Comparison of economic indexes of single engine or

  • Detail

In recent years, diesel engines with electronically controlled injection technology have adopted a series of new technologies, including adding high-pressure injection, supercharger with control valve, four valve technology, electronically controlled fuel injection technology, emission control technology, etc., which can reduce fuel injection by nearly 20%, improve engine power by 5% - 7%, and reduce fuel consumption by 3%, And reduce the engine noise by 3 dB. When driving, the engine emission can meet the Euro III emission standard, and even meet the more stringent emission standard in the future

now in the market, for truck cranes, whether one engine (single engine for short) or two engines (double engine for short) are used for lifting operation and driving respectively, which is higher or lower, is fair and reasonable, so what is the truth? Single engine or double engine should be considered from the perspective of users. Only when we think about it as a whole, can we maximize the benefits of product use and minimize the cost of process use for users, which is the best choice

generally speaking, from purchase to use to final scrap, the corresponding costs of user consumption of truck cranes include purchase costs (generally calculated at one time), use costs (mainly including oil and maintenance costs) and residual values (residual values, as income, can be calculated as negative costs). This paper starts with investigating the main consumption costs of products, and reveals the cost differences caused by the use of engine layout

the following table shows the relevant comparison parameters of QY70K, lt1070 and ltm1070-4.1 cranes

in the above table: the specific power is defined as the ratio of the maximum net power of the engine (or 0.9 times the rated power of the engine or 0.9 times the rated power of the engine) to the maximum allowable total mass of the motor vehicle according to GB7258-2004 technical conditions for safety of motor vehicles. GB7258-2004 requires this value to be greater than 5

in order to make the comparison consistent, the following will only carry out the corresponding analysis of the changed parts. Taking model 1 as a single engine, model 2 as a dual engine and the configuration that must be added by the two as an example, this paper explains the cost difference between the two if a single engine or dual engine is used in the design

1. Purchase cost comparison:

purchase cost includes purchase cost and manufacturing cost of outsourcing and purchased parts

due to the different number of engines (single engine or double engine), the general layout and structural form are also different, which will inevitably lead to differences in the required parts, resulting in a large difference between the purchase cost of outsourced and purchased parts and the cost of self-made parts. This paper only considers the differences caused by different engines, and the manufacturing cost in the production process is temporarily ignored

parts that must be added to model 1 (single engine):

center swivel and pipeline, the cost is about 4000 yuan, and the weight is about 120kg

parts that must be added to model 2 (double engine):

the lower hydraulic oil tank (with a capacity of about 70 liters) and oil filter, stop valve, outrigger hydraulic oil pump, upper engine, air filter, silencer, radiator, transfer case, fuel tank, battery, engine control mechanism and supports and protective devices equipped for the installation of the above parts need to be increased by 105000 yuan, The added weight is about 1500kg

according to the provisions on specific power in GB7258-2004 standard, the required engine power should be increased with the increase of vehicle weight. Therefore, when using dual engines, due to the increase in weight, the engine power must be increased accordingly. After increasing the engine power, measures such as increasing the bearing capacity of the transmission system, giving full play to the characteristics of lightweight materials, and improving the output torque of the braking system must be taken in the design. As a result, the corresponding cost increased in the later operation process is not a negligible number (omitted here due to complex calculations)

the extra cost of using dual engines is invested at one time when buying a car, so considering the interest of capital, there will be more expenses for using dual engines. Here, the approximate calculation is:

101000 × (1 + 5%) 10 ≈ 164500 yuan

of which: 5% is the average interest rate of commercial loans

summary 1: using a single engine saves at least 164500 yuan (yuan) than using a dual engine, and the weight is reduced by 1380kg

2. Comparison of use cost:

use cost mainly includes fuel cost, maintenance and repair cost

2. 1. Comparison of oil cost

the state stipulates that the life cycle of each motor vehicle is 10 years (which can be extended to 12 years at most). In view of the overall level of cranes in China, the calculation in this paper is considered as 10 years; In the whole service cycle, the ratio of lifting operation time to travel time of the crane is between 7:3 and 8:2. The calculation in this paper is considered as 7.5:2.5 (3:1)

calculate the lifetime of the crane: 10 × 305 × 8 = 24400 hours; The service time of 10 years is 305 days per year and 8 hours per day

