JPH01106963A - Exhaust heat recovery device of engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an engine exhaust heat recovery device.

(Prior art) As an engine exhaust heat recovery device, the heat radiation passage of the exhaust heat recovery device is interposed in the exhaust heat absorption circuit that absorbs the exhaust heat of the engine, and the heat absorption passage of the exhaust heat recovery device is used to recover the exhaust heat. Generally, a pump is inserted in the exhaust heat recovery circuit in series with the heat absorption passage of the exhaust heat recovery device, and the pump circulates the exhaust heat recovery liquid within the exhaust heat recovery circuit. The exhaust heat recovery liquid circulation pump was driven by an electric motor, and its power source was a generator driven by the engine.

(Problem to be solved by the invention) However, in the conventional pump drive type, the mechanical output of the engine is converted into electric power and then returned to mechanical power by the electric motor, so the drive efficiency of the pump is low. It had become a thing. Furthermore, the use of an expensive electric motor has been a factor in increasing costs.

An object of the present invention is to provide an engine exhaust heat recovery device that can reduce the cost and running cost of the device by improving the pump drive mode.

(Means for Solving the Problems) The characteristic configuration of the present invention for achieving the above object is to connect the pump in conjunction with the engine, connect the bypass passage to the exhaust heat recovery circuit in parallel with the pump, and connect the bypass passage to the exhaust heat recovery circuit. When the bypass passage is opened and opened by the bypass valve, the exhaust heat recovery liquid discharged from the discharge port of the pump passes through the bypass passage and short-circuits to the suction port of the pump. The present invention is configured to stop the circulation of the exhaust heat recovery liquid in the exhaust heat recovery circuit.

(Function) According to the above configuration, when the need for exhaust heat recovery is eliminated due to a reduction in heat load, the bypass valve of the bypass passage is opened, and the exhaust heat recovery liquid discharged from the discharge port of the pump is pumped through the bypass passage. The circulation of the exhaust heat recovery liquid in the exhaust heat recovery path is stopped by making a short circuit to the inlet of the exhaust heat recovery channel. By doing this, overloading of the pump, which is constantly driven by engine power, is avoided when exhaust heat recovery is not required.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the overall configuration of an engine generator equipped with an exhaust heat recovery device for a water-cooled horizontal engine according to the present invention, and FIG. 2 shows a system diagram of the exhaust heat recovery device.

The engine generator shown in FIG. 1 generates 8 units of power inside a soundproof case 1! IG and a water-cooled horizontal engine E that drives it with a belt.
are installed in parallel, a fuel tank 2 is installed on the ceiling wall of the soundproof case 1, and a radiator 5 equipped with a cooling fan 4 driven by an electric motor 3 is provided at one end of the soundproof case 1. It is what was done.

An exhaust heat recovery device A according to the present invention is disposed above the engine E. First, the basic configuration of the exhaust heat recovery device A will be explained based on the system diagram in FIG. 2.

After absorbing the combustion heat in the overjacket 6 formed inside the engine E, the heat medium liquid (water) drawn out is transferred to an exhaust heat absorption circuit a comprising an exhaust heat absorber 7 and an exhaust heat recovery device 8 in series.
sent to. The exhaust heat absorption circuit a includes a heat absorption passage that absorbs heat by exchanging heat with the engine exhaust gas in the exhaust heat absorber 7, and a heat radiation passage that radiates heat by exchanging heat with the exhaust heat recovery liquid in the exhaust heat recovery unit 8. After passing through the exhaust heat absorption circuit a, the heat medium liquid is cooled by the radiator 5, and then is forcibly returned to the rotor jacket 6 by the rotor pump 9 via the return circuit d. And exhaust heat recovery device 8
A heat absorption passage f of an exhaust heat recovery circuit e is interposed in which the exhaust heat recovery liquid flows, and the exhaust heat recovery liquid is passed through the exhaust heat recovery device 8 and heat load devices such as hot water supply equipment and heating equipment by the pump 10. It is configured for forced circulation. Further, the exhaust gas exiting the exhaust heat absorber 7 is discharged to the outside of the machine via a 77-wall 11.

Next, each part constituting the exhaust heat recovery device A will be explained in detail.

As shown in FIGS. 3 and 4, the exhaust heat absorber 7 includes an exhaust pipe 14 connected to an exhaust manifold 13 of a cylinder rad 12.
A multi-plate heat exchanger 15, which is connected in communication with the engine E, is installed inside an overtank 16 that is directly connected to the upper surface of the crankcase of the engine E. It flows directly into the heat absorption passage in the oak tank 16.

The exhaust heat recovery device 8 includes a water tank 18 that is bent and extended in an L shape from the outer tank 16 of the exhaust heat absorber 7 and installed on the side of the cell starter 17. The muffler is connected to the heat exchanger 15 of the exhaust heat absorber 7 at the corner formed by the two autotanks 16 and 18. 11 are installed.

A heat medium liquid outlet 20 is provided on the upper surface of the water tank 18 forming the heat radiation passage C of the exhaust heat recovery device 8, and the outlet 20 and the upper part of the radiator 5 are connected to each other by a hose 21.

