Patent Grant
6953022
This application is the U.S. National Phase under 35 U.S.C. §371 of International Application PCT/JP00/03426, filed May 26, 2000. The International Application was not published under PCT Article 21(2) in English.
This invention relates to a fuel injection pump used for a diesel type internal-combustion engine.
A fuel injection pump for diesel engines includes a governor, which adjusts the amount of fuel injection by rotating a plunger and adjusting the opening time of a plunger lead. For constituting the governor, a linearly movable control member directly engages with a control sleeve which is rotatable integrally with the plunger, and an actuator for moving the control member is connected to the control member by a governor link. For serving as the control member, there are a control rack meshing with a pinion provided on the control sleeve, a control slider whose fork arm pinches a lock pin provided on the control sleeve, and so on. For serving as the actuator for moving the control member, if the governor is a centrifugally operated governor, there is a governor sleeve which is moved with the centrifugal force of a camshaft, for example. If the governor is an electronic governor, for example, an electromagnetic solenoid may serve as the actuator.
Since a governor mechanism part including a governor weight and the governor sleeve etc. in the case of the centrifugally operated governor, or an electromagnetic solenoid part in the case of the electronic governor is large-scale, it is offset from a pump mechanism part equipped with a plunger, a delivery valve, etc. On the other hand, the above-mentioned link must engage with the control member in the pump mechanism part. Therefore, when attaching the plunger to the pump mechanism part, the governor link needs to be inserted together with the plunger into the pump mechanism and engaged to the control member while being finely tuned in its positioning, thereby complicating assembly operation of the pump mechanism part itself. Suppose that the governor link previously included in the governor mechanism part is automatically made to engage with the control member in the pump mechanism part during the assembling for combination of the governor mechanism part with the pump mechanism part incorporating the plunger etc. In this case, the assembly of a fuel injection pump becomes very easy. However, there is no conventional fuel injection pump of such a configuration.
Moreover, an end of the camshaft of a fuel injection pump is projected outside from a bearing of pump housing, and provided thereon with a key such as a woodruff key through which a reduction gear is fixedly provided thereon so as to be interlockingly connected to a crankshaft in a crankcase. If the bearing allows the key to pass therethrough, in the insertion process of the camshaft to the pump housing, this key can be provided only by passing the camshaft previously loaded with the key through the bearing to project the outer end of this camshaft outward. However, if the camshaft is loaded with a key in a conventional manner, the distance between the axis of the camshaft and a part of the key that is radially farthest from the axis of the camshaft will become larger than the radius of inner periphery of the bearing. Therefore, it becomes inevitable that the key is loaded on the projection end of the camshaft after the camshaft is passed through the pump housing and projected at its outer end outward from the pump housing. Furthermore, for removing the camshaft from the pump housing, not only the gear but also the key must be removed from the pump shaft so as to allow the projection end of the camshaft to pass the bearing.
Next, the problem of the conventional diesel engine will be explained in relation to the injection time of a fuel injection pump. In a diesel engine, the fuel pressurized by hundreds atmospheric pressure with the fuel injection pump is injected into a combustion chamber from a nozzle of a fuel injection valve attached to a cylinder head at about 20 degrees prior to the top dead center of the crankshaft in its rotational angle (in lead zone of crank angle).
Since combustion is performed in the integrity that air is superfluous, there is little concentration of CO and HC in exhaust gas of a diesel engine far compared with that of a gasoline engine. However, a diesel engine exhausts much NOx. Reduction of exhaustion of NOx is the most important problem for diesel engines.
NOx is generated when nitrogen and oxygen are heated to combine with each other. Therefore, generally, the better combustion is, the more NOx is exhausted. That is, the abundance of NOx increases, so that the combustion temperature is high and the duration of combustion is long. Furthermore, when the mixture ratio of air and a fuel is a certain value, this abundance reaches maximum.
In order to reduce NOx under exhaust gas, it is possible to adopt EGR system or a crankcase emission control system besides improvement of the combustion chamber in an engine, or improvement of an air intake-and-exhaust system. However, if EGR system is performed, the soot under exhaust gas will mix in lube through inhalation air, and early degradation of lube and wear of an engine sliding part will pose a problem. Moreover, when it is equipped with a crankcase emission control system, soot accumulates on the lube adhering to the wall in an intake manifold so as to choke the intake manifold, thereby reducing an engine performance.
As another reduction method of NOx, it is improvement of an injection system, especially a fuel injection pump so as to delay the start time of fuel injection. However, this leads to aggravation of combustion so as to decline the output force and thermal efficiency, increase CO or HC, aggravate the engine starting at low-temperature, and increase black smoke concentration, etc. Therefore, when an engine starts or high load is applied on the engine, priority should be given over advancing of fuel injection starting time for efficient combustion to reduction of NOx under exhaust gas. Thus, since the required time of a fuel injection start changes with engine operation situations, it becomes important how fuel injection start time is controllable so as to agree with conflicted required times.
Such control of fuel-injection time is well known by JP6-50237A. According to this document, a sub lead other than an original plunger lead (main lead) is formed in the head of a plunger. Corresponding to this sub lead, a leak port which is open for free passage to a fuel escaping circuit is formed in a plunger barrel. By bringing the sub lead into communication with the leak port, the fuel in a fuel-compression chamber is made to escape in early stages of the fuel-discharging stroke of the plunger so as to delay the fuel-injection time substantially.
In the cited plunger, when the rotational location of the plunger by the governor goes within a fixed range (for example, a range corresponding to the time of an engine start, or if the plunger is controlled by an electronic governor, a range corresponding to the time when the engine is high-loaded), the sub lead is located apart from the leak port so as to be shut off from the leak port so that the plunger starts discharging fuel of the predetermined pressure to the delivery valve shortly after it closes the inhalation port to finalize the fuel-inhaling stroke thereof. Whereby, the fuel-injection time can be advanced.
However, in the case of this cited example, strict accuracy is required in processing of the sub lead, the leak port and the like as well as positioning of the plunger. When an error is in these process tolerances, the fuel-injection start time does not correspond well to the control of fuel oil consumption based on engine operation situations. In this regard, if the amount of fuel escaping from each leak port is not unified exactly, the engine performance varies among fuel injection pumps. Particularly, it comes to be considered that a train type fuel injection pump or the like has a plurality of plungers whose injection characteristics are different from one another so as to cause variation of combustion ability among the cylinders of an engine. On the other hand, the amount of leaking fuel may be requested to increase or decrease according to variation of engines. Neither the dissolution of the variation in the engine performance by such process error nor adjusting of the amount of fuel leaks as occasion demands is attained depending on the above-mentioned reference technique.
A first object of the invention is to provide a fuel injection pump (especially, a distributor type pump) that is excellent in ease of assembly, especially in that of a governor linkage during the whole assembly.
To achieve the object, the fuel injection pump of this invention can be disassembled into three parts: a lower mechanism part which has pump driving means; a head mechanism part which has a rotatable plunger, a control sleeve that is rotatable integrally with the plunger and a linearly movable member for rotating the control sleeve; and a governor mechanism part having a governor link.
Especially in the lower mechanism part, a camshaft for actuating the plunger is passed through a bearing of a main body housing for its journalling so that the camshaft projects outward from the bearing so as to be loaded with a key for positioning fixation of a cam reduction gear onto the camshaft. Since the distance in the radial direction of the camshaft between a portion of the key which is the farthest from an axis of the camshaft and this axis is made smaller than the inner periphery radius of this bearing, the arrangement of the camshaft can be finished just when the camshaft loaded with the key beforehand is passed through the bearing, thereby simplifying assembly of the lower mechanism part.
