lowered by the operation of the first pilot check valve 16 shown in FIG.
When the oil pump 13 stops, the hydraulic pressure between the first pilot check valve 16 and the oil pump 13 in the raising oil passage 11 decreases due to internal oil leakage of the oil pump 13, so the pressure of the second pilot check valve 17 Falls below the set pilot pressure value, and the second pilot check valve 17 closes.
When the second pilot check valve 17 is closed, the pressure oil in the lower hydraulic chamber 5b of the cylinder 5 cannot be discharged, so that the piston rod 4 of the tilt cylinder device 3 cannot be extended. When the piston rod 4 of the tilt cylinder device 3 is fully extended, the piston rod 4 cannot be extended mechanically.

Thereafter, when the operator tries to tilt down the cab 1, the switching lever 15a is switched to the tilt-down side.
Subsequently, the oil pump 13 is operated by the driving force of the DC motor 25, and the pressure oil of the oil pump 13 is pumped to the lower side oil passage 12. The pressure oil pumped to the lower side oil passage 12 flows into the lower side hydraulic chamber 5b of the cylinder 5 of the tilt cylinder device 3 through the second pilot check valve 17, and shortens the extended piston rod 4, Tilt down cab 1.

Here, in order for the piston rod 4 to perform a shortening operation, it is necessary to discharge the pressure oil in the raising side hydraulic chamber 5 a of the cylinder 5.
When the pressure in the lower oil passage 12 becomes equal to or higher than the pilot pressure value set in the first pilot check valve 16, the first pilot check valve 16 opens.
In FIG. 2, when the first pilot check valve 16 is opened, the pressure oil in the raising side hydraulic chamber 5 a of the cylinder 5 is discharged to the tank 14 via the first pilot check valve 16, the switching valve and the return passage 62. Therefore, the piston rod 4 of the tilt cylinder device 3 can be shortened to tilt down the cab 1.

  According to this embodiment, the following effects can be obtained.

(1) By forming the end surface communication groove and the side surface communication groove in the cylinder press-fitted into the casing, it is possible to omit the processing of the suction passage for connecting the suction valve and the tank to the casing.

(2) According to the above (1), not only the processing of the casing can be simplified, but also the casing, the oil pump, the cabylt device, and thus the vehicle can be reduced in size and weight.

(3) By arranging a pair of cylinders around the rotating shaft and pressing the pair of pistons against the cam ring driven by the rotating shaft, the pulsation of the discharge pressure can be suppressed. Can be improved.

(4) By installing the oil pump on the frame so that the casing side is the top and the DC motor side is the ground, the suction port of the suction valve of the oil pump can be positioned at the lowest end in the tank. Can be used to the maximum.

  FIG. 6 shows a second embodiment of the present invention.

  This embodiment is different from the first embodiment in that a spring seat 35 is fitted on the outer periphery of the inner end of the piston 34 instead of the connecting member 64 and the pair of pins 63, 63 of the first embodiment. The point that a return spring 36 is interposed between the spring seat 35 and the cylinder 32, the point that a filter 49A is interposed on the outer peripheral portion of the valve cylinder 46, and the valve body 44 is made of a compression taper coil spring. The valve spring 45 is always urged in the direction of seating on the valve seat 43.

That is, as shown in FIG. 6, the inner end portion of the piston 34 projects into the cam ring housing chamber 28 so as to freely advance and retract. A spring seat 35 is fitted on the outer periphery of the inner end portion of the piston 34, and a return spring 36 is interposed between the spring seat 35 and the cylinder 32. The return spring 36 obtains a reaction force on the casing 21 via the cylinder 32 and always presses the piston 34 against the outer peripheral surface of the cam ring 27.
A filter 49 </ b> A is interposed on the outer periphery of the valve cylinder 46 and outside the cylinder 32 in the cylinder housing chamber 30. The filter 49 </ b> A filters oil flowing from the side surface communication groove 48 of the cylinder 32 to the end surface communication groove 47 of the valve cylinder 46.
The valve body 44 is always urged in the direction in which it is seated on the valve seat 43 by a valve spring 45 comprising a compression taper coil spring.
In the present embodiment, the valve spring 45 may be eliminated as necessary.

  This embodiment has the following operations and effects in addition to the operations and effects of the first embodiment.

(1) Since the filter 49A is disposed on the outer periphery of the valve cylinder 46, space can be saved.

(2) Instead of the connecting member 64 and the pins 63 and 63 of the first embodiment, the spring seat 35 is fitted on the outer periphery of the inner end of the piston 34, and the return spring 36 is interposed between the spring seat 35 and the cylinder 32. The cam ring 27 is attached to the DC motor 25 by shrinking the return spring 36 with a tool or the like even when there are obstacles such as other parts on the tank 14 side of the cam ring housing chamber 28. After that, if it is inserted into the cam ring accommodating chamber 28, the assembling work can be easily performed.

  FIG. 7 shows a third embodiment of the present invention.

