Dynamic Characteristics of an Automotive Air-Conditioning Electromagnetic Clutch

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper deals with the characterization of an electromagnetic clutch that is used in automotive applications. I appreciate the time and effort of the authors. I have the following comments.

1. The experimental setup is not clearly explained. I think it would be better to insert an illustration that shows the entire test system with block diagrams.

2. Readers who do not know how an electromagnetic clutch works may find the paper difficult to understand. Could you please add an illustration and explanation about the electromagnetic clutch?

3. There is not much background information and theory provided in the paper. It feels like a report rather than an academic article. If a characterization study is presented, a dynamic model should be provided. I think the materials and methods section should include more background information, especially the theory.

4. The caption of the Table 1 is not explanatory. "Test rig specifications" sounds more natural.

5. The results are not discussed enough and how the results are relevant to the dynamic model is not provided.

6. The results are obviously influenced by the compressor response time, and the nonlinear response characteristic of the compressor. This influence can be seen from the charts where the faster intermittent causes lower max torque.

 

Comments on the Quality of English Language

Grammatically, the English language seems correct. However, there are long sentences that may confuse the reader. Please consider revising them.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In the article under review, the authors presented the results of studies of the influence of various operating conditions on the characteristics of an automotive air-conditioning electromagnetic clutch.

The studies were carried out using the method of direct natural experiment from a specially created test rig.

In the Introduction and literature review, the authors presented a description of previous studies of various dry and wet clutches and formulated the purpose of their paper. In the main parts of the paper, the laboratory setup is described, the results of experimental studies are presented, and their analysis is given. The Conclusion provides a summary of the material presented in the paper.

However, during the review, I formed the opinion that the results obtained and presented by the authors may have practical significance and application, but the paper has no scientific value. In this form, the paper can be presented at a conference and published as a Conference Paper, but it cannot be recommended for publication in any highly-rated journal.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The aim of the work is to investigate the dynamic characteristics of an alternating current electromagnetic clutch. The research was aimed at improving the design, optimizing performance and extending the service life. The work is well designed, but for better reception a few modifications should be made:

1. The title could be more attractive and concise.

2. The summary does not show what modernization effects were achieved.

3. Briefly explain how this work differs from others already published.

4. Define specific goals. The abstract states that the aim of the work is to "...improve the design, optimize performance and extend the service life,...". How were these indicators achieved and estimated?

5. How did the research translate into optimizing the structure and extending its service life?

6. Nothing was mentioned about the materials from which the clutch structure was made and whether it had been modified.

7. What is the authors' scientific contribution to science?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

In the Abstract section, I guess that the term"exhaust pressure" is referring to the compressor exhaust pressure? This should be specified in the abstract.

Introduction section

The automotive clutches use special materials, with high friction coefficients, in order to transmit torque. So, at least a short description of the AC clutch would be needed for explaining the similarities between the two types of clutches.

rows 57-72: the AC clutch is a dry one, so the references to wet clutches have no significance in this context.

row 80-84: I understand that the authors have used an air compressor instead of the AC compressor during the tests. The air compressor takes air from the sorroundings and compresses it, while the intake pressure of the AC compressor is different from the atmospheric pressure. Maybe the pressure ratio (exhaust/intake pressure) would be more accurate? And be aware that refrigerants in gaseous state have different thermodynamic properties than air, leading to different compressor temperatures, as an example.

Materials ans Methods section

rows 86-100: a schematic of the test bench would be more useful for understanding the tests than the photos shown in fig. 1.

Some characteristics of the clutch are needed: basic diagram, dimensions, type of friction material etc.

rows 110-112: each cycle comprised a 3...10 s on and a 3...10 s off time?

rows 113-125: what was the data aquision rate? How many data readings during the 3...10 s of one cycle?

Results and discussion section

At least one chart of the torque vs. time would be useful, for one of the on/off time variants and one rotational speed, for 2....3 cycles, in order to display torque variation in time. And maybe the torque curves for one rotational speed and the 3 on/off times, in the same chart, in order to provide an overall view.

rows 157-160 and fig. 3a: what do you understand by "operating torque"? Is this the average torque for one on/off cycle? Or maybe the average torque for the 5 minutes test?

row 164: "...hydrodynamic forces..."? maybe this is a wet clutch, after all?

All the discussion referring to pressure should be clarified; for example, the exhaust pressure is the one recorded at the end of the 5 min running time? At least one pressure vs. time chart would be needed in order for the reader  to understand the concepts of maximum, average and minimum pressure. Then, how did the compressor operate? Did it discharge air into an air tank fitted with pressure transducer? This is not clear at all.

Regarding the temperatures: when were they measured (for example for the "moment of connection":  when the "on" command was given or when maximum torque was achived?).

rows 216-219: this is where a schematic of the clutch would have been useful (in section 2), in order to have a precise idea on its construction.

rows 230-232: the uniform heat distribution may explain the equal temperatures of the three points, but why are the temperatures relatively different when the clutch is engaged?

row 234 (and further down): what do you understand by "break-in time"? How is this related with the 5 minutes duration of each test?

Conclusions section

rows 336-338: "Higher rotational speeds played a crucial role in improving the compressor's exhaust pressure to meet specific performance requirements." - what are these specific requirements? There is no reference to them in the paper

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I appreciate the time and effort of the authors to revise the manuscript. I have the following comment.

1. The manuscript still seems like a report. I do not see a single equation to explain the system's behavior. Some dynamic models are cited in the text, at least a simple formulization that correlates the test results can be added.

 

 

Comments on the Quality of English Language

Grammatically, the English language seems correct.

Author Response

Thank you very much for your feedback!

Please check the attachment. The attachment includes point-by-point responses and the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors made significant changes to the new version of the paper. In this form, the paper may be of greater interest to scientists and researchers, specialists in the field of electromechanics. In their response to my comments, the authors articulated the originality of their research, but did not articulate its scientific value. I am convinced that a scientific article in a highly-rated journal should contain not only a description of experiments and their discussion, but also have a theoretical part. Therefore, noting the low scientific value of the paper, I still leave the final decision to the Editor.

Author Response

Thank you very much for your feedback!

Please check the attachment. The attachment includes point-by-point responses and the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Thank you for the detailed answers to my observations and for improving the original paper.

Author Response

Thank you so much for your professional review work, constructive comments, and valuable suggestions on our manuscript.

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for the revisions.

Comments on the Quality of English Language

Grammatically, the English language seems correct.