Moreover, in the head mechanism part, a plunger barrel and a support member are attached in a pump head. The plunger is slidably and rotatably inserted in the plunger barrel so as to partly project from the plunger barrel. The control sleeve is provided on the projection of the plunger. The linearly movable member for rotating the control sleeve engages with the control sleeve while the linearly movable member being supported by the support member to be guided for enabling its linear movement. Moreover, a receptacle member fittingly retained by the support member retains the plunger and the control sleeve so as to prevent them from escaping from the plunger barrel. In this way, the head mechanism part as a single block is composed.
After combining the lower mechanism part and the head mechanism part, the governor connection part is attached to the combined lower and head mechanism parts, thereby completing the assembly of the fuel injection pump as the whole. On attaching of the governor connection part to both the lower and head mechanism parts, a governor link extended from the governor mechanism part is detachably connected to the linearly movable member, thereby completing the governor.
For attachment and detachment of the governor link to and from the linearly movable member, the governor link pivotally supported by the governor mechanism part through a pivot point may be rotated centering on the pivot point after it is inserted into the combined lower and head mechanism parts and positioned therein. Alternatively, the governor link or the whole governor mechanism part may be rotated while the length of the positioned governor link is used as a fulcrum shaft.
Moreover, the engagement of the control sleeve with the linearly movable member may be configured as follows. In the head mechanism part, the control sleeve is provided with a lock pin, and the linearly movable member with a fork arm. The linearly movable member made to be rotatable is rotated so as to removably engage the fork arm with the lock pin when the lower mechanism part and the head mechanism part are combined with each other.
A second object of the invention is to provide a fuel injection pump that is excellent in the control of fuel-injection start time. In detail, without greatly depending on processing accuracy of a fuel channel and the like, an actual fuel-injection start time is made to properly correspond to the required time of the fuel-injection start which varies with engine operation situations, thereby offering high combustion efficiency during an engine start and effects such as reduction of NOx in exhaust gas in the phase in which the engine got warm.
The fuel injection pump has a fundamental structure as follows: A plunger is reciprocally and rotatably inserted in a plunger barrel so as to face the head of the plunger into a fuel-compression chamber formed in a plunger barrel. By reciprocation of the plunger, fuel is absorbed from a fuel gallery to the fuel-compression chamber and fed from the fuel-compression chamber to a delivery valve. In the plunger barrel is provided an inhalation port to be communicated with the fuel gallery and a leak port to be communicated with a fuel escaping circuit. A sub lead is formed in the head of the plunger. During the sliding of the plunger toward the fuel-compression chamber, the fuel-inhaling stroke for communicating the inhalation port with the fuel-compression chamber, and the fuel discharging-delay stroke for communicating the leak port with the fuel-compression chamber through the sub lead so as to leak fuel in the fuel-compression chamber to the fuel escaping circuit are finalized, and then the fuel-discharging stroke for discharging fuel of the predetermined injection pressure to the delivery valve is begun.
In this fundamental structure, according to the present invention, the sub lead is formed so as to prepare a variation in the depth thereof so that the confrontation period to the leak port of the sub lead in reciprocation of the plunger may vary with alteration of the rotation location of the plunger. Accordingly, the finalizing time of the discharging-delay stroke varies with control of the injection quantity so that, correspondingly to various situations of an engine, the fuel-injection start time can be changed by tie up thereof with control of the amount of injected fuel.
Moreover, in the above-mentioned fundamental structure, according to the invention, means for control the flow of fuel leaking from the leak port is attached to the fuel injection pump so that the means can be operated for the adjustment from the exterior of the fuel injection pump. Therefore, even if there is variation in the amount of leaking fuel among a plurality of fuel injection pumps having the same specification or among a plurality of plungers in a fuel injection pump such as a train type fuel injection pump because of processing error, the amount of leaking fuel flow can be unified among the pumps or the plungers by the flow control means. The flow control means may also be operated for adjusting the leak amount of fuel when the amount is desired to vary in correspondence to an engine operation situation or so on. The means may be so constructed so as to be manipulated outside the fuel injection pump or be connected to a controller so as to be electrically controlled, thereby facilitating its operation.
As an aspect of the flow control means, a valve chamber, which opens to a fuel passage from the leak port, is formed in a pump body. In the valve chamber are arranged a valve element which is shaped to close a junction between the valve chamber and the fuel channel, and a biasing member for biasing the valve element to close the junction. The pressured leaking fuel pushes the valve element against the biasing force of the biasing member so as to open the valve chamber to the fuel channel. Adjusting means for restricting and adjusting the movement of the valve element caused by the pressure of leaking fuel is arranged so as to be operable from the exterior of the fuel injection pump. This adjustment enables the amount of leaking fuel to be adjusted.
In this structure, the adjusting means may be an electromagnetic-controlled actuator. If the actuator is controlled in association with control of an electronic governor, the adjustment of leaking fuel flow tied up with the fuel-injection control corresponding to an engine speed and an engine load becomes exact.
Moreover, according to the invention, in the above-mentioned fundamental structure, an on-off valve is arranged in an intermediate portion of the fuel escaping circuit. By closing the on-off valve, the fuel-discharging stroke starts immediately after the fuel-inhaling stroke finalizing, without passing through the discharging-delay stroke. Therefore, for example, if it is made to perform opening-and-closing control of the on-off valve corresponding to an engine operation situation, an actual fuel-injection start time can be made to correspond at the required time of the fuel-injection start which changes with engine operation situations (for example, the low-temperature situation at the time of an engine start and the situation where the engine is driven for a while so as to get warm).
Furthermore, a timer for fuel-injection time control is composed. The timer has such a configuration that the movable on-off valve, a valve actuator and a biasing member are arranged in a valve chamber in communication with the fuel escaping circuit so that the on-off valve is sandwiched between the valve actuator and the biasing member.
The valve actuator is provided with a temperature sensing member so as to move the on-off valve against the biasing force of the biasing member according to increase of the temperature so that the on-off valve is closed when the temperature sensed by the temperature sensing member is under the predetermined, and it is open when not under the predetermined. Therefore, when an engine is in a low-temperature situation at its starting, the temperature of the fuel injection pump is also so low as to close the on-off valve, thereby bringing the injection start time of fuel forward. On the other hand, if an engine is operated for a while and the fuel injection pump gets warm more than a constant temperature, the on-off valve is opened so as to delay the injection start time.
Alternatively, the valve actuator may be provided with an operation member which operates by oil-pressure variation of engine lube so as to move the on-off valve against the biasing force of the biasing member according to increase of engine lube pressure so that the on-off valve is closed when the oil-pressure is under the predetermined, and it is open when not under the predetermined. Like the above, the injection start time will be advanced in the low-temperature situation when the engine starts, and the injection start time will become late in the elevated-temperature situation after driving the engine for a while. However, in this structure, since the valve actuator operates by the variation of lube pressure in immediate response to the temperature change in an engine, it can realize the on-off valve control that corresponds to the engine temperature situation exactly.
Alternatively, the valve actuator may be electromagnetically controlled so as to selectively put the on-off valve into either its valve-opening mode or valve-closing mode depending upon whether the valve actuator is energized or not energized. In this structure, the fuel-injection start time is controllable according to various conditions of the engine such as rotary speed and load as well as temperature.
