US3667431A

US3667431A - Engine temperature control system

Info

Publication number: US3667431A
Application number: US635A
Authority: US
Inventors: Don F Kueny; Howard M Pollari
Original assignee: Outboard Marine Corp
Current assignee: Outboard Marine Corp
Priority date: 1970-01-05
Filing date: 1970-01-05
Publication date: 1972-06-06
Anticipated expiration: 1989-06-06
Also published as: BE755473A; SE374167B; FR2074902A5; CA920009A; HK39176A; GB1289201A; DE2061762A1

Abstract

Disclosed herein is an internal combustion engine including a cooling system having a first coolant jacket portion for cooling the engine in the vicinity of the cylindrical portion of the cylinders and a second coolant jacket portion for cooling the engine in the vicinity of the cylinder heads. Flow of coolant from the first coolant jacket portion is selectively controlled by a restricted by-pass which leads to an overflow discharge, and by each of a thermostatic valve and a pressure responsive valve which are operable to afford coolant flow from the first coolant jacket portion to the second coolant jacket portion when the temperature or pressure in the first coolant jacket portion is above a predetermined value.

Description

United States Patent 51 3,667,43 1 Kueny et al. 1 1 June 6, 1972 s41 ENGINE TEMPERATURE CONTROL 3,105,472 10/1963 Jasper ..|23/41 .08

SYSTEM [72] Inventors:

[73] Assignee:

Filed:

Appl. No.:

US. Cl

Int. Cl

Don F. Kueny, Waukegan; Howard M. Pollari, Libertyville, both of I11.

Outboard Marine kegan, [11.

Jan. 5, 1970 Corporation, Wau- ..l23/4l.08, l23/41.72 ..F0lp 7/14, FOlp 7/16, F02f l/1O Field ofSearch ..l23/4l.72, 41.28, 41.82, 41.02,

References Cited UNITED STATES PATENTS Primary Examiner-Mark M. Newman Assistant Examiner-Cort Flint Attorney-Robert E. Clemency, Spencer B. Michael, Robert K. Gerling, John W. Michael, Gerrit D. Foster, Bayard H. Michael, Paul R. Puerner, Joseph A. Gemignani and Andrew 0. Riteris [5 7] ABSTRACT Disclosed herein is an internal combustion engine including a cooling system having a first coolant jacket portion for cooling the engine in the vicinity of the cylindrical portion of the cylinders and a second coolant jacket portion for cooling the engine in the vicinity of the cylinder heads. Flow of coolant from the first coolant jacket portion is selectively controlled by a restricted by-pass which leads to an overflow discharge, and by each of a thermostatic valve and a pressure responsive valve which are operable to afford coolant flow from the first coolant jacket portion to the second coolant jacket portion when the temperature or pressure in the first coolant jacket portion is above a predetermined value. 1

20 Claims, 6 Drawing Figures PATENTEDJUH 6 I972 SHEET 3 UP 3 a ONL We .3 KM .5

51 um, m. 14 Palm.

ATTORNEY) ENGINE TEMPERATURE CONTROL SYSTEM BACKGROUND OF THE INVENTION The invention relates generally to the cooling of internal combustion engines and, particularly to the cooling of twocycle marine engines. In the past, three general types of cooling systems have been employed. The first system includes simple engine cooling passages and a pump for delivering coolant through the passages. Such a system can be described as an uncontrolled system and, while this system prevented over heating of the engine, it generally resulted in the engine running cold under all conditions, i.e., under each of idle, midrange and full speed conditions.

The second type 'of system employed a thermostat in the cooling passages, adjacent to the discharge, for blocking flow through the passages until the coolant temperature reached a predetermined level. Such a system is sometimes referred to as a blocking system and, while the blocking system generally prevented over heating of the engine, the result was, at least after initial warm-up, that the engine was retained relatively warm during idle, mid-range, and full speed conditions.

The third system can be referred to as a recirculating system and was arranged to recirculate the coolant through the passages until the coolant was sufficiently warm and then to permit overflow and make-up in such amounts as to maintain the coolant temperature, at least after initial warming. The recirculating system prevented over heating but, like the blocking system, resulted in maintaining the engine relatively warm during idle, mid-range, and full speed conditions.

