Patent Application
20180135625
The present invention relates to a variable capacity oil pump which supplies oil which provides, for example, a lubrication of sliding locations of an internal combustion engine and a driving source of an auxiliary machinery of the internal combustion engine.
A conventional variable capacity oil pump is exemplified in a Patent Document 1 which will be described below. In the disclosed oil pump, a hydraulic pressure is supplied from a main gallery formed at a downstream side of a discharge passage to first and second control oil chambers or is exhausted via a drain passage. Thus, an eccentricity quantity with respect to a rotor of a cam ring is varied.
That is, the hydraulic pressure supplied from a first branch passage branched from the main oil gallery is introduced into an inside of the first control oil chamber so that the cam ring is moved in a direction in which the eccentricity quantity becomes small. On the other hand, the hydraulic pressure supplied from a second branch passage branched from the main oil gallery is introduced into the inside of the second control oil chamber caused so that the cam ring is moved in the direction in which the cam ring is moved in the direction in which the eccentricity becomes large.
Then, the introduction of the hydraulic pressure to the second control oil chamber is controlled in an on-and-off manner caused by a switching operation of an electromagnetic switching valve installed in the second branch passage. Thus, a pump discharge pressure is controlled in a two-stage characteristic between a low pressure and a high pressure.
In addition, a pilot valve which achieves a stability of the two-stage characteristic by adjusting an oil quantity of a working oil supplied into or exhausted from each of first and second control oil chambers is disposed in each of the above described branch passages.
This pilot valve includes a spool valve slidably housed at an inside of the corresponding pilot valve and controlled on a basis of a difference pressure between the hydraulic pressure supplied from the main gallery and a biasing force of a valve spring installed in the inside of the spool valve. Then, this pilot valve appropriately supplies or exhausts the hydraulic pressure into or from each of the first and second control oil chambers in accordance with its controlled positions. Then, when the hydraulic pressure is exhausted from each of these control oil chambers, each of the first and second control oil chambers and a pump external are communicated with each other via a spring housing chamber housing the valve spring and a drain port formed to be penetrated through a peripheral wall of the spring housing chamber.
However, since the conventional oil pump, as described hereinabove, is designed to exhaust the working oil within each of the first and second control oil chambers via the spring housing chamber of the pilot valve. In a case where the exhaust quantity is large and so forth, there is a possibility that, since the pressure within the spring housing chamber is raised and, accordingly, a variation in an internal pressure difference of the pilot valve occurs, a behavior of the spool valve becomes unstable and the pump discharge pressure cannot be controlled to a preset hydraulic pressure characteristic.
Patent Document 1: a Japanese Patent Application Laid-open Publication No. 2014-105623.
With the above-described conventional technical task in mind, it is an object of the present invention to provide a variable capacity oil pump which is capable of improving a control accuracy of the pump discharge pressure with respect to the preset hydraulic pressure characteristic.
According to one aspect of the present invention, there is provided a variable capacity oil pump comprising: a pump constituting member which operatively discharges a working oil sucked from a suction section through a discharge section, with a volume of a plurality of pump chambers varied by a rotational drive through an internal combustion engine; a movable member which is operatively moved to modify a volume variation quantity of the plurality of pump chambers according to a movement of the movable member; a biasing mechanism which is installed in a state in which a set load is provided to bias the movable member in a direction in which the volume variation quantity of the plurality of pump chambers is increased; a first control oil chamber configured to act a force in a direction in which the volume variation quantity of the plurality of pump chambers is decreased upon the movable member in response to a supply of the working oil into the first control oil chamber; a second control oil chamber configured to act a force in a direction in which the volume variation quantity of the plurality of pump chambers is increased upon the movable member in response to a supply of the working oil into the second control oil chamber; a switching mechanism formed to enable a switching between a state in which the working oil from the second control oil chamber is exhausted and another state in which the working oil is introduced into the second control oil chamber; and a control mechanism configured to take a state in which the working oil within the first control oil chamber is exhausted and another state in which the working oil whose pressure is decreased than a discharge pressure from the discharge section is introduced into the first control oil chamber and to perform a pressure regulation for the working oil while applying the pressure to the working oil within the first control oil chamber by introducing the working oil into the first control oil chamber as the discharge pressure becomes larger, in a case where the switching mechanism is in the state in which the working oil is exhausted from the second control oil chamber, and to take a further another state in which the working oil whose pressure is decreased than the discharge pressure from the discharge section is introduced into the second control oil chamber and a still further another state in which an introduction of the working oil into the second control oil chamber via the switching mechanism is interrupted and the working oil within the second control oil chamber is exhausted and to perform the pressure regulation for the working oil while reducing the pressure to the working oil within the second control oil chamber by exhausting the working oil within the second control oil chamber as the discharge pressure becomes larger, in a case where the switching mechanism is in the other state in which the working oil is introduced into the second control oil chamber, wherein the control mechanism is controlled by a hydraulic pressure of the working oil and a biasing force of a biasing member and the working oil is not introduced into a location of the control mechanism at which the biasing member is arranged.
According to the present invention, the control accuracy of the pump discharge pressure with respect to the preset hydraulic pressure characteristic can be improved.
Hereinafter, each preferred embodiment of a variable capacity oil pump related to the present invention will be described in details on a basis of the accompanied drawings.
Variable capacity oil pump 10 is rotated by a rotational driving force transmitted from a crankshaft of an internal combustion engine, sucks oil which is a working oil reserved in an oil pan 01 from a suction passage 03 via a strainer 02, and, thereafter, discharges the working oil from a discharge passage 04 to a main oil gallery 05 formed within an inside of the engine.
A check ball type relief valve 07 which returns oil within oil pan 01 when a pump discharge pressure is excessively raised is disposed in a relief passage 06 branched from discharge passage 04.
In addition, an oil cooler (not shown) which serves to cool oil flowing through the oil cooler is disposed at a more downstream side than relief passage 06 of discharge passage 04 and a first oil filter 1 which collects a foreign matter within the flowing oil by means of a metallic mesh section (not shown).
