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2016 | Book | 2. edition

Vehicular Engine Design

Authors: Kevin Hoag, Brian Dondlinger

Publisher: Springer Vienna

Book Series : Powertrain

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About this book

This book provides an introduction to the design and mechanical development of reciprocating piston engines for vehicular applications. Beginning from the determination of required displacement and performance, coverage moves into engine configuration and architecture. Critical layout dimensions and design trade-offs are then presented for pistons, crankshafts, engine blocks, camshafts, valves, and manifolds. Coverage continues with material strength and casting process selection for the cylinder block and cylinder heads. Each major engine component and sub-system is then taken up in turn, from lubrication system, to cooling system, to intake and exhaust systems, to NVH. For this second edition latest findings and design practices are included, with the addition of over sixty new pictures and many new equations.

Table of Contents

Frontmatter
1. The Internal Combustion Engine—An Introduction
Abstract
It is appropriate to begin with a simple definition of the engine as a device for converting energy into useful work. The goal of any engine is to convert energy from some other form into “mechanical force and motion.” The terms “mechanical force” and “motion” are chosen to convey the idea that the interest may be both in work output—how much force can be applied to move something a given distance—and also power output—how quickly the work can be done.
Kevin Hoag, Brian Dondlinger
2. Engine Maps, Customers and Markets
Abstract
In Chap. 1 the relationship between work, power, and engine speed was defined. It is this combination of work, power, and speed that is critical to an engine’s performance, the way it responds to changing demands, the way it “feels” to the driver. This subject will now be taken up in further detail. The work measured at the crankshaft of an engine is referred to as the brake work. The product of the brake work and engine speed (with the appropriate unit conversions) is the brake power. These terms reflect the history of engine testing, since early dynamometers typically consisted of friction brakes clamped around a spinning disk bolted to the engine’s crankshaft. While dynamometers have changed a great deal the fundamental principles remain the same.
Kevin Hoag, Brian Dondlinger
3. Engine Validation and Reliability
Abstract
An integral part of the engine design process is that of ensuring that the product has sufficient reliability and durability. As used in this book durability refers to the useful life of the engine. For the engine system this is the average life-to-overhaul. For most of the major engine components it includes an expectation of reuse when the engine is overhauled. Reliability includes also infant mortality and the unforeseen problems that require attention over the engine’s operational life. Engine design and development must include validation processes to ensure that the durability and reliability expectations are met. The success of this endeavor is crucial to the success of any engine design.
Kevin Hoag, Brian Dondlinger
4. The Engine Development Process
Abstract
The intent of this chapter is to provide an overview of the processes involved in developing a new engine from the initial need identification to production release. A flowchart of the processes has been developed by AVL List GmbH, and is presented in the Figure. For ease of reference, the paragraph headings in this chapter correspond to encircled numbers in the figure.
Kevin Hoag, Brian Dondlinger
5. Determining Displacement
Abstract
Once a market need has been identified the first step in designing a new engine is to determine its required displacement. In this context the engine should be viewed as a positive displacement air pump. In order to produce the required work one must burn sufficient fuel. In order to completely react the fuel to products one must supply sufficient air. Determining the displacement required for a given engine is thus a matter of working backwards from the desired work output (or power at a given shaft speed), as further depicted in Fig. 5.1. Each of the steps in this process will now be covered in greater detail.
Kevin Hoag, Brian Dondlinger
6. Engine Configuration and Balance
Abstract
Once the fuel type, engine operating cycle, total displacement, and supercharging decisions have been made for a new engine, the next tasks will be to decide upon the number of cylinders over which the displacement will be divided, and the orientation of the cylinders. The factors that must be considered include cost and complexity, reciprocating mass and required engine speed, surface-to-volume ratio, pumping losses, packaging, and the balancing of mechanical forces. The majority of this chapter will address the mechanical forces and engine balancing as this is a key factor explaining why particular numbers and orientations of cylinders are repeatedly chosen.
Kevin Hoag, Brian Dondlinger
7. Cylinder Block and Head Materials and Manufacturing
Abstract
