U.S. patent application number 10/438389 was filed with the patent office on 2004-11-18 for oil pressure control valve by sliding camshaft for an internal combustion engine.
Invention is credited to Burger, Wolf, Kasperbauer, Reinhard, Schempp, Jan, Wizgall, Eberhard.
Application Number | 20040226532 10/438389 |
Document ID | / |
Family ID | 33159458 |
Filed Date | 2004-11-18 |
United States Patent
Application |
20040226532 |
Kind Code |
A1 |
Burger, Wolf ; et
al. |
November 18, 2004 |
OIL PRESSURE CONTROL VALVE BY SLIDING CAMSHAFT FOR AN INTERNAL
COMBUSTION ENGINE
Abstract
The invention pertains to an internal combustion engine with a
crankcase, a crankshaft and a camshaft for controlling at least one
intake and exhaust valve, as well as an oil pump for delivering
lubricating oil to the crankshaft. Downstream on the outlet side of
the oil pump is an oil pressure regulating valve for limiting the
oil pressure. The valve gate, which is contacted by a spring
element in the closing direction, depending on the amount of oil
delivered and/or the oil temperature, the valve gate frees an
opening that can be connected with the inlet side of the oil pump.
It is suggested that the camshaft be seated in longitudinally
displaceable fashion within the crankcase and form the valve gate
of the oil pressure control valve. An oil pressure-limiting valve
for an internal combustion engine is thus implemented in a simple
way.
Inventors: |
Burger, Wolf; (Boeblingen,
DE) ; Wizgall, Eberhard; (Illingen, DE) ;
Schempp, Jan; (Sinzing, DE) ; Kasperbauer,
Reinhard; (Marbach, DE) |
Correspondence
Address: |
WEGMAN, HESSLER & VANDERBURG
6055 ROCKSIDE WOODS BOULEVARD
SUITE 200
CLEVELAND
OH
44131
US
|
Family ID: |
33159458 |
Appl. No.: |
10/438389 |
Filed: |
May 15, 2003 |
Current U.S.
Class: |
123/196R ;
184/6.5 |
Current CPC
Class: |
F01M 1/16 20130101 |
Class at
Publication: |
123/196.00R ;
184/006.5 |
International
Class: |
F01M 001/04 |
Claims
I/We claim:
1. An internal combustion engine comprising: a crankcase; a
crankshaft; a camshaft for controlling at least one intake and
exhaust valve; an oil pump for delivering lubricating oil to the
crankcase; an oil pressure regulating valve located on the outlet
side of the oil pump for limiting the oil pressure a valve gate
contacted by a spring element in the closing direction; wherein the
valve gate frees an opening that can be connected with the inlet
side of the oil pump depending on the amount of oil delivered
and/or the oil temperature; and, wherein the camshaft is seated in
longitudinally displaceable fashion within the crankcase and forms
the valve gate of the oil pressure control valve.
2. The internal combustion engine of claim 1, wherein the oil pump
is a rotor pump further comprising: an inner rotor arranged on the
camshaft an outer rotor seated in a recess of the crankcase wherein
the oil pump is sealed on the face by a spring-loaded sealing
washer.
3. The internal combustion engine of claim 2, wherein the spring
element is fixed between a bearing seat for a shaft journal of the
camshaft and a limit stop provided on the camshaft.
4. The internal combustion engine of claim 3, wherein the limit
stop is formed by a cam of the camshaft.
5. The internal combustion engine of claim 4, wherein the sealing
washer is slipped on the inner rotor of the oil pump and lies
against a gearwheel arranged on the camshaft.
6. The internal combustion engine of claim 5, wherein the inner
rotor of the oil pump is joined with the gearwheel as one piece.
Description
I. BACKGROUND OF THE INVENTION
[0001] A. Field of Invention
[0002] The invention pertains to internal combustion engines and
more specifically to a device and methods for limiting the oil
pressure generated by an oil pump.
[0003] B. Description of the Related Art
[0004] Use of oil pumps with a pressure control valve has long been
commonly known in the art in internal combustion engines (see DE 12
41 191 A1). For this purpose, provided in the pressure line is a
pressure control valve with a spring-loaded valve gate, which, at a
predefined oil pressure, creates an opening or a connection to the
inlet side of the pump.