Furthermore, a bypass passage 08 which bypasses first oil filter 1 is connected between an upstream side of first oil filter 1 and a downstream side of first oil filter 1 and located at a predetermined location of discharge passage 04 not passing through first oil filter 1 in discharge passage 04. A check ball type bypass valve 09 is disposed which is open to communicate the upstream side and the downstream side of bypass passage 08 when first oil filter 1, for example, clogs so that the oil flowing through first oil filter 1 becomes difficult.
The above-described main oil gallery 05 serves to supply oil to an oil jet which injects cooled oil to a slide section of the engine, for example, a piston, variably operated valve system (a valve timing control device), and bearings of a crankshaft of the engine. That is, oil passing through main oil gallery 05 is not only used as a lubricating oil lubricating a component provided in the inside of the engine but also used as a cooling purpose oil for a driving source of the variably operated valve system and which is injected through the oil jet.
A first branch passage 3 is branched in a midway through main oil gallery 05. This first branch passage 3 has an upstream section at which a second oil filter 2 is disposed and second and third branch passages 4, 5 are furthermore branched from a downstream side terminal section.
Second oil filter 2, as shown in
In addition, each of first and second oil filters 1, 2 is of a cartridge type whose mesh section is detachably attached to a corresponding one of main bodies thereof and is replaceable in a case where a clogging occurs. It should be noted that each of first and second oil filters 1, 2 may serve to perform a filtering of oil through a replaceably attached filter paper.
Second branch passage 4 is communicable to first control oil chamber 31 of oil pump 10 via a pilot valve 50 which is a control mechanism as will be described later and a first supply/exhaust passage 7a, as shown in
Oil pump 10 is disposed at a front end section or so forth of a cylinder block 35 of the internal combustion engine. As shown in
It should be noted that driving wheel 14, rotor 15, and each vane 16 constitute a pump constituting member.
Pump body 11 is integrally formed by means of an aluminum alloy material. As shown in
First and second seal sliding contact surfaces 11c, 11d on which two seal members 30, 30 as will be described later are respectively slidably contacted are formed at both sides of a straight line M (hereinafter called a cam ring reference line) connecting a center of bearing hole 11a and a center of supporting hole 11b, on an inner peripheral wall of pump housing chamber 13, as shown in
In addition, on a bottom surface 13a of pump housing chamber 13, as shown in
A suction hole 21a in a substantially circular shape in cross sectional surface which opens externally and is penetrated through a bottom wall of pump body 11 is formed on a substantially center position of suction port 21. Thus, oil reserved in oil pan 01 of the engine is sucked into each pump chamber 20 of the suction region via suction passage 03, suction hole 21a, and suction port 21.
It should be noted that suction hole 21a is arranged and formed to a suction side outer peripheral area including a spring housing chamber 28 as will be described later of cam ring 17.
On the other hand, a discharge hole 22a in a substantially circular shape in cross sectional surface which opens externally and is penetrated through the bottom wall of pump body 11 is formed at an upper position of drain port 22 in
Cover member 12 is formed in a substantially plate shape as shown in
Bearing hole 12 rotatably supporting the other end side of driving shaft 14 is penetrated through a substantial axial center position of this cylindrically shaped cover member 12. In addition, cover member 12 is attached onto an opening end surface of pump body 11 by a plurality of bolts 26.
Driving axle 14 is structured in order for rotor 15 to be rotated in a clockwise direction in
The plurality of slits 15a are cut out radially from an internal center side of rotor 15 toward a radial outside of rotor 15, as shown in
Each vane 16 is pushed out externally by a centrifugal force involved in the rotation of rotor 15 and back pressures of back pressure chambers 15b. Pump chambers 20 are defined in a liquid tight manner by an opposing inner side surface of adjacent vanes 16, 16, an inner peripheral surface of rotor 15, a bottom surface 13a of pump housing chamber 13 of pump body 11, and an inner side surface of cover member 12.
An outer peripheral surface of each ring member 19 is slidably contacted on an inner end surface of base end section of each vane 16 and presses each vane 16 externally under pressure by the centrifugal force, as shown in
Cam ring 17 is integrally formed in an annular shape by a sintered metal. As shown in
A spring housing chamber 28 which is communicated with pump housing chamber 13 via a communication section 27 is disposed at a position of pump body 11 opposite to supporting hole 11b. A tip section of arm section 17b and cam spring 18 are housed within spring housing chamber 28.
One end section of cam spring 18 is elastically contacted on a substantially arc shaped supporting projection 17c which is projected from a lower surface of the tip section of arm section 17b and the other end of cam spring 18 is elastically contacted on the bottom surface of spring housing chamber 29.
A spring force (a biasing force) at any time biases cam ring 17 toward a direction at which the eccentricity quantity is increased (in a clockwise direction in
In addition, a pair of first and second seal constituting sections 17d, 17e in a substantial triangular shape in cross section having first and second seal surfaces opposing against first and second seal sliding surfaces 11c, 11d are respectively projected on the other peripheral sections of the cam ring 17. First and second seal holding grooves in substantially arc recess shapes in cross section are cut out on respective seal surfaces along the axial direction of cam ring 17.
A pair of seal members 30, 30 are respectively housed and held which, during the eccentric swingable movement, slidably contacted on respective seal sliding contact surfaces 11c, 11d are housed and held at the insides of respective seal holding grooves.
As shown in
Respective seal members 30, 30, as shown in
Furthermore, first and second control oil chambers 31, 32 are respectively disposed with pivot section 17a side of cam ring 17 as a center, namely, on an outer peripheral area of the pump discharge side.
These respective control oil chambers 31, 32 are defined so that an inner space in substantially arc shape in cross section defined by the inner peripheral surface of pump body 11, the outer peripheral surface of cam ring 17, and respective seal members 30, 30 is divided into two control oil chambers in a vertical direction of
From among the first and second control oil chambers 31, 32, first control oil chamber 31 which is located at an upper side in
In addition, a first pressure receiving surface 33 is formed which receives the hydraulic pressure supplied within first control oil chamber 31 is formed on the outer peripheral surface of cam ring 17 which faces toward first control oil chamber 31.