SUMMARY OF THE INVENTION The invention is directed at selectively cooling different areas ofthe engine under idle, mid-range and full speed conditions so as to obtain optimum performance. Ideally, it is preferred, under idle conditions, to have the areas of the engine around the cylindrical portion of the cylinders relatively warm and to have the areas of the engine around the cylinder heads at a higher temperature, i.e., to have these portions of the engine relatively hot, so as to assist in maintaining smooth operation while, at the same time, preventing spark plug fouling. Prevention of spark plug fouling is particularly advantageous in connection with two-cycle engines wherein the lubricant is mixed with the fuel.

Under mid-range conditions, it is desirable to maintain both the cylinder head and the cylindrical portion of the cylinders relatively warm, i.e., at a temperature less than hot, but elevated above ambient temperature. In order to obtain the highest possible performance under full speed conditions, it is preferable to run the engine with the cylinder head and with the cylindrical portion of the cylinders as cool as possible, i.e., as close to the temperature of the ambient water from which the cooling water is pumped.

The invention provides an internal combustion engine cooling system having first and second coolant jacket portions. The first coolant jacket portion is connected to a pump, while the second coolant jacket portion is connected to an overflow outlet for freely discharging coolant. The first and second coolant jacket portions are connected by means for selectively controlling coolant flow from the first and second coolant jacket portions. Such means can be in the form of a thermostatic valve for affording coolant flow from the first coolant jacket portion to the second coolant jacket portion when the coolant is above a predetermined temperature and for preventing coolantflow from the first coolant jacket portion to the second coolant jacket portion when the coolant temperature is below the predetermined temperature. In addition, such selective control means can include pressure responsive means in the form of a pressure valve connected between the first and second coolant jacket portions for affording coolant flow from the first coolant jacket portion to the second coolant jacket portion when the pressure in the first coolant jacket portion is above a predetermined value and for preventing coolant flow from the first coolant jacket portion to the second coolant jacket portion when the pressure in the mo lant in the first coolant jacket portion is below the predetermined value. In addition, the first coolant jacket portion is connected by a restricted by-pass to the overflow outlet to afford a restricted flow of coolant at all times.

Also in accordance with the invention, the first coolant jacket portion is arranged to primarily cool the areas of the engine around or in the vicinity of the cylindrical portion of the cylinders, while the second coolant jacket portion is primarily arranged to cool the engine areas around or in the vicinity of the cylinder heads in the area of the spark plugs. Thus, under idle or low speed operating condition, the engine areas around the cylindrical portion of the cylinders will be sufficiently cooled to maintain such areas relatively warm, while the cylinder head area is permitted to become relatively hot. This result is accomplished as the pressure in the first coolant jacket portion is too low to open the pressure valve because of the low engine speed and because the coolant temperature is too low due to the low engine speed to open the thermostatic valve. Therefore, the system provides a restricted flow of coolant from the pump to the engine area around the cylindrical portion of the cylinders and then through the by-pass to discharge.

Under initial mid-range operating condition, when the engine speed is greater than at idle, the quantity of heat to be removed from the engine will increase. Accordingly, the resulting increase in coolant temperature will open the thermostatic valve to afiord coolant flow to the second coolant jacket portion, thereby effectively causing transition of the cylinders heads from a relatively hot condition to a relatively warm condition. Also under initial mid-range operating conditions, the increase in engine speed is not sufficiently great to cause opening of the pressure valve. However, upon further increase in engine speed, the pressure developed in the coolant in the first coolant jacket portion will open the pressure valve affording substantially increased flow from the pump through the first coolant jacket portion and to the second coolant jacket ponion. Such increased coolant flow will cause reduction in the over-all temperature of the coolant, thereby closing the thermostatic valve and effectively reducing the operating temperature of the engine to a relatively cool level.

One of the objects of the invention is to provide a new and improved cooling system for an internal combustion engine and, particularly for a two-cycle outboard motor internal combustion engine.

Another object of the invention is the provision of an internal combustion engine having an engine cooling system which will assist in the production by the engine of optimum performance.

Other objects and advantages of the invention will become known by reference to the following description and accompanying drawings in which:

DRAWINGS FIG. 1 is a partially diagrammatic view of an outboard motor in accordance with the invention.

FIG. 2 is a diagrammatic view of the cooling system embodied in the outboard motor shown in FIG. 1.

FIG. 3 is an enlarged elevational view, partially broken away and in section along line 33 of FIG. 4, of the engine incorporated in the outboard motor shown in FIG. 1.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 3.

FIG. 6 is a sectional view taken along line 6-6 of FIG. 3.