lifetime of boarding: 24400 × 3/4 = 18300 hours

lifetime of getting off: 24400 × 1/4 = 6100 hours

for the same lifting operation condition, the power consumption of single engine and dual engine is basically the same, but when using single engine, the power consumption will increase due to two reasons, that is, the fuel consumption will increase. First, the output power of the accessories of the engine itself, such as fans, power steering pumps, generators, etc., is larger than that of the dual engine on-board engine. Under the same conditions, the additional power consumed is more; Second, the operator cannot reasonably match the engine output power with the load absorption power during lifting operation. In order to prevent the sudden flameout of the engine and other reasons, the operator will operate the engine at a higher speed, resulting in a higher output power of the single engine than the dual engine upper engine, thus consuming more fuel

according to table 1: the rated power of the engine used in the lt1070 is 112KW. When the engine is working, its average output power is generally calculated as 75% of the rated power, that is, 112KW × 75% = 84kw calculation

due to the above two reasons, a single engine consumes 10% more fuel than a dual engine (5% more fuel in both aspects). Therefore, the average additional fuel consumption of a single engine in the whole life cycle of lifting operation is:

18300 × 210 × 84 × 10% ÷ 1000 ÷ 0.9 = 35868 (liters)

where: 210 - the average fuel consumption of the engine used (the average fuel consumption of the engine listed above is 200 ~ 220g/kw.h, here the value is 210g/kw.h)

0.9 is the specific gravity of fuel

1/1000 is the coefficient of G to kg

based on the current average sales price of about 4 yuan per liter of fuel, a single engine will increase the fuel consumption cost in 10 years:

35868 liters × 4 yuan/liter = 143500 yuan

on the other hand, according to GB7258-2004 safety technical conditions for motor vehicle operation, generally with the structure and operation method of the whole concrete pressure testing machine, do you really understand that the increase in vehicle weight requires a corresponding increase in engine power. The weight of the whole vehicle with dual engines (only considering the changing part of the engine) increases by 1380kg, which will additionally increase the fuel consumption of the driving. The proportion of the additional fuel consumption of the driving in the fuel consumption of the whole vehicle is 1380 ÷ 46000 = 0.03

lt1070 the rated power of the engine used for getting off the vehicle is 261kw. When the vehicle is running, its average output power is generally the market cooperation force. The improvement of modified plastic is calculated according to 75% of the rated power, that is, 261kw × 75% = 195.75kw calculation

the approximate calculation value of the total increased fuel consumption cost in 10 years is:

6100 × 210 × 195.75 × 0.03÷1000÷0.9 × 4 ≈ 334 (ten thousand yuan)

considering the above two aspects comprehensively: the cost saved by using two engines is: 14.35-3.34 = 1101 (ten thousand yuan)

2.2. comparison of maintenance cost

in the normal service cycle, the engines used in cranes need to be inspected, maintained and maintained as follows. For the lubrication system, the diesel engine lubricating oil needs to be changed at least once a year, and the oil filter or filter element needs to be changed at the same time; For the cooling system, the antifreeze should be replaced every two to three years. The freezing point of the coolant should be checked and adjusted before winter every year. If there is a water filter, the filter element should also be cleaned or replaced; For the combustion system, clean or replace the fuel filter element every year (including plastic packaging of beverage containers, ice cream and chocolate, including coarse filtration and fine filtration), check and adjust the opening pressure of the fuel injection nozzle, and check and adjust the fuel injection pump on the test bench; For the air intake system, check the air filter maintenance indicator or indicator light, regularly clean or replace the air filter element (including the main element and safety element) as required, clean the dust collecting cup of the air filter, check and tighten the air intake pipeline, and check the bearing clearance of the supercharger. Other maintenance includes piston and ring, bearing bush, belt, valve and push rod, timing gear chamber, etc

in the normal service cycle, one to two overhaul and two to four intermediate repairs of the engine should also be considered

therefore, in terms of maintenance and repair, the maintenance cost of using dual engines is higher than that of using single engines. Based on the average annual maintenance cost of 5000 yuan, an additional engine will need to pay an additional 50000 yuan in ten years

summary 2: Based on the comprehensive fuel consumption and maintenance cost, the cost saved by using a dual engine is 1101-5 = 60100 yuan

considering the residual value, after ten years, the difference between single engine and dual engine is very small, which is ignored here

summary: the cost savings of using a single engine compared with using a dual engine are: 16.45-6.01 = 104400 yuan

Copyright © 2011 JIN SHI