Furthermore, in the fuel escaping circuit, means for adjusting the fuel flow from the leak port may be arranged between the leak port and the on-off valve. Whereby, besides the control effectiveness of the fuel-injection start time according to the on-off valve control, the above-mentioned unification of the fuel leaks regardless of processing error can be obtained or the amount of leaking fuel leak flow can be adjusted corresponding to an engine situation or so on.
a)–(c) are fragmentary sectional side views of governor link 27 and control slider 21 which are being engaged with each other through flat spring 39 wherein governor link 27 is formed with a slope 27d so as to enable governor link 27 and control slider 21 to be engaged with each other without forcibly rotating flat spring 39 downward.
a)–(d) illustrate an engagement process of governor link 27 with control slider 21 by rotating governor link 27 centering on the length thereof according to a seventh embodiment, wherein
First, in accordance with
A cylinder portion 63 is formed in an upper part of a crankcase 61, and a cylinder head 64 is attached onto cylinder portion 63, thereby constituting a diesel engine DE. In cylinder portion 63 are formed one or more cylinders. Fuel injection valves and valve mechanism (intake and exhaust valves) for the respective cylinders are incorporated in cylinder head 64. A reference numeral 65 is an exhaust-air muffler and a reference numeral 66 is an exhaust manifold. A crankshaft (not shown) is journalled in crankcase 61. In a side base 62 attached to one end (in this embodiment, a front end) of crankcase 61, one end of the crankshaft is interlockingly connected through timing gears to camshafts for a fuel injection pump and the valve mechanism.
A front end of a fuel-injection-pump P is attached to side base 62, as shown in
Air is introduced into each of the cylinders from an intake valve in the fixed degree zone of crank angle regarding a piston in the cylinder, and fuel is injected into the combustion chamber of each cylinder from the fuel injection valve in the compression stroke (just before a top dead center, i.e., a lead zone of crank angle) of this piston, so that the compressed air is exploded and expanded in this cylinder. The air is scavenged after its explosion through an exhaust valve. The exhaust air from all the cylinders is collected together through an exhaust manifold 66 from cylinder head 64 and ejected outside through an exhaust-air muffler 65.
Fuel-injection-pump P shown in
The configuration of fuel-injection-pump P will now be described. Incidentally, in fact, fuel-injection-pump P may be attached to diesel engine DE in the shape of an inclination, as shown in
The distributor type fuel injection pump according to the invention, which is excellent in the ease of assembling, will be described. A distributor type pump may be provided with plural plungers or plural distributor shafts so as to distribute fuel from each distributor shaft to plural delivery valves. However, each of the distributor type pumps of the invention shown in
Fuel-injection-pump DP can be disassembled into three parts of a lower mechanism part A, a head mechanism part B and a governor mechanism part C. Lower mechanism part A comprises a main body housing 1 which rotatably supports camshaft 4 for driving plunger 7 and distributor shaft 9. Head mechanism part B comprises a head housing 2 in which plunger 7, distributor shaft 9 and delivery valves 18 are provided. Governor mechanism part C comprises a governor housing 3, which incorporates a governor arm 29 and a governor link 27 at least among component parts of a governor.
Referring to
During assembling, as shown in
In accordance with
A cam 4a for plunger actuation and a cam 4b for fuel-feed-pump actuation are formed of camshaft 4. They may be separate members fixed on camshaft 4. Moreover, a front end portion of camshaft 4 is integrally loaded with a woodruff key 13, another portion thereof behind cam 4b with a bevel gear 5, and another portion thereof just behind bevel gear 5 with a bearing 14.
For setting such camshaft 4 into main body housing 1, first, the front end portion of camshaft 4 is inserted from the back of joint surface 1b into cam chamber 1d through a bearing hole formed in bearing wall 1c. Camshaft 4 is further inserted forward so that the front end portion thereof is passed through bearing sleeve 12 and projected forward from flange 1a, whereby camshaft 4 is completely journalled.
Consequently, the front end portion of camshaft 4 loaded with woodruff key 13 projects forward from flange 1a. The forward projecting end thereof is arranged in side base 62 of engine DE shown in
In the conventional way of providing a key for positioning fixation of a cam gear onto a camshaft, the camshaft is completely journalled in a main body housing and then the key is provided on the outward projecting end of the camshaft, because a portion of the key farthest from axis of the camshaft in the radial direction of the camshaft is farther from the axis than the inner periphery of a bearing (in this embodiment, it is bearing sleeve 12) from the axis. In this embodiment, as shown in
With respect to the inside of cam chamber 1d, cam 4a is disposed just below tappet chamber 1f, bevel gears 5 and 20 engage with each other, and bearing 14 is fit in the bearing hole of bearing wall 1c.
The rear end portion of camshaft 4 completely journalled in main body housing 1 is extended backward from bearing wall 1b so as to project through joint surface 1b into governor housing 3 which is attached to main body housing 1 in a later-discussed way. In order to compose a centrifugally operated governor, the rear end portion of camshaft 4 is provided thereon with flyweight 31 and governor sleeve 30, as shown in
In addition, components needed for engagement and disengagement of later-discussed governor link 27 and control slider 21 are incorporated in lower mechanism part A.
Description will now be given of head mechanism part B in accordance with
A lower portion of plunger 7 projects downward from plunger barrel 8. As shown in
As shown in
Incidentally, in order to compose a governor (irrespective of a centrifugally operated governor or an electronic governor), a tab 21b provided with a lock pin 21a is integrally hung down from control slider 21 so as to be connected to later-discussed governor link 27. This governor structure will be detailed later.
As shown in
Furthermore, an upper spring bracket 23 is provided around control sleeve 17. Upper spring bracket 23 functions as a member which receives an upper end of a later- discussed plunger spring 22, and also as a retainer for preventing plunger 7 and control sleeve 17 from escaping. Plunger barrel 8 and control sleeve 17 are formed with respective steps for positioning upper spring bracket 23. The top of upper spring bracket 23 is made to abut against the step of plunger barrel 8. Furthermore, an annular engaging portion 23b integrally formed within upper spring bracket 23 is made to abut against the step of control sleeve 17, thereby positioning upper spring bracket 23. Moreover, a stop hole 23a is formed in a side wall portion of upper spring bracket 23. A stop portion 15a extensionally formed of slider guide 15 is inserted into stop hole 23a, thereby fixing upper spring bracket 23 to pump head 2 so as to prevent upper spring bracket 23 from falling out.
As the assembly sequence of upper spring bracket 23, control slider 21 and slider guide 15 shown in
In an embodiment shown in
Furthermore, the bottom end of plunger 7 extended downward from control sleeve 17 is engaged with a lower spring bracket 24, as shown in
Around distributor-shaft sleeve 10, as shown in
Moreover, as shown in
Description will now be given of governor mechanism part C. This serves as governor housing 3 incorporating at least a governor arm 29 to be pivotally connected with governor link 27. Incidentally, each of governor housing 3 and governor arm 29 for the centrifugally operated governor shown in
In governor housing 3 of governor mechanism part C for centrifugally operated governors, governor arm 29 pivoted on a governor shaft 28, other arms and a governing lever (not shown), etc. are assembled together and appropriately biased by springs, thereby constituting a governor arm mechanism, in which governor arm 29 is pivoted at the top end thereof onto a base end of governor link 27. As described above, as shown in
In the completed centrifugally operated governor, governor arm 29 rotates by the movement of the governing lever by accelerator operation, thereby rotating control slider 19 and plunger 7 through control slider 21 so as to change the amount of fuel injection. Moreover, if the rotary speed of camshaft 4 becomes large while the governing lever being held at the fixed position, flyweight 31 is opened and governor sleeve 30 is pushed out. Accordingly, governor arm 29 is rotated so as to rotate plunger 7 to the injection reduction side. As mentioned above, stopper plate 1i is erected so as to decide the bound of approaching governor link 27 in governor link chamber 1e. However, when governor link 27 abuts against stopper plate 1i, the rotational position of plunger 7 becomes the minimum injection position, i.e., a non-injection position. If the rotating speed of camshaft 4 becomes small, the opening of fly weight 31 reduces, governor arm 29 rotates to a reverse side by the biasing force, and governor slider 30 also slides toward governor weight 31, thereby rotating plunger 7 to the increase side in the injection quantity. Thus, engine power output is conserved to the value corresponding to accelerator setting.