GENERAL DESCRIPTION Shown in FIG. 1 is an outboard motor 11 embodying various of the features of the invention. The outboard motor 11 includes a power head 15 mounted on the top of a lower unit 19. The power head 15 includes an internal combustion engine 23 having one or more cylinders 27 each including a cylindrical portion 31 and a head portion 35 having mounted therein a spark plug 37. The power head also includes a crankshaft 39 which is connected to a drive shaft 43 in the lower unit 19. The drive shaft 43 is connected to and drives a water or coolant pump 47 which communicates through a suitable inlet 51 with the water from the lake or stream in which the boat mounted outboard motor 11 is operating. The pump 47 should be capable of providing an increasing volume of water at an increasing pressure upon an increase in engine speed. In the specifically disclosed construction, the pump 47 is of the conventional flexible vane type which is capable of at least partial performance as a positive displacement pump and which is also capable of providing an increasing volume of coolant water at increasing pressures upon increasing engine speed. As is shown, such flexible vane pumps include a plurality of flexible vanes 48 extending from a rotatably driven hub 49. The discharge from the pump is supplied through a conduit 55 to a water jacket 59 located in surrounding relation to the cylinders 27 and formed in accordance with the invention. While various arrangements are possible, in the particularly disclosed construction, the engine cooling water jacket 59 is divided into a first portion 63 which is primarily associated with cooling the engine 23 in the vicinity of the cylindrical portion 31 of the cylinders 27 and a second portion 67 which is primarily associated with cooling the engine 23 in the vicinity of the head portion 35 of the cylinders 27. In the specifically disclosed construction, the first and second

coolant jacket portions

63 and 67 are provided by fabricating the engine 23 to include a main casting or first engine block member 71 which defines the major part of the cylindrical portion 31 of each of the cylinders 27. Cast integrally into the main casting 71 in surrounding relation to each cylindrical portion 31 is a first or main section 75 of the first coolant jacket portion 63, which section 75 is in communication at the bottom thereof with the supply conduit 55 from the pump.

Detachably connected to the main casting 71, as by bolts or the like, is an intermediate or cylinder head casting or second engine block member 83 which defines the head portion 35 of each cylinder 27 and, along the surface which abuts the main casting 71, includes recesses or passages 87 which form another section of the first coolant jacket portion 63. As can be seen from FIG. 4, the waterpassages 87 have a common portion 89 at the top of the casting 83 and a common portion 'or well 91 at the bottom of the casting 83. It should also be noted that the part of the first coolant jacket portion 63 in the casting 83 is more in the nature of a passage or conduit than in the nature ofajacket for the cylinder heads 35.

Located between the main casting 71 andthe intermediate casting 83 is a gasket 96 which is aperatured at the top at 99, as shown in dotted outline in FIG. 4, so as to afford coolant flow from the main section 75 of the first coolant jacket portion 63 into the common portion 89 of the passages 87 in the intermediate casting 83 at a location remote from the supply conduit 55, ie, at the top of the engine block 71, and thereby insure flow generally throughout the main coolant jacket section 75.

Formed along the opposite surface of the intermediate casting See FIG. 5) and spaced from the passages 87 by a web 103 is an open recess or jacket 107 which, in part, forms the second coolant jacket portion 67 and which is of substantially greater extent than the section or part of the first coolant jacket portion 63 in the intermediate casing 83. As shown best in FIG. 5, the recess 107 is divided by a generally vertically extending wall or partition 109 into two parts 111 and 115 which communicate with each other at the top of the casting 83.

Fixed, as by the bolts 81 or the like, to the opposite side of the intermediate casting 83, i.e., the side remote from the main casting 71, is a cylinder head cover casting or third engine block member 123 which serves to complete the second water jacket 67. As will also be disclosed in greater detail, the intermediate casing 83 and the cover casting 123 cooperate with one another to provide a mounting for a pressure relief valve, still to be described. In this regard, the cover includes, at the bottom and at one side of the partition 109, a pocket 125 which communicates with the passage portion 1 11.

It should also be noted that the recess 107 covers a large portion of the head of the cylinder and provides an effective jacket for the cylinder heads.

The intermediate casting 83 further includes means for freely discharging coolant from the coolant jacket. In this regard, the intermediate casting includes, at the bottom, an overflow discharge passage or outlet or conduit 127 which, at one end, communicates with the portion of the second coolant jacket portion. The conduit 127 can communicate directly with the other portions of the outboard motor for discharging coolant so as to cool the exhaust pipe, if any, and to return the coolant to the lake or stream. However, in the specifically disclosed construction, the conduit 127 communicates through the gasket 95 with a conduit portion 129 in the main casting 71, which conduit portion 129, in turn, communicates with other portions of the outboard motor so as to cool the exhaust pipe and return the coolant to the lake or stream. Various arrangements can be employed for discharging coolant through an exhaust pipe and for conducting discharge coolant to the lake or stream, which arrangements are not a part of this invention.