[0005] Also commonly known in the art (see DE 85 17 900 U1) is the
arranging of elements of an oil pump for an internal combustion
engine on the camshaft that controls the intake and/or exhaust
valves.
II. Summary of the Invention
[0006] The purpose of the present invention is, specifically in the
case of an internal combustion engine that is designed as a small
engine, in a simple way to limit the oil pressure generated by the
oil pump, whereby few additional components as possible are
required for the implementation of the oil pressure valve.
[0007] The solution of the present invention is achieved through
the features which will be described below. The internal combustion
engine with the oil pressure limiting valve according to the
invention is distinguished by a simple design in which a gradual
shutoff flow from the oil pump back into the crankcase is possible
in a reliable way by means of the camshaft, which is axially
displaceable within the crankcase.
[0008] Additional advantageous developments and improvements of the
internal combustion engine according to the invention are in the
subclaims.
[0009] The oil pressure limiting function is achieved in a simple
way, in that one face of the oil pump, which is designed as a rotor
pump, is sealed off by a spring-loaded sealing washer, which, at a
predefined oil pressure generated by the oil pump, opens a defined
leakage gap, through which a flow of oil can flow back to the inlet
side of the oil pump in order to limit the maximum oil
pressure.
[0010] Provided between a bearing seat for a bearing journal of the
camshaft and a limit stop provided on the camshaft is a spring
element that presses the sealing washer against the face of the
rotor pump. The side area of one of the cams that controls the
intake or exhaust valve can advantageously be provided as the limit
stop for the spring element.
[0011] The sealing washer for the oil pump is advantageously
slipped onto the inner rotor, and lies against a driving gearwheel
arranged on the camshaft.
[0012] The device itself is made up of few components; for example,
the inner rotor of the oil pump is joined with the driving
gearwheel for the camshaft as one piece.
[0013] An embodiment of the invention is explained in more detail
in the following description and drawings.
III. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention may take physical form in certain parts and
arrangement of parts, a preferred embodiment of which will be
described in detail in this specification and illustrated in the
accompanying drawings which form a part hereof and wherein:
[0015] FIG. 1 shows a crankcase of a single-cylinder internal
combustion engine.
[0016] FIG. 2 shows a section along the line II-II of FIG. 1.
[0017] FIG. 3 shows a top view of the crankcase.
[0018] FIG. 4 shows a section along the line IV-IV of FIG. 3.
[0019] FIG. 5 shows an interior view of a crankcase half.
[0020] FIG. 6 shows a longitudinal section through a crankcase half
in the region of the oil pump.
IV. DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Referring now to the drawings wherein the showings are for
purposes of illustrating a preferred embodiment of the invention
only and not for purposes of limiting the same, FIGS. 1 and 2 show
a crankcase of an internal combustion engine designed as a
four-stroke single-cylinder engine and is comprised of two
crankcase halves that are designated in the following as crankcase
lower part 2 and crankcase upper part 4. Also visible on the
crankcase upper part 4 is a cylinder flange 5 to which the engine's
cylinder (not shown) is fastened. Arranged in the crankcase, which
is provided with a diagonal dividing plane 6, is a crankshaft 8
that is carried on two shaft journals 10 and 12 inside the
crankcase (cf. main bearings 14 and 16). The installed position of
the engine depends on the application. In regards to a vertical
arrangement of the crankshaft 8 as shown in FIG. 1 and 2, the
engine can be used in a lawnmower (not shown). For that
application, a cutting blade (not shown) can be mounted on the
lower shaft end 17 and a fanwheel (not shown) for cooling the
engine can be mounted at the upper shaft end 19.
[0022] In addition, attached to the crankshaft 8 are two weights 18
and 20 for balancing the inertial forces, between which is located
the crankshaft journal 22 for the connecting rod (not shown). Also,
attached to the crankshaft 8 is a gearwheel 24 that actuates the
camshaft 26 that is arranged parallel to the crankshaft 8. Provided
for that purpose on the camshaft 26 is a driven gearwheel 28 that
engages in intermeshing fashion with the gearwheel 24 via helical
gearing. Arranged on the camshaft 26 are two cams 26a and 26b that
serve to control intake and exhaust valves (not shown) that are
arranged in the cylinder head, whereby the transmission of power
takes place via suitable pushrods (not shown) and rocker arms (not
shown).