Thus, when the hydraulic pressure is supplied to first control oil chamber 31, a swing force in a direction against the biasing force of cam spring 18, viz., in a direction in which the eccentricity quantity is decreased is provided for cam ring 17.
On the other hand, second control oil chamber 32 is connected to second supply communication hole 25b penetrated through the side section of pump body 11 in parallel to first communication hole 25a. The pump discharge pressure flowing within main oil gallery 05 is appropriately supplied to second control oil chamber 32 via first and third branch passages 3, 5, electromagnetic switching valve 40, intermediate passage 70, pilot valve 50, and first communication hole 25a.
A second pressure receiving surface 34 is formed on the outer peripheral surface of cam ring 17 which faces toward the second control oil chamber 32. Thus, when the hydraulic pressure is supplied within second control oil chamber 32, the swing force in the direction in which the eccentricity quantity is increased is provided in a direction in which the biasing force of cam spring 18 is assisted via second pressure receiving surface 34.
It should, herein, be noted that, as shown in
It should, herein, be noted that electromagnetic switching valve 40 is, as described above, interposed between third branch passage 5 and intermediate passage 70 via which the hydraulic pressure is supplied to second control oil chamber 32.
Electromagnetic switching valve 40 is a two-port, three position valve, as shown in
That is, electromagnetic switching valve 40, as shown in
Valve body 41 has a communication port 45 which is communicated with intermediate passage 70.
Communication port 45 is radially penetrated through valve body 41 at a side section of ball valve body 43 which is a tip end side of a peripheral wall of valve body 41. On the other hand, a drain port 46 which is communicated with drain passage (discharge passage) 6 is radially penetrated through a basic end section side of the peripheral wall of valve body 41.
Solenoid unit 44 has an inside in which an electromagnetic coil, a fixture plunger, a movable plunger, or so forth are housed. When a signal is issued from the control unit (not shown) to the electromagnetic coil, solenoid unit 44 accordingly moves the movable plunger forwardly or backwardly in the axial direction.
In addition, a return spring (not shown) to bias at any time the movable plunger in the backward direction is disposed in the inside of solenoid unit 44.
One end section of a cylindrical rod shaped push rod 47 is coupled to a tip section of the movable plunger. This push rod 47 is housed in operation hole 41a. Ball valve body 43 can be pressed in the valve seat 42 direction via this push rod 47 under pressure.
In addition, a cylindrical passage 48 is formed between the outer peripheral surface of push rod 47 and the inner peripheral surface of a center section of operation hole 41a. This cylindrical passage 48 is formed to appropriately communicate communication port 45 and drain port 46.
The above-described control unit detects the present engine driving condition from an oil temperature of the engine, a coolant temperature of the engine, engine rotation numbers (the engine rotation speed), a load of the engine, and so forth, outputs the ON signal (the power is supplied) to the electromagnet coil of solenoid unit 44 particularly when the engine rotation numbers (speed) is equal to or below a predetermined value, and outputs the OFF signal to the electromagnetic coil described above when the engine rotation numbers (the engine speed) is higher than the predetermined value and the engine load is in a high load region.
In the structure described above, for example, when the engine rotation numbers (engine speed) is equal to or below the predetermined value and, thus, the engine control unit outputs the ON signal (the power is supplied) to the electromagnetic coil of solenoid unit 44, the movable plunger is moved in the forward direction against the spring force of the return spring so that, as shown in a solid line of
On the other hand, for example, in a case where the engine rotation speed (numbers) is higher than the predetermined value, an OFF signal (non-power supply) is outputted from the control unit of the engine to the electromagnetic coil of solenoid unit 44. At this time, the movable plunger moves into the backward direction (retreats) by the spring force of the return spring. Thus, the pushing pressure (force) toward ball valve body 43. Thus, the pushing pressure toward ball valve body 43 by push rod 47 is released. At this time, the pump discharge pressure from third branch passage 5 is acted upon ball valve body 43 so that, as denoted by a dot-and-dash line of
Hence, oil pump 10 is structured to select the supply or exhaust of the hydraulic pressure within second control of chamber 32 in association with the switching operation of electromagnetic switching valve 40 based on the driving state of the engine. Then, accordingly, oil pump 10 is structured to obtain two kinds of discharge pressure characteristics of a state in which the pump discharge pressure is controlled to a predetermined low pressure P1 by controlling the eccentricity quantity of cam ring 17 on a basis of the hydraulic pressure within first control oil chamber 31 supplied from main oil gallery 05 and the biasing force of cam spring 18 and another state in which the pump discharge pressure is controlled to a predetermined high pressure P2 by controlling the eccentricity quantity of cam ring 17 on a basis of the hydraulic pressure within first control oil chamber 31, the biasing force of cam spring 18, and the hydraulic pressure within second control oil chamber 32.
A setting load of cam spring 18 is set on a basis of the above-described two kinds of discharge pressure characteristics.
That is, for cam spring 18, the setting load is set in order to start operation when the hydraulic pressure of first control oil chamber 31 is equal to or above an operation start pressure P1′ lower than predetermined low pressure P1 in a case where the hydraulic pressure is supplied to only first control oil chamber 31 from among first and second control oil chambers 31, 32.
In addition, in a case where the same hydraulic pressure is supplied to each of first and second control oil chambers 31, 32, the force toward the direction against cam spring 18 is developed on a basis of a difference of the biasing force involved in a difference in area between both pressure receiving surfaces 33, 34. In this case, the setting load for cam spring 18 is set to start the operation when the hydraulic pressure supplied to both of first and second control oil chambers 31, 32 becomes equal to or above operation start pressure P2′ higher than predetermined high pressure P2.