In accordance with a preferred embodiment of the invention, coolant flow from the first coolant jacket portion 63 to the second coolant jacket portion 67 is selectively controlled by both thermostatic and pressure responsive means. More specifically in accordance with the invention, thermostatic valve means are provided for afiording coolant flow from the first coolant jacket portion 63 to the second coolant jacket portion 67 when the coolant is at a predetermined temperature above the ambient temperature of the water in the lake or stream and for preventing coolant flow from the first coolant jacket portion to the second coolant jacket portion when the coolant temperature is below the predetermined temperature. While various physical structures can be employed, in the disclosed construction, the bottom of the web 103 of the intermediate casting 83 between the first and second coolant jacket portions is apertured at 131 to receive a thermostatic valve 135 which can be of any conventional construction affording coolant flow when the temperature in the first coolant jacket portion 63 is above the predetermined temperature and for preventing such coolant flow when the temperature in the first coolant jacket portion 63 is below the predetermined temperature. For outboard motors, it is common for a thermostatic valve to begin to open when the coolant temperature reaches about F and to continue to open wider as may be required to attempt to prevent the coolant temperature from exceeding 140 F. Details of the construction of the thermostatic valve 135 and the means for securing the thermostatic valve to the intermediate casting web 103 are not a part of the invention. In operation, when the coolant temperature exceeds the predetermined temperature, for example, 140 F, the valve opens and permits flow from the first coolant jacket portion 63 to the second coolant jacket portion 67.

Also in accordance with the invention, the pressure responsive means comprises a pressure relief valve or arrangement including a second aperture or port 139 in the bottom part of the web 103 of the intermediate casting 83, together with a valve or valve member 141 which is received in the port 139, and a spring 145 which is principally housed in the pocket 125 in the cover casting 123 and which biases the valve member 141 against a seat 147 on the web 103. The spring 145 is preferably designed to permit initial opening of the valve when the engine speed is in the mid-range, for example, between about 2,000 RPM and 4,000 RPM. As is conventional, greater displacement of the valve member 141 from the seat 147 will afford greater coolant flow through the port 129. The details of the construction of the valve member, per se, or of its mounting, except as noted herein, are not a part of this invention.

In operation, when the pump 47 is driven by the engine 23 at relatively high mid-range engine speeds, the pressure developed by the pump 47 will cause opening of the valve member 141 to accommodate a substantial increase in flow from the first coolant jacket portion 63 to the second coolant jacket portion 67. Such substantially increased flow will result in much cooler coolant temperature and, if a thermostatic valve 135 is also employed, cause closure of such valve. Such closure and consequent restriction in flow will tend to increase the pressure and serve to effect greater opening of the pressure valve member 14].

Means in the form of a by-pass from the first coolant jacket portion 63 to the discharge conduit 127 are'provided for permitting a continuous but restricted flow from the first coolant jacket portion 63 whenever the pump is running. Preferably, the by-pass is dimensioned as, for instance, by use of a restriction 157 (See FIG. 2) to accommodate a water flow approximately equal to the flow generated by the pump at idling speed, i.e., for example, about 600 RPM. Various arrangements can be provided. In FIGS. 3, 4, and 5 there is shown a restricted by-pass or conduit 155 extending directly from the bottom of the first coolant jacket portion 63 to the discharge conduit 127. The by-pass can also alternatively comprise a conventional by-pass port (not shown) in the thermostatic valve 135 coupled with a restricted conduit leading from the bottom of the pocket 125 to the discharge conduit 127. The alternate construction has the advantage of assuring drainage of the part 1 11 of the jacket portion 67.

in operation under idle speed conditions, i.e., for example, under operation at speeds of about 600 RPM, the flow of coolant from the pump 47 travels through the first coolant jacket portion 63 and through the restricted by-pass 155 to the discharge conduit 127. Because of the relatively low engine speed and the consequent relative low rate of heat generation, the coolant or water passing through the first coolant jacket portion 63 is not sufficiently heated to open the thermostatic valve 135, although the heat generated is generally sufficient so that the cylindrical portion 31 of the cylinders 27 is relatively warm. Nor is the pressure developed by the pump 47 at the low idle speed sufficient to open the pressure relief valve member 141. Accordingly, there is no coolant flow through the second coolant jacket portion 67 and the cylinder head portion 35 of the cylinders 27 is relatively hot.