In order to compose an electronic governor, as shown in
As shown in
In order to assemble distributor-type pump DP, lower mechanism part A and head mechanism part B are combined up and down first. For combining lower mechanism part A and head mechanism part B when pump head 2 of head mechanism part B is installed on main body housing 1 of lower mechanism part A, lower spring bracket 24 and plunger spring 22 are automatically inserted into tappet chamber 1f, and while lower spring bracket 24 is positioned on tappet 11 beforehand arranged in tappet chamber 1f, tappet 11 is pressed against cam 4a by the biasing force of plunger spring 22. Simultaneously, the bottom of distributor shaft 9 integrally engages with the upper end of distributor driving shaft 19, and bevel gear 20 meshes with bevel gear 5. Moreover, governor link chamber 1e is formed in the state of being surrounded by main body housing 1 and pump head 2. In governor link chamber 1e, control slider 21 and slider guide 15 come to be arranged along the bottom surface of pump head 2.
Finally, by using screwed holes 2a bored in pump head 2 as shown in
Distributor-type pump DP is perfected by attaching governor mechanism part C to the side of such combined mechanism parts A and B, as shown in
In the completed governor, governor link 27 is moved by rotating governor arm 29 in the above-mentioned way. Then, control slider 21 engaging with governor link 27 slides horizontally so that control sleeve 17 and plunger 7 are rotated together. In this way, the opening time of plunger (main) lead 7a to inhalation port 8a is altered so as to change the fuel-discharging stroke period of plunger 7, thereby adjusting the amount of injected fuel.
For engaging or removing lock pin 21a of control slider 21 with and from hook groove 27a of governor link 27, it may be considered that the tip of governor link 27 vertically rotatably supported on governor arm 29 is swung vertically, or that governor link 27 is rotated centering on the length thereof.
According to a first embodiment shown in
Lift pin 33 projects outward from main body housing 1 (not shown) so as to enable its manipulation for rotation from the exterior of main body housing 1. Furthermore, a partial tip of lift pin 33 in main body housing 1 has a subtense-like cut in section so as to form a substantially hemicylindrical cam portion 33a. Governor link 27 inserted in governor link chamber 1e rides on cam portion 33a rectangularly when viewed in plan. When lift pin 33 is rotated so as to place a cut surface 33b downward as shown in
Therefore, in the case that governor mechanism part C is attached to combined mechanism parts A and B, lift pin 33 is previously placed to make cut surface 33b face upward. Then, while governor housing 3 approaching joint surface 1b of main body housing 1, governor link 27 is fit with cut surface 33b on the top of cam portion 33a and inserted into governor link chamber 1e until governor link 27 reaches the fixed position in governor link chamber 1e, that is, hook groove 27a reaches the position just under lock pin 21a. In addition, above-mentioned stopper plate 1i for defining the bound of approaching governor link 27 may be used for positioning of lock pin 21a directly under of hook groove 27a. That is, if control slider 21 is positioned so as to locate control sleeve 17 in rotation to the non-injection position, and the tip of governor link 27 inserted into governor link chamber 1e comes to abut against stopper plate 1i, hook groove 27a is naturally arranged just under lock pin 21a. In the later-discussed second and third embodiments, stopper plate 1i can also be used for positioning of governor link 27 similarly.
In this way, after positioning the point of governor link 27, lift pin 33 is rotated so as to make hook groove 27a swing upward, thereby bringing governor link 27 into engagement with lock pin 21a. For removal of governor mechanism part C from lower mechanism part A, by rotating lift pin 33 so as to make downward cut surface 33b face upward, hook groove 27a can be removed down from lock pin 21a.
In the second embodiment shown in
By rotational operation of lift pin 34, cam portion 34a revolves around the axis of lift pin 34 between a top dead center as the full line drawn in
Moreover, a flange 34b is integrally formed of lift pin 34. Flange 34b is formed with a couple of screwed holes 34c in the arrangement of a point symmetry focusing on the axis of lift pin 34 when viewed along the axis of lift pin 34. By screwing flange 34a to main body housing 1 using screwed holes 34c, cam portion 34a is fixed to the above-mentioned top dead center, whereby the connection of governor link 27 with control slider 21 can be conserved. The couple of screwed holes 34c also serve as points for location of the upper and bottom dead centers. For locating cam portion 34a to the bottom dead center, positions of both screwed holes 34c may be exchanged.
In addition, as shown in
Such a flange structure may be adapted to lift pin 33 of the first embodiment shown in
The third embodiment shown in
Lift pin 35 is so arranged as to make bolt-head 35c out of main body housing 1, and to make the main body portion thereof and taper portion 35a into main body housing 1 (along groove 1g in governor link chamber 1e) while screw portion 35b engaging with a female screw 1h formed in a side wall of main body housing 1. In this way, lift pin 35 is axially moved by rotating bolt-head 35c manually or so on in the exterior of main body housing 1.
Before attaching governor mechanism part C to combined lower mechanism part A and head mechanism part B, as shown in
When releasing this engagement, bolt-head 35c is rotated in reverse so as to remove screw portion 35b outward from female screw 1h and further make lift pin 35 slide to the exterior of main body housing 1 so that taper portion 35a retreats from the position directly under governor link 27, whereby governor link 27 rotates downward by deadweight so as to remove hook groove 27a downward from lock pin 21a.
Alternatively, in the exterior of main body housing 1, a flange as mentioned above may be formed on lift pin 35 instead of screw portion 35b and bolt-head 35c. In this case, it should be configured that the flange comes to contact main body housing 1 just when lift pin 35 slides to the final position thereof for engaging governor link 27 with control slider 21 (the position shown in
In the above first through third embodiments, the lift pin is needed and it must be operated for engagement and disengagement of governor link 27 and control slider 21. According to a fourth embodiment shown in
In this embodiment, the bottom surface of governor link chamber 1e of main body housing 1, which contacts governor link 27 so as to slidably guide it, is formed along the sliding course of governor link 27 so as to serve as a slope surface S and a horizontal surface H. Slope surface S is acclivitous from a bottom edge Sa (toward governor housing 3) to a top edge Sb (opposite to governor housing 3). Horizontal surface H is substantially horizontally formed continuously from top edge Sb of slope surface S.
Especially, governor link 27 used in this embodiment is required to have hook groove 27a in the tip thereof formed so that, of both vertical side edges 27b and 27c sandwiching the bottom of hook groove 27a, side edge 27c opposite to governor housing 3 has a reduction of the approximately diameter of lock pin 21a in height compared with side edge 27b toward governor housing 3.
On the occasion of attaching governor mechanism part C to both combined mechanism parts A and B, control slider 21 is beforehand positioned so as to place lock pin 21a above bottom edge Sa of slope surface S in governor link chamber 1e, as the phantom line drawn in
Further, governor housing 3 is made to approach joint surface 1b horizontally, so that the tip of governor link 27 ascends slope surface S, whereby edge 27b pushes lock pin 21a horizontally so as to make control slider 21 slide. In this way, the higher hook groove 27a is moved, the deeper lock pin 21a is inserted into hook groove 27a. When the tip of governor link 27 passes top edge Sb and rides on horizontal surface H as the full line drawn in
Incidentally, in completed fuel injection pump DP, by the faculty of the governor, the tip of governor link 27 moves so as to make control slider 21 slide as the rotating speed of camshaft 4 varies. However, the motion range of the tip of governor link 27 in this control is defined only as horizontal surface H, and since the tip does not go down slope surface S, lock pin 21a and hook groove 27a are not disengaged.