It should be noted that, although there is a possibility that the hydraulic pressure when cam spring 18 starts to operate is varied in a case where the engine rotation numbers (the engine speed) is high, bubbles are included in the working oil, or so forth, the setting load is set for operation start pressure P2′ to be equal to or above desired high pressure P2 regardless of the engine driving condition.
Then, pilot valve 50 is disposed in oil pump 10.
As shown in
An introduction port 57 whose diameter is smaller than sliding purpose hole 52 is formed on an upper end opening of sliding purpose hole 52 located at the upper direction in
In addition, a step difference tapered surface 51a which is a seat surface on which spool valve 53 is biased in the upper direction by means of the spring force of control spring 55 and is seated is formed on an end edge of sliding purpose hole 52 of valve body 51 at the introduction port 57 side.
Furthermore, on a peripheral wall to which sliding purpose hole 52 of valve body 51 is exposed, a first supply/exhaust port 58 which is a first control port communicated with first control oil chamber 31 via first supply/exhaust passage 7a, a second supply/exhaust port 59 which is a second control port communicated with second control oil chamber 32 via second supply/exhaust passage 7b, and a drain port 60 located at an under side than second supply/exhaust port 59 and which is communicated with the atmospheric pressure outside of the pump are formed and penetrated along the radial direction.
In addition, a connection port 61 which is connected to one end of intermediate passage 70 and is radially penetrated on a part of the outer peripheral wall of valve body 51 which is located at an opposite direction to both of first and second supply/exhaust ports 58, 59 and which is parallel between first and second supply/exhaust ports 58, 59. In addition, a back pressure escaping purpose back pressure port 62 is radially penetrated thereon to secure a favorable sliding characteristic of spool valve 53 communicated with the atmospheric pressure at a position in a substantially circumferential direction with connection port 61 and at a lower side than drain port 60.
It should, herein, be noted that drain port 60 and back pressure port 62 can be communicated with suction port 21 not to the atmospheric pressure outside the pump.
Spool valve 53 is integrally formed in a solid manner and includes cylindrically shaped first and second land sections 63, 64 disposed respectively on both ends of spool valve 53 and whose diameters are comparatively large and a cylindrically shaped small diameter section 65 whose diameter is comparatively small and which connects both of first and second land sections 63, 64.
The outer diameters of first and second land sections 63, 64 are mutually the same. First and second land sections 63, 64 are slid on the inner peripheral surface of sliding purpose hole 52 with a minute clearance.
In addition, a distance between both of first and second land sections 63, 64 is set to satisfy a condition of the communication or interruption among respective ports 58 through 61 in first through fourth operation states of oil pump 10 as will be described later.
That is, a distance L1 between mutually opposing side surfaces 63a, 64a of first land section 63 and second land section 64 is set to be larger than an interval L2 between a lower end edge 58a in
First land section 63 is set for an axial width of first land section 63 to be substantially equal to a hole diameter of first supply/exhaust port 58.
Furthermore, a cylindrically shaped pressure receiving section 66 whose diameter is slightly smaller than first land section 63 is projected on an end surface of first land section 63 at an introduction port 57 side. A flat surface shaped pressure receiving surface 66a which receives the pump discharge pressure introduced into sliding purpose hole 52 from introduction purpose hole 52 from introduction port 57 is formed on a tip of pressure receiving section 66.
In addition, a small diameter cylindrically shaped convex section, viz., retaining projection section 67 whose diameter is smaller than second land section 64 is projected from an end surface of second land section 64 at a press fit plug 56 side.
Oil is circulated through small diameter section 65, as shown in
Control spring housing chamber 54 is cylindrically defined by an inner peripheral surface of sliding purpose hole 52, one end surface of spool valve 53 at press fit plug 56 side of second land section 64, and an inner end surface of press fit plug 56.
A spring force of control spring 55 is set to be smaller than the spring force of cam spring 18.
While one end section of control spring 55 is elastically contacted on the end surface of second land section 64 faced toward the press fit plug 56 side, the other end section of control spring 55 is elastically contacted on an inner end surface of press fit plug 56. This spring force at any time biases spool valve 53 toward introduction part 57 side.
Furthermore, control spring 55 is held by the outer peripheral surface of retaining projection section 67 and a substantially whole of the outer peripheral section of control spring 55 is held by the inner peripheral surface of control spring housing chamber 54.
Then, spool valve 53 is moved in the downward direction or in the upward direction according to a relative pressure on pressure receiving surface 66a between the pump discharge pressure received from introduction port 57 and the spring force of control spring 55 so as to appropriately open or close (communicate) respective ports 57 through 61. The open or closure actions of respective ports 57 through 61 according to the operation of spool valve 53 will specifically be explained in an item of the following action in the first embodiment.
Hereinafter, the operation of the variable capacity oil pump in the first embodiment will be explained on a basis of
First, in a case where the engine is started and in the driving state of a low rotation of the engine, oil pump 10 is in a first operation state shown in
In this operation state, electromagnetic switching valve 40 is in a power supplied state upon receipt of the on signal in the internal electromagnetic coil from the control unit so as to push up ball valve body 43 in the direction of valve seat direction via the movable plunger and push rod 47 to close solenoid opening port 42a and communication port 45 and drain port 46 are communicated with each other.
In addition, in pilot valve 50, the rotation numbers (speed) of the engine and the hydraulic pressure are low and the pump discharge pressure (a pilot pressure) acted upon pressure receiving surface 66a is small, a state in which a tip end edge of pressure receiving surface 66 is seated on step-difference tapered surface 51a is maintained without movement of spool valve 53 toward press fit plug 56 direction.
Thus, pilot valve 50 becomes a state in which first and second supply/exhaust ports 58, 59 are communicated with connection port 61 via ring shaped groove 68 located on the outer periphery of small diameter section 65.
Hence, in the first operation state, both of first control oil chamber 31 and second control oil chamber 32 are communicated with drain port 46. Thus, the eccentricity quantity control of cam ring 17 is carried out since without introduction of the hydraulic pressure into both of first and second control oil chambers 31, 31.