Upon increase in engine speed above idle, the additional heat generated by the increased operational speed of the engine 23 will heat the water flowing through the first coolant jacket portion 63 to above the predetermined temperature, for example, 140 F, with consequent opening of the thermostatic valve 135 so as to attempt to maintain the predetermined temperature, thereby permitting flow of coolant to the second coolant jacket portion 67. At least initially, the pressure developed by the pump 47 will be insufficient to open the pressure relief valve. Under these circumstances, the water flowing through the first coolant jacket portion 63 is at about the predetermined temperature and therefor the engine in the vicinity of the cylindrical portions 31 remains relatively warm. However, with respect to the cylinder heads 35, the gradually opening of the thermostatic valve 135 will permit gradually greater coolant flow to and through the second coolant jacket portion 67, thereby gradually cooling the cylinder heads 35 from a relatively hot condition to a relatively warm condition.

Depending upon the particular configuration of the engine 23, during the period when the engine speed is increased from about 2,000 RPM to about 4,000 RPM, the pump 47 will produce sufficient pressure, notwithstanding flow through the by-pass 155 and notwithstanding flow through the thermostatic valve 135, so as to unseat the pressure valve member 141. Upon unseating of the pressure valve member 141, the resulting increased flow will be substantially cooler than the operating temperature of the thermostatic valve 135, and accordingly the thermostatic valve 135 will close. Closing of the thermostatic valve 135 will tend to cause an increase in the flow through the port 139 and thereby tend to further reduce the coolant temperature. Consequently, relatively cool coolant will thereafter be applied to the first coolant jacket portion 63, as well as to the second coolant jacket portion 67, causing both the cylindrical portion 31 and the head portion 35 of the cylinders 27 to function at temperatures which are relatively cool as compared to the temperatures which occur during operation in the mid-range prior to opening of the pressure valve.

At high speed conditions, the pump 47 will supply a relatively large volume of water at a relatively high pressure to the first coolant jacket portion 67, thereby causing the pressure valve to remain open and effecting maintenance of the cylindrical portion 31 and the head portion 35 of the cylinders 27 at relatively cool temperatures. in addition, the temperature of the coolant will generally be sufiiciently low so as to retain the thennostatic valve in closed condition.

It should be noted that various of the features of the invention can be achieved when omitting either the thermostatic valve 135 or the relief valve. Specifically, if the relief valve is omitted, and only the thermostatic valve 135 and by-pass 155 are employed, at least some of the beneficial advantages of the invention can be achieved. Specifically, under such circumstances, the cylinder head portions 35 of the cylinders 27 will operate, in accordance with the invention, at relatively hot temperatures during idle conditions because the thermostatic valve 135 will remain closed and there will be no coolant supply to the second coolant jacket portion 67. Under midrange and high speed operations, the thermostatic valve 135 will generally be open in an attemptto maintain the coolant temperature at approximately F. Accordingly, both the cylindrical portions 31 and the heads 35 of the cylinders 27 will be kept in a relatively warm condition.

If the coolant jacket arrangement is employed without the thermostatic valve 135, but with the by-pass and the pressure relief valve, operation of the engine 23 at speeds below the mid-range will result in the development by the pump 47 of insufficient pressure to unseat the pressure valve member 141. Thus, in accordance with the invention at idle speeds the cylinder heads 35 will be relatively hot. When operating sufficiently above idle, the increased pressure generated by the pump 47 will cause the pressure valve member 141 to open and accordingly, the cylinder portions 31 and head portions 35 of the cylinders 29 will be exposed to substantial flows of relatively cool coolant. Thus, in accordance with the invention, the cylinders 27 will be relatively cool under high speed conditions. It should be noted that when the thermostatic valve 135 is not employed, the pressure setting for the pressure valve can be set relatively low by properly designing the spring 145, or otherwise, so as to afford opening of the pressure valve at speeds only slightly higher than idle.

Although this disclosure has generally employed plural terminology with respect to the cylinders, it is to be understood that the structure disclosed herein is applicable to a single cylinder engine,'as well as to a multi-cylinder engine.