Before addressing cylinder block and head layout design it is important to understand the restrictions imposed by material and casting process selection. This chapter begins with a brief look at the aluminum and gray iron alloys typically used for cylinder blocks and heads. Magnesium alloys, and composite blocks with magnesium portions are receiving increased attention for weight reduction, and will also be briefly covered. Many of the design constraints are imposed by the capabilities of the chosen casting process, so the commonly used casting processes will next be introduced. The chapter concludes with an overview of the machining lines used for block and head production.
Kevin Hoag, Brian Dondlinger
8. Cylinder Block Layout and Design Decisions
Abstract
In Chap. 5 the required engine displacement was calculated, and in Chap. 6 the number of cylinders, cylinder layout, and bore-to-stroke ratio were determined. These earlier decisions form the starting point for the discussion of this chapter. It is in this chapter more than any other that it will be necessary to limit the discussion to designs specific to automotive applications. Over the entire range of reciprocating piston internal combustion engines there is an extremely wide range of cylinder configurations and block layout and construction techniques. By limiting the discussion to automobile engines and heavy-duty engines in mobile installations, primary attention will be placed on in-line four, five and six cylinder engines, and vee six, eight, ten, and twelve cylinder engines. Casting the net a bit wider allows discussion of horizontally opposed four, six, and eight cylinder engines, and mention of the recently revived ‘W-8’ and ‘W-12’. The cylinder block is the foundation of the engine, and supports the piston, cranktrain, cylinder head, and sometimes the valvetrain. It also houses the lubrication and cooling systems. It provides mounting points for the charging system, starting system, power take off (PTO), and typically has mounts which support the entire powertrain. The engine may be rigidly mounted as a structural member of the chassis, such as in a racecar or motorcycle. The cylinder block supports a variety of static, dynamic, and thermal loads, and must provide stiffness and alignment for many components. Because of the complexity of geometry, and complexity of loading, hand calculations are rarely used. Simplified finite element analysis (FEA) of a single power cylinder is usually the starting point, prior to analysis of the entire assembly.
Kevin Hoag, Brian Dondlinger
9. Cylinder Head Layout Design
Abstract
Several of the decisions discussed in previous chapters determine the starting point for cylinder head layout. In Chap. 6 the trade-offs determining cylinder bore were presented, as were those that determined the number of cylinders making up a bank. In Chap. 8 the variables that go into determining cylinder spacing were discussed, and the number and approximate placement of the head bolts was introduced. The question of camshaft placement was also introduced in Chap. 8, and will be taken up again later in this chapter.
Kevin Hoag, Brian Dondlinger
10. Block and Head Development
Abstract
The concepts of reliability and durability were previously introduced in Chap. 3. That chapter was introduced with the example of the cylinder head to emphasize the importance of ensuring the durability of such major structural components. In this chapter discussion returns to the cylinder block and head, applying the concepts of Chap. 3 to the durability validation of these components. Both the cylinder block and cylinder head are expected to perform without failure for the engine’s life to overhaul. In automobiles the expectation is extended to include reuse in at least one engine overhaul and in heavy-duty applications to several overhauls. This expectation translates into one of an extremely low failure rate (less than one in many thousands) after many miles or hours of operation. If this expectation is not met the engine quickly gains a bad reputation from which it is extremely difficult to recover. This is especially devastating when one considers the investment in tooling for a new engine. A battery of tests and analysis must be devised to absolutely ensure that these durability expectations are met—an extremely challenging endeavor, and a critical path in the timeline of engine development.
Kevin Hoag, Brian Dondlinger
11. Engine Bearing Design
Abstract
Within any given engine a large number of bearings incorporating several design, material, and operational variations are seen. While needle, ball, or roller bearings are sometimes seen in automotive and heavy-duty engines the majority of engines for these applications use primarily plain bearings. Roller bearings are receiving increasing attention due to their lower oil supply requirements and potential for reduced friction and parasitic losses in automotive engines. Increased space requirements, and in the case of connecting rod bearings increased rotating mass, must be weighed against potential attractions. Automotive engine examples of ball and roller bearing are seen in valvetrain and balancer shaft bearings. The discussion presented in the following sections will be limited only to plain bearings.
Kevin Hoag, Brian Dondlinger
12. Engine Lubrication
Abstract