The difference between the present embodiment and the first embodiment is the configuration of the connecting member.
As shown in FIG. 7, the connecting member 64A according to this embodiment is replaced with a pair of tool engaging holes 65, 65 at both ends of the connecting member 64 of the first embodiment. Portions 65A and 65A are provided, and the engaging portions 65A and 65A are engaged with the pins 63 and 63, respectively.
For example, even if the connecting member 64A cannot be inserted from the tank 14 side due to an obstacle such as a part disposed on the tank 14 side of the cam ring housing chamber 28, a hole is formed in the side surface of the casing 21. If the engagement portions 65A and 65A of the connecting member 64A are engaged with the pins 63 and 63 through the holes, the pistons 34 and 34 are expanded with a tool or the like, and the cam ring 27 is attached to the DC motor 25. By inserting the cam ring into the cam ring housing chamber 28, it can be easily assembled.

  This embodiment has the following operations and effects in addition to the operations and effects of the first embodiment.

(1) It replaces with the connection member 64 of 1st embodiment, and other parts can be arrange | positioned in the space by the side of the tank 14 of the cam ring accommodation chamber 28 by interposing the connection member 64A.

(2) Even when a tool for expanding the connecting member 64A from the tank 14 side cannot be inserted, the assembling work can be easily performed.

  Needless to say, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  The end face communication groove is not limited to being provided on the end face of the valve cylinder separate from the cylinder, but may be provided directly on the end face of the cylinder. That is, the valve cylinder can be formed integrally with the cylinder.

  A pair of cylinders and pistons is not limited to a single one, and may be provided alone or three or more.

  The oil pump may be formed integrally with the tilt cylinder device.

  The present invention is not limited to being applied to an oil pump of a cabylt device, but can be applied to all oil pumps used in a hydraulic drive circuit such as a tailgate opening / closing device.

DESCRIPTION OF SYMBOLS 1 ... Cab, 1a ... Supporting point, 2 ... Frame, 3 ... Cylinder device for tilting, 4 ... Piston rod, 4a ... Piston, 5 ... Cylinder, 5a ... Frame side hydraulic chamber (raising side hydraulic chamber), 5b ... Cab side hydraulic pressure Chamber (lower hydraulic chamber),
DESCRIPTION OF SYMBOLS 10 ... Hydraulic drive circuit, 11 ... Raising side supply / discharge oil path (raising side oil path), 12 ... Lowering side supply / discharge oil path (lowering side oil path), 13 ... Oil pump, 14 ... Tank, 15 ... Manual switching valve (Switching valve), 15a ... switching lever, 16 ... first pilot check valve, 17 ... second pilot check valve,
DESCRIPTION OF SYMBOLS 21 ... Casing, 22 ... Housing | casing, 24 ... Rotating shaft, 25 ... DC motor, 26 ... Cam, 27 ... Cam ring, 28 ... Cam ring storage chamber, 30 ... Cylinder storage chamber, 31 ... Plug part, 31A ... Plug, 32 ... Cylinder 33 ... Cylinder chamber 34 ... Piston 35 ... Spring seat 36 ... Return spring
DESCRIPTION OF SYMBOLS 40 ... Suction valve, 41 ... Valve chamber, 42 ... Valve port, 43 ... Valve seat, 44 ... Valve body, 45 ... Valve spring, 46 ... Valve cylinder, 47 ... End surface communication groove, 48 ... Side surface communication groove, 49, 49A ... Filter, 50 ... Discharge valve, 51 ... Valve chamber, 52 ... Valve port, 53 ... Valve seat, 54 ... Valve body, 58 ... Discharge path,
60 ... relief passage, 61 ... relief valve, 62 ... return passage,
63 ... Pins, 64, 64A ... Connecting members, 65 ... Tool engagement holes, 65A ... Engagement portions, 66 ... Sheets.

Claims (5)

A casing in which a cylinder storage chamber is formed, a cylinder that is press-fitted into the cylinder storage chamber, a piston that is slidably inserted into a cylinder chamber formed in the cylinder, and an oil that moves forward and backward with the piston. An oil pump that includes a suction valve that causes the cylinder chamber to inhale, and a discharge valve that discharges oil from the cylinder chamber as the piston advances and retreats,
An end surface communication groove that communicates with the suction valve is formed on an end surface of the cylinder that faces the suction valve, and a side surface communication groove that communicates with the end surface communication groove is formed at a press-fitting portion with the casing on the side surface of the cylinder. An oil pump characterized by being formed.   2. The oil pump according to claim 1, wherein a filter is interposed between the side surface communication groove and the end surface connection groove in the internal space of the cylinder housing chamber.   2. The oil pump according to claim 1, wherein a conical filter is interposed outside the cylinder in the cylinder housing chamber and on the cam ring housing chamber side.   4. The oil pump according to claim 1, wherein the end surface communication groove is formed on an end surface of a valve cylinder fitted in a cylinder chamber of the cylinder. A tilt cylinder device that is interposed between the cab and the frame and tilts the cab, and an oil pump that supplies pressure oil to the upside and downside supply / discharge oil passages of the tilt cylinder device,
The oil pump includes a casing in which a cylinder storage chamber is formed, a cylinder that is press-fitted into the cylinder storage chamber, a piston that is slidably inserted into a cylinder chamber formed in the cylinder, and a forward and backward movement of the piston. And a discharge valve that discharges oil from the cylinder chamber as the piston advances and retreats.
An end surface communication groove that communicates with the suction valve is formed on an end surface of the cylinder that faces the suction valve, and a side surface communication groove that communicates with the end surface communication groove is formed at a press-fitting portion with the casing on the side surface of the cylinder. A cabylt device characterized by being formed.

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