It is also noted that the discharge conduit 127, the by-pass 155 and the supply conduit 55 are arranged to drain the engine of coolant when the engine 23 and therefor the pump 47 is not working. It is also noted that the arrangement of the aperture 99 in the top of the gasket 95 in the first coolant jacket portion 63 and the vertical extent of the portion 109 to adjacent the top of the second coolant jacket portion 67, together with the location of the supply conduit 55, the bypass 155, the discharge conduit, and the thermostatic and pressure valves at the bottom of the coolant jacket 59, cooperatively provide, in each

coolant jacket portion

63 and 67, for an inverted U-shaped flow path thereby assuring effective cooling throughout the engine 23.

While the construction disclosed in FIGS. 3 through 6 includes passages 87 which are located in the intermediate casting 83 and which form a part of the first coolant jacket portion 63, it is to be understood that the invention also contemplates termination of the first coolant jacket portion 63 in the main casting 71 with provisionfor receipt in the main casting 71 of the thermostatic valve 135 and pressure responsive valve 141 in position for communication with the second coolant jacket portion 67 defined in the intermediate casting 83 on the side of the web 103 opposite from the main casting 71. It is also to be understood that under such circumstances, a restricted bypass port could beemployed between the water jacket portion 63 in the main casting 71 and the discharge conduit 129. Undersuch circumstances, with the thermostatic valve 135 and the pressure relief valve 141 primarily located within the main casting 71, the function of the pocket 125 employed in the cover casting 123 could be incorporated in the intermediate casting 83 and a more or less fiat cover casting could be employed.

Another modification which comes readily to mind is the provision of an intermediate casting without any particular provision for water jackets and with the second coolant jacket portion being provided by a recess in the cover casting which is connected to the intermediate casting.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. An internal combustion engine including a cooling system comprising a coolant jacket having a first portion for cooling of a first part of said engine and a second portion for cooling of a second part of said engine, means for supplying coolant to said first coolant jacket portion, a discharge conduit connected to said second jacket portion for freely discharging coolant from said second coolant jacket portion, by-pass means for affording restricted coolant flow between said first coolant jacket portion and said discharge conduit, and thermostatic valve means connecting said first and second coolant jacket portions for affording coolant flow from said first coolant jacket portion to said second coolant jacket portion when said coolant is above a predetermined temperature and for preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when said coolant temperature is below said predetermined temperature.

2. An internal combustion engine in accordance with Claim 1 including one or more cylinders each having a cylindrical portion and head with a spark plug mounted therein and wherein said first engine part includes the area in the vicinity ofsaid cylindrical portion and wherein said second engine part includes the area in the vicinity of said head and said spark plug.

3. An engine in accordance with claim 1 wherein said predetermined temperature is about 140 F.

4. An internal combustion engine including a cooling system comprising a coolant jacket having a first portion for cooling of a first part of said engine and a second portion for cooling of a' second part of said engine, means for supplying coolant to said first coolant jacket portion, a discharge conduit connected to said second jacket portion for freely discharging coolant from said second coolant jacket portion, by-pass means for affording restricted coolant flow between said first coolant jacket portion and said discharge conduit, and pressure responsive valve means connected between said first and second coolant jacket portions for afiording coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is above a predetermined value and for preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is below said predetermined value.

5. An internal combustion engine in accordance with claim 4 including one or more cylinders each having a cylindrical portion and head with a spark plug mounted therein and wherein said first engine part includes the area in the vicinity of said cylindrical portion and wherein said second engine part includes the area in the vicinity of said head and said spark plug.

6. An internal combustion engine including a cooling system comprising a coolant jacket having a first portion for cooling of a first part of said engine and a second portion for cooling of a second part of said engine, pump means for supplying coolant to said first coolant jacket portion, means for freely discharging coolant from said second coolant jacket portion, by-pass means for afiording restricted coolant flow between said first coolant jacket portion and said means for freely discharging coolant, thermostatic valve means connecting said first and second coolant jacket portions for affording coolant flow from said first coolant jacket portion to said second coolant jacket portion when said coolant is above a predetermined temperature and for preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when said coolant temperature is below said predetermined temperature, and pressure responsive valve means connected between said first and second coolant jacket portions for affording coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is above a predetermined value and for preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is below said predetermined value.

7. An engine in accordance with claim 6 wherein said predetermined temperature is about F.

8. An internal combustion engine in accordance with claim 6 wherein said pump means for supplying coolant and said bypass is connected to the bottom of said first coolant jacket portion and wherein said means for freely discharging coolant is connected to the bottom of said second coolant jacket portion.

9. An internal combustion engine in accordance with claim 6 wherein said thermostatic valve means is located at the bottom of said first coolant jacket portion.