Moreover, if governor housing 3 is removed from main body housing 1 and taken away from joint surface 1b, the tip of governor link 27, while engaging with control slider 21, is moved from horizontal surface H to slope surface S. At last, when the tip reaches bottom edge Sa, lock pin 21a is removed from hook groove 27a. If governor housing 3 is further taken away from main body housing 1, control slider 21 does not slide but governor link 27 further slides on the top surface of main body housing 1. Finally, governor link 27 is removed from main body housing 1, thereby completing the detachment of governor mechanism part C.
According to the fifth embodiment shown in
In the fifth embodiment shown in
In the case where governor mechanism part C is attached to both mechanism parts A and B put together, beforehand, lift plate 36 is depressed against spring 37 in any way and control slider 21 is arranged so as to place lock pin 21a above lift plate 36. In this situation, the tip of governor link 27 is made to slide on the bottom surface of governor link chamber 1e. Soon, the tip of governor link 27 falls onto lift plate 36 which falls a degree within recess 1j. When hook groove 27a reaches the underside of lock pin 21a, lift plate 36 is released from the downward pressure force so that the tip of governor link 27 is pushed up together with lift plate 36 by the biasing force of spring 37, thereby engaging lock pin 21 into hook groove 21a.
In addition, the tip of governor link 27 may be formed with a slope portion 27d which is shown in governor link 27 of
According to the sixth embodiment shown in
In the engagement process of the governor link 27 and control slider 21 at the time of attaching governor mechanism part C to both mechanism parts A and B put together, the upward biasing force of flat spring 39 replacing lift plate 36 is used similarly to the fifth embodiment. In the case of
Governor link 27 of
In the above-mentioned first through sixth embodiments shown in
When governor mechanism part C is attached to both combined mechanism parts A and B, at the beginning, as shown in
Alternatively, not governor link 27 but governor housing 3 may be rotated at 90 degrees from its original attitude at the beginning. In this case, when stopper portion 21a of governor link 27 inserted into governor link chamber 1e of main body housing 1 comes to abut against lock pin 21a, the entire of governor housing 3 is rotated so as to engage hook groove 27a with lock pin 21a.
In fuel injection pump DP having the above-mentioned configuration indicated in
In a following distributor-type fuel injection pump DP′ shown in
During assembly of fuel injection pump DP′, first, control sleeve 17 and slide rod 81 are connected at the combination process of lower mechanism part A and head mechanism part B. A governor (it may be either mechanical or electronic) can be completed by connecting governor link 82 extended from governor housing 3 with slide rod 81 without inserting governor link 82 deeply in main body housing 1 while governor mechanism part C is attached to both mechanism parts A and B which have been combined in the way.
Slide rod 81 is slidably and rotatably contained in a slide rod receipt portion 1m formed in main body housing 1 of lower mechanism part A so as to be laid substantially horizontally. Slide rod 81 has a doglegged fork arm 81a extended from the vicinity of an end portion thereof toward joint surface 1b, in perpendicular to axis of slide rod 81. On the other hand, a lock pin 17a projects upward from a top end of control sleeve 17. Fork arm 81a is rotated by rotating slide rod 81 centering on its axis, as shown in
As shown in
On the other hand, in governor mechanism part C, a base end of governor link 82 is pivoted onto the top end of governor arm 29 in governor housing 3, and a tip of governor link 82 serves as a joint end portion 82a. Compared with above-mentioned governor link 27, governor link 82 is so short as to be almost entirely contained in governor housing 3.
On the occasion of assembling fuel injection pump DP′ of the configuration shown in
Then, on the occasion of attaching governor mechanism part C to both combined mechanism parts A and B, governor housing 3 is made to approach joint surface 1b of main body housing 1 so that joint end portion 81b of slide rod 81 projecting from slide rod receipt portion 1m of main body housing 1 is connected to joint end portion 81b, the tip of above-mentioned slide member 30 inserted in governor housing 3 is made to abut against the lower portion of governor arm 29, and then, governor housing 3 is fit and fixed to main body housing 1, thereby completing the governor.
In distributor-type pump DP (including DP′, so hereinafter) completed in this way, camshaft 4 is rotated synchronously with a crankshaft of an engine. By rotating cam 4b integrally with camshaft 4, fuel feed pump 6 actuates to feed fuel into fuel gallery 42 in pump head 2. Moreover, by rotating cam 4a integrally with camshaft 4, plunger 7 reciprocates through tappet 11 so as to charge fuel from fuel gallery 42 into later-discussed fuel-compression chamber 43 and discharge it to distributor shaft 9. By meshing of bevel gears 5 and 20, distributor shaft 9 is rotated synchronously to the rotation of camshaft 4. During this rotation, distributor shaft 9 distributes the fuel to plural delivery valves 18 one by one so as to make each delivery valve 18 deliver the fuel to each fuel injection valve in each engine cylinder.
As mentioned above, fuel injection pump DP is excellent in its ease of assembly as the whole, especially with respect to assembly of a governor having a complicated connection structure. Also, each parts (sub mechanical parts) A, B and C after disassembling is made to facilitate the assembly excellently. For example, lower mechanism part A has camshaft 4 which can be inserted into main body housing 1 while key 13 is previously provided thereon, or head mechanism part B is provided with slider guide 15 for guiding and supporting control slider 21 which has a configuration for preventing upper spring bracket 23 from falling out. Such excellence in assembly can contribute to automation most of all the processes for assembling fuel injection pump DP.
Description will now be given of a fuel course formed within head mechanism part B of fuel injection pump DP. Incidentally, the following description is given of the fuel course concerning the present invention, mainly of fuel gallery 42 and fuel-compression chamber 43 in plunger barrel 43. The description of the fuel course concerning distributor shaft 9, distributor barrel 10 and delivery valves 18 will be omitted because it may adopt the general structure.
As shown in
In pump head 2, fuel-supply oil passage 41 and fuel gallery 42 are bored so as to communicate with each other. Fuel gallery 42 is formed so as to surround plunger barrel 8 and always open for free passage to inhalation port 8a formed in plunger barrel 8. In addition, as shown in
Oppositely to inhalation port 8a through plunger 7, plunger barrel 8 is provided with a leak port 8b, which is diametrically smaller than inhalation port 8a. Further, a fuel escaping circuit is formed, which is extended from leak port 8b through an on-off valve Ta serving as a portion of a later-discussed timer T so as to reach either fuel gallery 42 (including annular groove 8d) or a fuel tank in the exterior of the fuel injection pump, so that the fuel flowing out from fuel-compression chamber 43 through leak port 8b is supplied again as fuel to be injected.
Some examples will be described about the structure of this fuel escaping circuit. Referring to
Referring to the fuel escaping circuit of
The fuel escaping circuit of
Description will now be given of the configuration of plunger 7, process of fuel injection by motion of plunger 7, and the control of fuel-injection time by opening and closing motion of on-off valve Ta of timer T concerning the process, in accordance with
As shown in
When plunger 7 reaches its bottom dead center, the head thereof is positioned below inhalation port 8a. At this time (the fuel-inhaling stroke), fuel in fuel gallery 42 flows into fuel compression chamber 43 through inhalation port 8a. While plunger 7 rises from the bottom dead center, the head periphery of plunger 7 comes to close inhalation port 8a (finalizing the fuel-inhaling stroke). On the other hand, fuel-compression chamber 43 is brought into communication with leak port 8b through sub lead 7b.