That is, cam ring 17 is maintained in a maximum eccentricity state in the clockwise direction in
Consequently, in the first operation state, the pump discharge pressure of oil pump 10 is raised in a substantial proportion to the rise of rotation speed (numbers) of the engine, as shown in a rotation region a in
Thereafter, when the rotation numbers of the engine (the engine speed) exceed rotation region a in
Even in this second operation state, the power supplied state of electromagnetic switching valve 40 is maintained in the same way as the first operation state.
In pilot valve 50, in the same way as first operation state, second control oil chamber 32 is communicated with drain port 46 by communicating second supply/exhaust port 59 with connection port 61 via ring shaped groove 68.
In addition, when the pump discharge pressure which is higher than low pressure P1 is received on pressure receiving surface 66a of spool valve 53, pilot valve 50 is moved in the backward direction (retreated) against the spring force of control spring 55 so that introduction port 57 and first supply/exhaust port 58 are communicated with each other in an orifice state in which the opening area is throttled by means of first land section 63.
At this time, the hydraulic pressure supplied within first control oil chamber 31 indicates a pressure P1′ which is decreased than the pump discharge pressure due to the passage of this orifice section. However, since the set load of cam spring 18 is also set to be operated at operating start pressure P1′ in a case where the hydraulic pressure is supplied only to first control oil chamber from both of the first and second control oil chambers 31, 32. Thus, the control of pump discharge pressure can be carried out without influence of the pressure decrease by the orifice section.
Thus, the pressure decreased hydraulic pressure is supplied to first control oil chamber 31 via the orifice section which is expended in accordance with a height of the pump discharge pressure. The pump discharge quantity is decreased and the pump discharge quantity is reduced by biasing cam ring 17 in the direction in which the eccentricity quantity becomes small against the spring force of cam spring 53 on a basis of this supplied hydraulic pressure.
On the other hand, in pilot valve 50, in a case where the pump discharge pressure received by pressure receiving surface 66a is lower than low pressure P1, spool valve 53 is moved in the introduction port 57 direction by the spring force of control spring 55. In the same way as the first operation state, first land section 63 serves to interrupt between introduction port 57 and first supply/exhaust port 58 and drain port 46 is communicated with first supply/exhaust port 58.
Thus, the hydraulic pressure within first control oil chamber 31 is decreased and the eccentricity (quantity) of cam ring 17 is accordingly increased so that the pump discharge quantity is increased and the pump discharge pressure is raised.
Hence, in the second operation state, while pilot valve 50 reduces the pump discharge pressure by pressure adjusting first control oil chamber 31 by introducing oil into first control oil chamber 31 as the pump discharge pressure of oil pump 10 becomes larger (higher), pilot valve 50 increases the pump discharge pressure by decreasing pressure by introducing oil from first control oil chamber 31 when the pump discharge pressure becomes low and, thus, pressure regulation to low pressure P1 is carried out.
It should be noted that, in the first embodiment, the hole diameter of first supply/exhaust port 58 and the axial width of first land section 63 which closes the first supply/exhaust port 58 are set to be substantially same length. Hence, the supply and exhaust of oil with respect to first control oil chamber 31 can switchably be controlled only through a minute movement of spool valve 53.
Thus, since an influence of a spring constant of control spring 55 on the discharge pressure control is slight, the pump discharge pressure can be controlled to low pressure P1 with a high accuracy.
Consequently, in the second operation state, the pump discharge pressure of oil pump 10 is maintained at low pressure P1 not relating to the rise in the engine rotation numbers (speed), as shown in a rotation region b of
Next, when the load and the hydraulic pressure become high due to the further rise in the engine rotation numbers (speed) and the engine falls in the high load driving state in which the operation of the oil jet to inject oil toward the piston is required, oil pump 10 indicates a third operation state shown in
In this third operation state, electromagnetic switching valve 40 becomes the non-power supply state when the internal electromagnetic coil of electromagnetic switching valve 40 receives the OFF signal from the control unit. Accordingly, the biasing of ball valve body 43 toward valve seat 42 direction is released. Hence, solenoid ball valve body 43 is biased toward solenoid unit 44 direction by the pump discharge pressure supplied via solenoid opening port 42a. Hence, since one end of passage 48 is closed and the communication between communication port 45 and drain port 46 is interrupted.
Pilot valve 50 serves to communicate introduction port 57 with first supply/exhaust port 58 and to communicate second supply/exhaust port 59 with connection port 61. In addition, second land section 64 serves to interrupt between second supply/exhaust port 59 and drain port 60.
Hence, in the third operation state, the hydraulic pressure is introduced into both of first control oil chamber 31 and second control oil chamber 32. Hence, cam ring 17 is again moved in the clockwise direction in
Consequently, in the third operation state, the pump discharge pressure of oil pump 10 is again raised in a substantially proportion to the rise in the engine rotation numbers (speed), as shown in a rotation region c of
Thereafter, when the engine rotation numbers (speed) exceeds rotation region c and, accordingly, the discharge pressure of main oil gallery 05 reaches a high pressure P2 shown in
Even in the fourth operation state, electromagnetic switching valve 40 is maintained in the non-power supplied state, in the same way as third operation state.
Pilot valve 50 serves to communicate introduction port 57 with first supply/exhaust port 58, in the same way as third operation state.
In addition, when pilot valve 50 receives the pump discharge pressure higher than high pressure P2 on pressure receiving surface 66a, pilot valve 50 is moved in the backward direction (retreated) against the spring force of control spring 55 so that second supply/exhaust port 59 and drain port 60 are communicated to each other.
At this time, while the hydraulic pressure equal to the pump discharge pressure is supplied to first control oil chamber 31, the hydraulic pressure introduced in the third operation state is gradually exhausted from second control oil chamber 32 via drain port 60.