10. An internal combustion engine in accordance with claim 6 wherein said pressure responsive valve means is located adjacent to the bottom of said first coolant jacket portion. I

11. An engine in accordance with claim 6 wherein said bypass means is dimensioned so as to accommodate a maximum flow approximately equal to the quantity of coolant supplied by said pump under engine idle speed operation.

12. An engine in accordance with claim 6 wherein said pump includes a plurality of flexible vanes mounted on a rotating hub.

, 13. An internal combustion engine comprising a first engine block member including wall means at least partially defining a first coolant jacket portion connected to a source of coolant, a second engine block member connected to said first engine block member, a third engine block member connected to said second engine block member, said second and third engine block members including wall means defining a second coolant jacket portion, a passage connected to said second coolant jacket portion for discharging coolant from said second coolant jacket portion, means connected between said first and second coolant jacket portions for selectively controlling coolant flow from said first coolant jacket portion to said second coolant jacket portion, and means connected between said first coolant jacket portion and said discharging passage for by-passing a restricted amount of coolant around said second coolant jacket portion and said coolant flow control means from said first coolant jacket portion to said coolant discharging passage.

14. An internal combustion engine comprising a first engine block member including wall means defining a cylindrical cylinder portion and at least partially defining a first coolant jacket portion extending in heat exchanging relation to said cylindrical cylinder portion and connected to a source of coolant, a second engine block member connected to said first engine block member and including wall means defining a cylinder head portion aligned with said cylindrical cylinder portion, a third engine block' member connected to said second engine block member, said second and third engine block members including wall means defining a second coolant jacket portion extending in heat exchanging relation to said cylinder head portion, a passage connected to said second coolant jacket portion for discharging coolant from said second coolant jacket portion, means connected between said first and second coolant jacket portions for selectively controlling coolant flow from said first coolant jacket portion to said second coolant jacket portion, and means connected between said first coolant jacket portion and said discharging passage for by-passing a restricted amount of coolant around said second coolant jacket portion and said coolant flow control means from said first coolant jacket portion to said coolant discharging passage.

15. An engine in accordance with claim 14 wherein said means for selectively controlling coolant flow comprises a thermostatic valve means connecting said first and second coolant jacket portions for affording coolant flow from said first coolant jacket portion to said second coolant jacket portion when said coolant is above a predetermined temperature and for preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when said coolent temperature is below said predetermined temperature.

16. An engine in accordance with claim 15 wherein said predetermined temperature is about 140 F.

17. An engine in accordance with claim 14 wherein said means for selectively controlling coolant flow comprises a pressure responsive valve means connected between said first and second coolant jacket portions for affording coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is above a predetermined value and for preventing coolantflow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is below said predetermined value.

18. An engine in accordance with claim 17 and further including an engine driven pump for supplying coolant to said first coolant jacket portion from the source, and wherein said by-passing means and said pressure responsive valve means are dimensioned so that, under engine idle speed operation, said by-passing means will accommodate the coolant flow supplied by said pump and said pressure responsive valve means will remain closed and so that at speeds above engine idle speed, said by-passing means will accommodate flow of only a portion of the coolant supplied by said pump and said pressure responsive valve means will open to accommodate the flow of the remainder of the coolant supplied by said pump.

19. An internal combustion engine comprising a first member including wall means at least partially defining a first coolant jacket portion connected to a source of coolant, a second member connected to said first member, a third member connected to said second member, said second and third members including wall means defining a second coolant jacket portion, a passage for discharging coolant from said second coolant jacket portion, means for by-passing a restricted amount of coolant from said first coolant jacket portion to said coolant discharging passage, temperature responsive valve means for controlling coolant flow from said first coolant jacket portion to said second coolant jacket portion, said thermostatic valve means affording coolant flow from said first coolant jacket portion to said second coolant jacket portion when said coolant is above a predetermined temperature and preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when said coolant temperature is below said predetermined temperature, and pressure responsive valve means for controlling coolant flow from said first coolant jacket portion to said second coolant jacket portion, said pressure responsive valve means affording coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is above a predetermined value and for preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is below said predetermined value.

20. An internal combustion engine in accordance with claim 19 wherein said temperature responsive valve means and said pressure res onsive valve means are designed relative to each other and re ative to said first coolant acket portion such that, upon a first increase in engine speed above idle speed, said thermostatic valve means opens, and upon a further increase in engine speed, said pressure responsive valve opensv

Claims

2. An internal combustion engine in accordance with Claim 1 including one or more cylinders each having a cylindrical portion and head with a spark plug mounted therein and wherein said first engine part includes the area in the vicinity of said cylindrical portion and wherein said second engine part includes the area in the vicinity of said head and said spark plug.