If on-off valve Ta is opening at this time as shown in
If plunger 7 further goes up, soon, the side surface of plunger 7 below sub lead 7b closes leak port 8b (finalizing the discharging delay stroke), and the discharge of fuel of the regulation amount is started (starting the fuel discharging stroke). Incidentally, since leak port 8b is diametrically smaller than inhalation port 8a so as to restrict the escape of fuel, the pressure of fuel discharged from fuel-compression chamber 43 rises to the regular value immediately after plunger 7 closes leak port 8b. By this discharge of the regular amount of fuel, high-pressured fuel injection from delivery valves 18 to the fuel injection valves is performed. This fuel-discharging stroke is ended when main lead 7a of plunger 7 comes to be open for free passage to inhalation port 8a. Then, plunger 7 reaches the top dead center.
If plunger 7 is actuated while on-off valve Ta is closed as shown in
Incidentally, even in the discharging-delay stroke, fuel under the regular amount is discharged from discharge port 8c, thereby performing low-pressured fuel injection in the engine cylinders. However, henceforth, “feeding” and “fuel injection” point out those of regularly pressurized fuel. For example, “fuel injection start time” shall be the injection start time of the fuel discharged from discharge port 8c under the regular pressure.
Thus, while the cam angle, which measures the stroke of plunger 7, is within the angle range leading to that corresponding to the top dead center, the fuel-discharging stroke of plunger 7 for performing fuel injection is started and ended. The starting period thereof can be advanced by opening of on-off valve Ta and delayed by closing thereof.
In addition, plunger 7 is rotated around its axis by the governor so as to adjust the timing when main port 7a comes to open to inhalation port 8a, i.e., the end time of fuel-discharging stroke, thereby adjusting the fuel injection period for determination of the amount of injected fuel. If the sectionally horizontal area of sub lead 7b (that is, a lead width w in the radial direction of plunger 7 shown in
Furthermore, the end time of the discharging delay distance which corresponds at the fuel injection start time becomes so late that the position of leak port 8b is made high, and sub lead 7b is made deep. Then, according to the embodiment of
Alternatively, the depth of bottom surface of sub lead 7b may vary as shown in
In
On the other hand, in
If leak port 7b of the form as shown in
In addition, it is considerable that both plungers 7 having respective sub leads 7b which incline oppositely to each other may be prepared so as to correspond to reversing of the spiral direction of main lead 7a or of the rotational direction of plunger 7 with the governor control. Moreover, it may be determined which plunger 7 is applied when it is decided which is suitable whether the discharging-delay stroke is lengthened or shortened (whether the amount of escaping fuel is increased or decreased) with the variation of the fuel-discharging stroke period (with the variation of the amount of injected fuel).
Description will be given of a fundamental structure of timer T in accordance with
Incidentally, in
A passageway 44 is formed in on-off valve Ta. One opening end of passageway 44 is open to the interior of valve chamber 45 subsequent to on-off valve Ta, and the other opening end is switched between the state where it is open to leak port 42 and the state where it is shut from leak port 42 according to the actuation of valve actuator Tb.
In short, on-off valve Ta is acceptable only if it can move in valve chamber 45 and be controlled in location so as to connect and disconnect primary leak port 8b and subsequent valve chamber 45 through passageway 44. Typical on-off valve Ta which is acceptable to later-discussed various embodiments of timer T shown in
If the pressing force of valve actuator Tb to on-off valve Ta is weak, on-off valve Ta is so located as to arrange annular port 44a thereof above leak port 8b because of the biasing force of biasing member Tc, as shown in
On the other hand, by increasing the pressing force of valve actuator Tb onto on-off valve Ta so as to slide on-off valve Ta downward against biasing member Tc, on-off valve Ta is so set as to make annular port 44a open to leak port 8b, i.e., on-off valve Ta is put into the valve-opening state.
If the purpose of reduction of NOx under exhaust gas and noise reduction at the time of an idling concerning diesel engines is considered, it is desirable that the cam angle leading to the top dead center is reduced as far as possible, that is, the fuel injection time is delayed if possible. However, at the time of engine start, rising of combustion efficiency for avoiding misfire in an engine cylinder of low-temperature is requested prior to the above-mentioned purpose. In this case, it is requested to advance the lead cam angle, that is, to make the fuel injection time early as far as possible. Moreover, after engine starting but before the engine sufficiently gets warm, delay of the fuel injection time causes white smoke or black smoke. Timer T is provided to correspond to both the requested times of fuel injection start which exchanges with change of the condition of engine operation.
In this regard, for a while from engine starting until the engine fully gets warm, on-off valve Ta is closed so that plunger 7 starts the fuel-discharging stroke simultaneously with the end of the fuel-inhaling stroke. On the other hand, after the engine fully gets warm, on-off valve Ta is opened so that, even if the fuel-inhaling stroke of plunger 7 ends, fuel in fuel-compression chamber 43 is leaked from leak port 7b for a while so as to delay the discharging stroke. Timer T has such structure.
Description will now be given of examples of timer T focusing on valve actuator Tb for controlling the vertical sliding of on-off valve Ta, i.e., for controlling opening-and-closing of on-off valve Ta. They are a first embodiment of
Incidentally, a fuel-escaping-circuit structure is common among the first to fourth embodiments. Valve chamber 45 is formed within pump head 2, and a fuel passage 2b from leak port 8b and a fuel passage 2c to annular groove 8d of plunger barrel 8 which is open to fuel gallery 42 are connected to valve chamber 45, thereby constituting the fuel escaping circuit. However, in each of the embodiments, the fuel escaping circuit including valve chamber 45 may be alternatively formed within plunger barrel 8 as shown in
The first embodiment illustrated by
In this structure, when the vertical length of spring 51 is natural length, annular port 44a of passageway 44 in valve element 50 is located above fuel passage 2b from leak port 8a so that fuel passage 2b is intercepted from valve chamber 45 by the side surface of valve element 50 (refer to
In timer T of
If pump head 2 gets warm, thermostat portion 52a is warmed in connection with it so that push rod 52 moves below so as to push down valve element 50. Soon, annular port 44a of valve element 50 comes to match with fuel passage 2b, thereby opening the fuel escaping circuit for free passage from leak port 8b to fuel gallery 42 (or the fuel tank).
Moreover, when pump head 2 gets cold and a temperature-sensing member (like wax) in thermostat portion 52a contracts, push rod 52b moves upward so that valve element 50 is slid upward by the biasing force of spring 51, thereby intercepting fuel passage 2b from valve chamber 45 by the side surface of valve element 50.
Valve actuator Tb of timer T shown in
When pump head 2 gets warm, shape-memory spring 53 is extended, and the lower end of valve element 50 arrives at the bottom of valve chamber 45, annular port 44a of valve element 50 matches with fuel passage 2b. When pump head 2 gets cold and shape-memory spring 53 contracts, valve element 50 is slid by spring 51 so as to make the side surface thereof close fuel passage 2b.
Therefore, in timer T as the first embodiment shown in
After engine starting, while pump head 2 gets warm, either the temperature-sensing member in thermostat portion 52a of timer T shown in
After a while after the engine starting, the engine and pump head 2 get warm sufficiently, the bottom of valve element 50 reaches the bottom of valve chamber 45, whereby valve element 50 becomes open so that plunger 7 starts discharging fuel at the late time in the cam angle range leading to the top dead center, thereby realizing the reduction of NOx under exhaust gas. Moreover, since the fuel injection period is delayed after the engine fully gets warm, reduction of white smoke is realized.