Thus, the force in the direction against cam spring 28 is not only a difference in the biasing force involved in an area difference between both of pressure receiving surfaces 33, 34 but receives the influence in the hydraulic pressure difference within both of first and second control chambers 31, 32, Consequently, the same state such that the pressure applied P2′ than the pump discharge pressure is supplied to both of first and second control oil chambers 31, 32.
Whereas, the setting load of cam spring 18 is set to be operated under operation start pressure P2′ in a case where the hydraulic pressure is supplied to both of first and second control oil chambers 31, 32. The control of the pump discharge pressure can be carried out without receiving the influence of the pressure decrease due to the exhaust of second control oil chamber 32.
Thus, second control oil chamber 32 is appropriately pressure decreased in accordance with a height of the pump discharge pressure. On a basis of the appropriate pressure decrease, cam ring 17 is moved in the direction in which the eccentricity quantity becomes small so that the pump discharge quantity is decreased and the pump discharge quantity is reduced.
On the other hand, in pilot valve 50, in a case where the pump discharge pressure under which pressure receiving surface 66a receives becomes lower than high pressure P2, spool valve 53 moves in introduction port 57 direction by the spring force of control spring 56 and, in the same way as the third operation state, second supply/exhaust port 59 and drain port 60 are interrupted by second land section 64.
Thus, since the hydraulic pressure within second control oil chamber 32 is added (applied) and, accordingly, the eccentricity quantity of cam ring 17 is increased. Hence, when the pump discharge quantity is increased and the rise in the pump discharge pressure is achieved.
Hence, in the fourth operation state, while the pump discharge pressure is reduced by pressure decrease adjusting by a derivation of oil within second control oil chamber 32 as the pump discharge pressure of oil pump 10 becomes larger, the pressure applied adjusting by introducing oil into second control oil chamber 32 to increase the pump discharge pressure to perform a pressure regulation for the pump discharge pressure to high pressure P2.
It should, herein, be noted that, in this embodiment, since distance L1 between axially opposing side surfaces 63a, 64a of first and second land sections 63 and 64 is set to be substantially equal to an interval L3 of drain port 60 and connection port 61, the supply or exhaust of oil with respect to second control oil chamber 32 is switchably controlled only through a minute movement of spool valve 53. Thus, since the influence of the spring constant of control spring 55 is not easily given to the discharge pressure control, the pump discharge pressure can be controlled to high pressure P2 with a high accuracy.
Consequently, in the fourth operation state, the pump discharge pressure of oil pump 10 is substantially maintained at high pressure P2 without relation to the rise in the engine rotation numbers (speed).
In this way, in the first embodiment, the operation of pilot valve 50 is controlled via electromagnetic switching valve 40 so that the pump discharge pressure can be controlled to the two-stage characteristic of low pressure P1 and high pressure P2.
Then, in the first embodiment, pilot valve 50 is structured in order for oil to be circulated within control spring housing chamber 54 in all of first, second, third, and fourth operation states described before.
That is, in a case where oil is exhausted from first and second control oil chambers 31, 32 on a basis of the eccentricity quantity control of cam ring 17, this oil is exhausted to an external of oil pump 10 via ring shaped (annular) groove 68 formed at the center position of spool valve 53.
Because of this, in such a conventional technique that the hydraulic pressure of oil discharged from first and second control oil chambers 31, 32 is caused to flow into control oil spring housing chamber 54 and the back pressure within control oil spring housing chamber 54 occurs, such a problem that this back pressure causes the pump discharge pressure (pilot valve pressure) applied to pressure receiving surface 66a and the position control of spool valve 53 by the spring force of control spring 55 to become unstable can be avoided.
Therefore, in the first embodiment, the control accuracy of the pump discharge pressure with respect to the set hydraulic pressure characteristic can be improved by improving a stability of the position control of spool valve 53. It should be noted that this effect is particularly effective in the fourth operation state in which a relatively high pressure oil is exhausted from second control oil chamber 32.
Incidentally, the bottomed cylindrical shaped spool valve having a pressure receiving wall on the one end section as in the conventional capacity oil pump is, in general, frequently used as the spool valve to be applied to pilot valve 50.
However, in such a bottomed cylindrically shaped spool valve as described above, a passage through which oil is circulated is needed on its peripheral wall. Hence, the shape thereof becomes complex.
In addition, since, in the inside of the bottomed cylindrically shaped spool valve, the one end side of control spring 55 is housed, a valve diameter larger than an outer diameter of control spring 55 is needed to be formed and, accordingly, the hole diameter of sliding purpose hole 52 is needed to become large in diameter to meet with the valve diameter. Thus, a large sizing of pilot valve 50 is resulted to be introduced.
Furthermore, since the outer diameter of control spring 55 with respect to hole diameter of control spring 55 becomes inevitably small, the other end side of control spring 55 becomes unstable state floating in the air. Thus, as a plug which seals sliding purpose hole 52, it is necessary to hold the other end side of control spring 55 using a screw plug having a groove section to hold the other end section of control spring 55 at an inside thereof. Consequently, there is a possibility that the large sizing of pilot valve 50 would be introduced.
In contrast, in the first embodiment, spool valve 53 is formed in the solid manner and the oil circulation is carried out via annular (ring shaped) groove 68 located on the outer periphery of small diameter section 65. Hence, the shape of spool valve 53 is relatively simple.
In addition, since control spring 55 is elastically contacted on the end surface of press fit plug 56 side of second land section 64, it becomes possible to set the valve diameter of spool valve 53 (the outer diameter of each of first and second land sections 63, 64) to be substantially equal to the outer diameter of control spring 55. Accordingly, the hole diameter of sliding purpose hole 52 can substantially be equal to or substantially be equal to the outer diameter of control spring 55. Consequently, the small sizing of pilot valve 50 can be achieved. In addition, since control spring 55 is guided on the outer peripheral surface of sliding purpose hole 52, the spring force of control spring 55 can be exhibited for the pump discharge pressure (pilot pressure) acted upon pressure receiving surface 66a.