3. An engine in accordance with claim 1 wherein said predetermined temperature is about 140* F.

4. An internal combustion engine including a cooling system comprising a coolant jacket having a first portion for cooling of a first part of said engine and a second portion for cooling of a second part of said engine, means for supplying coolant to said first coolant jacket portion, a discharge conduit connected to said second jacket portion for freely discharging coolant from said second coolant jacket portion, by-pass means for affording restricted coolant flow between said first coolant jacket portion and said discharge conduit, and pressure responsive valve means connected between said first and second coolant jacket portions for affording coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is above a predetermined value and for preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is below said predetermined value.

6. An internal combustion engine including a cooling system comprising a coolant jacket having a first portion for cooling of a first part of said engine and a second portion for cooling of a second part of said engine, pump means for supplying coolant to said first coolant jacket portion, means for freely discharging coolant from said second coolant jacket portion, by-pass means for affording restricted coolant flow between said first coolant jacket portion and said means for freely discharging coolant, thermostatic valve means connecting said first and second coolant jacket portions for affording coolant flow from said first coolant jacket portion to said second coolant jacket portion when said coolant is above a predetermined temperature and for preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when said coolant temperature is below said predetermined temperature, and pressure responsive valve means connected between said first and second coolant jacket portions for affording coolant flow from said first coolant jacket portIon to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is above a predetermined value and for preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is below said predetermined value.

7. An engine in accordance with claim 6 wherein said predetermined temperature is about 140* F.

8. An internal combustion engine in accordance with claim 6 wherein said pump means for supplying coolant and said by-pass is connected to the bottom of said first coolant jacket portion and wherein said means for freely discharging coolant is connected to the bottom of said second coolant jacket portion.

10. An internal combustion engine in accordance with claim 6 wherein said pressure responsive valve means is located adjacent to the bottom of said first coolant jacket portion.

11. An engine in accordance with claim 6 wherein said by-pass means is dimensioned so as to accommodate a maximum flow approximately equal to the quantity of coolant supplied by said pump under engine idle speed operation.

13. An internal combustion engine comprising a first engine block member including wall means at least partially defining a first coolant jacket portion connected to a source of coolant, a second engine block member connected to said first engine block member, a third engine block member connected to said second engine block member, said second and third engine block members including wall means defining a second coolant jacket portion, a passage connected to said second coolant jacket portion for discharging coolant from said second coolant jacket portion, means connected between said first and second coolant jacket portions for selectively controlling coolant flow from said first coolant jacket portion to said second coolant jacket portion, and means connected between said first coolant jacket portion and said discharging passage for by-passing a restricted amount of coolant around said second coolant jacket portion and said coolant flow control means from said first coolant jacket portion to said coolant discharging passage.

14. An internal combustion engine comprising a first engine block member including wall means defining a cylindrical cylinder portion and at least partially defining a first coolant jacket portion extending in heat exchanging relation to said cylindrical cylinder portion and connected to a source of coolant, a second engine block member connected to said first engine block member and including wall means defining a cylinder head portion aligned with said cylindrical cylinder portion, a third engine block member connected to said second engine block member, said second and third engine block members including wall means defining a second coolant jacket portion extending in heat exchanging relation to said cylinder head portion, a passage connected to said second coolant jacket portion for discharging coolant from said second coolant jacket portion, means connected between said first and second coolant jacket portions for selectively controlling coolant flow from said first coolant jacket portion to said second coolant jacket portion, and means connected between said first coolant jacket portion and said discharging passage for by-passing a restricted amount of coolant around said second coolant jacket portion and said coolant flow control means from said first coolant jacket portion to said coolant discharging passage.

16. An engine in accordance with claim 15 wherein said predetermined temperature is about 140* F.

17. An engine in accordance with claim 14 wherein said means for selectively controlling coolant flow comprises a pressure responsive valve means connected between said first and second coolant jacket portions for affording coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is above a predetermined value and for preventing coolant flow from said first coolant jacket portion to said second coolant jacket portion when the pressure in the coolant in said first coolant jacket portion is below said predetermined value.

20. An internal combustion engine in accordance with claim 19 wherein said temperature responsive valve means and said pressure responsive valve means are designed relative to each other and relative to said first coolant jacket portion such that, upon a first increase in engine speed above idle speed, said thermostatic valve means opens, and upon a further increase in engine speed, said pressure responsive valve opens.