Review Reports - Reducing Pressure Pulsation and Noise in Micro-Hydraulic Systems of Machine Equipment

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript presents a well-structured study on the reduction of pressure pulsations and noise in micro-hydraulic systems using spiral and broadband dampers. The theoretical formulation, supported by detailed experimental validation, demonstrates scientific merit.

The work is generally well-written, clear, and comprehensive. The figures and equations are informative and the logical flow between the theoretical modeling, experimental setup, and validation results is coherent. The study provides practical implications for industrial applications and contributes valuable insights into noise reduction strategies for micro-hydraulic systems.

The paper can be published after minor revisions.

Figure Readability (Figures 2 and 3)
- Please increase the size of the axis labels, legends, and figure titles in Figure 2 and Figure 3. The current font size is too small, making it difficult to read when printed or viewed digitally. Improving the readability of these figures will enhance the overall presentation quality.
Justification for Choosing the Spiral Passive Damper
- In Section 3, it would be helpful to include a short explanation for why the spiral passive damper was chosen.
In the Conclusion section, please add a short paragraph acknowledging the limitations of the present study.

Author Response

Reviewer #1

Thank you for your comments and suggestions in the review. All comments and suggestions have been carefully addressed by the authors. The changes were marked in the text of the manuscript by yellow color.

Comment: Figure Readability (Figures 2 and 3)

Please increase the size of the axis labels, legends, and figure titles in Figure 2 and Figure 3. The current font size is too small, making it difficult to read when printed or viewed digitally. Improving the readability of these figures will enhance the overall presentation quality.

Response: The axis labels, graph titles and legends have been enlarged to improve the readability of the graphs and figures was increase in quality and size.

Comment: Justification for Choosing the Spiral Passive Damper

In Section 3, it would be helpful to include a short explanation for why the spiral passive damper was chosen.

Response: In the paper, it was decided to analyse the effects of the spiral damper in order to reduce its dimensions. Compared to a straight-axis branch damper, the spiral damper has a much more compact design, which in our opinion is particularly important in microhydraulic systems. A comment has been added in section 3.

Comment: In the Conclusion section, please add a short paragraph acknowledging the limitations of the present study.

Response: Information about the limitations of the effectiveness of the spiral damper has been added to the Conclusions section. The following has been added: ‘The branch-type spiral damper presented in this paper is most effective for the selected excitation frequency (pressure pulsation). This means that if the pressure pulsation comes from the pulsation of the displacement pump capacity, it must operate at a constant rotational speed.’

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This work describes about reducing pressure pulsation and noise in micro-hydraulic 2 systems of machine equipment. In order to have your paper ready for publications, however, you should answer and revise the paper following comments:

Organize the differences (include the advantages and disadvantages) between the proposed method and conventional methods into a table and add it in the chapter 1 or 2.
Why did you choose frequency from 10 to 40Hz?
According to the Figure 12 and 13, the effectiveness with damper is very good at 60Hz and 1600Hz approximately. What do you think for the reason?
Write the Conclusion chapter using the experimental numerical results.
In this paper experiment was done at 1000 rpm pump speed. Is there a reason? If not, I recommend also you experiment at another speed.

Author Response

Reviewer #2

Comment: Organize the differences (include the advantages and disadvantages) between the proposed method and conventional methods into a table and add it in the chapter 1 or 2.

Response: A table comparing selected features of spiral damper and straight-axis damper designed to reduce pressure pulsations of the same frequency has been added to the manuscript.

Table 1. Comparison of selected features of spiral damper and straight-axis damper designed to reduce pressure pulsations of the same frequency.

Feature	Spiral damper	Straight-axis damper
Compact design	+	-
Length	+	-
Mass	+	-
Simplicity of design	-	+
Mathematical description	-	+

Comment: Why did you choose frequency from 10 to 40Hz?

Response: It was decided to adopt a vibration frequency range of 10 to 40 Hz, as this range includes the resonance frequencies of the control elements (poppet, spool, ball, etc.) of conventional hydraulic valves.

Comment: According to the Figure 12 and 13, the effectiveness with damper is very good at 60Hz and 1600Hz approximately. What do you think for the reason?

Response: Figures 12 and 13 show the effectiveness of noise reduction in a microhydraulic system equipped with a broadband damper. The design concept (Fig. 10) of this damper is based on combining a passive branch damper and an active damper. The passive damper is effective for higher pressure pulsation frequencies, while the active damper (movable piston and hydropneumatic accumulator) is effective for lower pressure pulsation frequencies.

Comment: Write the Conclusion chapter using the experimental numerical results.

Response: The section Conclusions has been supplemented with an analysis of the numerical data presented in the paper: “The analytical considerations presented (Equation 5 and Fig. 5) show that the spiral damper will be shorter than the linear damper. For a forcing frequency of 120 Hz, the minimum impedance of the spiral damper is at a length of approx. 2.53 m, and for the linear damper, the minimum is at a length of approx. 2.64 m. The use of a broadband damper reduced the noise of the hydraulic microcircuit by 20 dB at a frequency of 50 Hz.”

Comment: In this paper experiment was done at 1000 rpm pump speed. Is there a reason? If not, I recommend also you experiment at another speed.

Response: Experimental tests were performed for a rotational speed of 1000 rpm, as this falls within the speed range specified for the positive displacement pump used in the tests. Furthermore, this is the rotational speed of the drive shaft of the internal combustion engine driving the pump when idling. It was assumed that the mobile machine performing the working movement remains stationary (does not move).