Furthermore, since control spring 55 is held by the inner peripheral surface of control spring housing chamber 54 (an inner peripheral wall of valve body 51), the sealing of sliding purpose hole 52 and the supporting of the other end section of control spring 55 can be carried out only by press fitting press fit plug 56 of a simple shape.
In addition, in the first embodiment, retaining projection section 67 is projected on one of the end surfaces of second land section 64 faced toward press fit plug 56 side. Since one end section of control spring 67 is grasped between the inner peripheral surface of valve body 51 and the outer peripheral surface of retaining projection section 67, a holding characteristic of control spring 55 is furthermore improved.
Furthermore, in the first embodiment, electromagnetic switching valve 40 is structured in such a way that, when oil is enabled to be exhausted from second control oil chamber 32, namely, in a case of the first operation state and the second operation state, electromagnetic switching valve 40 is in the non-power supply state and, when oil is enabled to be introduced into second control oil chamber 32, namely, in the case of the third and fourth operation states, electromagnetic switching valve 40 is in the non-power supplied state.
Thus, in a case, for example, the electromagnetic coil of electromagnetic switching valve 40 and a harness (not shown) are broken (line breakage), the high pressure characteristic is left even under a loss of the low pressure characteristic. Hence, the driving can be continued in a relatively safe manner.
A length of the axial width of second land section 64 of spool valve 53, in this embodiment, is longer than that in the first embodiment. In addition, in second land section 64, retaining projection section 67 is eliminated from the end surface of second land section 64 at control spring side 55 but, in this embodiment, a retaining groove section 71 which is a cylindrically shaped recess section is recessed at a substantial center position of the end surface of second land section 64 at control spring 55 side. A diameter of this retaining groove section 71 is smaller than the outer diameter of second land section 64 and is slightly larger than the outer diameter of control spring 55. A groove bottom of retaining groove section 71 is elastically contacted on one end section of control spring 55 and holds the one end section of control spring 55 by the peripheral wall of the retaining groove section 71.
In addition, press fit plug 56 is eliminated from the other end section side of control spring 55 of valve body 51 and a screw plug 72 which is a bottomed cylindrically shaped tubular member is screwed and fixed to the other end section side of control spring 55. An inner wall of a lid section 72a of screw plug 72 is elastically contacted on the other end section of control spring 55 and an inner peripheral wall of a cylinder section 72b holds the other end section of control spring 55.
Hence, also in this embodiment, in the same way as the first embodiment, oil exhausted from first and second control oil chambers 31, 32 is not circulated into control spring housing chamber 54. Hence, the stability of the position control of spool valve 53 can be improved and the control accuracy of the pump discharge pressure with respect to the set hydraulic pressure characteristic can be improved.
In addition, since both axial end sections of control spring 55 can be held in the stable state by the retaining groove section 71 of second land section 64 and the inner wall of screw plug 72, the spring force can accurately be exhibited against the pump discharge pressure (the pilot pressure) acted upon pressure receiving surface 66a.
It should, herein, be noted that
The present invention is not limited to the structures of the respective embodiments and various modifications and changes are made without departing from the gist of the present invention.
For example, in the second embodiment, a switching timing at which each port is switched by first and second land sections 63, 64 of spool valve 53 is simultaneous. However, such a state that both of drain port 60 and back pressure port 62 may simultaneously be communicated with each other or that both of drain port 60 and back pressure port 62 may be interrupted.
In addition, since chamfering or R shaping are carried out on axial both end edges of first and second sections 63, 64, characteristics of opening areas may be modified. These are adjusted to match with the characteristic of the engine.
In addition, in the second embodiment, with a fail-safe characteristic during the failure of electromagnetic switching valve 40 taken into consideration, the state of electromagnetic switching valve 40 enters the non-power supply state in a case of third and fourth operation states (engine high revolution state). However, it is possible to set reversely the power supply and the non-power supply.
Furthermore, a timing at which the power supply or non-power supply may appropriately be possible according to the various structures. For example, when the switching to the non-power supply state is carried out at a time point at which the engine rotation state becomes further high rotations. Oil pump 10 is directly switchable from the second operation state to the first operation state.
As the variable capacity oil pump based on the embodiment explained above, for example, the following aspects of the present invention may be considered.
In one aspect of the variable capacity oil pump, there is provided the variable capacity oil pump comprising: a pump constituting member which operatively discharges a working oil sucked from a suction section through a discharge section, with a volume of a plurality of pump chambers varied by a rotational drive through an internal combustion engine; a movable member which is operatively moved to modify a volume variation quantity of the plurality of pump chambers according to a movement of the movable member; a biasing mechanism which is installed in a state in which a set load is provided to bias the movable member in a direction in which the volume variation quantity of the plurality of pump chambers is increased; a first control oil chamber configured to act a force in a direction in which the volume variation quantity of the plurality of pump chambers is decreased upon the movable member in response to a supply of the working oil into the first control oil chamber; a second control oil chamber configured to act a force in a direction in which the volume variation quantity of the plurality of pump chambers is increased upon the movable member in response to a supply of the working oil into the second control oil chamber; a switching mechanism formed to enable a switching between a state in which the working oil from the second control oil chamber is exhausted and another state in which the working oil is introduced into the second control oil chamber; and a control mechanism configured to take a state in which the working oil within the first control oil chamber is exhausted and another state in which the working oil whose pressure is decreased than a discharge pressure from the discharge section is introduced into the first control oil chamber and to perform a pressure regulation for the working oil while applying the pressure to the working oil within the first control oil chamber by introducing the working oil into the first control oil chamber as the discharge pressure becomes larger, in a case where the switching mechanism is in the state in which the working oil is exhausted from the second control oil chamber, and to take a further another state in which the working oil whose pressure is decreased than the discharge pressure from the discharge section is introduced into the second control oil chamber and a still further another state in which an introduction of the working oil into the second control oil chamber via the switching mechanism is interrupted and the working oil within the second control oil chamber is exhausted and to perform the pressure regulation for the working oil while reducing the pressure to the working oil within the second control oil chamber by exhausting the working oil within the second control oil chamber as the discharge pressure becomes larger, in a case where the switching mechanism is in the other state in which the working oil is introduced into the second control oil chamber, wherein the control mechanism is controlled by a hydraulic pressure of the working oil and a biasing force of a biasing member and the working oil is not introduced into a location of the control mechanism at which the biasing member is arranged.