Although each of above-mentioned timers T of the first and second embodiments shown in
Lube in engine DE is introduced into fuel injection pump DP through a lube pipe 58. Although the lube introduced into fuel injection pump DP may be used lubriciously for a tappet portion and a bevel gear portion etc. However, in this embodiment, the lube must be introduced at least into a pilot oil chamber 45a in which a hydraulic piston 56 serving as valve actuator Tb is fit.
A pipe joint 57 for connecting lube pipe 58 is attached onto an outside end of main body housing 1. A pilot oil passage 1n is bored within main body housing 1 so as to be extended from pipe joint 57 and joined to pilot oil passage 45a which is also bored within main body housing 1.
Valve chamber 45 which is a sliding chamber of on-off valve Ta is formed within pump head 2 continuously coaxially to pilot oil chamber 45a and is diametrically as large as pilot oil chamber 45a. Hydraulic piston 56 serving as valve actuator Tb is slidably inserted in pilot oil chamber 45a. A valve element 55 serving as on-off valve Ta of this embodiment is slidably inserted in valve chamber 45 so that the bottom end of valve element 55 contacts the top end of hydraulic piston 56. The lube introduced in pilot oil chamber 45a from lube passage 1n is isolated from the fuel in valve chamber 45 (the inside of valve element 55) with hydraulic piston 56.
Passageway 44 of valve element 55 serves as that of valve element 50 plus one more annular port 44a. That is, a pair of annular ports 44a is formed in vertically parallel on the perimeter surface, and both annular ports 44a are open for free passage to each other through axial hole 44c etc. within valve element 55. Moreover, similarly to valve element 50, a recess 55a is formed so as to enclose spring 51 serving as biasing member Tc, and passageway 44 (especially, axial hole 44c thereof) is open for free passage to recess 55a.
In the third embodiment shown in
Spring 51 is infixed between the ceiling of valve chamber 45 and the bottom of recess 55a so as to bias valve element 55 downward.
Lube of engine DE is increased in its fluidity and pressure as engine DE gets warm. The time of a stop of engine DE, and after starting, for a while, the lubricous oil pressure of engine DE is low. At this time, since there is little volume of the lube which permeates into pilot oil chamber 45a below hydraulic piston 56, the force for make hydraulic piston 56 push valve element 55 upward does not work so that valve element 55 is located by the downward biasing force of spring 51 so as to place upper annular port 44a below fuel passage 2b and lower annular port 44a below fuel passage 2c. Therefore, at the end of fuel-inhaling stroke of plunger 7, the fuel in fuel-compression chamber 43 does not flow out of leak port 42, so that the fuel-discharging stroke starts immediately with the end of fuel-inhaling stroke. That is, fuel is injected at an early stage.
If engine gets warm, the lube in engine DE increased in fluidity is introduced into pilot oil chamber 45a through lube pipe 58 and lube passage 1n. The pressure of this lube makes hydraulic piston 56 slide upward, and valve element 55 slides upward with it. Soon, the top of valve element 55 comes to abut against the ceiling of valve chamber 45 so that upper annular port 44a is opened for free passage to leak port 8b through fuel passage 2b and lower annular port 44a is opened for free passage to fuel gallery 42 through fuel passage 2c. Therefore, for a while from the end of fuel-inhaling stroke of plunger 7, fuel in fuel-compression chamber 43 flows out from leak port 8b to fuel gallery 42, thereby delaying the fuel-discharging stroke for discharging fuel to delivery valves 18. That is, the fuel injection time is set up late.
Each of above-mentioned timers T of the first and second embodiments has opening-and-closing of on-off valve Ta controlled by use of the variation of the fuel injection pump accompanying an engine drive. Strictly, this control is not correctly correspondent to the temperature in the engine. Timer T of the third embodiment shown in
With respect to timer T of a fourth embodiment shown in
Therefore, annular port 44a serving as the upper one in
In this way, valve element 55 may be vertically reversed so as to be applicable to both the configuration where biasing member Tc is above valve actuator Tb as shown in
If electromagnetic solenoid 59 serving as valve actuator Tb is energized and excited, spool 59a is pulled up so that valve element 55 slides up by the upward biasing force of spring 51. If energization of electromagnetic solenoid 59 is cut, spool 59a is pushed out below so as to slide valve element 55 below.
In this embodiment, when electromagnetic solenoid 59 is excited, annular port 55a comes above fuel passage 2b so that the side surface of valve element 55 closes fuel passage 2b. By un-exciting electromagnetic solenoid 59, spool 59a is pushed out downward so as to make the lower end of valve element 55 reach the bottom of valve chamber 45, thereby opening annular port 44a to fuel passage 2b, and recess 55a to fuel passage 2c, whereby the open-valve state is established. However, alternatively, it is possible that on-off valve Ta is opened by exciting electromagnetic solenoid 59 and closed by un-exciting thereof by changing the port position of on-off valve Ta, the connection position of fuel passages 2b and 2c to valve chamber 45, or the length of valve chamber 45 or spool 59a.
The on-off operation of energization of electromagnetic solenoid 59 is automatically controlled on the base of temperature detection means, for example. Suppose that on-off valve Ta (valve element 55) is established so as to be closed by energizing (exciting) electromagnetic solenoid 59 and opened by un-energizing (un-exciting) it. When an engine is not warmed during lock ping or starting, electromagnetic solenoid 59 is energized based on that the temperature detection means detects the low temperature, thereby opening on-off valve Ta so as to advance the fuel injection time. If the engine gets warm and the temperature detection means detects temperature more than the fixed value, the energization of electromagnetic solenoid 59 is cut off so as to close on-off valve Ta, thereby delaying the fuel injection time.
Alternatively, instead of the temperature detection means, a certain energization period from a time of engine start may be set up so that when the period is passed, electromagnetic solenoid 59 is un-energized so as to open on-off valve Ta. What is necessary is to set up the length of the energization period so as to make it correspond for every engine.
Furthermore, valve actuator Tb constituted by electromagnetic solenoid 59 like this embodiment can control opening-and-closing of on-off valve Ta easily corresponding to various conditions of the same engine requiring different fuel injection start times as well as the temperature condition.
Moreover, electromagnetic solenoid 59 is attached from the exterior of pump head 2, thereby facilitating assembly thereof. It does not require a great change of the fuel injection pump structure, thereby enabling the on-off valve structure of the present invention to be realized easily.
The concrete embodiment of timer T is over. Description will now be given of some embodiments concerning flux-adjusting means for adjusting the amount of escaping fuel in accordance with
The fuel flux from leak port 8b to the fuel escaping circuit during the discharging-delay stroke is determined by the cross-sectional area of leak port 8b and other passages formed in the fuel injection pump. Moreover, there is a case where the optimal flux may change with difference of engine to be applied or another reason even in the same fuel injection pump. Furthermore, even if fuel injection pumps of the same scale are manufactured, variation of the flux may arise according to a processing error etc. Each of following flux adjusting mechanisms (flux adjusting valve devices V1, V2, V3 and V3′) according to embodiments shown in
According to the first embodiment of
In addition, one or both of valve chambers 45 and 47 may be formed within plunger barrel 8.