The water pump 9 for forced circulation of the heat medium liquid is installed in the cylinder head 12 and driven by the engine output, and its suction port 22 and the lower part of the radiator 5 are connected to a hose 23.
and is directly connected to the lower part of the overjacket 6, which has a discharge port (not shown).

A more detailed configuration of the exhaust heat recovery device 8 is shown in FIG. An inlet case 25 equipped with an inlet 24 for waste heat recovery liquid is attached to the rear end of the two-way tank 18 that forms the heat dissipation passage C for the heat transfer liquid.
At the front end of the
An outlet case 28 having an outlet 27 communicating with the outlet 26 of the case 2 is attached, and the jackets of both the cases 25 and 28 are continuously connected through a multi-tubular heat exchanger 19 forming a heat absorption passage f. .

An input converter 29 for receiving engine output through belt transmission is connected to the pump 10, and the pump 10 is constantly driven during engine operation. Further, a bypass passage g is formed between the discharge port 26 of the pump 10 and the inlet case 25, and a bypass valve 30 which can be opened and closed is interposed in the bypass passage g, and an inlet for the exhaust heat recovery liquid. 24 and the outlet 27 are also provided with on-off valves 31 and 32, respectively.

The exhaust heat recovery device A according to the present invention is configured as described above, and during normal exhaust heat recovery operation, as shown in FIG. 5, the bypass valve 30 is closed and both the on-off valves 31 32, the exhaust heat recovery liquid introduced from the inlet 24 passes through the multi-tubular heat exchanger 19 forming the heat absorption passage f, and absorbs heat from the high temperature heat medium liquid, and the heated exhaust heat recovery liquid is It is sucked in through the inlet 33 of the pump 10, sent out through the outlet 27, and circulated to the exhaust heat recovery circuit e.

In addition, when exhaust heat recovery is no longer necessary due to a decrease in the load on a heat load device, etc., the bypass valve 30 is opened and both on-off valves 31 and 32 are closed. Exhaust heat recovery device 8 without circulating to recovery circuit e
Short-circuit circulation is performed only through the bypass passage g.

Note that the bypass valve 30 and the on-off valves 31 and 32 may be implemented as electromagnetic valves that automatically open and close based on the detection of the necessity of exhaust heat recovery.

Further, as shown in FIG. 6, the bypass valve 30 remains closed at the pump discharge side pressure during normal operation when the on-off valves 31 and 32 are opened, and when the on-off valves 31 and 32 are closed, the pump discharge It can also be configured with a check valve that opens when the side pressure exceeds a set value.

(Effects of the Invention) As explained above, in the engine exhaust heat recovery device according to the present invention, the pump that circulates the exhaust heat recovery liquid is directly driven by the engine output, so an expensive electric motor is not required. We were able to reduce costs.

In addition, since the pump is directly driven by the engine output, the pump drive efficiency is higher than when the engine output is first converted to electric power and then converted back to mechanical power by an electric motor.
It is also effective in reducing running costs.

In addition, even if the pump is constantly driven by the engine, when the exhaust heat recovery operation is not performed, the exhaust heat recovery liquid is short-circuited through the bypass passage, so the pump can be operated without overloading, and the pump can be operated without overloading. It can also increase durability.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional rear view of an engine generator equipped with an exhaust heat recovery device according to the present invention, FIG. 2 is a system diagram of the exhaust heat recovery device, FIG. 3 is a partially cutaway plan view of the engine section, and FIG. FIG. 4 is a partially cutaway side view, FIG. 5 is a vertical sectional side view of the exhaust heat recovery device, and FIG. 6 is a system diagram showing the main parts of the separate ramrod. 8... Exhaust heat recovery device, 10... Exhaust heat recovery liquid circulation pump, a... Exhaust heat absorption circuit, C... Heat radiation passage, e... Exhaust heat recovery circuit, f.・・Passage for heat absorption,
g...Bypass passage, 30...Bypass valve, E
···engine. Patent applicant Kubota Iron Works Co., Ltd. Figure 3 Figure 4

Claims (1)

[Claims] 1. The heat radiation passage c of the exhaust heat recovery device 8 is interposed in the exhaust heat absorption circuit a that absorbs the exhaust heat of the engine E, and the heat absorption passage f of the exhaust heat recovery device 8 is interposed in the exhaust heat recovery circuit e. , an engine configured such that a pump 10 is interposed in the exhaust heat recovery circuit e in series with the heat absorption passage f of the exhaust heat recovery device 8, and the pump 10 circulates the exhaust heat recovery liquid in the exhaust heat recovery circuit e. In the exhaust heat recovery device, a pump 10 is interlocked and connected to the engine E, a bypass passage g is connected to the exhaust heat recovery circuit e in parallel with the pump 10, and the bypass passage 8 is configured to be openable and closable by a bypass valve 30. In the bypass open state where the passage g is opened by the bypass valve 30, the discharge port 2 of the pump 10
The exhaust heat recovery liquid discharged from the exhaust heat recovery circuit e is short-circuited to the suction port 33 of the pump 10 through the bypass passage g, thereby stopping the circulation of the exhaust heat recovery liquid in the exhaust heat recovery circuit e. Features of engine exhaust heat recovery device