[0023] The driven gearwheel 28 is formed of plastic and is slipped
onto the camshaft 26 that is formed as a steel tube and is fixed in
place axially by means of a limit stop 30 that is joined with the
camshaft 26 as one piece. In addition, provided on the camshaft 26
is an externally toothed inner rotor 32, which is joined with the
driven gearwheel 28 as one piece and which, together with an
internally toothed outer rotor 34, forms an oil pump 36 for
supplying the engine's lubricating oil. In that regard, the outer
rotor 34 is seated in rotating fashion in an opening 38 in the
lower part 2 of the crankcase. The oil pump is designed as a
generally known positive-displacement pump in which the inner rotor
32 has one less tooth than the outer rotor 34.
[0024] Referring to FIG. 5, joining into an opening 38 on the face
is an intake channel 40 that is formed in a kidney shape at the
mouth of the opening 38. The suction channel 40 leads to an oil
suction location 44, which is provided with an oil screen 42 and
through which the oil, as will be described in more detail later,
is withdrawn for lubricating the consumers from an oil sump that
forms in the lower half of the crankcase 2. In addition, provided
in the opening 38 is a pressure oil channel 46, which is also
formed in a kidney shape in the region of the mouth to the opening
38.
[0025] Referring to FIGS. 2 and 4-6, the pressure oil channel 46
leads through a feed section 46a to an oil filter 48, and from
there through a return section 46b through a bore hole 50 provided
in the camshaft 26 to the main bearing 14 provided in the upper
part 4 of the crankcase, while an additional bore hole 52 provided
in the lower half 2 of the crankcase that leads to main bearing 16.
The camshaft 26 is carried by its two shaft journals 54 and 56 in
two openings 58 and 60, which are formed as bearings in the
crankcase lower and upper parts 2, 4, in such a way that it can be
displaced axially by an amount x. In addition provided on the
camshaft 26 is a spring assembly 62 that is fixed between a face of
the cam 26a and crankcase wall surrounding the opening 60. In this
regard, the spring assembly 62 is comprised of individual disk
elements between which spring washers are arranged. Arranged on the
inner rotor 32 of the oil pump 36 is a sealing washer 64, which on
one side lies in sealing fashion against the face of the gearwheel
28, and on the other side against the crankcase lower part 2
housing wall that surrounds the opening 38, axially sealing the oil
pump 36.
[0026] During operation, the engine draws oil through the oil pump
36, driven by the camshaft 26, from the oil sump that forms in the
crankcase lower part 2, through the suction channel 40, and
delivers it through the feed segment 46a of the pressure channel 46
to the oil filter 48, and from there through the return line 46b,
on the one hand through the hollow bored camshaft 26 to the main
bearing 14, and on the other, through the bore hole 52 to the main
bearing 16 of the crankshaft 8. Among other things, the lubricating
oil supply to the main bearings of the crankshaft 8 is thus
assured.
[0027] If under certain operating conditions (among others, in
dependency on oil temperature and engine rpm) the oil pressure
forming in the individual chambers of the oil pump 36 becomes
excessive, the camshaft 26 is displaced axially in the direction
shown in FIG. 2 by the dotted arrow against the spring force of the
spring assembly 62. When this occurs, forming between the sealing
washer 64 and the housing wall against which the sealing washer 64
normally lies is a leakage gap through which the oil leakage flow
66 flows back into the oil sump of the lower part 2 of the
crankcase to limit the maximum oil pressure.
[0028] The preferred embodiments have been described, hereinabove.
It will be apparent to those skilled in the art that the above
methods may incorporate changes and modifications without departing
from the general scope of this invention. It is intended to include
all such modifications and alterations in so far as they come
within the scope of the appended claims or the equivalents
thereof.
[0029] Having thus described the invention, it is now claimed:
* * * * *