The portion of valve chamber 47 connected to fuel passage 2b is conic. A needle valve-like flux adjusting valve 72 is arranged coaxially to fuel passage 2b and inserted in valve chamber 47 so as to turn the tip thereof toward fuel passage 2b. The outside end of flux adjusting valve 72 projects outward from pump head 2 so as to be formed into a screw portion 72a, around which an adjusting nut 73 is screwed. Thus, flux adjusting valve device V1 is constituted. By rotational operation of adjusting nut 73, flux adjusting valve 72 is moved to or from fuel passage 2b so as to change the flux permission area of the junction of fuel passage 2b and valve chamber 47, thereby adjusting the amount of introductory fuel into valve chamber 47.
Thus, the fuel flux from leak port 8b to the fuel escaping circuit is adjusted so that the amount of escaping fuel during the discharging-delay stroke in a fuel injection pump can be adjusted corresponding to each engine, or that the amount of escaping fuel during the discharging-delay stroke can be unified even when there are process errors in the fuel passages like leak ports 8b among fuel injection pumps of the same scale.
In a second embodiment shown in
Referring to
The conic tip of flux adjusting valve 74 is turned coaxially toward leak port 8b. The tip of flux adjusting valve 74 which is biased to the most advancing position by spring 75 is located so as to plug the junction of valve chamber 47 and leak port 8b by rotational operation of adjusting nut 77, as shown in
If the pressure of fuel pushed out to leak port 8b from fuel-compression chamber 43 through sub lead 7b becomes more than the predetermined value, the fuel retreats flux adjusting valve 74 against the biasing force of spring 75 and introduced into valve chamber 47. If the opening degree of flux adjusting valve 74 is going to be reduced, adjusting nut 77 is rotated so as to increase the penetration degree of screw shaft 76 into pump head 2, thereby reducing the stroke of flux adjusting valve 74. In this way, by adjusting the opening degree of flux adjusting valve 74, the amount of fuel escaping from leak port 8b can be adjusted.
In addition, the fuel introduced in valve chamber 47 in this way may be returned to fuel gallery 42 or fuel tank FT. In this embodiment, as shown in
According to a third embodiment shown in
If a voltage is applied to electromagnetic solenoid portion 78, core 78a slides (leftward in
By the voltage control of electromagnetic solenoid portion 78, flux control valve device V3 is used for adjusting the amount of fuel escaping from leak port 8b so as to correct the performance error of the fuel injection pump. Also, it can be used for controlling the fuel injection time corresponding to the engine operational conditions. That is, similarly to timer T having valve actuator Tb serving as electromagnetic solenoid 59, at the time of engine starting, by applying a voltage to electromagnetic solenoid portion 78, the stroke of flux adjusting valve 74 is set to zero so as to hold the closing-valve state for preventing fuel from leaking from leak port 8b, thereby advancing the fuel injection time. If the engine gets warm, the voltage applied to electromagnetic solenoid portion 78 is reduced or set to zero so as to enable flux adjusting valve 74 to be opened by the fuel escaping from leak port 8b, thereby delaying the fuel injection time.
Moreover, the voltage may be controlled corresponding to the variation of actual engine speed so as to enable the amount of fuel escaping from the leak port to be adjusted in connection with the regulation of injected fuel by the governor. Especially, if the governor is an electronic governor, it can be controlled on base of engine speed and engine load factors serving as parameters of the electronic governor control.
Furthermore, electromagnetic solenoid portion 78 of a flux adjusting valve device V3′ shown in
Moreover, if it is applied to an electronic governor type fuel injection pump especially, the opening degree of flux adjusting valve 74 can be adjusted based on the electronic governor control. That is, the detected value of rotary speed or load of an engine, and the position value detected by position sensor 78c are input to a controller (for the electronic governor) which memorizes a control map indicating the relation of the optimal condition of the escaping fuel to the engine rotary speed or engine load. The detection values are compared with the map indicating the relation of the optimal condition of leaking fuel to the engine rotary speed or engine load, whereby the controller makes the electromagnetic solenoid slide so as to adjust the leak amount of fuel. On the contrary, based on the value detected by position sensor 78c, for example, when the detected value is an unusual value, it is also possible to control the governor so as to adjust the amount of injected fuel.
In this way, the relation value of effective stroke of plunger 7 to the amount of escaping fuel is rectified appropriately by tie up of the control of opening degree of flux adjusting optimizing the combustion condition of the engine. Thereby, engine durability can be improved while improving an engine performance.
Furthermore, description will be given of an embodiment of a train-type fuel injection pump P having a plurality of plungers 7 in a line as shown in
In pump body housing 90, fuel-compression chamber 43 is formed between each plunger 7 and each delivery valve 18. Each plunger barrel 8 is formed with inhalation port 8a and leak port 8b. Main lead 7a and sub lead 7b are formed in plunger 7, and the fuel escaping circuit is formed for letting fuel escape from each fuel-compression chamber 43 to fuel gallery 42 or fuel tank FT through sub lead 7b, leak port 8b and fuel adjusting valve chamber 47. In this embodiment, valve chamber 47 is formed between plunger barrel 8 and the interior of pump body housing 90. Sub port 8b is opened for free passage through valve chamber 47 to annular groove 8d of plunger barrel 8 which is open to fuel gallery 42. In
Hence, in a fuel injection pump having a plurality of plungers (e.g., a train-type fuel injection pump), by forming the fuel injection circuit having the flux adjusting valve for each plunger, the amount of fuel escaping from each plunger can be adjusted. Therefore, even if process errors of the plungers cause variation of passage area among the fuel escaping passages, the escape of fuel can be unified among plural plungers of one fuel injection pump, thereby unifying fuel injection characteristics among cylinders of an engine adopting the fuel injection pump. Other characteristics in control of fuel injection start time are as the above-description about distributor-type fuel injection pump DP.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP00/03426 | 5/26/2000 | WO | 00 | 11/25/2002 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO01/90569 | 11/29/2001 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2223755 | Dillstrom | Dec 1940 | A |
| 3739809 | Ulbing | Jun 1973 | A |
| 3857374 | Glikin et al. | Dec 1974 | A |
| 4211203 | Kobayashi | Jul 1980 | A |
| 4395987 | Kobayashi et al. | Aug 1983 | A |
| 4526150 | Guntert et al. | Jul 1985 | A |
| 4593668 | Yuzawa | Jun 1986 | A |
| 4625700 | Elsbett et al. | Dec 1986 | A |
| 4754737 | Ishida et al. | Jul 1988 | A |
| 4800861 | Oshizawa et al. | Jan 1989 | A |
| 4831988 | Hoefken et al. | May 1989 | A |
| 5086742 | Vogtmann | Feb 1992 | A |
| 5115783 | Nakamura et al. | May 1992 | A |
| 5273017 | Braun et al. | Dec 1993 | A |
| 5396871 | Faupel et al. | Mar 1995 | A |
| 5592915 | Ishiwata et al. | Jan 1997 | A |
| Number | Date | Country |
|---|---|---|
| 2314596 | Oct 1973 | DE |
| 0055245 | Jun 1982 | EP |
| 482680 | Apr 1938 | GB |
| 1 462 210 | Jan 1977 | GB |
| 48-14816 | Feb 1974 | JP |
| JU 50-61216 | Oct 1975 | JP |
| JU 51-21020 | Aug 1976 | JP |
| JU 55-156219 | Apr 1980 | JP |
| JU 58-27574 | Aug 1981 | JP |
| JU 59-68143 | May 1984 | JP |
| 04-066772 | Mar 1992 | JP |
| JU 04-32258 | Mar 1992 | JP |
| 06-050237 | Feb 1994 | JP |
| 10-030515 | Feb 1998 | JP |
| 10-196405 | Jul 1998 | JP |