The functions that come immediately to mind when one thinks of the lubricant and lubrication system are wear reduction and friction reduction. This is of course a correct list but an incomplete one. Several further important lubricant functions are described in the paragraphs that follow. It is important to keep all of these functions in mind in the design and development of an engine’s lubrication system.
Kevin Hoag, Brian Dondlinger
13. Engine Cooling
Abstract
In turning to the subject of engine heat transfer it is instructive to begin with a detailed look at where all of the fuel energy goes. If the entire engine is treated as a thermodynamic system, energy enters the system with the fuel. Air enters the system at ambient conditions and therefore, by convention, with zero energy. Under steady-state conditions, and averaged over an operating cycle, no energy is stored, and energy exits the system at the same rate it enters. In other words, all of the energy entering the engine in the fuel exits the engine at the same rate. The energy exits the system as either work, heat transfer, or with the exhaust flow.
Kevin Hoag, Brian Dondlinger
14. Gaskets and Seals
Abstract
An important challenge in engine design is that of providing leak-free joints at each of the component mating surfaces exposed to one or more of the working fluids. Minimizing the number and complexity of joints is one design goal. Another is that of providing durable, effective seals at each of the remaining joints. The working fluids include fuel, lubricant, coolant, intake air, and combustion products. Some joints must maintain separation between two or more of the engine’s working fluids, while others seal one of the working fluids from the atmosphere. Some joints are stationary, while others include the need for one component to move relative to the other. These moving joints include the interface between the pistons and cylinder walls, those between the valve stems and guides, and those associated with spinning shafts protruding from the engine (the crankshaft and the water pump are examples). A categorization of seal types is presented in Fig. 14.1. Piston rings and valve stem seals will be covered in Chaps. 15 and 17 respectively.
Kevin Hoag, Brian Dondlinger
15. Pistons and Rings
Abstract
The piston remains one of the most challenging components to successfully design, and is certainly quite critical to the performance and durability of the engine. The root of the challenge lies in the piston’s role as the moving combustion chamber wall. It is thus directly exposed to the severe conditions of the combustion chamber, and must manage the work transfers between the combustion gases and the connecting rod. Further challenges implied by this role include the necessity of maintaining a combustion seal at this moving boundary, under a wide variety of operating conditions; the need to provide adequate lubrication and minimal friction and wear at an elevated temperature, and under continually starting and stopping conditions; and the requirement of managing the reciprocating forces as well as secondary forces resulting from the pivoting motion at its pin to the connecting rod.
Kevin Hoag, Brian Dondlinger
16. Cranktrain (Crankshafts, Connecting Rods, and Flywheel)
Abstract
The Cranktrain is at the heart of the reciprocating piston engine, and its purpose is to translate the linear motion of the pistons into rotary motion for the purpose of extracting useful work. The cranktrain is typically composed of connecting rods, the crankshaft, and a flywheel or power takeoff device.
Kevin Hoag, Brian Dondlinger
17. Camshafts and the Valve Train
Abstract
The poppet valve, as previously detailed in Fig. 9.5, is now used universally in four-stroke vehicular engines—both to draw fresh charge into the cylinder, and to exhaust the spent products. The valves face an especially harsh environment. Because they are exposed directly to the combustion chamber, and provide very restrictive heat transfer paths they operate at especially high temperatures. The demand for rapid opening and closing results in high impact loads, and a requirement for high hardness valves and seats. The combination of high hardness and high temperature requirements drives the selection of special steel alloys, typically with high nickel content for both the valve head and the valve seat. Most automobile valves are made as a single piece, while the valves in heavy-duty engines generally have the nickel alloy head inertia welded to a mild steel stem. Hollow stem two-piece valves are generating interest in automobile applications, for savings of both weight and cost. A valve spring and retainer assembly as shown in Fig. 9.5 completes the installation. The retainer is typically stamped from mild steel, and holds the spring in a partially compressed position with two hardened steel keepers fitted near the top of the valve stem.
Kevin Hoag, Brian Dondlinger
Erratum to: Chapter 4 "The Engine Development Process"
Abstract
Erratum to:
Chapter 4 in: K. Hoag, B. Dondlinger, Vehicular Engine Design, Powertrain, DOI 10.1007/978-3-7091-1859-7_4
Kevin Hoag, Brian Dondlinger
Backmatter
Metadata
Title
Vehicular Engine Design
Authors
Kevin Hoag
Brian Dondlinger
Copyright Year
2016
Publisher
Springer Vienna
Electronic ISBN
978-3-7091-1859-7
Print ISBN
978-3-7091-1858-0
DOI
https://doi.org/10.1007/978-3-7091-1859-7

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