In a preferable aspect of the variable capacity oil pump, the control mechanism includes: a valve body having an introduction port through which the hydraulic pressure of the working oil discharged from the discharge section is introduced, a first control port communicated with the first control oil chamber, a second control port communicated with the second control oil chamber, and a drain port communicated with a connection port and a low pressure section connected to the switching mechanism; a spool valve slidably housed in an axial one end side of the valve body to switch between a communication state of the introduction port and the connection port with respect to the first control oil chamber and a communication state of the connection port and the drain port with respect to the second control oil chamber; and a control spring which is the biasing member and housed in the axial other end side of the valve body to blase the spool valve toward the axial one end of the valve body according to its biasing force smaller than that of the biasing mechanism.
According to another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, both axial end sections of the spool valve have the large-diameter land sections which slide the valve body and the small diameter sections are formed between respective land sections. The connection port is approximately communicated with respect to the first control oil chamber and is formed to appropriately communicated with the connection port and drain port with respect to the second control oil chamber.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, the introduction port is installed at axial one end section of the valve body and pressure receiving surfaces on which the hydraulic pressure of working oil is acted are formed on axial end sections of the introduction port side.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, the first and second control port and the drain port are penetrated through the peripheral wall of the valve body, respectively.
According to further another preferable aspect of the present invention, in any one of the aspects of the present invention, the spool valve is formed in the solid (body) manner.
According to further another preferable aspect of the present invention, in any one of the aspects of the present invention, the cylindrical recess section whose diameter is smaller than the land section is projected on the end surface of the land section at the control spring side and the convexity section is held by the convexity section.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, the control spring is supported on the inner peripheral wall of the valve body.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, the cylindrical recess section whose diameter is smaller than the land section is recessed toward the introduction port and one end side of the control spring is held by the recess section.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, the bottomed cylindrically shaped tubular member is arranged on the valve body at the control spring side end section and the control spring other end section is held on the inner wall surface of the tubular member.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, in a case of the state in which the working oil is simultaneously exhausted from the first and second control oil chambers, the working oil is exhausted via the outer periphery of the small diameter section and, thereafter, via the switching mechanism.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, the switching mechanism is an electromagnetically controlled valve electrically switching controlled.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, the electromagnetically control valve takes a non-power supply state when the working oil is introduced into the second control oil chamber and takes the power supply state when the working oil is exhausted from the second control oil chamber.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, the electromagnetically control valve carries out the switching of the working oil supply or exhaust with respect to the second control oil chamber through the ball valve.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, the working oil discharged from the discharge section is used as the lubricating oil which lubricates the constituent member that the internal combustion engine has in its inside.
According to further another preferable aspect of the present invention, in any one of the aspects of the variable capacity oil pump, the working oil discharged from the discharge section is used in the oil jet which supplies the working oil to the piston of a drive source of the variably operated valve device and the piston of the internal combustion engine.
In addition, from another viewpoint, the variable capacity oil pump comprising: a rotor configured to be drivingly rotated by an internal combustion engine; a plurality of vanes movable out and into an outer peripheral section of the rotor; a cam ring configured to partition an inner peripheral side of the cam ring into a plurality of pump chambers while accommodating the rotor and the vanes into an inner peripheral side of the cam ring, to move to vary an eccentricity quantity with respect to an axial center of the rotor, and thereby to vary a volume variation quantity of the plurality of pump chambers; a suction section which is open to a suction region of the plurality of pump chambers in which a volume is increased in association with a rotation of the rotor; a discharge section which is open to a discharge region of the plurality of pump chambers in which the volume is decreased in association with the rotation of the rotor; a biasing mechanism disposed to have a set load and to bias the cam ring in a direction in which the eccentricity quantity becomes large; a first control oil chamber configured to act a force in a direction in which the eccentricity quantity becomes small upon the cam ring in response to a supply of the working oil into the first control oil chamber; a second control oil chamber configured to act a force in a direction in which the eccentricity quantity becomes large upon the cam ring in response to a supply of the working oil into the second control oil chamber; a switching mechanism formed to enable a switching between a state in which the working oil from the second control oil chamber is exhausted and a state in which the working oil is introduced into the second control oil chamber; and a control mechanism configured to take a state in which the working oil within the first control oil chamber is exhausted and another state in which the working oil whose pressure is decreased than a discharge pressure from the discharge section is introduced into the first control oil chamber and to perform a pressure regulation for the working oil while applying the pressure to the working oil within the first control oil chamber by introducing the working oil into the first control oil chamber as the discharge pressure becomes larger, in a case where the switching mechanism is in the state in which the working oil is exhausted from the second control oil chamber, and to take a further another state in which the working oil whose pressure is decreased than the discharge pressure from the discharge section is introduced into the second control oil chamber and a still further another state in which an introduction of the working oil into the second control oil chamber via the switching mechanism is interrupted and the working oil within the second control oil chamber is exhausted and to perform the pressure regulation for the working oil while reducing the pressure to the working oil within the second control oil chamber by exhausting the working oil within the second control oil chamber as the discharge pressure becomes larger, in a case where the switching mechanism is in the other state in which the working oil is introduced into the second control oil chamber, wherein the control mechanism is controlled by a hydraulic pressure of the working oil and a biasing force of a biasing member and the working oil is not introduced to into a location of the control mechanism at which the biasing member is arranged.
In a preferable aspect of the variable capacity oil pump, the first and second control oil chambers are installed on the outer peripheral side of the cam ring and are defined by the swing fulcrum disposed on the outer peripheral side of the cam ring.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-079654 | Apr 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/060701 | 3/31/2016 | WO | 00 |
